Written by Sig Silber

Despite the best efforts of the Global Warming folks to sell the meme that Warming means Drier, Nature has the last say in these debates. In High School or in life we learn that when it is warmer there is more evaporation which then means – MORE PRECIPITATION. Not sure the explanation of the blocking pattern that has kept Harvey in essentially the same place for two days with two more to come is as easily explained.

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The Seasonal Outlook Update Report was issued in two parts because JAMSTEC was late. Part I which focused on the NOAA forecast comparing the new forecast to the prior forecast can be accessed here and Part II which focused on the comparison between the NOAA forecast and the JAMSTEC forecast can be accessed here. The Part II report was also used to provide updates on Harvey because I can only publish two reports at the same time and be able to update them. Remember, if you leave this page to visit links provided in this article, you can return by hitting your “Back Arrow”, usually top left corner of your screen just to the left of the URL box.

Update on Harvey (this information is current as of the time we published. A separate article was published where we will continually update both the meteorological situation relative to Harvey and also the impact assessment. You can access that website by clicking here. And again if you leave this page to visit links provided in this article, you can return by hitting your “Back Arrow”, usually top left corner of your screen just to the left of the URL box.

Harvey continues to have impacts but these impacts are likely to moderate over the next few days. The most current information on Harvey can be found here.

One can see the problem here with a storm that is half on land and half over warm water. But it is definitely moving.

Latest Harvey Discussion.

Tropical Storm Harvey Discussion Number 35 NWS National Hurricane Center Miami FL 1000 PM CDT Mon Aug 28 2017
The center of Harvey has been moving east-southeastward over the extreme western Gulf of Mexico this evening. Although there is no deep convection near the center of Harvey, thunderstorm activity has continued to increase well north of the center, along the immediate northwest Gulf Coast and has spread inland over the Greater Houston area, worsening the catastrophic flooding situation. Another band of heavy rainfall is moving inland over portions of southern and southwestern Louisiana. Widespread rainfall totals of 30 to 36 inches have been observed in southeastern Texas and the Houston Metropolitan Area. Storm totals could reach 50 inches in some locations, which would be historic for the area.
A NOAA National Ocean Service observing site near Matagorda Bay has continued to report sustained tropical-storm-force winds this evening, and data from this and other nearby stations still support an initial intensity of 40 kt. Given the current structure of the cyclone and the lack of convection near the center, little change in strength is expected while Harvey moves over the northwestern Gulf of Mexico. After landfall in about 36 hours, gradual weakening should occur as the circulation moves farther inland.
Harvey has been moving east-southeastward or 120/3 kt. The storm is forecast to turn northeastward, then north-northeastward over the next couple of days as a ridge to the northwest of the system weakens and Harvey is steered around the western side of a ridge over the eastern Gulf of Mexico. The track guidance has shifted slightly eastward and the new NHC track has been adjusted in that direction.
Key Messages:
1. Ongoing catastrophic and life-threatening flooding will continue across southeastern Texas. Additional rainfall accumulations of 10 to 20 inches are expected across the upper Texas coast, with isolated storm totals as high as 50 inches. Please heed the advice of local officials. Do not attempt to travel if you are in a safe place, and do not drive into flooded roadways. Refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard. A summary of rainfall totals compiled by the Weather Prediction Center can be found at: www.wpc.ncep.noaa.gov/discussions/nfdscc1.html [Editor’s Note: Click Here to Read]
2. The flood threat has spreading farther east into Louisiana. Additional rainfall amounts of 10 to 20 inches are expected in southwestern Louisiana, with rainfall amounts of 5 to 15 inches expected in south-central Louisiana. Rainfall amounts of 5 to 10 inches are expected in southeast Louisiana and coastal Mississippi and Alabama. Please heed the advice of local officials and refer to products from your local National Weather Service office and the NOAA Weather Prediction Center for more information on the flooding hazard in these areas.
3. While Tropical Storm Warnings have been extended eastward along the coast of Louisiana and a Storm Surge Watch has been issued, the impacts of winds and storm surge are expected to be secondary compared to that of the rains.
FORECAST POSITIONS AND MAX WINDS [Editor’s Note: Looks like two days of have precipitation and the this storm finally moves inland]
INIT 29/0300Z 28.2N 95.3W   40 KT 45 MPH
12H 29/1200Z 28.1N 95.0W   40 KT 45 MPH
24H 30/0000Z 28.5N 94.5W   40 KT 45 MPH
36H 30/1200Z 29.5N 94.0W   40 KT 45 MPH
48H 31/0000Z 30.7N 93.4W   35 KT 40 MPH…INLAND
72H 01/0000Z 33.4N 91.9W   30 KT 35 MPH…INLAND
96H 02/0000Z 35.5N 90.0W   25 KT 30 MPH…INLAND
120H 03/0000Z 38.0N 86.5W   20 KT 25 MPH…POST-TROP/INLAND

Precipitation Totals as of 10PM CDT August 28, 2017. Updated totals can be found Here

August 28, 2017 Louisiana Precipitation Totals

Economic Impacts.

The usual impacts of a disaster are first very negative and later very positive and essentially reflect Keynesian Economics. Unfortunately the first phase comes first and it can be very heartbreaking. One clue to how this might work out is provided by this excellent article.

More Than 50 Percent Of Properties In Houston At High And Moderate Risk Of Flood Are Not In Designated Flood Zones

We will now shift gears and resume our normal order of presentation: Forecast Summary with a Focus on the Southwest Monsoon

	Temperature	Precipitation
6 – 10 Day
8 – 14 Day

The above is what I am looking at Monday Night i.e. the NOAA forecast that is issued every day between 3pm and 4pm New York City time. It might be different if you do not read my report until after 3pm New York Time on Tuesday as the above maps will have updated and may look a little (and sometimes more than a little) different. The forecast can change and even if it does not change the dates that fit into the day 6 to 10 period and day 8 – 14 period change each day. So the forecast can remain the same but the maps showing a particular period of time will change and of course with weather it is not unusual for the forecast to change.

A. Focus on Alaska and CONUS (all U.S.. except Hawaii)

First Let us focus on the Current (Right Now to 5 Days Out) Weather Situation.

Water Vapor.

This view of the past 24 hours provides a lot of insight as to what is happening.

Below is the same graphic as above but without the animation to show the current situation with respect to water vapor imagery for North America. It also covers more of CONUS.

Tonight, Monday evening August 28, 2017, as I am looking at the above graphic, you can see the “comma” which locates Harvey with the bands of wind and precipitation in the Northeast (in this case mostly east) Quadrant as is usual. It is a large pattern especially if you conclude as I have that the activity over Florida and the East Coast has become part of Harvey’s circulation. At this point the Monsoon has deferred to Harvey although one can make an argument that Harvey was the eastern foci of the Southwest Monsoon.

Looking at the current activity of the Jet Stream.

Not all weather is controlled by the Jet Stream (which is a high altitude phenomenon) but it does play a major role in steering storm systems especially in the winter The sub-Jet Stream level intensity winds shown by the vectors in this graphic are also very important in understanding the impacts north and south of the Jet Stream which is the higher-speed part of the wind circulation and is shown in gray on this map. In some cases however a Low-Pressure System becomes separated or “cut off” from the Jet Stream. In that case it’s movements may be more difficult to predict until that disturbance is again recaptured by the Jet Stream. This usually is more significant for the lower half of CONUS with the cutoff lows being further south than the Jet Stream. Some basic information on how to interpret the impact of jet streams on weather can be found here and here.

One sees the current jet stream above. It is

This graphic provides a good indication of where the moisture is. It is a bit different than just moisture imagery as it is quantitative.

This graphic is about Atmospheric Rivers i.e. thick concentrated movements of water moisture. More explanation on Atmospheric Rivers can be found by clicking here or if you want more theoretical information by clicking here. The idea is that we have now concluded that moisture often moves via narrow but deep channels in the atmosphere (especially when the source of the moisture is over water) rather than being very spread out. This raises the potential for extreme precipitation events.

This evening we see Harvey. We see a second possibly separate and possibly connected storm over Florida. One also sees that moisture attempting to enter CONUS from the Pacific is entering north of CONUS in Canada.

You can convert the above graphic in to a flexible forecasting tool by clicking here. One can obtain views of different geographical areas by clicking here.

60 Hour Forecast.

Here is a national animation of weather fronts and precipitation forecasts with four 6-hour projections of the conditions that will apply covering the next 24 hours and a second day of two 12-hour projections the second of which is the forecast for 48 hours out and to the extent it applies for 12 hours, this animation is intended to provide coverage out to 60 hours. Beyond 60 hours, additional maps are available at links provided below.

The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic because they are implemented by color coding.

Tropical Activity

When there is activity and I have not provided the specific links to the storm of “immediate” interest, one can obtain that information at this link. At this point in time, no tropical events are expected to impact CONUS. If that changes, we will provide an update.

Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 6. The Day 3 forecast can be found here. I used to present the Day 3 with a link to Day 6 but showing Day 6 may be more useful.

When I look at this Day 6 forecast, there is a large low centered just south of the Middle Aleutians having a surface central pressure of 996 hPa. There is another low near Kamchatka with a surface low pressure of 1000 hPa.

The High Pressure off of the West Coast, the familiar RRR or more properly called the Eastern Pacific Semi-tropical High or the Hawaiian High, is reduced in size, partly on land, and has a surface central pressure of 1016 hPa. This configuration makes it almost impossible for the Northwest to be other than dry. There also is a cut-off low shown off of Baja with a central surface pressure of 1008 hPa. The is also a big Hudson Bay Low.

I provided this K – 12 write up that provides a simple explanation on the importance of semipermanent Highs and Lows and another link that discussed possible changes in the patterns of these highs and lows which could be related to a Climate Shift (cycle) in the Pacific or Global Warming. Remember this is a forecast for Day 6. It is not the current situation.

Now looking at the Day 5 Jet Stream Forecast.

This is a Day 5 forecast by one model. You can see the Jet Stream is quite far north. The small arrows which which winds that are not robust enough to be considered to be part of the Jet Stream but measured at 300 mb and for Texas those are westerlies to southwesterlies and play a role in keeping Harvey pinned to the coast. It is hard to find what might be called the Four Corners High. .

Putting the Jet Stream into Motion and Looking Forward a Few Days Also

To see how the pattern is projected to evolve, please click here. In addition to the shaded areas which show an interpretation of the Jet Stream, one can also see the wind vectors (arrows) at the 300 Mb level.

This longer animation shows how the jet stream is crossing the Pacific and when it reaches the U.S. West Coast is going every which way.

When we discuss the jet stream and for other reasons, we often discuss different layers of the atmosphere. These are expressed in terms of the atmospheric pressure above that layer. It is kind of counter-intuitive to me. The below table may help the reader translate air pressure to the usual altitude and temperature one might expect at that level of air pressure. It is just an approximation but useful.

Re the above, H8 is a frequently used abbreviation for the height of the 850 millibar level (which is intended to represent the atmosphere above the Boundary Layer most impacted by surface conditions), H7 is the 700 mb level, H5 is the 500 mb level, H3 is the 300 mb level. So if you see those abbreviations in a weather forecast you will know what they are talking about.

Click here to gain access to a very flexible computer graphic. You can adjust what is being displayed by clicking on “earth” adjusting the parameters and then clicking again on “earth” to remove the menu. Right now it is set up to show the 500 hPa wind patterns which is the main way of looking at synoptic weather patterns. This amazing graphic covers North and South America. It could be included in the Worldwide weather forecast section of this report but it is useful here re understanding the wind circulation patterns.

You can enlarge the below daily (days 3 – 7) weather maps for CONUS by clicking on Day 3 or Day 4 or Day 5 or Day 6 or Day 7. These maps auto-update so whenever you click on them they will be forecast maps for the number of days in the future shown.

Here is the seven-day cumulative precipitation forecast. More information is available here.

We see more precipitation to be added to that which has already fallen. It is all over the East but the level in East Texas and just into Louisiana is very concerning.

The map below is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows only the major pressure gradients. This graphic auto-updates so when you look at it you will see NOAA’s latest thinking. The speed at which these troughs and ridges travel across the nation will determine the timing of weather impacts. This graphic auto-updates I think every six hours and it changes a lot. Because “Thickness Lines” are shown by those green lines on this graphic, it is a good place to define “Thickness” and its uses. The 540 Level general signifies equal chances for snow at sea level locations.Thickness of 600 or more suggests very intensely heat and fire danger.

Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.

What we see for Day 7 is a dome of High Pressure centered on Nevada and Utah. This is not a good set-up for the Southwest Monsoon. We also see a Western Ridge and a Great Lakes trough.

Remember this is a forecast for Day 7. Note the 540 Thickness Line re the above discussion of thickness and snow likelihood. Thickness lines near or over 600 tend to suggest very warm temperatures. Sometimes Meteorologists work with the 500 mb heights which provides somewhat similar readings to the “Thickness” lines but IMO provide slightly less specific information. The Southwest Heat Wave appears to potentially be ready to make a comeback as High Pressure and warm temperatures go together. Where the air pressure is highest often is an indication of where the warmest places will be.

Four- Week Outlook

I use “EC” in my discussions although NOAA sometimes uses “EC” (Equal Chances) and sometimes uses “N” (Normal) to pretty much indicate the same thing although “N” may be more definitive.

First – Temperature

I am starting with a summary of small images of the three short-term maps. This summary provides a quick look. I could have made it so you could click and enlarge the small images but for the moment I prefer that you go past the summary for the larger versions because if I set up such links, the chances increase that you will not back out of the link properly and get lost. For most people the summary with the small images will be sufficient. Following the graphic with the three small images, you can find the larger maps and a discussion and for reference purposes I then also provide the forecast map for the current or soon to be current full month and the three-month forecast map. These are issued and updated less frequently than the first three maps shown.

Small Images of Temperature Maps
6 to 10 Days	8 to 14 Days	Weeks 3 and 4

The above shows the progression of forecasts from six days out through four weeks out. Larger maps with discussion appear below. But this set of three maps paints a pretty good picture of what the forecast is.

Now the larger maps followed by a discussion that describes what is happening and any inconsistences that I see.

6 – 10 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on August 28, 2017 was 4 out of 5)

8 – 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on August 28, 2017 was 4 out of 5).

Looking further out.

Consolidation of 6 – 10, 8 – 14 and Experimental Week 3-4 Temperature Forecasts
Interpreted on August 28, 2017
September 3 to September 11	September 9 to September 22
Days 6 – 10: Eastern Alaska plus the Panhandle is warm. CONUS West is warm. The Eastern 2/3rds of CONUS is mostly Normal with Florida and a small part of the Southeast warm and Texas cool with the cool anomaly stretching up to the Great Lakes.	For CONUS, The West is warm and a narrow edge of the East Coast is warm with most of Florida warm. There is a large cool swath starting in Texas and trending NNE to the Great Lakes. In between the warm and cool areas is a lot of EC. Alaska is warm. The transition to the pattern shown in the Week 3 – 4 Forecast from the pattern shown in the 8-14 Day forecast appears to be feasible if the west to east normal progression of weather ceases.
Week 2: As the period evolves a large cool anomaly stretching from Texas to the Great Lakes strengthens. The Alaska warn anomaly grows in coverage
Remember the Week 3-4 Experimental Outlook was issued last Friday and I am looking at the 6 – 10 and 8 – 14 day forecasts issued today i.e. Monday. So that explains the overlap of dates. Remember that the Week 3 – 4 Forecast covers two weeks so it can appear to not mesh perfectly but actually do so over the two-week period. For all three time periods, in between the cool and warm anomalies it is usually EC i.e. the boundary is usually not sharp.

Reference Forecasts Full Month and Three Months.

Below is the Temperature Outlook for the month shown in the Legend. This map is first issued on the Third Thursday of the Month for the following month and then updated on the last day of the month. The 6 – 10 day and 8 – 14 Day update daily and the Week 3/4 Map Updates every Friday so usually these are more up-to-date. Note that the three maps shown at the beginning of this discussion on temperature may cover a slightly different time period since they update as the month progresses and the map below covers a particular month shown in the Legend. It is useful if one wants to understand how that month is forecast to play out.

Here is the Temperature Outlook issued on the date and for the three-month period shown in the Map Legend. Again this is provided for reference only. It is the same map that is included in our Saturday night report that follows the NOAA third Thursday of the month Seasonal Outlook Update. It provides a longer time frame than the above maps. It uses a totally different methodology as it is not possible to use the dynamical models to project out three months. The dynamical models work by figuring out how the current conditions will evolve over a fairly short period of time. To look out three months or longer the approach is more statistical using the forecasted ENSO Phase and Climate Trends.

The theory behind using dynamical models for short-term forecasts (6 10 Days, 8 – 14 Days, and recently Weeks 3-4) and statistical models (Monthly and Three-Months) for longer-term forecasts makes perfect sense but sometimes we see that the short term forecasts and then the actuals do not match the statistical forecasts very well. This tells us that either the statistical forecasts were based on incorrect assumptions or that the actual weather patterns are different from what we might have expected.

Now – Precipitation

I am starting with a summary of small images of the three short-term maps. This summary provides a quick look. I could have made it so you could click and enlarge the small images but for the moment I prefer that you go past the summary for the larger versions because if I set up such links, the chances increase that you will not back out of the link properly and get lost. For most people, the summary with the small images will be sufficient. Following the graphic with the three small images, you can find the larger maps and a discussion and for reference purposes I then also provide the forecast map for the current or soon to be current full month and the three-month forecast map. These are issued and updated less frequently than the first three maps shown.

Small Images of Precipitation Maps
6 to 10 Day	8 to 14 Day	Weeks 3 and 4

The above shows the progression of forecasts from six days out through four weeks out. Larger maps with discussion appear below. But this set of three maps paints a pretty good picture of what the forecast is.

Now the larger maps followed by a discussion that describes what is happening and any inconsistencies that I see.

6 – 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on August 28, 2017 was 4 out of 5)

8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on August 28, 2017 was 4 out of 5)

Looking further out.

Consolidation of 6 – 10, 8 – 14, and Week 3-4 Precipitation Forecasts
Interpreted on August 28, 2017
September 3 to September 11	September 9 to September 22, 2017
Days 6 -10: CONUS Northwest is dry but the more intense part of the dry anomaly is in North Central CONUS. New England is wet as is Southern California an unusually westward expression of the Southwest Monsoon. The area impacted by Harvey shows as wet due to the recycling of the water. Alaska is dry in the Northwest and gradually becomes wet to the south including the Panhandle.	For CONUS, Utah and most of Florida are wet. The western half of CONUS is dry except for Utah and a large buffer area around Utah. This odd shaped cool anomaly has two centers. One is the Northwest and the other is the same area that is shown as cool on the temperature map. Alaska is EC. The transition to the pattern shown in the Week 3 – 4 Forecast appears to be feasible.
Week 2: As the period evolves, The dry anomaly in Northwest Alaska is no longer in the forecast. The dry anomaly expands to the east and south and this turns the Florida wet anomaly into Normal.
Remember the Week 3-4 Experimental Outlook was issued last Friday and I am looking at the 6 – 10 and 8 – 14 day forecasts issued today i.e. Monday. So that explains the overlap of dates. Remember that the Week 3 – 4 Forecast covers two weeks so it can appear to not mesh perfectly but actually do so over the two-week period. In between the dry and wet anomalies, it is usually EC i.e. the boundary is usually not sharp.

Reference Forecasts Full Month and Three Months.

Below is the Precipitation Outlook for the month shown in the Legend. This map is first issued on the Third Thursday of the Month for the following month and then updated on the last day of the month. The 6 – 10 day and 8 – 14 Day update daily and the Week 3/4 Map Updates every Friday so usually these are more up to date. Note that the three maps shown at the beginning of this discussion about precipitation may cover a slightly different time period since they update as the month progresses and the map below covers a particular month shown in the Legend. It is useful if one wants to understand how that month is forecast to play out.

Below is the Precipitation Outlook issued on the date and for the three-month period shown in the Map Legend. Again, this is provided for reference only. It is the same map that is included in our Saturday night report that follows the NOAA third Thursday of the month Seasonal Outlook Update. It provides a longer time frame than the above maps. It uses a totally different methodology as it is not possible to use the dynamical models to project out three months. The dynamical models work by figuring out how the current conditions will evolve over a fairly short period of time. To look out three months or longer, the approach is more statistical using the forecasted ENSO Phase and Climate Trends.

The theory behind using dynamical models for short-term forecasts (6 – 10 Days, 8 – 14 Days and recently Weeks 3-4) and statistical models for longer-term forecasts (Month and three months) makes perfect sense but sometimes we see that the short-term forecasts and then the actuals do not match the statistical forecasts very well. This tells us that either the statistical forecasts were based on incorrect assumptions or that the actual weather patterns are different from what we might have expected.

Here is the NOAA discussion released today August 28, 2017

6-10 DAY OUTLOOK FOR SEP 03 – 07 2017
TODAY’S MODELS ARE IN GOOD AGREEMENT ON THE PREDICTED MID-TROPOSPHERIC CIRCULATION PATTERN OVER THE FORECAST DOMAIN. AN AMPLIFIED PATTERN FOR THIS TIME OF YEAR IS PREDICTED WITH A RIDGE EXPECTED OVER THE WESTERN CONUS EXTENDING INTO WESTERN CANADA AND EASTERN ALASKA, WHILE TROUGHS ARE ANTICIPATED OVER THE EASTERN CONUS, AND THE ALEUTIANS. SPREAD AMONG THE ENSEMBLE MEMBERS IS LOW TO MODERATE OVER MUCH OF THE FORECAST DOMAIN. TODAY’S 500-HPA BLEND CHART DEPICTS BELOW NORMAL HEIGHTS OVER MUCH OF THE EASTERN CONUS, WESTERN MAINLAND ALASKA, AND THE ALEUTIANS, WHILE ABOVE NORMAL HEIGHTS ARE FORECAST ACROSS THE WESTERN CONUS, FLORIDA, PARTS OF EASTERN MAINLAND ALASKA, AND THE ALASKA PANHANDLE. THE GREATEST WEIGHT FOR THE BLENDED HEIGHT FORECAST WAS GIVEN TO TODAY’S 00Z ECMWF ENSEMBLE MEAN BASED ON CONSIDERATIONS OF RECENT SKILL AND ANALOG CORRELATIONS, WHICH MEASURE HOW CLOSELY THE FORECAST PATTERN MATCHES CASES THAT HAVE OCCURRED IN THE PAST.
RIDGING AND ABOVE NORMAL HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES FOR THE WESTERN CONUS. TROUGHS AND BELOW NORMAL HEIGHTS TILT THE ODDS TO NEAR TO BELOW NORMAL TEMPERATURES FOR MUCH OF THE EASTERN AND CENTRAL CONUS EXCEPT FOR THE FLORIDA PENINSULA NORTHWARD TO THE CAROLINA COAST WHERE ABOVE NORMAL TEMPERATURES ARE FAVORED. ANOMALOUS SOUTHERLY FLOW AHEAD OF THE TROUGH AND NEAR TO ABOVE NORMAL HEIGHTS INCREASE PROBABILITIES FOR ABOVE NORMAL TEMPERATURES FOR THE ALASKA PANHANDLE AND EASTERN MAINLAND ALASKA.
A TROUGH OVER THE EASTERN CONUS AND MOISTURE FROM THE REMNANTS OF HURRICANE HARVEY ENHANCE PROBABILITIES FOR NEAR TO ABOVE NORMAL PRECIPITATION FOR MUCH OF THE EASTERN CONUS, EASTERN TEXAS, LOUISIANA, AND PARTS OF ARKANSAS. MONSOONAL FLOW TILTS THE ODDS TO ABOVE NORMAL PRECIPITATION FOR SOUTHERN CALIFORNIA. RIDGING AND NEAR TO ABOVE NORMAL HEIGHTS FAVOR BELOW NORMAL PRECIPITATION FOR THE NORTHWEST AND MUCH OF THE NORTH-CENTRAL CONUS EXTENDING TO THE SOUTHERN HIGH PLAINS AND SOUTHERN ROCKIES. THE TROUGH PREDICTED OVER THE ALEUTIANS TILTS THE ODDS TO ABOVE NORMAL PRECIPITATION FOR SOUTHEASTERN MAINLAND ALASKA, THE SOUTH COAST, AND THE ALASKA PANHANDLE, WHILE ANOMALOUS EASTERLY FLOW FAVORS BELOW NORMAL PRECIPITATION FOR PARTS OF WESTERN MAINLAND ALASKA.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO GOOD MODEL AGREEMENT ON AN AMPLIFIED FLOW PATTERN OVER MUCH OF THE FORECAST DOMAIN.
8-14 DAY OUTLOOK FOR SEP 05 – 11 2017
DURING THE WEEK-2 PERIOD, MOST MODEL SOLUTIONS CONTINUE AN AMPLIFIED PATTERN WITH A RIDGE OVER THE WESTERN CONUS AND TROUGHS OVER THE EASTERN CONUS AND OVER THE BERING SEA. TODAY’S 500-HPA BLEND CHART (BASED MOSTLY ON THE ECMWF, CANADIAN, AND GFS ENSEMBLE MEANS) INDICATES BELOW NORMAL HEIGHTS OVER MUCH OF THE EASTERN CONUS, AND SOUTHWESTERN ALASKA, WHILE ABOVE NORMAL HEIGHTS ARE FORECAST ACROSS THE WESTERN CONUS, THE FLORIDA PENINSULA, AND THE REMAINDER OF ALASKA.
THE RESULTING TEMPERATURE OUTLOOK IS VERY SIMILAR TO THAT FOR THE 6-10 DAY PERIOD. RIDGING AND ABOVE NORMAL HEIGHTS ELEVATE CHANCES FOR ABOVE NORMAL TEMPERATURES FOR THE WESTERN THIRD OF THE CONUS. NEAR TO ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR THE ALASKA AHEAD OF A TROUGH OVER THE BERING SEA. TROUGHS AND BELOW NORMAL HEIGHTS TILT THE ODDS TO NEAR TO BELOW NORMAL TEMPERATURES FOR MUCH OF THE EASTERN AND SOUTH-CENTRAL CONUS EXCEPT FOR THE FLORIDA PENINSULA WHERE ABOVE NORMAL TEMPERATURES ARE FAVORED.
RIDGING LEADS TO ENHANCED PROBABILITIES FOR BELOW NORMAL PRECIPITATION FOR MUCH OF THE NORTHWESTERN CONUS EXTENDING TO THE SOUTHERN HIGH PLAINS AND SOUTHERN ROCKIES. TROUGHING TILTS THE ODDS TO ABOVE NORMAL PRECIPITATION FROM THE GULF COAST TO THE NORTHEAST. ENHANCED NORTHERLY FLOW BEHIND THE TROUGH OVER THE GREAT LAKES LEADS TO INCREASED ODDS FOR BELOW NORMAL PRECIPITATION FOR THE NORTH-CENTRAL CONUS. PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ARE ELEVATED FOR PARTS OF THE SOUTHWESTERN CONUS DUE TO THE POTENTIAL ADVECTION OF MONSOONAL MOISTURE INTO THE REGION. MOIST FLOW AHEAD OF A TROUGH OVER THE BRING SEA LEADS TO ENHANCED PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FOR THE ALASKA PANHANDLE AND PARTS OF EASTERN AND CENTRAL MAINLAND ALASKA.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 4 OUT OF 5, DUE TO GOOD AGREEMENT ON AN AMPLIFIED FLOW PATTERN OVER MUCH OF THE FORECAST DOMAIN.
THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON SEPTEMBER 21

Some might find this analysis which you need to click to read interesting as the organization which prepares it focuses on the Pacific Ocean and looks at things from a very detailed perspective and their analysis provides a lot of information on the history and evolution of ENSO events.

Analogs to the Outlook.

Now let us take a detailed look at the “Analogs” which NOAA provides related to the 5 day period centered on 3 days ago and the 7 day period centered on 4 days ago. “Analog” means that the weather pattern then resembles the recent weather pattern and was used in some way to predict the 6 – 14 day Outlook.

Here are today’s analogs in chronological order although this information is also available with the analog dates listed by the level of correlation. I find the chronological order easier for me to work with. There is a second set of analogs associated with the Outlook but I have not been regularly analyzing this second set of information. The first set which is what I am using today applies to the 5 and 7 day observed pattern prior to today. The second set, which I am not using, relates to the correlation of the forecasted outlook 6 – 10 days out with similar patterns that have occurred in the past during the dates covered by the 6 – 10 Day Outlook. The second set of analogs may also be useful information but they put the first set of analogs in the discussion with the second set available by a link so I am assuming that the first set of analogs is the most meaningful and I find it so.

Centered Day	ENSO Phase	PDO	AMO	Other Comments
Aug 30, 1955	La Nina	–	+
Aug 25, 1971	La Nina	–	–
Aug 7, 1981	Neutral	+	–
Aug 18, 1981	Neutral	+	–
Aug 31, 1988	Neutral	+(t)	-(t)
Aug 28, 1998	La Nina	–	+	Following the MegaNino
Aug 30, 1998	La Nina	–	+	Following the MegaNino
Aug 12, 2008	Neutral	–	+	Just after a La Nina
Aug 13, 2008	Neutral	–	+	Just after a La Nina

(t) = a month where the Ocean Cycle Index has just changed or does change the following month.

One thing that jumped out at me right away was the spread among the analogs from August 7 to August 31 which is 24 days which is a much tighter spread in dates than recently. I have not calculated the centroid of this distribution which would be the better way to look at things but the midpoint, which is a lot easier to calculate, is about August 19 (about the same as last week). These analogs are centered on 3 days and 4 days ago (August 24 or August 25). So the analogs could be considered to be out of sync with the calendar meaning that we will be getting weather that we would normally be getting five or six days earlier. For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are zero ENSO El Nino analogs (finally), four Neutral Analogs and five La Nina analogs. The phases of the ocean cycles of the analogs are most consistent with McCabe D and least consistent with McCabe C. Being least consistent with McCabe C reinforces the consistency with McCabe D since C and D are opposites. This leads me to suspect that the Northwest might end up being wetter than forecast in the NOAA 6 to 14 Day Outlook.

The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. Water Planners might usefully pay attention to the low-frequency cycles such as the AMO and the PDO as the media tends to focus on the current and short-term forecasts to the exclusion of what we can reasonably anticipate over multi-decadal periods of time. One of the major reasons that I write this weather and climate column is to encourage a more long-term and World view of weather.

Sometimes it is easier to work in black and white especially if you print this report so there is a black and white version from the later report by the same authors. Darker corresponds to red in the color graphic i.e. higher probability of drought.

McCabe Condition	Main Characteristics
A	Very Little Drought. Southern Tier and Northern Tier from Dakotas East Wet. Some drought on East Coast.
B	More wet than dry but Great Plains and Northeast are dry.
C	Northern Tier and Mid-Atlantic Drought
D	Southwest Drought extending to the North and also the Great Lakes. This is the most drought-prone combination of Ocean Phases.

You may have to squint but the drought probabilities are shown on the map and also indicated by the color coding with shades of red indicating higher than 25% of the years are drought years (25% or less of average precipitation for that area) and shades of blue indicating less than 25% of the years are drought years. Thus drought is defined as the condition that occurs 25% of the time and this ties in nicely with each of the four pairs of two phases of the AMO and PDO.

Looking Out Beyond Three Months

Historical Anomaly Analysis

When I see the same dates showing up often I find it interesting to consult this list.

Recent CONUS Weather

This is provided mainly to see the pattern in the weather that has occurred recently.

Here is the 30 Days ending August 19, 2017

Quite a bit wetter from Texas north but to the west of Texas, not as wet signifying a fairly normal Monsoon for Arizona and New Mexico but wetter east of the areas usually most impacted. One sees more blue this time in the North Central area and even further east Remember, this is a 30 average so the most distant seven days are removed and the most recent seven days are added.

And the 30 Days ending August 26, 2017

You can see a little bit of the pattern shift east. It will be a lot clearer in a week. Remember, this is a 30 average so the most distant seven days are removed and the most recent seven days are added.

B. Beyond Alaska and CONUS Let’s Look at the World which of Course also includes Alaska and CONUS

I will be including the above two graphics regularly as they really help with understanding why things are happening the way they are. I think the (at least intermediate) Source is The Weather Channel and I was able to download the full presentation with difficulty and you can attempt the same thing by clicking here.

I think these two slides are from a much larger set but these two really highlight the position of the Bermuda High which they are calling the Azores High in the January slide and is often called NASH and it has a very big impact on CONUS Southeast weather and also the Southwest. You also see the north/south migration of the Pacific High which also has many names and which is extremely important for CONUS weather and it also shows the change of location of the ITCZ which I think is key to understanding the Indian Monsoon. A lot of things become much clearer when you understand these semi-permanent features some of which have cycles within the year, longer period cycles and may be impacted by Global Warming.

We are now approaching September so we are 1/3 between the set of positions shown above for July and the ones shown for January. For CONUS, the seasonal repositioning of the Bermuda High and the Pacific High are very significant. Notice the Summer position of the Pacific High.

Forecast for Today

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. From North Africa to Eastern Siberia it is warmer than climatology except for Northeast China and Eastern Siberia and Northwest Russia which are cool. CONUS East is cool.

This graphic is actuals not anomalies as is the case in the temperature map. We again see the dry area from North Africa through Asia (other than Southeast Asia) but it is not extending all the way to the Pacific. South America south of the ITCZ is mostly dry. Africa north and south of the Equator and the ITCZ is mostly dry. And CONUS is mostly dry in the West. From Texas east it is a different story.

Additional Maps

showing different weather variables can be found here.

Forecast for Day 6 (Currently Set for Day 6 but the reader can change that)

World Weather Forecast produced by the Australian Bureau of Meteorology. Unfortunately I do not know how to extract the control panel and embed it into my report so that you could use the tool within my report. But if you visit it Click Here and you will be able to use the tool to view temperature or many other things for THE WORLD. It can forecast out for a week. Pretty cool. Return to this report by using the “Back Arrow” usually found top left corner of your screen to the left of the URL Box. It may require hitting it a few times depending on how deep you are into the BOM tool. Below are the current worldwide precipitation and temperature forecasts for six days out. They will auto-update and be current for Day 6 whenever you view them. If you want the forecast for a different day Click Here

Temperature

Please remember this graphic updates every six hours so the diurnal pattern can confuse the reader.

Precipitation

Notice that in the Day 6 Forecast, the Bermuda High also called NASH again extends way to the west. It retreated and allowed Harvey in but is closing that window. The Pacific has some significant features. I can not tell if they are Highs or Lows but I am guessing they are Lows.

Looking Out a Few Months

Here is the precipitation forecast from Queensland Australia:

It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. Notice the change from the forecast last month due to the change from a falling SOI to a rising SOI. It is more like a La Nina forecast than a El Nino forecast. CONUS looks pretty dry, Europe pretty wet. India wet, Australia wet.

JAMSTEC Forecasts

One can always find the latest JAMSTEC maps by clicking this link. You will find additional maps that I do not general cover in my monthly Update Report. Remember if you leave this page to visit links provided in this article, you can return by hitting your “Back Arrow”, usually top left corner of your screen just to the left of the URL box.

Sea Surface Temperature (SST) Departures from Normal for this Time of the Year i.e. Anomalies

My focus here is sea surface temperature anomalies as they are one of the two largest factors determining weather around the World.

And when we look at the current Sea Surface anomalies below, we see a lot of them not just along the Equator related to ENSO.[NOAA may be having problems updating their daily SST Anomaly Report so I am working with the latest version that I have]

First the categorization of the anomalies.

Mediterranean, Black Sea and Caspian Sea	Western Pacific	West of North America	East of North America	North Atlantic
The Black Sea, Caspian Sea and Persian Gulf are very warm with the Mediterranean only slightly warm.	Warm.	Fairly Neutral. Warm out to sea and very spotty cool anomaly closer to shore to barely create a visible PDO Signal. .	Fairly Neutral Hudson Bay warm Gulf of St Lawrence Warm	Warm
The Equatorial	Cool east of Dateline. Cool southwest of Maritime Continent.
Africa	West of Australia	North, South and East of Australia	West of South America	East of South America
Warm west of North Africa and Equator. Cool in the Gulf of Guinea and mixed off of South Africa	Cool northwest, west and southwest	Cool to the south and warm east.	Cool mostly in conjunction to the ENSO Cycle	Slightly warm 20S to 40S. Cool offshore of 20S

What you see in the below graphic is the change in the anomaly over the last four weeks So you have to refer to the graphic above this one to really interpret the below graphic as what we are seeing here is the change in the anomalies. So blue means a trend that is either cooler or less warm than four weeks ago. Red means a trend that is warmer or less cool than four weeks ago. So this graphic is a way of understanding how the anomalies shown in the above graphic have changed over the past four weeks. It is important to understand the distinction between these two graphics. The top one shows the recent conditions, the bottom one shows the direction of change.

The categorization of the four week change in the anomalies.

Mediterranean, Black Sea and Caspian Sea	Western North Pacific	West of North America	East of North America	North Atlantic
Fairly stable i.e. the anomalies are not changing much.	Mix of warming and cooling.	Cooling in the Bering Straits. and south of the Aleutians. Warming west of CONUS. Slight cooling for Baja California and in Gulf of California	Cooling off of Yucatan Warming southern part of Hudson Bay	Warming south of 40S
The Tropical Pacific	Eastern Pacific Cooling East of 130W.
Africa	West of Australia	North, South and East of Australia	West of South America	East of South America
Warming west of North Africa. Cooling south of Africa	Cooling to the west	Cooling to the northeast.	Cooling off Ecuador and Peru	Mostly stable

It is very interesting that the entire North Pacific is showing Neutral or warm anomalies but when you look at the changes in the anomalies one gets a very different picture with many areas that are cooling (from their current temperature which is warmer than climatology).

This may be a good time to show the recent values to the indices most commonly used to describe the overall spacial pattern of temperatures in the (Northern Hemisphere) Pacific and the (Northern Hemisphere) Atlantic and the Dipole Pattern in the Indian Ocean.

Most Recent Six Months of Index Values	PDO Click for full list	AMO click for full list.	Indian Ocean Dipole (Values read off graph)
October	-0.68	+0.39	-0.3
November	+0.84	+0.40	0.0
December	+0.55	+0.34	-0.1
January	+0.10	+0.23	0.0
February	+0.04	+0.23	+0.2
March	+0.12	+0.17	+0.0
April	+0.52	+0.29	+0.2
May	+0.30	+0.32	+0.2
June	+0.19	+0.31	0.0
July	-0.41	+0.31	0.0

Switching gears, below is an analysis of projected tropical hazards and benefits over an approximately two-week period.

This graphic updates on Tuesdays and I post on Monday which is almost a week later than when this graphic was last updated. So Week Two applies at the time I write this article on Monday but by the time you read it on Tuesday, the Week Two that I am looking at is updated and becomes Week One. Mostly I see as I look at this on August 28 for what is shown as Week Two, the period August 30 to September 5, 2017 we see wet conditions* over the western part of the Maritime Continent and the risk of tropical cyclone development east of Indochina with dry conditions* in between. We also see wet conditions* impacting the eastern part of the Maritime Continent. We see wet conditions* and a risk* of cyclone development impacting Western Mexico and possibly even CONUS. There are wet conditions shown* for areas in Africa just north of the Equator. There is a dry area* in Central America.

* Moderate Confidence that the indicated anomaly will be in the upper or lower third of the historical range as indicated in the Legend.

** High Confidence that the indicated anomaly will be in the upper or lower third of the historical range as indicated in the Legend.

Now let us look at the Western Pacific in Motion.

The above graphic which I believe covers the area from the Dateline west to 100E and from the Equator north to 45N normally shows the movement of tropical storms towards Asia in the lower latitudes (Trade Winds) and the return of storms towards CONUS in the mid-latitudes (Prevailing Westerlies). This is recent data not a forecast. But, it ties in with the Week 1 forecast in the graphic just above this graphic. Information on Western Pacific storms can be found by clicking here. This (click here to read) is an unofficial private source but one that is easy to read.

C. Progress of ENSO

A major driver of weather is Surface Ocean Temperatures. Evaporation only occurs from the Surface of Water. So we are very interested in the temperatures of water especially when these temperatures deviate from seasonal norms thus creating an anomaly. The geographical distribution of the anomalies is very important.

To a substantial extent, the temperature anomalies along the Equator have disproportionate impact on weather so we study them intensely and that is what the ENSO (El Nino – Southern Oscillation) cycle is all about.

Subsurface water can be thought of as the future surface temperatures. They may have only indirect impacts on current weather but they have major impacts on future weather by changing the temperature of the water surface.

Winds and Convection (evaporation forming clouds) is weather and is a result of the Phases of ENSO and also a feedback loop that perpetuates the current Phase of ENSO or changes it. That is why we monitor winds and convection along or near the Equator especially the Equator in the Eastern Pacific.

Starting with Surface Conditions.

TAO/TRITON GRAPHIC (a good way of viewing data related to the part of the Equator and the waters close to the Equator in the Eastern Pacific where we monitor to determining the current phase of ENSO. It is probably not necessary to follow the discussion below, but here is a link to TAO/TRITON terminology.

And here is the current version of the TAO/TRITON Graphic. The top part shows the actual temperatures, the bottom part shows the anomalies i.e. the deviation from normal.

*Location Bar for Nino 3.4 Area Above and Below*
————————————————	A	B	C	D	E	—————–

If one were to track this day by day over the past month one would see both the northern intrusion from south of the Equator strengthening (temperature) but being squeezed from both the east and the west. We now see it gradually being squeezed but not south as I had anticipated but to the north. Most like soon it will be totally out of the Nino 3.4 Measurement Area. There is now also some cooler water in the eastern end of the Nino 3.4 Measurement Area and also just to the west.

The below table only looks at the Equator and shows the extent of anomalies along the Equator. The ONI Measurement Area is the 50 degrees of Longitude between 170W and 120W and extends 5 degrees of Latitude North and South of the Equator so the above table is just a guide and a way of tracking the changes.The top rows show El Nino anomalies. The two rows just below that break point contribute to ENSO Neutral.

Subareas of the Anomaly	Westward Extension	Eastward Extension	Degrees of Coverage
Subareas of the Anomaly	Westward Extension	Eastward Extension	Total	Portion in Nino 3.4 Measurement Area
These Rows below show the Extent of El Nino Impact on the Equator
1C to 1.5C (strong)	LAND	LAND	0	0
+0.5C to +1C (marginal)	LAND	LAND	0	0
These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly (warmish neutral)	170E	140W	45	30
0C or cooler Anomaly (coolish neutral)	140W	135W	5	5
These Rows Below Show the Extent of La Nina Impacts on the Equator.
-0.5C or cooler Anomaly	135W 110W	130W LAND	20	5
-1.0C or cooler anomaly	130W	110	20	5

My Calculation of the Nino 3.4 Index

I calculate the current value of the Nino 3.4 Index each Monday using a method that I have devised. To refine my calculation, I have divided the 170W to 120W Nino 3.4 measuring area into five subregions (which I have designated from west to east as A through E) with a location bar shown under the TAO/TRITON Graphic). I use a rough estimation approach to integrate what I see below and record that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions.

So as of Monday August 28, in the afternoon working from the August 27 TAO/TRITON report [Although the TAO/TRITON Graphic appears to update once a day, in reality it updates more frequently.], this is what I calculated.

*Calculation of ONI from TAO/TRITON Graphic*
Anomaly Segment	Estimated Anomaly
	Last Week	This Week
A. 170W to 160W	+0.0	+0.4
B. 160W to 150W	-0.1	+0.3
C. 150W to 140W	-0.3	+0.4
D. 140W to 130W	-0.5	0.0
E. 130W to 120W	-0.8	-0.5
Total	-1.7	+0.6
Total divided by five i.e. the Daily Nino 3.4 Index	(-1.7)/5 = -0.3	(+0.6)/5 = +0.1

My estimate of the daily Nino 3.4 SST anomaly tonight is +0.1 which is an ENSO Neutral Value. NOAA has reported the weekly Nino 3.4 to be -0.1 which is an ENSO Neutral value and much higher (less negative) than last week.

Nino 4.0 is reported a little higher at +0.2. Nino 3 is quite a bit higher at -0.4. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported much lower -1.0. It was up there close to 3 at one time so this index has been declining quite a bit and also fluctuating quite a bit which is not surprising as it is the area most impacted by the Upwelling off the coast. So it is an indication of the interaction between surface water and rising cool water. Thus it is subject to larger changes. Most likely it will be negative for a while.

I am only showing the currently issued version of the NINO SST Index Table as the prior values are shown in the small graphics on the right with this graphic. Notice that all the indices have been declining. The same data in table form but going back a couple of more years can be found here.

This is probably the best place to AGAIN express the thought that this way of measuring an ENSO event leaves a lot to be desired. Only the surface interacts with the atmosphere and is able to influence weather. The subsurface tells us how long the surface will remain cool (or warm). Anomalies are deviations from “Normal”. NOAA calculates and determines what is “Normal” which changes due to long ocean cycles and Global Warming. So to some extent, the system is “rigged”. Hopefully it is rigged to assist in providing improved weather forecasts. But to assume that any numbers reported can be assumed to be accurate to a high level of precision is foolhardy. It is strange to me that the Asian forecasting services generally conclude that that this cool ENSO Phase is not a La Nina but a near La Nina and NOAA concludes it is a La Nina. It is the same ocean. The reported readings are very close but the Asian readings are generally slightly higher (less La Nina-ish) than the NOAA reading and their cut-off points for declaring a La Nina are a bit different and the parts of the Equator they look at are a bit different. It might be explained by what part of the ENSO pattern impacts their area of geography but it just seems to me that NOAA has been a bit over eager. And I wonder why.

Sea Surface Temperature and Anomalies

It is the ocean surface that interacts with the atmosphere and causes convection and also the warming and cooling of the atmosphere. So we are interested in the actual ocean surface temperatures and the departure from seasonal normal temperatures which is called “departures” or “anomalies”. Since warm water facilitates evaporation which results in cloud convection, the pattern of SST anomalies suggests how the weather pattern east of the anomalies will be different than normal.

A major advantage of the Hovmoeller method of displaying information is that it shows the history so I do not need to show a sequence of snapshots of the conditions at different points in time. This Hovmoeller provides a good way to visually see the evolution of this ENSO event. I have decided to use the prettied-up version that comes out on Mondays rather that the version that auto-updates daily because the SST Departures on the Equator do not change rapidly and the prettied-up version is so much easier to read.

The bottom of the Hovmoeller which shows the current readings is now almost totally a mix of light blue and white. White is Neutral but the small amount of light Blue is where the temperature is in the marginal La Nina range. Remember the +5, -5 degree strip around the Equator that is being reported in this graphic. So it is the surface but not just the Equator. One now sees more white than light yellow in the Nino 3.4 Measurement Area and some blue no longer restricted to east of 120W. So the Nino 3.4 Index is likely to be negative but still remain in the neutral range or perhaps not and become marginally La Nina.

Week to week there have been no substantial changes. It was until recently ENSO Neutral with a warm bias. But since the end of July this has changed and you can see that in this Hovmoeller Graphic. The bottom sentence in the legend to the left of the graphic proper says it all.

I had stopped showing the below graphic which is more focused on the Equator but looks down to 300 meters rather than just being the surface. But recently there has been sufficient change to warrant including this graphic. And now that we are back tracking a possible La Nina, it is the graphic of choice.

The bottom of the Hovmoeller shows the current situation. If you look from the bottom of the graphic up you can see that any La Nina conditions (which NOAA declared to be a full La Nina event and we disagree) ended in December. At any rate the 2016 Cool Event is long gone. Successive Kevin waves early in 2017 which some thought might be initiating an El Nino in retrospect were not very impressive. We now see a blue (cool) area. I don’t think it is the upwelling phase of the prior Kelvin Wave but NOAA is in a better position to make that determination and I would not be surprised if they did so. It does not matter that much what you call it. It is subsurface cool water showing up in the imagery.

Let us look in more detail at the Equatorial Water Temperatures.

We are now going to look at a three-dimensional view of the Equator and move from the surface view and an average of the subsurface heat content to a more detailed view from the surface down This graphic provides both a summary perspective and a history (small images on the right).

We now have no warm water near the surface in the area where the Nino 3.4 Index is measured. There is another graphic that shows it better. There is “probably” not enough cool water at depth to fully flip the situation to La Nina other for a few months which is not long enough to be a La Nina but simply to create La Nina conditions for a month or two. But we will be on the cool side of Neutral with nothing to the west suggesting any change in the near term. There is cool water at depth from 160W to 100W so we should expect lower Nino 3.4 readings. JAMSTEC it seems is paying attention to that yellow/orange area which I gather they believe will this winter record as Neutral with a warm bias.

Anomalies are strange. You can not really tell for sure if the blue area is colder or warmer than the water above or below. All you know is that it is cooler than usual for this time of the year. A later graphic will provide more information. Aside from buoyancy the currents tend to bring water from that depth up to the surface mostly farther east.

Now for a more detailed look (there is some redundancy with the above graphic). Notice by the date of the graphic (dated August 21, 2017) that the lag in getting this information posted so the current situation may be a bit different than shown although this graphic was just updated this afternoon. The date shown is the midpoint of a five-day period with that date as the center of the five-day period.

Below is the pair of graphics that I regularly provide.

The bottom graphic shows the absolute values, the upper graphic shows anomalies compared to what one might expect at this time of the year in the various areas both 130E to 90W Longitude and from the surface down to 450 meters. At different times and today in particular, I have discussed the difference between the actual values and the deviation of the actual values from what is defined as current climatology (which adjusts every ten years except along the Equator where it is adjusted every five years) and how both measures are useful for other purposes.

Re the top graphic, let us first look at surface temperature anomalies. Almost the entire surface of the Equatorial Pacific has a surface temperature consistent with ENSO Neutral with an occasional cooler area. Subsurface Temperature Anomalies: There is a lot of cool water below 50 meters, especially between 160W and 100W, but probably not enough to cause a La Nina (insufficient duration), but enough to cause La Nina Conditions for this winter. In places the cool subsurface water is reaching the surface.

The bottom half of the graphic (Absolute Values which highlights the Thermocline) is now more useful as we track the transition from last winter’s ENSO Cool Event to ENSO Neutral to ENSO Neutral with a warm bias which may possibly become an El Nino. More likely we will soon see the situation change to ENSO Neutral with a warm bias and then to just plain ENSO Neutral. It shows the thermocline between warm and cool water. The 28C Isotherm is now located further west at about 175W. This graphic does not show a 27.5C anomaly which might more precisely indicate where convection is likely to occur. The 27C isotherm is now at 170W. The 25C Isotherm reaches the surface at 135W. What we have is ENSO Neutral but almost La Nina.

The flattening of the Isotherm Pattern is an indication of ENSO Neutral just as the steepening of the pattern indicates La Nina or El Nino depending on where the slope shows the warm or cool pool to be. That flattening has occurred. At this point, we have gone to ENSO Neutral.

The conditions to create an El Nino simply do not exist. The conditions to create a sustainable La Nina also do not appear to exist.

Here are the above graphics as a time sequence animation. You may have to click on them to get the animation going.

And now Let us look at the Atmosphere.

Low-Level Wind Anomalies near the Equator

Here are the low-level wind anomalies.

We now see westerlies all over the Equator which should be favorable for the development of an El Nino but do not seem to be having much of an impact.

And now the Outgoing Long wave Radiation (OLR) Anomalies which tells us where convection has been taking place.

The pattern has changed. We no longer see suppressed Outgoing Long Wave Radiation (OLR) at the Dateline (no longer dry) but we again see enhanced OLR at 120E ( wet)

And Now the Air Pressure which Shows up Mostly in an Index called the SOI.

This index provides an easy way to assess the location of and the relative strength of the Convection (Low Pressure) and the Subsidence (High Pressure) near the Equator. Experience shows that the extent to which the Atmospheric Air Pressure at Tahiti exceeds the Atmospheric Pressure at Darwin Australia when normalized is substantially correlated with the Precipitation Pattern of the entire World. At this point there seems to be no need to show the daily preliminary values of the SOI but we can work with the 30 day and 90 day values.

**Current SOI Readings**
The 30 Day Average on August 6 was reported as +4.49 which is an ENSO Neutral value with somewhat of a cool bias i.e. somewhat close to a La Nina value. The 90 Day Average was reported at +0.38 which is an ENSO Neutral value. The change from last week is insignificant. Looking at both the 30 and 90 day averages is useful and right now both are in agreement. They seem to be tracking the Nino 3.4 Index pretty well and reflect the downturn in marginal El Nino Conditions and short-term conditions in the Western Pacific where there there had been a long string of negative values for a while. Now the 30 day average is actually positive i.e. in the direction of a La Nina but still in the Neutral Range.

SOI = 10 X [ Pdiff – Pdiffav ]/ SD(Pdiff) where Pdiff = (average Tahiti MSLP for the month) – (average Darwin MSLP for the month), Pdiffav = long term average of Pdiff for the month in question, and SD(Pdiff) = long term standard deviation of Pdiff for the month in question. So really it is comparing the extent to which Tahiti is more cloudy than Darwin, Australia. During El Nino we expect Darwin Australia to have lower air pressure and more convection than Tahiti (Negative SOI especially lower than -7 correlates with El Nino Conditions). During La Nina we expect the Warm Pool to be further east resulting in Positive SOI values greater than +7).

To some extent it is the change in the SOI that is of most importance. The MJO or Madden Julian Oscillation is an important factor in regulating the SOI and Ocean Equatorial Kelvin Waves and other tropical weather characteristics. More information on the MJO can be found here. Here is another good resource.

Forecasting the Evolution of ENSO

The newly issued on August 18 CPC/IRI fully model-based report is shown on the right The earlier August 10 IRI/CPC Meteorologist survey is shown on the left.

Not much change from a week ago. More detail was provided in our August 19, 2017 Seasonal Outlook Update Report which can be accessed here. Remember, if you leave this page to visit links provided in this article, you can return by hitting your “Back Arrow”, usually top left corner of your screen just to the left of the URL box.

Here is the primary NOAA model.

I have frozen a portion of the above and added some lines to make reading easier.

Looking at the forecast today it looks like it would if it happened as forecast be declared to be a La Nina since there would have been five overlapping three-month periods with the Nino 3.4 Index being -0.5C or cooler. It is way too soon to draw any conclusions. The estimated current value of the Nino 3.4 Temperature Anomaly after the adjustments have been applied is about -0.4 for the end of August which is ENSO Neutral. But we are starting to see this model flirting with La Nina conditions for a period of time this winter. We have not expected this cool event to last long enough to be declared to be a La Nina but it will be close and it would not take too much to have us change our minds on this. Click here to see a month by month version of the same model but without some of the correction methodologies applied. It gives us a better picture of the further out months as we are looking at monthly estimates versus three-month averages.

From Tropical Tidbits.com

The above is from a legacy “frozen” NOAA system meaning the software is maintained but not updated. Notice since mid-July the collapse of Nino 3.4 values from the range of 0.5C to 0.6C down to Zero C and then down to -0.6C but recently moved back closer to 0C. .

Forecasts from Other Meteorological Agencies.

Here is the Nino 3.4 report from the Australian BOM (it updates every two weeks)

Discussion Issued August 29, 2017

ENSO and Indian Ocean Dipole persist at neutral levels
The El Niño–Southern Oscillation (ENSO) remains neutral. International climate models surveyed by the Bureau suggest the tropical Pacific Ocean is likely to persist at ENSO-neutral levels until at least late 2017. One model, out of eight, predicts cooling of the central equatorial Pacific to occur during summer.
Sea surface temperatures (SSTs) have cooled over much of the central tropical Pacific during the past several weeks, yet have remained within the neutral range. Other indicators of ENSO, such as the Southern Oscillation Index (SOI), cloudiness near the Date Line and trade winds are also at neutral levels.

Here are the July 1 and Aug 1 JAMSTEC Nino 3.4 forecasts side by side.

August 1, 2017 JAMSTEC Nino 3.4 Forecast

As you can see there has been some change but not a lot in the JAMSTEC Nino 3.4 forecast and there is a period of time where JAMSTEC is in the warm range of ENSO Neutral while NOAA is in the cool side of ENSO Neutral bordering on La Nina. So we would expect to have very different forecasts from these two agencies and we did when we reported on that on August 24. .

Here is the discussion from JAMSTEC:

Aug. 25, 2017 Prediction from 1st Aug., 2017
ENSO forecast:
A neutral state in the tropical Pacific will persist until boreal winter. Then, a weak La Niña-like pattern will appear in the spring of 2018.
Indian Ocean forecast:
All ensemble members of SINTEX-F now predict a positive Indian Ocean Dipole [Editor’s Note: The Australian BOM does not agree with that forecast see next graphic] ; the ensemble mean prediction suggests that it peaks in boreal fall. In accord to the positive IOD evolution, sea level anomalies are expected to be negative (positive) in the eastern (western) tropical Indian Ocean.
Regional forecast:
On a seasonal scale, most part of the globe will experience a warmer-than-normal condition, while some parts of central Russia will experience a colder-than-normal condition in the boreal fall.
As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for some parts of East Africa and West Africa during the boreal fall, whereas most parts of Indonesia, Australia, eastern China, U.S, and Brazil will experience a drier condition during the boreal fall. Those are partly due to the positive Indian Ocean Dipole.
Most parts of Japan will experience warmer-than-normal conditions in the boreal fall. The wind and pressure anomalies averaged in September-November suggest that Japan might be covered by an equivalent barotropic high. Those may be due to the combined effect of the “monsoon-desert mechanism” of the positive Indian Ocean Dipole and the “Silk Road pattern” along the Asian jet.

Indian Ocean IOD (It updates every two weeks)

The IOD Forecast is indirectly related to ENSO but in a complex way.

Discussion Issued August 29, 2017

The Indian Ocean Dipole (IOD) is neutral, though index values have generally been above zero for the past several months. The weekly index value to 27 August was +0.34 °C. Most climate models suggest a neutral IOD is likely to continue. However, two of the six climate models surveyed suggest a positive IOD may develop during spring. Positive IOD events are typically associated with below average winter–spring rainfall, and increased spring–summer fire potential over central and southern Australia.

It is important to understand how and where the IOD is measured.

IOD Positive is the West Area being warmer than the East Area (with of course many adjustments/normalizations). IOD Negative is the East Area being warmer than the West Area. Notice that the Latitudinal extent of the western box is greater than that of the eastern box. This type of index is based on observing how these patterns impact weather and represent the best efforts of meteorological agencies to figure these things out. Global Warming may change the formulas probably slightly over time but it is costly and difficult to redo this sort of work because of long weather cycles.

D. Putting it all Together.

At this time it would seem that the more likely deviation from Neutral right now would be in the direction of a La Nina but we do not believe that there will be a sufficiently long period of La Nina Conditions for a La Nina to be declared but the La Nina Conditions will definitely impact the Boreal Winter.

Forecasting Beyond Five Years.

So in terms of long-term forecasting, none of this is very difficult to figure out actually if you are looking at say a five-year or longer forecast.

The research on Ocean Cycles is fairly conclusive and widely available to those who seek it out. I have provided a lot of information on this in prior weeks and all of that information is preserved in Part II of my report in the Section on Low Frequency Cycles 3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS. It includes decade by decade predictions through 2050. Predicting a particular year is far harder.

The odds of a climate shift for the Pacific taking place has significantly increased. It may be in progress. The AMO is pretty much neutral at this point (but more positive i.e. warm than I had expected) so it may need to become a bit more negative for the “McCabe A” pattern to become established. That seems to be slow to happen so I am thinking we need at least a couple more years for that to happen. So our assessment is that the standard time for Climate Shifts in the Pacific are likely to prevail and it most likely will be a gradual process with a speed up in less than five years but more than two years.

E. Relevant Recent Articles and Reports

Weather in the News

We have reported on Harvey at the beginning of this report.

Weather Research in the News

Nothing to Report

Global Warming in the News

Nothing to Report

F. Table of Contents for Page II of this Report Which Provides a lot of Background Information on Weather and Climate Science

The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page II where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.

1. Very High Frequency (short-term) Cycles PNA, AO,NAO (but the AO and NAO may also have a low frequency component.)

2. Medium Frequency Cycles such as ENSO and IOD

3. Low Frequency Cycles such as PDO, AMO, IOBD, EATS.

4. Computer Models and Methodologies

5. Reserved for a Future Topic (Possibly Predictable Economic Impacts)

G. Table of Contents of Contents for Page III of this Report – Global Warming Which Some Call Climate Change.

The links below may take you directly to the set of information that you have selected but in some Internet Browsers it may first take you to the top of Page III where there is a TABLE OF CONTENTS and take a few extra seconds to get you to the specific section selected. If you do not feel like waiting, you can click a second time within the TABLE OF CONTENTS to get to the specific part of the webpage that interests you.

1. Introduction

2. Climate Impacts of Global Warming

3. Economic Impacts of Global Warming

4. Reports from Around the World on Impacts of Global Warming

H. Useful Background Information

The current conditions are measured by determining the deviation of actual sea surface temperatures from seasonal norms (adjusted for Global Warming) in certain parts of the Equatorial Pacific. The below diagram shows those areas where measurements are taken.

NOAA focuses on a combined area which is all of Region Nino 3 and part of Region Nino 4 and it is called Nino 3.4. They focus on that area as they believe it provides the best correlation with future weather for the U.S. primarily the Continental U.S. not including Alaska which is abbreviated as CONUS. The historical approach of measurement of the impact of the sea surface temperature pattern on the atmosphere is called the Southern Oscillation Index (SOI) which is the difference between the atmospheric pressure at Tahiti as compared to Darwin Australia. It was convenient to do this as weather stations already existed at those two locations and it is easier to have weather stations on land than at sea. It has proven to be quite a good measure. The best information on the SOI is produced by Queensland Australia and that information can be found here. SOI is based on Atmospheric pressure as a surrogate for Convection and Subsidence. Another approach made feasible by the use of satellites is to to measure precipitation over the areas of interest and this is called the El Nino–Southern Oscillation (ENSO) Precipitation Index (ESPI). We covered that in a weekly Weather and Climate Report which can be found here. Our conclusion was that ESPI did not differentiate well between La Nina and Neutral. And there is now a newer measure not regularly used called the Multivariate ENSO Index (MEI). More information on MEI can be found here. The jury is still out on MEI and it it is not widely used.

The below diagram shows the usual location of the Indo-Pacific Warm Pool. When the warm water shifts to the east we have an El Nino; to the west a La Nina.

Click for Source

Interaction between the MJO and ENSO

This Table is a first attempt at trying to relate the MJO to ENSO

Relationship of MJO and ENSO
	El Nino	La Nina	MJO Active Phase	MJO Inactive Phase
Eastern Pacific Easterlies	Weaker	Stronger Part of Decay Process	Counteracts Easterlies	Enhances Easterlies
Western Pacific Westerlies	Stronger May Create or Stimulate the Onset of El Nino via Kelvin Waves	Weaker Part of Decay Process	Strengthens Westerlies	Weakens Westerlies
MJO Active Phase	More likely Stimulates	Less likely and weak Retards development of a new La Nina	Stimulates the Jet Stream
MJO Inactive Phase	Less Likely Suppresses	More likely but weak Accelerates development of a new La Nina and the Decline of a mature La Nina		Slows the Jet Stream and can induce a Split Stream especially during a La Nina

Table needs more work. Is intended to show the interactions. What is more difficult is determining cause and effect. This is a Work in Progress.

History of ENSO Events

With respect to relating analog dates to ENSO Events, the following table might be useful. In most cases this table will allow the reader to draw appropriate conclusions from NOAA supplied analogs. If the analogs are not associated with an El Nino or La Nina they probably are not as easily interpreted. Remember, an analog is indicating a similarity to a weather pattern in the past. So if the analogs are not associated with a prior El Nino or prior La Nina the computer models are not likely to generate a forecast that is consistent with an El Nino or a La Nina.

	El Ninos					La Ninas
	Start	Finish	Max ONI	PDO	AMO	Start	Finish	Max ONI	PDO	AMO
						DJF 1950	J FM 1951	-1.4	–	N
T	JJA 1951	DJF 1952	0.9	–	+
	DJF 1953	DJF 1954	0.8	–	+	AMJ 1954	AMJ 1956	-1.6	–	+
M	MAM 1957	JJA 1958	1.7	+	–
M	SON 1958	JFM 1959	0.6	+	–
M	JJA 1963	JFM 1964	1.2	–	–	AMJ 1964	DJF 1965	-0.8	–	–
M	MJJ 1965	MAM 1966	1.8	–	–	NDJ 1967	MAM 1968	-0.8	–	–
M	OND 1968	MJJ 1969	1.0	–	–
T	JAS 1969	DJF 1970	0.8	N	–	JJA 1970	DJF 1972	-1.3	–	–
T	AMJ 1972	FMA 1973	2.0	–	–	MJJ 1973	JJA 1974	-1.9	–	–
						SON 1974	FMA 1976	-1.6	–	–
T	ASO 1976	JFM 1977	0.8	+	–
M	ASO 1977	DJF 1978	0.8	N
M	SON 1979	JFM 1980	0.6	+	–
T	MAM 1982	MJJ 1983	2.1	+	–	SON 1984	MJJ 1985	-1.1	+	–
M	ASO 1986	JFM 1988	1.6	+	–	AMJ 1988	AMJ 1989	-1.8	–	–
M	MJJ 1991	JJA 1992	1.6	+	–
M	SON 1994	FMA 1995	1.0	–	–	JAS 1995	FMA 1996	-1.0	+	+
T	AMJ 1997	AMJ 1998	2.3	+	+	JJA 1998	FMA 2001	-1.6	–	+
M	MJJ 2002	JFM 2003	1.3	+	N
M	JJA 2004	MAM 2005	0.7	+	+
T	ASO 2006	DJF 2007	0.9	–	+	JAS 2007	MJJ 2008	-1.4	–	+
M	JJA 2009	MAM 2010	1.3	N	+	JJA 2010	MAM 2011	-1.3	+	+
						JAS 2011	JFM 2012	-0.9	–	+
T	MAM 2015	AMJ 2016	2.3	+	N	JAS 2016	NDJ 2016	-0.8*	+	+

*The GEI Weather and Climate Report does not accept this as a legitimate La Nina. It is not unusual for different Meteorological Agencies to maintain different lists of El Ninos and La Ninas. This is usually because the criteria for classification differ slightly. Obviously the GEI Weather and Climate Report has no standing but nevertheless for any analysis we do, we will either not include or asterisk this La Nina to indicate that NOAA has it on their list and we consider that to be Fake News. The alternative is to conclude that the other Meteorological Agencies are not able to measuring things correctly. .

ONI Recent History

The full history of the ONI readings can be found here. The MEI index readings can be found here.

Four Quadrant Jet Streak Model Read more here This is very useful for guessing at weather as a trough passes through.

If the centripetal accelerations owing to flow curvature are small, then we can use the “straight” jet streak model. The schematic figure directly below shows a straight jet streak at the base of a trough in the height field. The core of maximum winds defining the jet streak is divided into four quadrants composed of the upstream (entrance) and downstream (exit) regions and the left and right quadrants, which are defined facing downwind.

Isotachs are shaded in blue for a westerly jet streak (single large arrow). Thick red lines denote geopotential height contours. Thick black vectors represent cross-stream (transverse) ageostrophic winds with magnitudes given by arrow length. Vertical cross sections transverse to the flow in the entrance and exit regions of the jet (J) are shown in the bottom panels along A-A’ and B-B’, respectively. Convergence and divergence at the jet level are denoted by “CON” and “DIV”. “COLD” and “WARM” refer to the air masses defined by the green isentropes.

[Editor’s Note: There are many undefined words in the above so here are some brief definitions. Isotacs are lines of equal wind speed. Convergence is when there is an inflow of air which tends to force the air higher with cooling and cloud formation. Divergence is when there is an outflow of air which tends to result in air sinking which causes drying and warming, Confluence is when two streams of air come together. Diffluence is when part of a stream of air splits off.]

August 28, 2017 Weather and Climate Report – Warmer Means Wetter

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August 28, 2017 Weather and Climate Report – Warmer Means Wetter

More Than 50 Percent Of Properties In Houston At High And Moderate Risk Of Flood Are Not In Designated Flood Zones

Total

Portion in Nino 3.4 Measurement Area

LAND

LAND

0

0

LAND

LAND

0

0

170E

140W

45

30

140W

135W

5

5

135W

110W

130W

LAND

20

5

130W

110

20

5

E. Relevant Recent Articles and Reports

G. Table of Contents of Contents for Page III of this Report – Global Warming Which Some Call Climate Change.

H. Useful Background Information

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