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posted on 07 November 2017

November 6, 2017 Weather and Climate Report

Written by Sig Silber

The Active Phase of the MJO has played out. We now have a pattern in the short term of high pressure in Mexico and a trough off the coast of Oregon and Washington State the combination controlling the path of Pacific Storms. There is some thought that the Arctic Oscillation (AO) may go into a Negative Phase where northern cold air can move into CONUS. This is discussed in this week's report. A new government climate study, the Fourth National Climate Assessment (NCA4) has been released but we will report on that separately as it will take some time to fully analyze it and our assessment will include a fair number of graphics from that report. 


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This is a difficult graphic to follow but I thought it was best to select one than four to make the point.

November 6  Low level Wind anomalies

There are two ways to look at this graphic. One is to follow the little dashed lines that NOAA has provided for those who are graphically challenged or to just look at it and form your own conclusions. Either way is good. What you can see is that the pattern after October 12 or so is different. 850 hPa means just under a mile up. So it is not impacted by surface winds or the temperature of the ocean water. But it is not up there with the jet stream. We discussed the MJO last week. The brown is the lesser easterlies or actual westerlies that have shifted the La Nina cool water further east than the Nino 3.4 measurement area giving us a non-La Nina reading this week. One dashed line shows the track of the Easterlies and the next dashed line is the  track of the westerlies. The MJO is in-between. Remember the Hovmoeller diagram is like a paper tape that ratchets up after the current day's readings are recorded. so you  kind of read it by looking at that dashed line sloping to the right and down. The Active Phase of the MJO is over now. It was less strong than anticipated but had impacts. it will be back but right now we are still in it but in the dry not wet phase.

A. Now we focus on Alaska and CONUS (all U.S.. except Hawaii)

I am starting with a summary of small images of the three short-term maps first for temperature and then for precipitation 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. Later in the article for those with sufficient interest, 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.

There is also a full description of the factors determining the maps shown next and a detailed analysis of the ENSO situation which so dramatically impacts the forecasts below.

First Temperature

6 - 10 Day Forecast Temperature

Transitioning from the 6 to 10 day outlook on the left to the 8 to 14 day outlook on the right         →

8 - 14 Day Temperature

Zonal.shift to the east. But a bit different for Alaska.

To the right is the week 3 and 4 Forecast.

There are now two warm anomalies and two cool  anomalies. Typical La Nina North/South Divide. Some thought of AO- pushing the  pattern to the south   →

3 - 4 Week Temperature

                     ↑

←  The transition from the 8 -14 day forecast shown above to the week 3/4 shown to the left seems feasible.
 

 

And then Precipitation

6 - 10 Day Forecast Precipitation Transitioning from the 6 to 10 day outlook on the left to the 8 to 14 day outlook on the right.         → 8 - 14 Day Precipitation

Pattern is fairly stagnant. Some movement to the east but not as fast as the temperature.

To the right is the week 3 and 4 Experimental Forecast.          →

Notice the dry Southeast and wet northern coasts.

 3 - 4 Week Precipitation

                        ↑

←  The transition from the 8 -14 day forecast shown above  to the week 3/4 shown to the left seems to be feasible.

 

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.

Eastern Pacific Animation

You can see moisture approach CONUS from the Pacific but where will it enter CONUS?

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.

Water Vapor Imagery

Tonight, Monday evening November 6, 2017, as I am looking at the above graphic, you do not see very much water vapor. There is more up in Canada.

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.

Current Jet Stream

One sees a mostly  zonal flow (directly across CONUS) rather than meridional flow (up and down higher to lower latitude and vice versa...planetary waves). The situation in Canada is different. 

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. You can convert this graphic into a flexible forecasting tool by clicking here. One can obtain views of different geographical areas by clicking here.

 Center for Western Weather and Water Extremes, Scripps/UCSD.

You see some activity from the southern branch of the jet stream.

Day One CONUS Forecast

Day 1 Forecast Map

Day Two CONUS Forecast

Day 2 Forecast

You can see SNOW forecast for Montana and the Dakotas. This is not just mountain snow.

60 Hour Forecast Animation

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.

current highs and lows

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

Eastern Pacific Two Day Tropical Weather Outlook

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 (new) tropical events are expected to appear in this graphic during the next 48 hours. 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.

Day 6 Highs and Lows

When I look at this Day 6 forecast, there is a huge Low over the Bering Sea. The surface central pressure is 996 hPa. There is also a Low approaching Kamchatka with surface central pressure of 992 hPa.  And you can also see another Low off of British Columbia with surface central pressure of 1008 hPa. And for good measure we see the Hawaiian High with surface central pressure of 1020 hPa or is it the 1036 High. The Low off of British Columbia creates a path for Pacific Storms to enter the Northwest Coast. The High over Mexico prevents this moisture from moving far down into the Great Basin. There is also a huge High over the Northeast with central surface pressure of 1036 hPa. This graphic which is a forecast for Day 6 will have updated by the time you read it. These feature are moving very rapidly. So my advice is to ignore my commentary and just look at the graphic. The commentary is useful mainly as a guide to what to look for but it is changing so quickly. In the future, I may try a different approach to suggesting what to look for depending on the time of the year.

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 by one weather forecasting model.

Jet Stream Five Days Out .

You can again see both the Polar and to a limited extent the Southern Jet Streams. It appears to be mostly zonal flow across CONUS. There is a weak trough passing the Rocky Mountains on Day  5.

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.

air pressure and altitude

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.

Short term forecasts

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

Seven Day WPC Quantitative precipitation forecast

We see mostly small pockets of heavy QPF in two areas one the Northwest and the other the eastern half of CONUS.

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 generally 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.

7 Day 500 MB Geopotential Forecast

What we see for Day 7 is an Eastern CONUS trough. We stil have that High in Mexico. And you can see the next Trough ready to enter off British Columbia.  Remember this is a Day 7  forecast.
Note the 540 Thickness Line re the above discussion of thickness and snow likelihood. We are this week NOT down to 540 so areas north of this snowline have a good chance to have snow in valleys not just mountains.  But that means for Day 7 mostly in Canada not CONUS. Thickness lines near or over 600 (which we generally do not have this time of the year) tend to suggest very warm temperatures. Sometimes Meteorologists work with the 500 mb heights which provide somewhat similar readings to the "Thickness" lines but IMO provide slightly less specific information.

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

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

6 - 10 Day Temperature Outlook

8 - 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on November 6, 2017 was 3 out of 5).

8-14 Day Temperature Outlook

Looking further out.

Experimental Week 3-4 Temperature Outlook

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.

November Temperature Outlook Updated on October 31, 2017

Below 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.

NDJ 2017 - 2018 Temperature Outlook Issued on October 19, 2017

Now - Precipitation

6 - 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on November 6 was 4 out of 5)

6 - 10 Day Precipitation Outlook

8 - 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on November 6, 2017 was 3 out of 5)

Current 8 - 14 Day Precipitation Outlook

Looking further out.

Weeks 3 and 4 Experimental Forecast..

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.

November 2017 Precipitation Outlook Updated on October 31, 2017

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.

NDJ 2017-2018 Precipitation Outlook Issued on October 19,  2017

Here is the 6 - 14 Day NOAA discussion released today November 6, 2017 and the  Week 3/4 discussion released Friday November 3, 2017

6-10 DAY OUTLOOK FOR NOV 12 - 16 2017

TODAY'S DYNAMICAL MODEL SOLUTIONS ARE IN GOOD AGREEMENT ON THEIR 500-HPA CIRCULATION FORECASTS FOR THE 6-10 DAY PERIOD OVER THE NORTH AMERICAN REGION. A STRONG RIDGE IS FORECAST OVER THE ALEUTIANS AND BERING SEA, WHILE A TROUGH IS PREDICTED IN THE NORTH PACIFIC NEAR THE ALASKA PANHANDLE AND PACIFIC NORTHWEST. ABOVE NORMAL 500-HPA HEIGHTS ARE PREDICTED OVER THE SOUTHWEST, THE CENTRAL CONUS, AND THE NORTHEAST. ENSEMBLE SPREAD IS RELATIVELY LOW INDICATING GOOD AGREEMENT AMONG MEMBERS ON THE CIRCULATION PATTERN.

ABOVE NORMAL TEMPERATURES ARE MOST LIKELY FOR WESTERN ALASKA WITH POSITIVE 500-HPA HEIGHT ANOMALIES UNDER THE PREDICTED RIDGE. BELOW NORMAL TEMPERATURES ARE LIKELY FOR SOUTHEASTERN ALASKA, INCLUDING THE ALASKA PANHANDLE, AND PARTS OF THE PACIFIC NORTHWEST UNDER BELOW NORMAL 500-HPA HEIGHTS ASSOCIATED WITH A PREDICTED TROUGH. ABOVE NORMAL TEMPERATURES ARE MOST LIKELY FOR MUCH OF THE REMAINING AREAS OF THE CONUS UNDER PREDICTED ABOVE NORMAL 500-HPA HEIGHTS. NEAR NORMAL TEMPERATURES ARE MORE LIKELY FOR PARTS OF THE NORTHEAST CONUS WITH PREDICTED TROUGHING AND POTENTIAL BELOW NORMAL TEMPERATURES EARLY IN THE 6-10 DAY PERIOD.

ABOVE NORMAL PRECIPITATION IS LIKELY FOR NORTHERN ALASKA AND THE ALASKA INTERIOR, WITH PREDICTED NORTHERLY MID-LEVEL FLOW, WHILE BELOW NORMAL PRECIPITATION IS MORE LIKELY FOR THE SOUTHERN COAST OF ALASKA. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST REGION AHEAD OF THE PREDICTED TROUGH OVER THE NORTH PACIFIC. THE PROBABILITIES OF ABOVE NORMAL PRECIPITATION ARE SLIGHTLY ELEVATED FOR THE 6-10 DAY PERIOD AVERAGE OVER THE NORTHEASTERN AREAS OF THE CONUS, INCLUDING THE OHIO VALLEY, MID-ATLANTIC, AND NEW ENGLAND, WITH A TROUGH AND PRECIPITATION FORECAST EARLY IN THE PERIOD.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO GOOD MODEL AGREEMENT ON THE EXPECTED CIRCULATION PATTERN, LOW ENSEMBLE MEMBER SPREAD, AND FAIRLY GOOD AGREEMENT AMONG THE TEMPERATURE AND PRECIPITATION TOOLS.  

8-14 DAY OUTLOOK FOR NOV 14 - 20 2017   

THE OVERALL 500-HPA CIRCULATION PATTERN PREDICTED FOR THE WEEK 2 PERIOD CHANGES LITTLE FROM THE 6-10 DAY PERIOD FORECAST, HOWEVER, ENSEMBLE SPREAD INCREASES SUBSTANTIALLY, INDICATING GREATER FORECAST UNCERTAINTY. SOME RETROGRESSION OF A PREDICTED TROUGH OVER SOUTHEASTERN ALASKA IS INDICATED BETWEEN 6-10 DAY AND WEEK 2 PERIODS BY ALL ENSEMBLE MEAN SOLUTIONS. MEAN 500-HPA HEIGHT ANOMALIES ARE SOMEWHAT WEAKER OVER THE CONUS IN THE WEEK 2 FORECASTS, RELATED TO INCREASING SPREAD AMONG ENSEMBLE MEMBERS.

BELOW NORMAL TEMPERATURES ARE MOST LIKELY FOR A LARGER AREA OF SOUTHEASTERN ALASKA WITH DECREASING PREDICTED 500-HPA HEIGHTS. ABOVE NORMAL TEMPERATURES REMAIN MOST LIKELY FOR PARTS OF THE WESTERN ALEUTIANS, THE NORTHWEST COAST, AND THE NORTH SLOPE. BELOW NORMAL TEMPERATURES REMAIN MOST LIKELY FOR PARTS OF THE PACIFIC NORTHWEST WITH PREDICTED BELOW NORMAL 500-HPA HEIGHTS. ABOVE NORMAL TEMPERATURES ARE LIKELY FROM CENTRAL AND SOUTHERN CALIFORNIA, ACROSS THE SOUTHWEST, AND FOR THE EASTERN TWO-THIRDS OF THE CONUS, UNDER PREDICTED ABOVE NORMAL 500-HPA HEIGHTS AND MEAN ZONAL FLOW. THE PROBABILITIES OF ABOVE NORMAL TEMPERATURES HAVE INCREASED FOR THE NORTHEAST, WHERE MODEL FORECASTS INDICATE TROUGHING IS LESS LIKELY INTO THE WEEK 2 PERIOD. 

ABOVE NORMAL PRECIPITATION IS MOST LIKELY ACROSS MUCH OF THE NORTHERN TIER OF THE CONUS, FROM THE PACIFIC NORTHWEST TO THE GREAT LAKES REGION, WITH ZONAL  FLOW INDICATED AHEAD OF A PREDICTED TROUGH. BELOW NORMAL PRECIPITATION IS INDICATED FOR MOST OF THE REMAINING AREAS OF THE CONUS, EXCEPT FOR CLIMATOLOGICALLY DRY AREAS OF THE SOUTHWEST WHERE NEAR NORMAL PRECIPITATION IS INDICATED. AREAS OF SOUTHERN ALASKA THAT ARE WEST OF THE MEAN LOCATION OF THE RETROGRESSING TROUGH AXIS, ARE PREDICTED TO HAVE BELOW NORMAL PRECIPITATION IN THE WEEK 2 PERIOD. ABOVE NORMAL PRECIPITATION IS LIKELY FOR PARTS OF THE NORTH  SLOPE UNDER PREDICTED NORTHERLY FLOW. 

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOUT AVERAGE, 3 OUT OF 5, DUE  TO GOOD AGREEMENT AMONG THE ENSEMBLE MEAN SOLUTIONS ON THE 500-HPA CIRCULATION  PATTERN DURING WEEK 2, OFFSET BY LARGE SPREAD AMONG THE ENSEMBLE MEMBERS.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  NOVEMBER 16

Week 3-4 Forecast Discussion Valid Sat Nov 18 2017-Fri Dec 01 2017

The MJO weakened considerably over the past few days, following an event that generated the highest amplitude projections on the CPC velocity potential based index over the past six months. Hovmoller diagrams of OLR anomalies reveal constructive interference between a Rossby wave and the low frequency state resulting in a return of enhanced convection over the Maritime Continent, which is out of phase with the intraseasonal signal. Therefore, the MJO's role in the evolution of the tropical convective pattern - and any poleward midlatitude response - is more uncertain for the Week 3/4 period. The low frequency state which tilts towards cold ENSO conditions may influence the pattern, but any ENSO-related impacts would be more pronounced later in the boreal winter season.

Dynamical model forecasts during the Week-2 period have recently depicted a potential transition towards a negative-AO pattern, with generally above-normal height anomalies over the Arctic, and a quasi-annular pattern of below-normal heights across the northern mid-latitudes. These forecasts suggest the potential for the buildup of a substantial cold air mass over western and central Canada, which increases the potential for cold air outbreaks across the northern tier of the CONUS. During the Week 3/4 period, the CFS and ECMWF both depict below-normal heights and temperatures across much of Canada and an upstream ridge over the Aleutians. Downstream of this, the CFS forecasts a ridge axis along the eastern seaboard, while the ECMWF centers the ridge across the Southwest. The JMA height anomaly pattern is out of phase with the other models, depicting a positive-AO pattern, although the mid-latitude pattern is roughly similar to the CFS. Blends of the dynamical model height patterns show weak troughing over the north-central and northwestern CONUS, with positive height anomalies across the southern tier and East.

The dynamical model temperature forecasts consistently depict below-normal temperatures across much of Canada and the northern Plains, with the CFS and JMA extending the below-normal temperatures to the Northwest. Consistent with their height anomaly patterns, the CFS and JMA forecast anomalous warmth across much of the East and the south-central CONUS. The ECMWF maintains the highest probabilities for above-normal temperatures across the Four Corners region, with much less warmth (generally near normal) across the East, due to a height pattern that may allow for periods of cold air intrusion. Due to the weak MJO and ENSO states, statistical guidance generally reflects the long-term trend. Based on the model guidance, below-normal temperatures are favored across much of Washington eastward to the upper-Mississippi Valley, with the highest probabilities over the northern Plains. Above-normal temperatures are favored across the southern tier, with the highest probabilities across the Four Corners, which is consistent with the ECMWF solution. Equal chances for above- or below-normal temperatures are maintained across the Northeast, with above-normal temperatures favored across parts of the mid-Atlantic. Height patterns favoring anomalous northerly flow support a potential for below-normal temperatures across southeastern Alaska, while above-normal SSTs and delayed sea-ice buildup favor above-normal temperatures along the North Slope region and western coastal areas.

The precipitation outlook is complex, so consensus among the dynamical models where it could be found, and where it was reasonably consistent with the favored height pattern, was used to guide the outlook. The potential for cold high pressure to spill into the northern Plains supports enhanced chances for below-normal precipitation across much of the Plains, although equal chances for above- or below-normal precipitation were maintained across both the high Plains due to a potential for upslope snow events, and the Great Lakes region due to possible lake-effect snow events. Dynamical model forecasts consistently depict suppressed rainfall across the Southeast as well. The dynamical model forecasts suggest a favored storm track extending from the Ohio Valley through New England, with the ECMWF depicting a much smaller footprint than the CFS, so enhanced probabilities for above-normal precipitation were added to the outlook across the eastern Ohio Valley through the Northeast. The CFS and ECMWF both show enhanced precipitation across the Northwest, and a height pattern favoring anomalous offshore flow supports enhanced chances for below-normal precipitation for much of Alaska.

Persistent anomalously warm sea surface temperatures around the Hawaiian islands continues to support enhanced chances for above-normal temperatures. The CFS and ECMWF both support enhanced rainfall across the northwestern islands, with near-normal or suppressed rainfall across the big island.

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

Nov 2, 1971 La Nina - -  
Nov 9, 1985 Neutral + - Right after a La Nina
Nov 15, 1986 El Nino + - Modoki
Oct 22, 1991 El Nino + - Modoki
Oct 31, 2003 Neutral + +  
Nov 5, 2003 Neutral + +  

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

The spread among the analogs from October 22 to November 15 is 24 days which is tighter than last week. 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 November 3. These analogs are centered on 3 days and 4 days ago (November 3 or November 4). So the analogs could be considered to be in sync with respect to weather that we would normally be getting right now. For more information on Analogs see discussion in the GEI Weather Page Glossary.

Including the duplicate analogs, and I have not shown the number of them, there are three El Nino analogs, five Neutral Analogs and two La Nina analogs. The phases of the ocean cycles of the analogs are most consistent with McCabe Condition A and least consistent with McCabe Condition D. This provides little guidance for agreeing or disagreeing with the NOAA 6 - 14 Day forecast.

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.

McCabe Maps modified to include the subtitles

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 Conditions from 2007 report with labels corrected with authors permission

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

On Saturday October 21, we published our Three to Four Season Outlook and compared the forecasts of NOAA and JAMSTEC for the first three seasons namely Fall, Winter, and Spring. This report can be accessed here. There will be a new Seasonal Outlook issued by NOAA on November 16 which we will report on November 18.

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 October 28, 2017

October 28, 2017 30 Day Temperature and Precipitation Departures

Overall both the temperature and precipitation anomalies have moderated. There is a new dry area in the North Central states. 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 November 4, 2017

November 4, 2017 30 Day Temperature and Precipitation Departures

 Lots of dry in Southwest. More warm there also. 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

Same as above but for July

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 graphics 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 graphic 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 moving into November so we are 2/3rds 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

Temperature at 2 Meters

Notice that below the map there is a tabulation of magnitude of the current anomalies by region. Overall it is warmer than climatology. The anomalies at the Poles are very high. Notice the cool/warm divide in North America.

Maine Reanalyer

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 (a small part of) extreme Southeast Asia but including most of India. South America south of the ITCZ is mostly wet until you get south of Brazil. Africa north of the Equator and the ITCZ is mostly dry but the wet zone extends fairly far south. Australia is dry. Western Europe is wet.

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

BOM Current Temperature Wedensday

Please remember this graphic updates every six hours so the diurnal pattern can confuse the reader. Brazil is forecast to be warm. Not so much for CONUS Northwest. The coast off of Peru is La Nina cool.

Precipitation

BOM World Preciptation  Wednesday

Notice that in the Day 6 Forecast northern South America is quite wet. The Hawaiian High may be displaced.

Looking Out a Few Months

Here is the precipitation forecast from Queensland Australia:

Consistently positive SOI  forecast for November to January  2017.- 2018

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 a change from a consistently near zero SOI  to a consistently positive SOI. CONUS now looks like a north south divide with the northern tier wet. Southern Africa is wet. Eastern Australia is 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 SST anomalies.

Mediterranean, Black Sea and Caspian Sea Western Pacific West of North America North and East of North America North Atlantic
Fairly Neutral.

Mostly slightly cool (from cyclones churning up the water).

Warm between Japan and China

Cool Kamchatka to but not including the Aleutians

Slightly warm off Baja

Warm off East Coast

Warm around Scandinavia,

Fram Strait cool but less so than last week.

Equator

Pacific cool east of 140E

SST Daily Anomalies
Africa West of Australia North, South and East of Australia

West of South America

East of South America

Warm west of North Africa and Spain.

Cool and extending way off-shore to the Northwest

Cool southwest

Warm east and southeast.

Cool, cool, cool

Cool east of 20S

Warm 30S to 50S

 

Then we look at the change in the anomalies.  Here it gets a little tricky as red does not mean a warm anomaly but a warming of the anomaly which could mean more warm or less cool and blue does not mean cool but more cool or less warm.

Mediterranean, Black Sea and Caspian Sea Western North Pacific West of North America East of North America North Atlantic

Western Mediterranean warming, Eastern Mediterranean cooling.

Cooling east of Southeast Asia.

Warming between Japan and Asia.

Cooling east Kamchatka

Cooling South of Alaska.

.

Warming offshore east of CONUS

Cooling Hudson Bay and  Great Lakes

Warming around Spain,

Warming south of Greenland and British Isles. .

Equator Warming Indian Ocean Pacific cooling east of 160W
Change in weekly anomalies November 6, 2017
Africa West of Australia North, South and East of Australia West of South America East of South America

Warming west of North Africa

Warming south of African and south and east of Madagascar

Fairly Neutral

Warming north and  east

Fairly neutral except  cool off 20S and warm off 40S.

.

Cooling 30S and slight warming south of 40S

 

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   +0.13 +0.17 +0.0
April   +0.52 +0.29 +0.2
May   +0.29 +0.32 +0.2
June   +0.18 +0.31 0.0
July   -0.54 +0.31 0.0
August   -0.67 +0.31 +0.4
September   -0.28 +0.35 +0.2
October   NA NA  0.0

 

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

Tropical Hazards

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 November 6 for what is shown as Week Two, the period November 8 to November 15, 2017, we see wet conditions* for the Maritime Continent , Somalia and near the Bay of Guinea. Dry conditions* are indicated for southern Central America. Bangladesh is an area with cyclonic likelihood*.

 * 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.

Western Pacific Tropical Activity

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 in order 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.

Current SST and wind anomalies

Location Bar for Nino 3.4 Area Above and Below

------------------------------------------------ A B C D E -----------------

 

The pattern now is very cold water to the south of the Equator with warm water to the north of the Equator. That means ENSO Neutral.

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

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)

NA

NA

0

0

+0.5C to +1C (marginal)

170W

158W

12

12

These Rows Below Show the Extent of ENSO Neutral Impacts on the Equator
0.5C or cooler Anomaly (warmish neutral)

158W

148W

10

10

0C or cooler Anomaly (coolish neutral)

148W

140W

8

8

These Rows Below Show the Extent of La Nina Impacts on the Equator.
-0.5C or cooler Anomaly

140W

132W

8

8

-1.0C or cooler Anomaly

132W

LAND

37

12

-1.5C or cooler Anomaly

LAND

LAND

0

0

-2.0C or cooler Anomaly

LAND

LAND

0

0

-2.5C or cooler Anomaly

LAND

LAND

0

0

 

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 November 6, in the afternoon working from the November 5 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 Nino 3.4 from TAO/TRITON Graphic

Anomaly Segment Estimated Anomaly
  Last Week This Week
A. 170W to 160W +0.4 +0.6
B. 160W to 150W +0.3 +0.5
C. 150W to 140W +0.0 +0.1
D. 140W to 130W -0.4 -0.4
E. 130W to 120W -0.5 -0.6
Total -0.2 +0.2
Total divided by five i.e. the Daily Nino 3.4 Index (-0.2/5 = 0.0 (0.2)/5 = 0.0

 

My estimate of the daily Nino 3.4 SST anomaly tonight is  which is  0.0 which is again a dead neutral ENSO valued. NOAA has reported the weekly Nino 3.4 to be -0.4 which is an ENSO Neutral value. Nino 4 is reported warmer at +0.1. Nino 3 is warmer at -0.6. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported warmer at -0.8 [Editor's Note: This appears to be in error. Not only does CDAS report a much lower value but just looking at Tao/Triton raises questions about this value]. 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. 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 had been declining. The same data in table form but going back a couple of more years can be found here.

The cool anomaly has shifted west this week and again records as La Nina.

Novermber 6, 2017 Nino Readings

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.

This overlaps with the next topic but I will show it here.

Equatorial (0 - 300) meter heat content As reported November 6, 2017

The discussion in this slide says it better than I could. One might compare the current reading to Oct/Nov 2016. Three weeks ago it looked a bit like the La Nina would have a short life with the anomaly having peaked, But not with the today's graphics. We may be at Peak La Nina. One week does not provide enough data to draw a sound conclusion.

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.

November 6, 2017 Equatorial Pacific SST Anomalies

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 shows the current readings. 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 this week less blue in the Nino 3.4 Measurement Area than least week especially in the Nino 3.4 Measurement Area. So the Nino 3.4 Index is likely to be neutral this week. You can see where La Nina took a vacation but it was a short vacation.

This next graphic is more focused on the Equator and looks down to 300 meters rather than just being the surface.

November 6, 2017 Upper Ocean Heat Anoma

The bottom of the Hovmoeller shows the current situation. It almost looks like a second Upwelling wave. It is shifted to the east. 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).

.November 6, 2017 Kelvin Wave Analysis.

Winds or currents are keeping most of the cool water just below the surface. There is cool water at depth from the 170W to LAND. The cool water is reaching the surface mostly east of 120W so it is not in the Nino 3.4 Measurement Area. But there is some cool water reaching the surface between 150W and 140W. We also see a growing warm water anomaly extending from the west to about 140E. This may well signal the end of this La Nina but it will take quite a while for that warm water to arrive in the Nino 3.4 Measurement Area. . 

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. Below is the pair of graphics that I regularly provide. The date shown is the midpoint of a five-day period with that date as the center of the five-day period. 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 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.

There is cold water from 170W to Land. To the west it is 200 meters deep. We now have warm water developing west of the Dateline. Soon it will be intruding into the Eastern Pacific Nino 3.4 Measurement Area.
Subsurface temperature Anomalies
The 28C Isotherm is at the Dateline, the 27C Isotherm is at 170W, the 25C Isotherm is at 145W.

 

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 and we have gone to a Weak La Nina thermocline.

Tracking the change.

Sepember 15, 2017 Subsurface Water Temperatures Equatorial Ocean Subsurface as of october30, 2017

 

I have "frozen" these two charts. The one on the left shows the situation as reported for September 15, 2017. The one on the right shows the situation now.  The situation is not much different east of the Dateline from the situation as reported for September 15, 2017. But west of the Dateline is looks a bit different. We will use the graphic on the left as a reference and see how the current situation changes over time.

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

Equatorial Temperature Simulation

Isotherm Simulation

And now Let us look at the Atmosphere.

Low-Level Wind Anomalies near the Equator

Here are the low-level wind anomalies.

Low Level Wlind Anomalies

We now see easterly anomalies in the Nino 3.4 Measurement Area which means that the cool water below the surface will be rising to the surface as the water on the surface is blown to the west.

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

OLR Anomalies Along the Equator

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 November 6 was reported as 7.84 which is a marginal La Nina value. The 90 Day Average was reported at 7.79 which is also a marginal La Nina value. Looking at both the 30 and 90 day averages is useful and right now both are in agreement with the 90 day lagging the 30 day as one would expect. But the decline in the 90 Day average needs to be watched.

 

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

Here is the primary NOAA model for forecasting the ENSO Cycle.

CFSv2 spread and bias correct ENSO forecast

This model is forecasting a La Nina. It probably is the most aggressive model re being so definitive about the ENSO Phase for this Fall and Winter.

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

CDAS Legacy System

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 -0.9C but recently moved back closer to 0C.

The CFS.v2 is not the only forecast tool used by NOAA. The CPC/IRI Analysis which is produced out of The International Research Institute (IRI) for Climate and Society at Columbia University is also very important to NOAA. Below is the October 12 and October 19 CPC/IRI ENSO Forecasts

CPC/IRI October 19, 2017 ENSO Forecast

As you can see there has been some recent change to limit the period where La Nina is favored to just the Fall and Winter. The CFS.v2 model holds the La Nina conditions for perhaps an additional two months.

Forecasts from Other Meteorological Agencies.

Australia POAMA ENSO model run

 

 

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

 

 

POAMA, run at the Bureau of Meteorology, generates a nine-month forecast each fortnight. The most recent model run (generated 5 November) indicates NINO3.4 will just touch on La Niña thresholds during the austral summer before warming again and returning to near average values by autumn 2018.

Here is the new JAMSTEC forecast issued on October 1, 2017

October 1, 2017 JAMSTEC Forecast

The discussion is available in the Seasonal Outlook we published on October 21 which can be accessed here.

Indian Ocean IOD (It updates every two weeks)

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

IOD POAMA Model Run

Discussion Issued November 5

The IOD is currently neutral with the weekly IOD index value (to 5 November) at –0.1 °C.

All six models favour a neutral IOD for the rest of 2017 and early 2018.

Indian Ocean Dipole events are typically unable to form between December to April. This is because the monsoon trough shifts south over the tropical Indian Ocean changing wind patterns, which prevents the IOD pattern from being able to form. It has little effect on Australian climate at this time of year.

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

IOD Measurement Regions

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 a La Nina is likely for this Winter and Spring. But the situation for next Summer is not yet clear.

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. The next El Nino may be the trigger.

E. Relevant Recent Articles and Reports

Weather in the News

Typhoon floods Vietnam

Weather Research in the News

Nothing to Report

Global Warming in the News

Blockbuster Assessment

Is it time to rent an Ark?

Watts Up With That?  Discovers the ENSO Cycle

Cornell University Researchers Discovers the PDO and also the AMO

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.

El Nino Zones

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 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.

Western Pacific Warm Pool

Click for Source

Interaction between the MJO and ENSO

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

El Nino La Nina MJO Active Phase MJO Inactive Phase Relationship of MJO and ENSO Eastern Pacific Easterlies Western Pacific Westerlies MJO Active Phase MJO Inactive Phase

  • Weaker
  • Stronger
  • Part of Decay Process
  • Counteracts Easterlies
  • Enhances Easterlies
  • Stronger
  • May Create or Stimulate the Onset of El Nino via Kelvin Waves
  • Weaker
  • Part of Decay Process
  • Strengthens Westerlies
  • Weakens Westerlies
  • More likely
  • Stimulates
  • Less likely and weak
  • Retards development of a new La Nina
  • Stimulates the Jet Stream
 
  • 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 and 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

November 6-, 2017 Revised Historical ONI Readins.

Note: Without fanfare the base climatology was changed from ERSST.V4 to ERSST.V5

The JAS reading was adjusted to -0.2 which remains an ENSO Neutral Reading and the new ASO reading of -0.4 is also an ENSO Neutral Reading. 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. Isotachs 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.]

Click here for a list of Sig Silber's Weather Posts

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