August 7, 2017 Weather and Climate Report – Short Monsoon Break – East Cool

Written by Sig Silber

The forecast is for a short (perhaps one week or less) break in the Southwest Monsoon especially as it impacts Arizona and Southern California. NOAA adopts new color coding which complicates knowing when their forecast was off because it is now harder to interpret the forecast maps. Very clever! Death Valley sets World Temperature Record. PDO turns negative. NOAA “adjusts” ONI values that were prepping for an El Nino call. Wavenumber – 5 suggests rapid changes.

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The Seasonal Outlook Update Report was published on Saturday July 22 and 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.

NOAA  “Adjusts” the ONI Record.

Forecast Summary with a Focus on the Southwest Monsoon.

	Temperature	Precipitation
6 – 10 Day
8 – 14 Day

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.

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.

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

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. Franklin may in two weeks reinvigorate the Southwest Monsoon.

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.

Now looking at the Day 5 Jet Stream Forecast.

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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.

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.

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 7, 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 7, 2017 was 3 out of 5).

Looking further out.

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.

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 7, 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 7, 2017 was 3 out of 5)

Looking further out.

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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.

Here is the NOAA discussion released today August 7. 2017

6-10 DAY OUTLOOK FOR AUG 13 – 17 2017  

TODAY’S DYNAMICAL MODELS ARE IN FAIRLY GOOD AGREEMENT ON THE PREDICTED MID-TROPOSPHERIC FLOW PATTERN ACROSS THE FORECAST DOMAIN. A ZONAL WAVE NUMBER-5 PATTERN IS EXPECTED OVER THE MIDDLE AND HIGH LATITUDES OF THE NORTHERN HEMISPHERE, WHICH REPRESENTS A CONSIDERABLE AMOUNT OF SHORTER-WAVELENGTH ACTIVITY. THIS, IN TURN, FAVORS MORE UNCERTAINTY IN THE TIMING OF INDIVIDUAL SHORTWAVE FEATURES EMBEDDED WITHIN THE MEAN FLOW. THE MANUAL 500-HPA HEIGHT BLEND DEPICTS A MEAN TROUGH OVER ALASKA, AND A RIDGE OVER THE EAST-CENTRAL PACIFIC. WHERE THESE TWO FEATURES MEET OVER THE GULF OF ALASKA, THERE IS AN ENHANCED HEIGHT GRADIENT, AND ENHANCED WESTERLY FLOW ALOFT. THIS TROUGH IS APPARENTLY FORCED TO SPLIT INTO TWO TROUGHS, ONE ON EITHER SIDE OF THE RIDGE, WHICH HELPS CONTRIBUTE TO THE HIGHER ZONAL WAVENUMBER MENTIONED ABOVE.  [Editor’s note: I am not a meteorologist but I read the maps differently and do not see what NOAA is reporting.  But to a large extent it matters not if we have a split trough or if there were two troughs from the get-go which is what I have seen looking at the relevant graphics each day this week]. NORTH AMERICA IS ANTICIPATED TO BE UNDER A TROUGH-RIDGE-TROUGH PATTERN, WITH CONSIDERABLE AMPLITUDE. POSITIVE HEIGHT ANOMALIES IN EXCESS OF +180 METERS ARE FORECAST IN THE VICINITY OF NORTHERN HUDSON BAY. THE ECMWF ENSEMBLE MEAN CONTINUES TO OUTSCORE THE OTHER DYNAMICAL MODELS, AND WAS THEREFORE GIVEN THE HIGHEST WEIGHT IN THE MANUAL HEIGHT BLEND. THE VARIOUS SPAGHETTI MAPS (5820 METER LEVEL) DEPICT LOW SPREAD WITH REGARD TO THE PREDICTED TROUGHS OVER THE WESTERN AND EASTERN THIRDS OF NORTH AMERICA, THOUGH MODERATE TO HIGH SPREAD IS PREDICTED WITH REGARD TO THE EXPECTED RIDGE OVER CENTRAL NORTH AMERICA.  

ODDS OF BELOW NORMAL TEMPERATURES ARE ELEVATED OVER MOST OF ALASKA, AND FROM APPROXIMATELY THE CENTRAL AND SOUTHERN ROCKIES EASTWARD TO THE APPALACHIANS. THIS IS GENERALLY DUE TO THE FORECAST PROXIMITY OF 500-HPA TROUGHS AND NEAR TO BELOW NORMAL HEIGHTS. ABOVE NORMAL TEMPERATURES ARE FAVORED FROM THE NORTHERN ROCKIES SOUTHWESTWARD ACROSS CALIFORNIA, SOUTHERN TEXAS, FLORIDA AND THE IMMEDIATE SOUTHERN ATLANTIC COAST, COASTAL NEW ENGLAND, THE SOUTHERN ALASKA PANHANDLE, AND THE ALEUTIANS. THIS IS GENERALLY ATTRIBUTED TO NEAR OR MODESTLY ABOVE NORMAL HEIGHTS NEAR AND TO THE SOUTH OF PREDICTED BAROCLINIC ZONES, AND/OR RELATIVELY WARM SEA-SURFACE TEMPERATURES.

ODDS OF BELOW NORMAL PRECIPITATION ARE FAVORED OVER THE WESTERN AND CENTRAL GREAT LAKES REGION, IN THE SUBSIDENCE REGION WEST OF A TROUGH AXIS. ABOVE NORMAL PRECIPITATION IS FAVORED OVER MOST OF THE CONUS, AND ALL BUT SOUTHWESTERN PORTIONS OF ALASKA. THIS IS ATTRIBUTED PRIMARILY TO MOIST FLOW IN ADVANCE OF MID-LEVEL TROUGHS, AND THE PROXIMITY OF BAROCLINIC ZONES.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO FAIRLY GOOD MODEL AGREEMENT, OFFSET SOMEWHAT BY THE INCREASED ZONAL WAVENUMBER AND THE SPREAD MAPS.  

8-14 DAY OUTLOOK FOR AUG 15 – 21 2017 

TODAY’S ENSEMBLE MEAN SOLUTIONS FOR WEEK-2 ARE IN REASONABLE AGREEMENT, AND SHOW GOOD CONTINUITY WITH THE 6-10 DAY PERIOD. MOST MODEL RUNS PREDICT A DEAMPLIFIED FLOW PATTERN ACROSS THE FORECAST DOMAIN, WITH THE EXCEPTION OF THE LAST 3 RUNS OF THE DETERMINISTIC GFS (0Z, 6Z, AND 12Z), WHICH CONTINUE TO FORECAST A HIGH-AMPLITUDE FLOW PATTERN.  

THE PREDICTED WEEK-2 TEMPERATURE OUTLOOK DEPICTS A COOLER SOLUTION (THAN THE 6-10 DAY TEMPERATURE OUTLOOK) ACROSS MUCH OF THE NORTHWESTERN QUARTER OF THE CONUS, AS A TROUGH IS EXPECTED TO PUSH ACROSS THAT REGION. SOME WARMING IS ALSO INDICATED ACROSS THE FAR NORTHERN BORDER STATES, EAST OF THE CONTINENTAL DIVIDE. THIS IS CONSISTENT WITH CPC’S TEMPERATURE CONSOLIDATION FORECAST, AND THE AUTO-BLEND TEMPERATURE FORECAST. THE WEEK-2 PRECIPITATION OUTLOOK ALSO DIFFERS FROM ITS 6-10 DAY COUNTERPART IN SEVERAL WAYS. THE FAVORED AREA OF BELOW NORMAL PRECIPITATION OVER THE GREAT LAKES IN THE 6-10 DAY PERIOD BECOMES MORE UNCERTAIN DURING WEEK-2, WARRANTING A FORECAST OF NEAR NORMAL PRECIPITATION. THE HIGHER PROBABILITIES FOR ABOVE NORMAL PRECIPITATION FROM THE CENTRAL AND SOUTHERN PLAINS ACROSS THE LOWER MISSISSIPPI VALLEY HAVE BEEN REDUCED CONSIDERABLY DUE TO INCREASED DIFFERENCES IN MODEL GUIDANCE.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: NEAR AVERAGE, 3 OUT OF 5, DUE TO REASONABLE MODEL AGREEMENT AND CONTINUITY WITH THE 6-10 DAY OUTLOOK.

THE NEXT SET OF LONG-LEAD MONTHLY AND SEASONAL OUTLOOKS WILL BE RELEASED ON  AUGUST 17

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.

(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 July 28 to August 12 which is only 15 days which is very tight set of analogs. 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 4. These analogs are centered on 3 days and 4 days ago (August 3 or August 4). So the analogs could be considered to be in sync with the calendar meaning that we will be getting weather that we would normally be getting this time of the year. For more information on Analogs see discussion in the GEI Weather Page Glossary.

There are seven ENSO Neutral Analogs and two La Nina analogs. The phases of the ocean cycles of the analogs are most consistent with McCabe A which is the wet scenario for the Southwest and Great Lakes area and to the east. Thus I am less confident than NOAA about their 6 – 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.

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.

The Monthly Seasonal Outlook Update which we published Saturday June 17 can be accessed by clicking here. It looks out 15 months for NOAA (the next month plus 14 more) and for JAMSTEC three three-month periods which right now is through February 2018. So it is a very useful reference and it gets updated each month. We will publish an Update on Saturday July 22. 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.

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 July 29, 2017

And the 30 Days ending August 5, 2017

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

Forecast for Today

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

Precipitation

Looking Out a Few Months

Here is the precipitation forecast from Queensland Australia:

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

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.

The categorization of the four week change in the anomalies.

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.

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

Now let us look at the Western Pacific in Motion.

C. Progress of ENSO

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.

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.

My Calculation of the Nino 3.4 Index

So as of Monday August 7, in the afternoon working from the August 6 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.

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.

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 El Nino it is the graphic of choice.

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). 

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Now for a more detailed look (there is some redundancy with the above graphic). Notice by the date of the graphic (dated August 1, 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.

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.

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

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.

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 July 19 CPC/IRI  fully model-based report is shown on the right. The earlier July 13 IRI/CPC Meteorologist survey is shown on the left.

Here is the primary NOAA model.

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 0.5C down to near Zero C but rebounding just a bit.

Forecasts from Other Meteorological Agencies.

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

Discussion Issued July 30, 2017

Tropical Pacific remains ENSO-neutral

The El Niño-Southern Oscillation (ENSO) remains neutral. All climate models surveyed by the Bureau indicate the tropical Pacific Ocean is likely to stay ENSO-neutral for the rest of 2017.

Sea surface temperatures (SSTs) in the central tropical Pacific have cooled over the past fortnight, but remain slightly warmer than average, and well within the neutral range. The 30-day Southern Oscillation Index (SOI) has been somewhat volatile over the past two months, but remains neutral. Other indicators

Here is the JAMSTEC June 1 forecast of the Nino 3.4 values which are the most looked at index used to forecast El Nino.

Here is the discussion that corresponds to the JAMSTEC July 1 Nino 3.4 Forecast. We will issue our analysis of the NOAA and JAMSTEC Seasonal Outlooks on Saturday July 22.

Jul. 13, 2017

Prediction from 1st Jul., 2017

ENSO forecast:

A slightly warmer-than-normal sea surface temperature is predicted for the whole tropical Pacific. This condition will persist until boreal winter. Then, it will return into a neutral state by next spring.

Indian Ocean forecast:

All ensemble members of SINTEX-F continue to predict a positive Indian Ocean Dipole [Editor’s Note: The Australian BOM disagrees see BOM graphic and discussion below] ; 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 and central U. S. 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, 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 moderately warmer-than-normal and drier-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 July 30, 2017

The Indian Ocean Dipole (IOD) is neutral. The weekly index value to 30 July was +0.1 °C.  Four out of six climate models used by the Bureau predict the IOD will remain neutral for winter–spring of ENSO, such as cloudiness near the Date Line and trade winds also remain at neutral levels.

Two of the six climate models suggest positive IOD thresholds could be reached in the coming months but only one model maintains these values long enough to be considered a positive IOD event. Positive IOD events are typically associated with below average winter and spring rainfall over central and southern Australia.

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

D. Putting it all Together.

At this time there is reduced interest as to whether or not this Summer and Fall will be El Nino situations. It would seem that the chances of other than a marginal El Nino are fairly low.

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.

E. Relevant Recent Articles and Reports

Weather in the News

Nothing to Report.

Weather Research in the News

Wavenumber – 5 and West Coast Winter Drought (Seems NOAA is fascinated by this even though the research applies to winters).

Global Warming in the News

Death Valley Sets World Monthly Temperature Record

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. 

Click for Source

Interaction between the MJO and ENSO

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

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.

ONI Recent History

The Apr/May/Jun preliminary was reported as +0.5. and now “adjusted” to 0.4. May/June/July has just been released at 0.3. This means that the NOAA El Nino watch is over. The full history of the ONI readings can be found here. The MEI index readings can be found here.