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posted on 03 August 2015

3 August 2015 Weather and Climate Report - NOAA Issues August Update - Perhaps Another Break in the Monsoon

Written by Sig Silber

NOAA updates their August Outlook with marginal changes. El Nino continues to strengthen but with no discernible impacts on CONUS despite heroic efforts by NOAA to conjure up such impacts. The Monsoon is at least temporarily ramping down. That may actually be to some extent an El Nino impact on Eastern Mexico but attribution is always difficult. El Nino provides increased Pacific moisture for the Monsoon but also reduces the differential between land and ocean temperatures so one might say that an El Nino can eat the Monsoon. Mostly it is pretty much normal summer weather for CONUS (usually contiguous U.S. but sometimes probably incorrectly interpreted to include Alaska). Indonesia is drying out. El Nino is a Worldwide Event and right now is mostly impacting other parts of the World. 

This is the Regular Edition of my weekly Weather and Climate Update Report. Additional information can be found here on Page II of the Global Economic Intersection Weather and Climate Report.

NOAA as usual at the end of a month updates their early update for the following month, in this case August, which they previously issued as is their normal schedule on the third Thursday of the month.

Here is the commentary that came with the update.

30-DAY OUTLOOK DISCUSSION FOR AUGUST 2015

SEA SURFACE TEMPERATURES (SSTS) CONTINUE TO BE MORE THAN ONE DEGREE C ABOVE NORMAL ALONG THE EQUATOR IN THE PACIFIC OCEAN FROM THE INTERNATIONAL DATE LINE EASTWARD TO THE SOUTH AMERICAN COAST. SST ANOMALIES ARE GREATER THAN +2.0 DEGREES C IN THE EAST PACIFIC FROM ABOUT 135 W LONGITUDE TO THE SOUTH AMERICAN COAST AND EXCEED +3.0 C EASTWARD OF 100 W LONGITUDE. THERE CONTINUES TO BE A LARGE AREA OF POSITIVE SST ANOMALIES OVER MUCH OF THE NORTH PACIFIC ALONG THE WEST COAST OF NORTH AMERICA. [Editors Note: Suggestive of a Positive PDO] SUBSURFACE OCEAN TEMPERATURES NEAR THE EQUATOR HAVE BEEN PERSISTENTLY ABOVE NORMAL TO DEPTHS EXCEEDING 100 METERS EAST OF THE INTERNATIONAL DATE LINE, CONTRIBUTING TO SUSTAINED POSITIVE SST ANOMALIES.  NEGATIVE OLR ANOMALIES ABOVE THE EASTERN PACIFIC TO THE NORTH OF THE EQUATOR INDICATE ANOMALOUSLY ACTIVE CONVECTION. ANOMALOUS LOW-LEVEL (850-HPA) WESTERLY WINDS EXTENDED FROM THE WEST PACIFIC TO THE EAST-CENTRAL EQUATORIAL PACIFIC. ANOMALOUS UPPER-LEVEL (200-HPA) EASTERLIES WERE OBSERVED OVER THE EAST-CENTRAL EQUATORIAL PACIFIC. THESE ATMOSPHERIC AND OCEANIC CONDITIONS INDICATE STRONG OCEAN-ATMOSPHERE COUPLING ASSOCIATED WITH EL NINO CONDITIONS.

THE MONTHLY UPDATE TO THE AUGUST 2015 U.S. CLIMATE OUTLOOK IS BASED LARGELY ON DYNAMICAL MODEL FORECASTS, INCLUDING WEATHER PREDICTION MODELS FOR THE FIRST WEEK IN THE MONTH, AS WELL AS THE NORTH AMERICAN ENSEMBLE FORECAST SYSTEM (NAEFS) AND THE REFORECAST-CALIBRATED GLOBAL ENSEMBLE FORECAST SYSTEM (GEFS) FOR THE SECOND WEEK, THE ECMWF ENSEMBLE PREDICTION SYSTEM FORECASTS FOR THE THIRD AND FOURTH WEEK, AND THE NCEP CLIMATE FORECAST SYSTEM (CFS) FOR THE FULL MONTH.

THE UPDATE TO THE AUGUST TEMPERATURE OUTLOOK INDICATES ONLY SMALL CHANGES TO THE TEMPERATURE PATTERN RELATIVE TO THE HALF-MONTH LEAD OUTLOOK. ENHANCED PROBABILITIES OF BELOW-NORMAL TEMPERATURES OVER THE SOUTHWEST EXTEND FURTHER NORTHWARD INTO THE CENTRAL ROCKIES AND NORTHERN PLAINS FOLLOWING CHANGES IN DYNAMICAL MODEL GUIDANCE. GUIDANCE ALSO INDICATES INCREASING LIKELIHOODS OF ABOVE-NORMAL TEMPERATURES FOR AN EXPANDED AREA OF EAST TEXAS AND THE SOUTHEAST.

THE UPDATE TO THE AUGUST PRECIPITATION OUTLOOK SHOWS ONLY SMALL CHANGES IN THE PREDICTED PRECIPITATION PATTERN COMPARED TO THE HALF-MONTH LEAD OUTLOOK. A LARGE AREA WITH ENHANCED PROBABILITIES OF ABOVE-MEDIAN PRECIPITATION FROM THE SOUTHWEST NORTHWARD INTO THE CENTRAL ROCKIES AND EASTWARD ACROSS THE CENTRAL PLAINS TO THE MISSISSIPPI RIVER EXTENDS FARTHER TO THE NORTH IN THE UPDATED OUTLOOK AS INDICATED BY MOST DYNAMICAL MODEL GUIDANCE, INCLUDING THE CFS. AN AREA OF GREATER PROBABILITIES OF BELOW-MEDIAN PRECIPITATION WAS REMOVED FROM THE PACIFIC NORTHWEST IN THE UPDATED OUTLOOK, AS MODEL GUIDANCE FOR THE FIRST TWO WEEKS OF AUGUST FORECASTS INCREASED PRECIPITATION AMOUNTS. AN AREA OF ENHANCED PROBABILITIES OF BELOW-MEDIAN PRECIPITATION FOR SOUTH FLORIDA WAS REMOVED FOLLOWING MODEL GUIDANCE FOR THE MONTH.

A useful way of looking at this is to compare the updated August outlook with the prior three - month outlook

Aug-Sep-Oct Update Issued July 31, 2015

One always wonders if the changes to the August Outlook suggest changes to the September and October Outlooks as the three month Outlook, which includes the early outlook for August, is not updated at the end of the month from their third Thursday issuance. We can see some minor changes in August that might carry over into September and October and you can see where they are by studying this graphic.

Switching from the Updated August Outlook to the Current (Right Now to 5 Days Out) Weather Situation:  

A more complete version of this report with daily forecasts is available in Part II. This is a summary of that fuller report. This link Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks will take you directly to that set of information but in some Internet Browsers it may just take you to the top of Page II where there is a TABLE OF CONTENTS and you may have to wait for a few seconds for your Browser to redirect to the selected section with that Page or if that process is very slow you can simply lick a second time within the TABLE OF CONTENTS to get to that specific part of the webpage.

First, here is a national 12 hour to 60 hour forecast of weather fronts shown as an animation. Beyond 60 hours, the maps are available at the link provided above.

current highs and lows

The explanation for the coding used in these maps, i.e. the full legend, can be found 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. You can see the location of the Four Corners area where Utah, Colorado, Arizona, and New Mexico meet. At this time of the year there is typically a high pressure system near that area and it is called the Four Corners High. When the Four Corners High is centered directly over the Four Corners area, it creates pretty much a block for the Sonoran Monsoon which only visits its northern neighbor when the highs and lows are located in a way that draws the moist air north. Small changes in the location of that feature make a big difference in the weather of probably about ten or more states. Note the Day 7 location of the Four Corners High is now projected to be in Texas which is a bit east of the most favorable location for the circulation to bring up warm moist air from Mexico. But this High moves around a lot so by the time you view this report, it most likely it will be located somewhere else. The models are moving it around run to run and each location results in a different circulation pattern plus the jet stream is involved although I am not showing those graphics here (but they are available on Page II of this Report). If you know where the High is, you can always imagine the clockwise circulation and how that might impact the movement of moisture in from the Gulf of Mexico and up from Mexico and in from the Gulf of California. So this graphic can be very very useful. And it auto-updates, I think every six hours. Even without a weather map, you generally can figure it out. Wind to your back, High to your right, Low to your left.

7 Day 500 MB Geopotential Forecast

In the Tropical Weather Outlook graphic below, notice that there is no Pacific Tropical Storm projected to be close enough to the coast to impact CONUS. That is why two weeks ago I raised the question as to a possible temporary break in the action. That is common in the Summer for CONUS. The Sonoran Monsoon which we commandeered and renamed the North American Monsoon or the Southwest Monsoon is a series of bursts and pauses in activity as it impacts the ten or so states in CONUS with the major impacts being with respect to New Mexico and Arizona. That break in the action occurred and after about a week or so the pause ended with the Monsoon regaining its impact on CONUS. But another weak period within the Monsoon may again occur in the near future. There seems to be an active debate on this within the meteorological community.

.Eastern Pacific Tropical Storms

The below graphic is harder to look at but provides more detail on the water vapor being generated by these storms and the normal summer action of the Southwest Monsoon. It covers a much larger area within CONUS so you can see where the moisture currently is and is going. At this point in time one still sees Monsoonal Moisture entering CONUS via New Mexico and Texas but local forecasters are projecting that this flow of moisture will soon be greatly reduced without clear guidance as to when the flow might resume.

Water Vapor Imagery

Looking at an even larger area, below is a view which highlights the surface highs and the lows re air pressure on Day 6 (Day 3 can be seen in Part II of this Report). The Eastern Pacific Subtropical High is no longer serving as a block to all storms attempting to move from the Pacific into CONUS. So for at least this week, we do not have to denigrate this feature by calling it the RRR. But it still plays a role in directing most of our weather north into Canada or along the Northern Tier of CONUS and it impacts the positioning of the Four Corners High and thus the strength and location of the Monsoon. The real action remains from the remnants of the cold air intrusion which first impacted the Great Lakes area and extended quite far south and this intrusion from Canada is to a large extent still dominating weather for a large part of CONUS. But this will gradually play out over the next two weeks.

Day 6 Weather Forecast

Case Study of a Forecasting Fiasco this Past Week

I would like to discuss excerpts from the NOAA discussion from Wednesday July 29. I realize this is rehashing past history but I found it interesting and important.

8-14 DAY OUTLOOK FOR AUG 06 - 12 2015 

DUE TO THE FAIRLY POOR MODEL SKILL SCORES AT THIS LEAD AND TIME OF YEAR, INCREASED ATTENTION IS PAID TO THE LOW-FREQUENCY CLIMATE BACKGROUND, WHICH IS HIGHLIGHTED BY THE ONGOING STRONG WARM ENSO EVENT. REGRESSIONS OF THE MONTHLY  NINO 3.4 SSTS WITH AUGUST 500-HPA HEIGHT, SURFACE TEMPERATURE, AND PRECIPITATION, SERVE AS A BASELINE AGAINST WHICH TO COMPARE MODEL FORECASTS.  THE FORECAST CIRCULATION OVER THE NORTH PACIFIC DURING WEEK-2 (AND THE 6-10 DAY PERIOD, FOR THAT MATTER) IS REMARKABLY CONSISTENT WITH THE PROMINENT FEATURES  OBSERVED IN THE WARM ENSO FOOTPRINT. THE GEFS-DERIVED SURFACE CLIMATE TOOLS ARE  MORE CLOSELY ALIGNED WITH THE SURFACE TEMPERATURE AND PRECIPITATION REGRESSION PATTERNS, SO AGAIN THE FIRST GUESS BLEND IS ALTERED TO RELY MORE HEAVILY UPON  THE GEFS-BASED TOOLS.

THE USE OF THE LOW-FREQUENCY STATE SHOULD YIELD INTERESTING RESULTS AS WE HEAD TOWARD A TIME OF YEAR WITH HISTORICALLY LOW FORECAST SKILL. IT IS IMPORTANT TO NOTE THAT THE MODELS DO NOT ALWAYS GENERATE EXTRATROPICAL TELECONNECTIONS MOST CONSISTENT WITH ENSO. TODAY'S COMPOSITE ANALOG PACKAGE OFF THE MANUAL BLEND IS ONLY WEAKLY TILTED TOWARD EL NINO EVENTS, SO THE ALIGNMENT OF THE MODELS' SURFACE FORECASTS WITH THE ENSO FOOTPRINT COULD BE SOMEWHAT COINCIDENTAL. NONETHELESS, OVER WEEK-LONG AVERAGED PERIODS, A STRONG ENSO EVENT COULD BE LEVERAGED STATISTICALLY TO ADD VALUE TO LOW-SKILL MODEL FORECASTS IN LATE SUMMER AND AUTUMN.   

And take a look at the analogs for that forecast.

Analog

Centered

Day

ENSO

Phase

PDO AMO Other Comments
1954 July 23 La Nina Neutral Neutral  
1957 July 21 El Nino - + Some think a Modoki
1957 July 31 El Nino - + Some think a Modoki
1975 Aug 1 La Nina - -  
1981 Aug 2 Neutral + -  
1996 Aug 4 Neutral + Neutral  
1996 Aug 5 Neutral + Neutral  
2008 July 20 Neutral - +  

 

And here is the 6 - 10 Day Precipitation Forecast on July 29

July 29, 2015 6 - 10 Day Precipitation Outlook

And here is the 6 - 10 Day Precipitation Forecast on July 30

July 30 6 - 10 Day Precipitation Outlook

Well in my way of thinking they kind of blew that forecast at last in the sense of lack of day to day consistency even recognizing that each day one day drops out of the 6 - 10 Day Outlook and another day gets included but I am shocked by some of what I read.

A.. ENSO is not properly described as a low-frequency cycle. It is a medium frequency cycle which repeats perhaps every 5 to 9 years on an irregular basis. The 60 year AMO and PDO are low-frequency cycles. This has been known since sometime in the nineties.

B. NOAA wants us to believe that ocean conditions on the days of the analog were consistent with El Nino conditions even though the dates of the analogs corresponded to dates when there was not an El Nino or in one case perhaps an El Nino Modoki. That is illogical.

C. There is no consistency in the analogs re the low-frequency cycles: the PDO and the AMO (which apparently NOAA is not even aware of or at least rarely mentions). Thus IMO the analogs were not suggestive of either El Nino Conditions or any of the McCabe Conditions. The information on the analogs is in the table that I created above the two maps. The analogs were suggestive of forecast difficulty more than anything else. And that is what has occurred with daily changes in the maps issued.

I do not think it was a very good job of forecasting. I hate to appear to be arrogant but really the NOAA forecasters need to learn about the impact of the PDO and AMO on weather patterns and the interconnection of the PDO with El Nino and the difficulty of really separating them when there is an El Nino and warm water off the Pacific Coast. It is better to simply indicate that one has low confidence in the ability to forecast on a particular day than to have a labile forecast which one day is rated as 3 out of 5 on their confidence scale and the next day after drastic changes is labeled as 4 out of 5 on their level of confidence scale. It demonstrates what happens when one starts with a hypothesis (that our weather is being controlled by the El Nino) and then makes forecasts that are consistent with the hypothesis rather than using the available tools and seeing what the analogs are telling us about days 6 - 14.

I recognize that it is not easy to make forecasts right now. Summer generally has less weather which "progresses" across the nation driven by well defined meteorological processes. And we have an unusual El Nino which unlike the Faux El Nino of last year is strong but has progressed so far to the East that it may not be impacting weather patterns in the Northern Pacific at this point in time. So I am not being critical of the ability of NOAA to make accurate forecasts but their effort to shoehorn our current weather into a particular hypothesis whether or not there is evidence that the hypothesis is actually impacting our weather in a significant way right now.

Outlook Days 6 - 14 (but only showing the 8 - 14 Day Maps)

Let's more ahead to today August 3.

Here is the Temperature Outlook for August that was released on July 16, 2015

August 2015, Early Temperature Outlook Issued on July 16, 2015

And here is the updated August Temperature Outlook Issued on July 31, 2015. It is a bit different from the "Early Outlook" but not much.

Update August Temperature Outlook July 31, 2015

Last week I compared both the NOAA temperature and precipitation forecasts with those of JAMSTEC. That comparison is still available on Page II of this Report.

And here is the current 8 - 14 Day Temperature Outlook which will auto-update and thus be current when you view it. It covers the week following the current week. Today's 6 - 14 Day Outlook is just nine days of the month and the map shown below of the 8 to 14 day Outlook only shows seven days. The 6 - 10 Day Map is available on Page II of this report. As I view this map on August 3 (it updates each day), it suggests that mid-August may be quite a bit warmer especially for the Southern Tier of CONUS than thought just three days ago. .

8-14 Day Temperature Outlook

Here is the Precipitation Outlook for August that was released on July 16, 2015

August 2015 Early P recitation Outlook Issued on July 16, 2015

And here is the Updated Precipitation Outlook for August released on July 31, 2015. There are some differences but not a lot.

August Precipitation Outlook Updated July 31, 2015

Below is the current 8 - 14 Day Precipitation Outlook which will auto-update daily and thus be current when you view it. And again remember that this map shows only seven days and the  6 - 14 Day map is available on Page II of this report. As I view this map on August 3 (it updates each day), it suggests that Mid-August may have a very different precipitation pattern than anticipated just three days ago. .

Current 8 - 14 Day Precipitation Outlook

Here are excerpts from the NOAA discussion released today August 3, 2015.\

6-10 DAY OUTLOOK FOR AUG 09 - 13 2015  

TODAY'S MODELS EXHIBIT VERY GOOD AGREEMENT ON THE PREDICTED 500-HPA FLOW PATTERN DURING THE 6-10 DAY PERIOD. THE MODELS GENERALLY DEPICT A TROUGH OVER  WESTERN ALASKA, A TROUGH NEAR THE WEST COAST OF THE CONUS, RIDGING OVER THE  CENTRAL CONUS, AND A TROUGH NEAR THE EAST COAST. THE ENVIRONMENT CANADA MODEL  DEPICTS A SLIGHTLY STRONGER RIDGE OVER THE CENTRAL CONUS WITH THE WEAKEST REPRESENTATION IN THE EUROPEAN CENTER SOLUTIONS. THERE ARE SLIGHT VARIATIONS IN THE POSITION OF THE TROUGH NEAR THE WEST COAST, WITH THE GFS ENSEMBLES PREDICTING A GENERALLY SHARPER TROUGH, WITH THE WEAKEST AND BROADEST TROUGH IN THE 0Z CANADIAN ENSEMBLE MEAN SOLUTION.

THE MANUAL BLEND IS CONSTRUCTED FROM EUROPEAN CENTER AND GFS BASED MODEL SOLUTIONS, AS THOSE MODELS HAD GENERALLY HIGHER ANALOG CORRELATION SCORES AND  ANOMALY CORRELATION SCORES OVER THE PAST 60 DAYS. ANALOG CORRELATIONS OFF THE CANADIAN ENSEMBLE MEAN SOLUTIONS WERE VERY LOW TODAY, INDICATING A MISALIGNMENT OF THE MODEL OUTPUT WITH THE HISTORICAL RECORD.

THE RESULTANT UPPER-LEVEL PATTERN FAVORS ABOVE NORMAL TEMPERATURES ACROSS THE ENTIRE SOUTHERN TIER OF THE CONUS AND ACROSS THE CENTRAL GREAT PLAINS, ALL DUE TO THE FORECAST RIDGING. BELOW NORMAL TEMPERATURES OVER THE GREAT BASIN AND NORTHERN ROCKIES ARE FAVORED DUE TO THE INFLUENCE OF THE TROUGH PREDICTED OVER THE PACIFIC NORTHWEST. TROUGHING ALOFT AND IN THE LOW LEVELS FAVORS BELOW NORMAL TEMPERATURES FROM THE GREAT LAKES TO THE NORTHEAST. A SOUTHERLY COMPONENT TO THE LOW-LEVEL FLOW FAVORS ABOVE NORMAL TEMPERATURES OVER ALASKA, SOUTH OF THE ALASKA RANGE.

SOUTHWESTERLY FLOW FAVORS ABOVE MEDIAN PRECIPITATION FOR SOUTHERN ALASKA. THE MAIN STORM TRACK OVER THE CONUS IS LIKELY TO BE OVER THE NORTHERN TIER OF THE CONUS, DEFLECTED NORTHWARD BY THE LARGE RIDGE FORECAST OVER THE CENTRAL CONUS. THEREFORE, ABOVE MEDIAN PRECIPITATION IS FAVORED FROM THE PACIFIC NORTHWEST TO THE UPPER GREAT LAKES, WHILE BELOW MEDIAN PRECIPITATION IS FAVORED FROM THE SOUTHWEST TO THE CENTRAL ROCKIES TO THE TENNESSEE VALLEY. TROUGHING ALONG THE EAST COAST FAVORS ABOVE MEDIAN PRECIPITATION FROM THE SOUTHEAST COAST TO THE MID-ATLANTIC AND NORTHEAST.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO GOOD AGREEMENT AMONG VARIOUS TOOLS, OFFSET SLIGHTLY BY UNCERTAINTY OVER THE NORTHERN GREAT PLAINS AND SOME DISAGREEMENT BETWEEN THE REFORECAST TOOLS IN THE PRECIPITATION PATTERN.

8-14 DAY OUTLOOK FOR AUG 11 - 17 2015 

MODEL FORECASTS DURING THE WEEK-2 PERIOD FAVOR RIDGING OVER THE CENTRAL CONUS, WITH WEAK TROUGHING FROM EASTERN ALASKA TO THE PACIFIC NORTHWEST, AND WEAK TROUGHING FROM THE NORTHEAST TO THE MID-ATLANTIC. ANOMALIES ARE GENERALLY WEAK,  ALTHOUGH THE 6Z DETERMINISTIC GFS DEVELOPS A DEEP TROUGH OVER THE EASTERN THIRD  OF THE CONUS. THAT SOLUTION IS DISCOUNTED DUE TO THE AMPLITUDE, BUT THE OVERALL PATTERN AGREES WITH THE REMAINING ENSEMBLE MEAN SOLUTIONS.

THE 500-HPA HEIGHT MANUAL BLEND CONSISTS OF MOSTLY EUROPEAN CENTER AND GFS  BASED MODEL SOLUTIONS, ALTHOUGH A SMALL PORTION OF THE BLEND IS FROM YESTERDAY'S 12Z CANADIAN ENSEMBLE MEAN.  THE ANALOG CORRELATION SCORES FROM THE ENVIRONMENT CANADA MODELS ARE HIGHER DURING THE WEEK-2 PERIOD, BUT STILL LOWER THAN OTHER MODELS. IN GENERAL, THE 0Z MODELS HAD LOWER ANALOG CORRELATION SCORES, POTENTIALLY HINTING AT A SENSITIVITY TO THE INITIAL CONDITIONS NOT IMPACTING THE 6Z MODEL SUITE.

THE UPPER-LEVEL PATTERN, WITH GENERALLY NEAR OR ABOVE AVERAGE HEIGHTS, FAVORS ABOVE NORMAL TEMPERATURES FOR MOST OF ALASKA AND THE CONUS. THE EXCEPTIONS ARE THE NORTHERN HALF OF ALASKA, THE NORTHERN ROCKIES, AND FROM THE LOWER GREAT LAKES TO NEW ENGLAND, WHERE NEAR NORMAL TEMPERATURES ARE FAVORED.

WEAK TROUGHING OVER EASTERN ALASKA FAVORS BELOW (ABOVE) MEDIAN PRECIPITATION  OVER WESTERN (EASTERN) ALASKA, WHILE ABOVE MEDIAN PRECIPITATION IS FAVORED OVER THE ALASKA PANHANDLE. RIDGING OVER THE CENTRAL CONUS AND A WEAKER TROUGH OVER THE NORTHWEST (AS COMPARED TO THE 6-10 DAY PERIOD) FAVORS BELOW MEDIAN  PRECIPITATION FROM THE NORTHERN ROCKIES TO THE SOUTHWEST, EASTWARD TO THE MISSISSIPPI VALLEY. ODDS FOR BELOW MEDIAN PRECIPITATION OVER THE SOUTHWEST ARE LOWER DURING THIS PERIOD, SUGGESTING SOME POTENTIAL FOR A RETURN OF MONSOONAL MOISTURE. TROUGHING NEAR THE EAST COAST SUPPORTS ABOVE MEDIAN PRECIPITATION FROM THE GREAT LAKES TO NEW ENGLAND AND SOUTHWARD TO THE SOUTHEAST, EAST OF THE APPALACHIANS.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD IS: ABOVE AVERAGE, 4 OUT OF 5, DUE TO RELATIVELY GOOD AGREEMENT AMONG THE ENSEMBLE MEANS AND A RELATIVELY STABLE PATTERN, OFFSET BY A FORECAST LOW-AMPLITUDE ANOMALIES.

Analogs to Current Conditions

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 analyzing this second set of information. This first set applies to the 5 and 7 day observed pattern prior to today. The second set which I am not using relates to the forecast outlook 6 - 10 days out to similar patterns that have occurred in the past during the dates covered by the 6 - 10 Day Outlook. That may also be useful information but they put this set of analogs in the discussion with the other set available by a link so I am assuming that this set of analogs is the most meaningful.

Analog

Centered

Day

ENSO

Phase

PDO AMO Other Comments
1956 July 13 La Nina - Neutral  
1962 July 23 Neutral - Neutral  
1972 August 8 El Nino - - Powerful El Nino
1973 July 15 La Nina - - Powerful La Nina
1984 July 15 Neutral + - Followed by a La Nina
1984 July 17 Neutral + - Followed by a La Nina
1992 July 30 El Nino + - Tail End of a Modoki

 

The first thing I noticed is that today is August 3 and these are analogs centered on dates 3 or 4 days ago which for four of the non-duplicative analogs is a fairly narrow span from July 13 to July 17. Are we going to experience weather that normally would occur about two weeks earlier in the summer? The 1972 powerful El Nino is interesting as is the showing as an analog the powerful La Nina that occurred in the following year. Overall the analogs are slightly La Nina-ish not El Nino-ish. And the forecast reflects that. Again like last week, the analogs suggest to me that the current El Nino is not going to impact our weather significantly over the next two weeks. The ocean phases associated with the analogs this week lean towards McCabe Condition B and to a lesser extent McCabe Condition A. They are both associated with the Atlantic rather than the Pacific being in control. The seminal work on the impact of the PDO and AMO on U.S. climate can be found here.

 McCabe Maps modified to include the subtitles

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.

Historical Anomaly Analysis

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

Progress of the Warm Event

Let us start with the SOI.

Below is the Southern Oscillation Index (SOI) reported by Queensland, Australia. The first column is the tentative daily reading, the second is the 30 day moving/running average and the third is the 90 day moving/rolling average.

Date Current Reading 30-Day Average 90 Day Average
28 July 2015 -18.9 -13.13 -11.85
29 July 2015 -31.7 -13.24 -12.12
30 July 2015 -31 -13.56 -12.46
31 July 2015 -21.9 -13.57 -12.75
1 August 2015 -22.4 -13.22 -13.02
2 August 2015 -29.6 -13.05 -13.32
3 August 2015 -37.8 -13.29 -13.64

 

This past week has been very favorable for the continued development of the current El Nino. The 30-day average, which is the most widely used measure, on August 3 was reported as being -13.29 which is clearly an El Nino reading although not quite as extreme as the prior week as some of the earlier very extreme values dropped out of the 30 day running average. The 90-day average also is solidly in El Nino territory at -13.64 and it is more negative than last week. The SOI is clearly indicative of an El Nino Event happening.

Here are the low-level wind anomalies. This graphic is not as compact as the graphic provided by the weekly NOAA ENSO Report (more white space) but this version auto-updates so you will always have the latest version of this Hovmoeller. There has been another mid-Pacific wind burst in the Date Line to 160W area and yet again from 160E to the Data Line. This is consistent with an active SOI.

Low Level Wlind Anomalies

Here is another graphic that is less compact than the prettied up version published by NOAA on Mondays but which has the advantage of auto-updating. You can see how the convection pattern (really cloud tops has since May shifted to the East from a Date Line (180) Modoki pattern to a 170W to 120W Traditional/Canonical El Nino Pattern. But recently the signs of an El Nino are getting quite faint and shifting to the west.  The probably impacts on CONUS are thus lessened. The impacts of an El Nino during the summer in the Northern Hemisphere are subtle.

OLR Anomalies Along the Equator

Let us now take a look at the progress of the Kevin wave which is the key to the situation.  I like this Hovmoeller a lot and I have now been able to find a version that autoupdates but is not prettied up.  I will take the auto-update feature.  You can see the Kelvin Wave that got started in February which started this Warm Event. There have been earlier such events that proved to be not very strong. But if you look at the bottom of the Hovmoeller which represents the current situation, you can see that this latest Kelvin Wave is moving to the East fairly rapidly and we will see the impact of that on declining ONI estimates fairly soon. The strongest impact along the Equator is no longer shown on this graphic as it occurred a few weeks ago. The main impact of that Kelvin Wave is already close to 140W and about to exit the Nino 3.4 ONI measurement area.

But as you can see there is yet another Kelvin Wave. There is some other information that I will discuss later in this report that suggests this Kelvin Wave is weak so far re the subsurface impacts but it has occurred and is likely to extend the life of this El Nino at least into late Winter and perhaps as projected by the models into early Spring 2016. We do not know yet the intensity of the El Nino beyond its peak in late Fall. I think we can also see the beginning of the next upwelling wave off to the left and in other graphics which may signal the playing out of this series of Kelvin Waves. But continued SOI activity could create yet another Kelvin Wave although I think the Pacific Warm Pool at this point has been substantially depleted. The ENSO "battery" is weakening and will need a La Nina to recharge itself.  

Kelvin Waves Auto-updates

You can see below in the graphic which shows temperature along the Equator as a function of depth, both the magnitude of the anomalies and their size. You can now see where 2C (anomaly) water is impacting the area where the ONI is measured i.e. 170W to 120W. The 2C anomaly now extends to beyond 140W but not quite to 150W. The subsurface warm water appears to be making its way to the surface to some extent in the Eastern Pacific and also over at 170W which is probably related to the new Kelvin Wave. In the Central Pacific we now see a relatively small pod of warm water at about 175E to 170W where the westerly wind burst occurred and where we see above the beginning of one more Kelvin Wave. So far it seems to be fairly minor compared to what has occurred in prior months but that might change. It certainly has delayed the movement of the leading edge of the warmer water to 170W. At that point we are likely to see the ONI decline week to week. We may get some additional insight when we discuss the TAO/TRITON graphic.

The big issue is where will the +6C and +5C anomaly water go as it reaches the beaches of Ecuador? To the extent it surfaces, it can create convection and impact the Walker Circulation which could then provide positive feedback to this El Nino. But that warm water might tend to go north or south or both. That is part of the phase out process for an El Nino and that is where we are in the life of this El Nino. It is peaking and will soon begin its decline. But it is certainly taking its sweet time probably because of the large amount of the subsurface warm water. Water is a very good insulator: I believe it has the second highest specific heat capacity of all known substances.  So that means that other than by mixing, that warm water under the surface will stay warm until it rises to the surface where it can be cooled by evaporation (while making clouds) or moves to the north where it will impact Mexico and the the Southern Coast of the U.S. That is part of the basis for models predicting that the ONI of this El Nino will continue to rise but I am a bit skeptical because I see it as rising to the east of the ONI measurement area and not being counted.

Subsurface Heat Anomalies

The bottom half of the graphic is not that useful in terms of tracking the progress of this Warm Event as it simply shows the thermocline between warm and cool water which pretty much looks like this as shown here during a Warm Event and you can see that the cooler water is not making it to the surface to the east along the coast of Ecuador. However, one is beginning to see the increase in the slope of the thermocline (look at the 25C dividing line for example) and the increase in that slope would be the final change as the El Nino dies or turns back into a Modoki. I believe that process has already begun and will accelerate. We can now begin to monitor the 20C Isotherm which is often thought of as being the lower edge of the thermocline.

When I put all the information together I still conclude that I believe the ONI will soon peak and begin to decline. The possibility that there could be yet another Kelvin Wave forming, given the strength of the SOI, is a piece of information that at this point is difficult to assess. And there is the issue of how the Walker Circulation might extend the life of this Warm Event. The question of the Walker Circulation is not separate from the question of the forming of another Kelvin Wave. Pretty much all of the issues I am discussing are interrelated.

Back to the TAO/TRITON graphic below, notice that the 1.5C+ anomaly has just about reached 170W. When the leading edge of the warm water area moves beyond 170W, the anomalies in the western parts of Nino 3.4 are likely to start to decline. But at the same time, the subsurface warm water is coming to the surface and that makes the anomalies in the eastern part of Nino 3.4 larger.

To me, this being a summer El Nino, the near-term potential impacts on CONUS may currently be over-hyped since the real impacts will be felt this Fall and Winter. But on the other hand, there are signs that this may develop into a very powerful El Nino in the Fall. So we have to watch what happens carefully.. 

For my own amusement, I calculate the ONI each week using a method that I have devised. To refine my calculation, I have divided the 170W to 120W ONI measuring area into five subregions (that I have designated A through E (from west to east) with a location bar shown under the TAO/TRITON Graphic) and have mentally integrated what I see below and recorded that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions.

Current SST and wind anomalies

Location Bar for Nino 3.4 Area Above
-----------------------------------------------  A      B      C      D      E      ----------------

 

So as of Monday August 3 in the afternoon working from the August 2 TAO/TRITON report, this is what I calculated which is basically the same as my calculation last week although the patterns of the anomalies have been changing around quite a bit but the changes have been cancelling each other out.

Calculation of ONI from TAO/TRITON Graphic
Anomaly Segment Estimated Anomaly
A. 170W to 160W 1.5
B. 160W to 150W 1.6
C. 150W to 140W 1.7
D. 140W to 130W 1.8
E. 130W to 120W 1.9.
Total 8.5
Total divided by five subregions i.e. the ONI (8.5)/5 = 1.7

 

My estimate of the Nino 3.4 ONI is now 1.7. NOAA has today reported the weekly ONI as being 1.7 a slight increase from what was reported last week and identical with my rough calculation. The increase in the ONI is mostly due to the subsurface water in the Eastern Pacific backing up to the west as it comes to the surface. This warm water certainly impacts the weather in Ecuador and Peru but may not have a direct impact on weather in CONUS other than by spawning tropical cyclones which move north and enter the circulation of the Southwest Monsoon. That activity seems to have decreased recently.

Nino 4.0 is again reported as being 1.0.  You can already see (in my calculation table) the gradient from West to East that has formed with the higher values in the East and the Western part of the Zone having a smaller anomaly which I believe will soon decline slightly. But the new Kelvin Wave will arrive and then cause another rise in the ONI for the western part of the Nino 3.4 measurement area but so far that to me appears to me of smaller magnitude. This then may well result in a very complicated Walker Circulation pattern.

The real action is in Nino 1+2 which is reported as 2.7. The issue is how warm water off of Ecuador and Peru impacts CONUS weather. I think it has very little impact and that is what we are seeing right now.

Here is another way of looking at it:

.SST Anomalies Hovmoeller

This Hovmoeller shows a lot of useful information which I have discussed in previous weeks and I will not repeat the same interpretation over and over again. Today I see a slight tendency for the areas east of Nino 3.4 to be less warm than in prior weeks. That could be an indication of the process slowly working its way through the process of disposing of the subsurface very warm water.

You will not see the ONI substantially decline until the warm water over at 180, The International Date Line, has moved east of 170W. Until then, the ONI could easily continue to rise but probably not by very much although some models are predicting it will peak at about 2.0.or more. I personally believe they have overestimated the peak value of the ONI for this El Nino. Once the warm surface water no longer extends west of 170W, the ONI should begin to decline although apparently the seasonal pattern of sea surface temperatures along the Equator used to calculate the ONI declines into Fall (not sure why that is) and thus the reported ONI values might increase even as the sea surface temperatures (SST) decline. This of course in my mind suggests that there needs to be a seasonal adjustment made to the ONI for purposes of estimating the impacts. 

Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.

First the 90-Day

August 3 2015 90 Day Temperature and Precipitation Departures.

And the 30-Day which shows the more recent impacts

August 3, 2015 90 Day Temperature and Precipitation Departure

These are not the best graphics because the 90 day includes the most recent 30 days. I could have and perhaps should have displayed the 90 day graphic from a month ago and may consider doing that in the future. I am not sure I have them all saved.

But you can still see how the 30 differs if it does from the 90 day that includes the 30 day. I do not see much change. Parts of Texas and Mexico have dried up. The temperature anomaly has shifted a bit to the east but my friends on the East Coast do not seem to have observed that personally. Overall it is not much of a change but you can look at where you live and may notice more than I have as look at this graphic.

View from Australia

El Nino

Australia POAMA ENSO model run

Here is the just released discussion:

El Niño to persist into early 2016

Issued on 4 August 2015

The 2015 El Niño is now well-established and continues to strengthen. In the coming weeks, the central tropical Pacific Ocean (the NINO3.4 region) may exceed the peak values reached during the 2002 and 2009 El Niño events, but current anomalies remain well short of the 1982 and 1997 peaks. Note that peak values are normally recorded late in the year. Trade winds remain weakened and are likely to contribute to more warming of the tropical Pacific Ocean. Other indicators such as cloudiness near the Date Line, the Southern Oscillation Index, and sub-surface temperatures in the tropical Pacific Ocean remain typical of an established El Niño.

International climate models surveyed by the Bureau of Meteorology all indicate that El Niño will continue to strengthen, and persist into early 2016. Typically, El Niño peaks during the late austral spring or early summer, and weakens in the following year.

El Niño is usually associated with below-average winter–spring rainfall over eastern Australia and above-average daytime temperatures over the southern half of the country. However, El Niño is not the only influence on rainfall and temperature; other factors, such as sea surface temperatures to the north of Australia and in the Indian Ocean, also affect Australia's climate.

The Indian Ocean Dipole (IOD) remains neutral. A positive IOD event remains possible, with three of the five international models indicating a positive IOD is likely during late winter to spring. A positive IOD is typically associated with reduced winter and spring rainfall over parts of southern and central Australia.

Next update expected on 18 August 2015

IOD (Indian Ocean Dipole)

IOD POAMA Model Run

It comes with only a very short discussion and here it is:

The Indian Ocean Dipole (IOD) is currently neutral. The weekly value of the IOD index to 2 August was −0.10 °C. Sea surface temperatures in the Indian Ocean are warmer than average over much of the basin.

Three of the five surveyed international climate models indicate a positive IOD event will occur during the southern hemisphere winter and spring.

Positive IOD events, often associated with lower rainfall in central and southeastern Australia, are more likely to occur during El Niño. Between 50% and 60% of all historical El Niño events have seen a positive IOD develop at the same time. Positive IOD events are often associated with lower rainfall in parts of central and southeastern Australia. Conditions will be monitored closely.

Pulling it All Together

We are in El Nino conditions now. The actually impacts on CONUS are not clear. We have had wetter conditions than usual in the Southwest. But this is the Summer so El Nino impacts on Summer conditions in the Northern Hemisphere are muted even though this is a powerful El Nino. So it is somewhat of a confusing situation as the impacts are not currently proportional to the current strength of this El Nino.

It is probably influencing the IOD to tend towards being positive thus providing a double whammy for parts of Asia and Australia. The length and intensity of this El Nino is still not clear mostly in terms of whether or not it will extend into the early part of 2016.  All the computer models predict that it will last longer than my mental model suggests to me. The disagreement is in terms of a couple of months but a couple of months makes a difference in terms of agriculture and other economic impacts. Actually the JAMSTEC model is not very different from my assessment. We may or may not have a Pacific Climate Shift as the PDO+ may be simply related to the Warm Event (and quite frankly at this point appears to be). But for now we do have PDO+. The AMO being an overturning may be more predictable so the Neutral status moving towards AMO- is probably fairly reliable but not necessarily proceeding in a straight line. So none of this is very difficult to figure out actually if you are looking at say a five-year 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. But we are beginning to speculate on the winter of 2016/201 which I believe will tend to be ENSO Neutral. One thing is fairly certain for the U.S. it will be less wet and warmer than the winter of 2015/2016 which will be quite wet and cool. JAMSTEC is predicting that the Spring of 2017 will begin a mild La Nina.

TABLE OF CONTENTS FOR PART II OF THIS REPORT  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. 

A. Worldwide Weather: Current and Three-Month Outlooks: 15 Month Outlooks   (Usefully bookmarked as it provides automatically updated current weather conditions and forecasts at all times. It does not replace local forecasts but does provide U.S. national and regional forecasts and, with less detail, international forecasts)

B. Factors Impacting the Outlook

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

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

C. Computer Models and Methodologies

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

TABLE OF CONTENTS FOR PART 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.

D1. Introduction

D2. Climate Impacts of Global Warming

D3. Economic Impacts of Global Warming

D4. Reports from Around the World on Impacts of Global Warming.

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

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