June 4, 2018 Weekly Weather and Climate Report – Plus Atlantic Hurricane Forecast

Written by Sig Silber

The hotter it gets, the sooner there will be relief from the Sonoran (yes it is a Mexican weather pattern that the U.S. has appropriated) Monsoon. Unfortunately the MJO seems to have stalled and may not be as helpful in June as one might have hoped. So the drought continues and East Coast baseball games continue to be impacted. In this report, we will try to explain why the weather is not wonderful and the changes that hopefully soon will lead to improvement. “Soon” may turn out to be sooner than anticipated in the NOAA June forecast. We will be closely tracking this and have more to say on it on Thursday when we publish our Drought and Agriculture Report. 

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Colorado State U posts their updated Atlantic Hurricane Forecast

You can  track their updates here. Their reports are very informative. Most likely they are too high this year; but beware of the Pacific. This would include Pacific storms that cross into the Gull of Mexico and develop there into tropical events. hello!!!!!!! the Tropical Atlantic is cool: the Eastern Pacific is heating up.

We show this later.

I like to  provide this graphic from time to time.

And this from the NWS Report out of Albuquerque today.

Models continue with the idea of the above mentioned ridge shifting  ewd and closing off over West Texas or southeast nm Wednesday. This shift allows some mid-level subtropical moisture to push north and northeast into the southern half of the state Wednesday night and Thursday. A few high-based showers and storms are a fair bet over the southern mountains and southeast plains Thursday afternoon and evening. Upper high shifts slightly farther east Friday, allowing more mid-level sub-tropical moisture to move north into central nm. By the weekend, models Orient the moisture plume in a southwest to northeast fashion, focusing relatively high-based convection from the Southwest Mountains to the northeast Highlands and plains. Pwats gradually increase Friday night into Saturday as southerly winds @ 700mb transport sub-tropical moisture northward into the state. Low level moisture is still lacking so it’s tough to call it the start of the North American monsoon (nam) but it’s getting there…several weeks ahead of schedule.

A. Now we will begin with our regular approach and focus on Alaska and CONUS (all U.S.. except Hawaii).

I am starting with a summary first for temperature and then for precipitation of small images of the three short-term maps. You can click on these maps to see larger versions. The easiest way to return to this report is by using the “Back Arrow” usually found top left corner of your screen to the left of the URL Box. Larger maps are available later in the article with the discussion and analysis.

First Temperature

This shows magnitude rather than probability of  being higher or lower than Normal and shows the middle day of the five day period.			It is difficult to compare this with the other maps that show deviation from climatology as we expect the north to be cooler than the south. But it does seem to be consistent with the 6 – 10 day map. You can  see the difference between North and South is now normal and not impacted by cold air intrusions from Canada.
		Click to Enlarge
		Transitioning from the 6 to 10 day outlook on the left (also called Week One) to the 8 to 14 day outlook (Week Two) on the right   →
		The pattern is fairly stagnant. There also appears to be some retrogression and some deamplification. But the forecast may be changing.
To the right is the week 3 and 4 Forecast.                                                   → There is a warm anomaly for Northern Alaska. There is a warm anomaly for much of CONUS extending to the east of the Mississippi River and north to the latitude that defines the southern boundary of South Dakota except further west it extends north to the Canadian Border. There is a small West Coast cool anomaly. There is an EC area north and east of the warm anomaly.			↑ ←  The transition from the 8 -14 day forecast shown above to the week 3/4 forecast seems feasible. But the Southwest may not be as warm as forecast if a Monsoon-like pattern develops.

then Precipitation

The five day QPF is shown to the right. The units are different than the other maps i.e. in units of precipitation (inches) not probabilities of exceeding or being less than climatology.			It is difficult to compare this with the  other maps as some places are naturally more wet than others. But it seems to be somewhat consistent with the 6 – 10 day map and this is a Day 1 – 5 Map and the precipitation pattern for Days 6 – 10 may be very different.
		Transitioning from the 6 to 10 day outlook on the left to the 8 to 14 day outlook on the right.     →
		The precipitation pattern is fairly stagnant.
To the right is the week 3 and 4 Experimental Forecast.    →                Northwest Alaska is wet. For CONUS there are two dry anomalies: one stretches from the Northwest to Texas; the other is in southern Florida. A wet anomaly stretches from the Ohio River Valley south to the Gulf Coast.			↑ ←  The transition from the 8 -14 day forecast shown above to the week 3/4 shown to the left seems feasible. But te EC for the Southwest may turn into wet not EC.

Let’s now return our focus back on Alaska and CONUS (all U.S.. except Hawaii).

Water Vapor.

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

You can see from this animation that there has been some limited moisture entering the Northwest and moisture moving into CONUS from the Gulf of Mexico.

Tonight, Monday evening June 4, 2018, as I am looking at the above graphic, you see pretty much the same pattern that has existed for a number of days. There is a lot of dryline activity. There is also moisture crossing Baja and entering CONUS.

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.

And Now the Day One and Two CONUS Forecasts

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. 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.

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.

What is Behind the Forecasts? Let us try to understand what NOAA is looking at when they issue these forecasts.

Below is a graphic which highlights the forecasted surface Highs and the Lows re air pressure on Day 7. The Day 3 forecast can be found here. the Day 6 Forecast can be found here. Actually all the small graphics below can be clicked on to enlarge them.

When I look at this Day 7 forecast, there is a Low south of the Eastern Aleutians with surface central pressure of 1008 hPa. Behind it east of Kamchatka there is a trailing Low with surface central pressure of 1004. This week, the Hawaiian High with surface central pressure of 1024 hPa is large and on Day 7 is projected to be close to shore or on shore. This would make it difficult for storms to attempt to come down the Pacific Coast and enter CONUS further south (see PNA index shown later). Other than the Bermuda High off the East Coast, there is a Canadian Low with surface central pressure of 1000 hPa (impacting Montana and neighboring states) and a Great Lakes High with surface central pressure of 1020 hPa. We are into the time of the year when warming and convection become the dominant determinant of weather. But there is a small Low southwest of Baja with surface central pressure of 1004 hPa which may turn out to be significant and all eyes are on the Monsoonal Ridge which shows up as high pressure over Mexico.

I provided this 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 7. It is not the current situation.

The table below showing the Day 3, Day 4, Day 5, Day 6 and Day 7 of this graphic can be useful in thinking about how the pattern of Highs and Lows is expect to move during the week.

From left to right and then down, Days 3 and 4 top row, Days 5 and 6 second row and Day 7 to the right. These are small images but you can if you want click on them and get larger images but even with the small images you can trace the evolution of the pattern. The graphics update but my commentary below does not so it is just a guide for how to read these graphics. It is difficult to see how the picture evolves day by day in this set of forecasts as the maps seem quite similar day by day.  But that Low southwest of Baja seems to be in the picture the entire week.
Things to look for in general are the position and strength of the Aleutian Low, the Hawaiian High and any troughs especially if they extend far to the south and are over water.

Looking at the current activity of the Jet Stream.  The below graphics and the above graphics are very related.

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.  I have not provided the ability to click to get larger images as I believe the smaller  images shown are easy to read.

Current	Day 5
We do not see a consistent pattern for the Jet Stream right now. That is probably seasonal i.e. the Polar Jet Stream has taken its Summer Break. What we do see however is northerly displaced. This may open the door to moisture entering CONUS from the south. You see some indication of this on Day 5 if you look carefully at the tiny wind direction arrows.

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.

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.

500 MB Mid-Atmosphere View

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. Sometimes Meteorologists work with the 500 mb heights which provide somewhat similar readings to the “Thickness” lines but IMO provide slightly less specific information. Thinking about clockwise movements around High Pressure Systems and counter- clockwise movements around Low Pressure Systems provides a lot of information.

Here is the whole suite of similar maps for Days 3, 4, 5, 6 and repeated for Day 7. In this set of graphics one can see a Pacific Closed Low attempting to enter CONUS and not moving to the east very rapidly and pushed back north. That is very significant and if the forecast changes with respect to that outcome, it would make a big difference.

Day 3 Above, 6 Below	Day 4 Above,7 Below	Day 5 Above.

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

Four – Week Outlook: Looking Beyond Days 1 to 5, What is the Forecast for the Following Three + Weeks?

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 June 4, 2018 was 3 out of 5

8 – 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on June 4, 2018 was 3 out of 5).

Looking further out.

Now – Precipitation

6 – 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on June 4, 2018 was 3 out of 5)

8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on June 4, 2018 was 3 out of 5)

Looking further out.

Here is the 6 – 14 Day NOAA discussion released today June 4, 2018 and the Week 3/4 discussion released Friday June 1, 2018.

6-10 DAY OUTLOOK FOR JUN 10 – 14 2018

TODAY’S ENSEMBLE MEANS AND DETERMINISTIC MODEL RUNS ARE IN GOOD AGREEMENT ON THE PREDICTED 500-HPA CIRCULATION PATTERN OVER NORTH AMERICA FOR THE 6-10 DAY PERIOD. TROUGHS ARE PREDICTED OVER THE U.S. ATLANTIC COAST, THE PACIFIC COAST AND THE WESTERN ALEUTIANS, WHILE A RIDGE IS FORECAST OVER THE CENTRAL CONUS. TODAY’S MANUAL 500-HPA HEIGHT BLEND IS BASED PRIMARILY ON THE OPERATIONAL AND ENSEMBLE MEANS FROM THE EUROPEAN AND NCEP MODEL SUITES. THE RESULTANT MANUAL BLEND INDICATES POSITIVE 500-HPA HEIGHT ANOMALIES OVER MOST OF THE CONUS EXCEPT FOR FLORIDA, THE PACIFIC NORTHWEST AND THE NORTHEAST WHERE NEGATIVE ANOMALIES ARE INDICATED. 

TEMPERATURE FORECAST TOOLS CONSISTENTLY PREDICT ABOVE NORMAL TEMPERATURES OVER MOST PARTS OF THE CONUS, UNDER ABOVE NORMAL 500-HPA HEIGHTS. NEAR TO BELOW NORMAL TEMPERATURES ARE MOST LIKELY OVER PARTS OF THE PACIFIC NORTHWEST, THE SOUTHWEST AND THE SOUTHEAST U.S., UNDER THE PREDICTED TROUGHS AND CONSISTENT WITH DYNAMICAL MODEL FORECAST TOOLS. NEAR TO ABOVE NORMAL TEMPERATURES ARE MOST LIKELY FOR MOST OF ALASKA, CONSISTENT WITH DYNAMICAL MODEL FORECAST TOOLS.  

BELOW NORMAL PRECIPITATION IS PREDICTED OVER PARTS OF THE CENTRAL GREAT BASIN, THE NORTHERN INTERMOUTAIN WEST AND THE NORTHERN AND CENTRAL ROCKIES, THE NORTHERN AND CENTRAL PLAINS, THE MIDDLE MISSISSIPPI VALLEY, THE GREAT LAKES AND MUCH OF THE NORTHEAST, ASSOCIATED WITH THE PREDICTED RIDGE OVER CENTRAL NORTH AMERICA AND CONSISTENT WITH CALIBRATED PRECIPITATION FORECAST TOOL. NEAR NORMAL PRECIPITATION IS INDICATED IN PARTS OF THE CLIMATOLOGICALLY ARID REGIONS OF THE SOUTHWESTERN CONUS, WHERE PRECIPITATION IS NOT LIKELY FOR THE 6-10 DAY PERIOD. HOWEVER, ABOVE NORMAL PRECIPITATION IS MOST LIKELY IN PARTS OF FOUR CORNERS STATES, RELATED TO MOISTURE FROM THE EASTERN TROPICAL PACIFIC. NORTHWEST FLOW ALOFT AND THE POTENTIAL FOR MESOSCALE CONVECTIVE SYSTEMS INCREASE CHANCES FOR ABOVE NORMAL PRECIPITATION ACROSS PARTS OF THE UPPER MISSISSIPPI VALLEY.  NEAR TO BELOW NORMAL PRECIPITATION IS MOST LIKELY FOR MOST OF ALASKA, IN ASSOCIATION WITH THE PREDICTED ABOVE NORMAL HEIGHTS THERE. 

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO GOOD AGREEMENT ON THE AVERAGE CIRCULATION PATTERN OVER THE REGION, OFFSET BY SOME DISAGREEMENT AMONG TEMPERATURE AND PRECIPITATION TOOLS.  

8-14 DAY OUTLOOK FOR JUN 12 – 18 2018   

ENSEMBLE MEAN MODEL FORECASTS FOR THE 8-14 DAY PERIOD ARE IN GOOD AGREEMENT ON THE 500-HPA CIRCULATION PATTERN OVER NORTH AMERICA, GENERALLY INDICATING PERSISTENCE OF THE CIRCULATION FORECAST FROM THE 6-10 DAY PERIOD, WITH SOME WEAKENING OF THE TROUGH NEAR THE PACIFIC NORTHWEST.

A PREDICTED WEAK RIDGE AND PREDICTED POSITIVE 500-HPA HEIGHT ANOMALIES FAVOR ABOVE NORMAL TEMPERATURES OVER MOST OF THE CONUS, EXCEPT FOR PARTS OF THE SOUTHWEST AND THE SOUTHEAST WHERE ENHANCED PROBABILITIES OF NEAR TO BELOW NORMAL TEMPERATURES ARE INDICATED, WITH THE PREDICTED TROUGH OVER THE AREA IN THE 8-14 DAY PERIOD AND CONSISTENT WITH DYNAMICAL FORECAST TOOLS. THE PREDICTED TEMPERATURE PATTERN FOR ALASKA IS SIMILAR BETWEEN THE 6-10 DAY PERIODS.   

BELOW NORMAL PRECIPITATION IS MOST LIKELY FOR THE NORTHWEST CONUS, UNDERNEATH ABOVE NORMAL 500-HPA HEIGHTS. ABOVE NORMAL PRECIPITATION IS MOST LIKELY FOR PARTS OF THE SOUTHWEST, WITH PREDICTED NORTHWARD FLOW OF MOISTURE FROM THE EASTERN TROPICAL PACIFIC. ABOVE NORMAL PRECIPITATION IS FAVORED FOR MUCH OF THE GULF OF MEXICO REGION, NORTHWARD TO PARTS OF THE NORTHERN PLAINS AND THE UPPER MISSISSIPPI VALLEY, WHILE BELOW NORMAL PRECIPITATION IS FORECAST FOR THE NORTHEAST, CONSISTENT WITH CALIBRATED PRECIPITATION FORECAST TOOLS. NEAR TO ABOVE NORMAL PRECIPITATION CONTINUES TO BE MOST LIKELY FOR MUCH OF ALASKA IN ASSOCIATION WITH A PREDICTED TROUGH. BELOW NORMAL PRECIPITATION IS FAVORED FOR  CENTRAL EASTERN MAINLAND ALASKA, CONSISTENT WITH DYNAMICAL CALIBRATED FORECAST TOOLS.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: AVERAGE, 3 OUT OF 5, DUE TO FAIR  AGREEMENT AMONG MODEL CIRCULATION FORECASTS, OFFSET BY SOME DISAGREEMENT IN  PRECIPITATION AND TEMPERATURE FORECAST TOOLS.

Week 3-4 Forecast Discussion Valid Sat Jun 16 2018-Fri Jun 29 2018

The MJO has been active during the past few weeks, with the enhanced (suppressed) phase now over the Maritime Continent (central Pacific). Dynamical model MJO index forecasts, including the monthly run from the European Center (ECWMF), indicate potential eastward propagation of the MJO over the next couple weeks. Multiple linear regression (MLR) using the MJO indices indicates impacts to the temperature forecast for the Week 3-4 period, including enhanced probabilities of below normal temperatures from the Northern Plains into the Central and Upper Mississippi Valleys. ENSO-neutral conditions are currently present over the Tropical Pacific and not a factor in the Week 3-4 outlook.

Dynamical model ensemble mean anomaly forecasts for the Week 3-4 period generally show a continuation of the circulation pattern present in Week 2 forecasts. Ridging and above normal 500-hPa heights are predicted over central North America, by the CFS and ECMWF operational models and a consensus of models from the Subseasonal Prediction Experiment (SubX), an experimental multi-model ensemble (MME) of subseasonal dynamical models. A trough and negative 500-hPa height anomalies are predicted over the Aleutian Islands by the SubX MME, as well as the CFS, ECMWF and JMA operational ensembles. Troughing and weaker positive 500-hPa height anomalies are forecast over the Northeast CONUS. This circulation pattern is largely persistence of the predicted circulation pattern for the Week 2 outlook. There is considerable variance among each of the constituent model circulation forecasts of the SubX MME and between the ECMWF, CFS and JMA operational model forecasts.

The Week 3-4 temperature outlook is based on a blend of dynamical model forecasts and the MLR statistical forecast tool, which incorporates the impacts of the MJO and decadal trends. Above normal temperatures are most likely for much the CONUS, including the Pacific Northwest, the Rocky Mountains, the Southwest, the Central and Southern Plains, and the Central and Lower Mississippi Valleys. Below normal temperatures are most likely for parts of the central California coast, ahead of a predicted trough over the eastern Pacific. Component models of SubX, including the NCEP Global Ensemble Forecast System (GEFS) and the Environment Canada (ECCC) ensemble prediction system, are consistent with impacts of the active MJO, indicating a greater likelihood of below normal temperatures for parts of the northern central CONUS. Equal chances (EC) of above and below normal temperatures are indicated in the official outlook for this region where tools are inconsistent. The ECMWF temperature forecasts indicate a lower probability of above normal temperatures for the eastern CONUS, where equal chances is indicated. Above normal temperatures are most likely for western and northern Alaska, while equal chances is indicated for southeastern Alaska, supported by a consensus of statistical and dynamical tools including the SubX MME.

The Week 3-4 precipitation outlook indicates below median precipitation is most likely over a large area of the western and central CONUS, from Oregon and northern California across the central Rockies into the Central and Southern Plains, under a predicted ridge. Equal chances is indicated in climatologically arid regions of the Desert Southwest, where little precipitation is expected in the Week 3-4 period. Some models, such as the NCEP CFS, indicate the potential for some precipitation in parts of this region, although this forecast is somewhat uncertain. Above median precipitation is most likely for parts of the eastern Gulf Coast into the interior Southeast, where dynamical model forecasts, including the ECMWF, CFS, JMA, and SubX MME, indicate enhanced atmospheric moisture flow from the tropics, including the potential for tropical storm activity. Above median precipitation is likely for much of western Alaska, east of the trough predicted by most dynamical model forecasts.

Dynamical model forecasts support enhanced chances for above median precipitation for southeastern islands of Hawaii. Above normal temperatures are most likely for southeastern islands, as predicted by most dynamical models, where SSTs are currently above-normal.

Some Indices of Possible Interest:

Madden Julian Oscillation (MJO)

NCEP-NEFS	CFSv2

Analogs to the Outlook.

Now let us take a detailed look at the “Analogs”.

NOAA normally provides two sets of Analogs.

A. Analogs 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 the recent pattern is used to initialize the models to predict the 6 – 14 day Outlook.

B. There is a second set of analogs associated with the Outlook. It compares the forecast (rather than the prior period) to past weather patterns. I have not been regularly analyzing this second set of information. The first set applies to the 5 and 7 day observed pattern prior to today. The second set, relates to the correlation of the forecasted outlook 6 – 10 days out and 8 – 14 days out with similar patterns that have occurred in the past during a longer period that includes the dates covered by the 6 – 10 Day and 8 – 14 Day Outlook. The second set of analogs also has useful information as it indicates that the forecast is feasible in the sense that something like it has happened before. I am not very impressed with that approach. But in some ways both Approach A and B are somewhat similar. I conclude that if the Ocean Condition now are different then the analogs and if the state of ENSO now is different than the analogs that is a reason to have increased lack of confidence in the forecasts and vice versa.

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. But NOAA prefers the first set (A) as it helps them (or at least they think it does) assess the quality of the forecast.

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. It also helps the reader see the impact of the phases of the PDO and AMO which are shown. The first set (A) which is what I am using today applies to the 5 and 7 day observed pattern prior to today.

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

The spread among the analogs from May 15 to June 7 is 23 days. 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, and fairly accurate if the dates are reasonably evenly distributed, is about May 26. These analogs are centered on 3 days and 4 days ago (May 31 or June 1). So the analogs could be considered to be out of sync with respect to weather that we would normally be getting right now but weather we might have expected almost a week ago.

For more information on Analogs see discussion in the GEI Weather Page Glossary.  For sure it is a rough measure as there are so many historical patterns but not enough to be a perfect match with current conditions. I use it mainly to see how our current conditions match against somewhat similar patterns and the ocean phases that prevailed during those prior patterns. If everything lines up I have my own measure of confidence in the NOAA forecast. Similar initial conditions should lead to similar weather. I am a mathematician so that is how I think about models.

Including duplicates, there is one Neutral Analog, six La Nina analogs and three El Nino Analogs. The pre-forecast analogs this week do not strongly favor any particular McCabe Condition but they do favor the two McCabe conditions which are associated with a Positive PDO which suggests that the forecast may indeed be wet.

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.

In color	Black and White same graphics

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.

A Useful Read

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.

Recent CONUS Weather

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

And the 30 Days ending May 27	And the 30 Days ending June 2, 2018
Enormous change in the temperature pattern…hot, hot, hot. Re Precipitation, there is a clear reduction in the dryness in the Northwest	Not much change but the Southeast is definitely a lot more wet.
Remember, these maps are a 30 average so the most distant seven days are removed and the most recent seven days are added.

The U.S. Drought Monitor is a comprehensive way of understand the drought situation for the U.S. If is issued every Thursday and reflects the conditions as of the prior Tuesday. The drought monitor is not just based on precipitation but the condition of the land so it generally reflects more than a month’s precipitation and temperature and wind. The latest version of our report can be found here.

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

It is Useful to Understand the Semipermanent Pattern that Control our Weather and Consider how These Change from Winter to Summer. These two graphics (click on each one to enlarge) are from a much larger set available from the Weather Channel.  They 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 mid-June and should be returning to the set of positions shown below for July (and that appears to be happening at least in the Pacific).For CONUS, the seasonal repositioning of the Bermuda High and the Pacific High are very significant. Notice the Winter position of the Pacific High (Hawaiian High). It has been further south than usual for this time of the year. But it is forecast to retreat north to allow the Southwest Monsoon to happen.

Forecast for Today (you can click on the maps to enlarge them)

Temperature.	Precipitation.
Not a lot of surprises here.  But Equatorial Africa is again very warm. So is India	The pattern is changing. We no longer see the well defined dry belt.

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

And now we have experimental forecasts from the U.S. NAEFS Model. They are difficult to read without first enlarging them.

Looking Out a Few Months

Here is the precipitation forecast from Queensland Australia:

It is kind of amazing that you can make a worldwide forecast based on just one parameter the SOI and changes in the SOI. This graphic has been updated and now is in line with the actual SOI. Of interest is the wet China.

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. If we want to have a good feel for future weather we need to look at the oceans as our weather mostly comes from oceans and we need to look at

• Surface temperature anomalies (weather develops from the ocean surface and
• The changes in the temperature anomalies since that may provide clues as to how the surface anomalies will change based on the current trend of changes. This is not that easy to do since the oceans are deep, there are many currents, winds have an impact etc. Two ways that are available to use are to look at the change in the situation today compared to the average over a period of time and NOAA also produces a graphic of monthly changes. I use both. The first set of graphics is simply looking at the average compared to today and that is below.

Three Month Average Anomaly	Current Anomaly
La Nina starts to be displaced to the west.	We see a lot of white where we used to see blue.

And when we look in more detail at the current Sea Surface anomalies below, we see a lot of them not just along the Equator related to ENSO.

First the categorization of the current daily SST anomalies.
Mediterranean, Black Sea and Caspian Sea	Western Pacific	West of North America	North and East of North America	North Atlantic
The Eastern Mediterranean is warming as is the Persian Gulf.	Mostly warm far offshore of  eastern coast of Asia to the Dateline; Cool east of Kamchatka.	Warm Bering and Chukchi Seas Warm west of Baja and Mexico offshore	Warm offshore of North America Cool eastern Hudson Bay Cool south of Greenland and in the Labrador Sea Warm western Gulf of Mexico	Baltic and North Sea Warm British Isles warm
Equator	It is total ENSO Neutral at this point.
Africa	West of Australia	North, South and East of Australia	West of South America	East of South America
Cool west of North Africa Warm offshore of Angola Cool south and Southeast of Africa	Cool	Cool to the south	Cool down to 40S Cool offshore of 60S.	Cool off Venezuela Cool off 10S to 20S Warm off 30S to 50S

Then we look at the change in the anomalies. The SST anomaly is sort of like the first derivative and the change in the anomaly is somewhat like a second derivative. It tells us if the anomaly is becoming more or less intense.

Here it gets a little tricky as for this graphic 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
Central Mediterranean warming, western Black Sea cooling. Cool off Somalia and Gulf of Aden.	Cooling Kamchatka almost to Alaska Warming off Southeast Asia	Warming west of British Columbia Warmings west of Baja and Mexico   .	Cooling  off Nova Scotia and to the East. Warming off CONUS East Coast Warming western Gulf of Mexico Cooling Antilles	Cooling  south of Greenland Warming British Isles.
Equator	Eastern Pacific showing warming.
Africa	West of Australia	North, South and East of Australia	West of South America	East of South America
Cooling West of North Africa. Mixed pattern north and south of Gulf of Guinea Cooling south of Africa	Warm way offshore	Cooling to the northwest. Cooling to the Southeast and now extending beyond New Zealand.	Cooling off 30S Warming off 50S to 60S	Cooling off northern Brazil Cooling off 30S and further south offshore.

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. Notice the change in the PDO in July of 2017 and the stability of the AMO index.

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

 * 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.

Tropical Activity Possibly Impacting CONUS.

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.

Now let us look at the Western Pacific in Motion.

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

C. Progress of ENSO

A major driver of weather is Surface Ocean Temperatures. Evaporation only occurs from the Surface of Water. So we are very interested in the temperatures of water especially when these temperatures deviate from seasonal norms thus creating an anomaly. The geographical distribution of the anomalies is very important. To a substantial extent, the temperature anomalies along the Equator have disproportionate impact on weather so we study them intensely and that is what the ENSO (El Nino – Southern Oscillation) cycle is all about. Subsurface water can be thought of as the future surface temperatures. They may have only indirect impacts on current weather but they have major impacts on future weather by changing the temperature of the water surface. Winds and Convection (evaporation forming clouds) is weather and is a result of the Phases of ENSO and also a feedback loop that perpetuates the current Phase of ENSO or changes it. That is why we monitor winds and convection along or near the Equator especially the Equator in the Eastern Pacific.

Starting with Surface Conditions.

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

Location Bar for Nino 3.4 Area Above and Below

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 June 4, in the afternoon working from the June 3 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

My estimate of the daily Nino 3.4 SST anomaly tonight is again +0.2 which is clearly an ENSO Neutral value. NOAA has (strangely) reported the weekly Nino 3.4 to be close to last week at 0.0 which is clearly an ENSO Neutral value but we think way too cool for the situation as shown in the TAO/TRITON Graphic and the Australian BOM estimate shown in the    following graphic. Nino 4 is reported to be the same as last week at +0.2. Nino 3 is reported to be warmer than last week at +0.2. Nino 1 + 2 which extends from the Equator south rather than being centered on the Equator is reported much warmer than last week at -0.1. It was up there close to -3.0 at one time so this index has been declining as an anomaly (rising) 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. The same data in graphic form but going back a couple of more years can be found here.  The full table of values can be found here.

This graphic brings the Nino 3.4 up to date and is easy to read. It may be more reliable than the NOAA readings. And Memorial Day is not a Holiday in Australia.

Here is another way of looking at the TAO/TRITON Graphic. It is a fast way to assess the strength of an ENSO Event and provides a way to track it.  

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.

The next graphic overlaps with the subsequent topic but I will show it here.

The discussion in this slide says it better than I could. One might compare the current reading to Oct/Nov 2017. The anomaly had returned to zero then reversed for a month and then returned to zero and now has gone positive. In retrospect it was the Kelvin Wave (#1) Activity the Upwelling Phase and the MJO which caused the brief reversal of the warming trend. We now have Kelvin Wave #2 and perhaps Kelvin Wave #3 so we should expect this warm anomaly to steadily increase for a while.

Side by side comparison can be useful

Comparison Week Probably Third Week of December 2017	Current Week

Sea Surface Temperature and Anomalies

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

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

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

We wondered if there might be a third Kelvin Wave forming which would result in an El Nino rather than ENSO Neutral. We said: “It almost looks like we have another Down-welling Kelvin Wave without ever having the upwelling phase. That could be very important: It seems that NOAA agrees with our eyeballing of the graphic and last week drew in another down-welling Kelvin Wave. We do not want to go overboard on this but it is pretty significant. It is somewhat difficult to tell exactly how many separate Kelvin Waves they have been with the up-welling phase of Wave #2 non-existent or very faint.

 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).

.

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. These currents are very complicated and made even more so by the uneven nature of the ocean floor. So the exact pattern of where this warm water will erupt is beyond my level of understanding. But it will erupt to the surface in multiple different places.

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 neutral water from the Dateline to beyond 100W but a small amount of cool water to the east. We now have warm water with a maximum anomaly of +4C crossing the Dateline at depth to 150W and extending to 100W, the result of another Down-welling Kelvin Wave: Wave #2. We also see that the Warm Pool moving to the East does not appear to be sufficient to fully reverse the prior La Nina into a El Nino unless more warm water appears. Notice the warmest water is from just west of the Dateline to 150W. Also notice there is a break west of 155E. Sometimes the human eye is better than a computer model with respect to pattern recognition.

The 28C Isotherm is now east of the Dateline at 170W, the 27C Isotherm is at 130W, the 25C Isotherm is now east of 100W. The 20C Isotherm is no longer close to reaching the surface near the coast due to reduced impact of the cool water being pushed to the surface by Kelvin Wave #2.

Tracking the change.

And now let us look at the atmosphere.

This graphic shows the Low-Level Wind Anomalies near the Equator. The 850 hPa level is above the surface but close to the surface.	And now the Outgoing Long-wave Radiation (OLR) Anomalies which tell us where convection has been taking place. The bottom of a Hovmoeller graphic shows the most recent readings.
Reds and browns would be suppressed easterlies or enhanced westerlies and are typical of El Nino. It looks pretty neutral.	We see the change in the pattern of suppressed OLR as the La Nina declines.

And Now the Air Pressure to Confirm that the Atmosphere is Reacting to the Sea Surface Temperature Pattern. The most Common way to do that is to use 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

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 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.

Here is the most recent update.

The above is based on looking at a variety of models and other information but we should not forget that NOAA has their own model. Which was shown earlier and can be clicked on. So I do not plan to show the larger version as I have been doing in this part of the Report.

And here is what is called the plume of a variety of forecast models. We will have an update on this graphic soon.

Forecasts from Other Meteorological Agencies.

Here is the newly issued JAMSTEC Model Forecast

And the short recently issued discussion related to the May 1 ENSO forecast.

May 22, 2018 Prediction from 1st May, 2018

ENSO forecast:

The SINTEX-F predicts that a moderate-to-strong El Niño event may start in late summer this year and reach its peak in winter.

Indian Ocean forecast:

Occurrence of a positive Indian Ocean Dipole is clearly predicted by the SINTEX-F seasonal prediction system; the ensemble mean prediction suggests its evolution from early summer and its peak in fall. In accord to the positive IOD evolution, sea level anomalies are expected to be negative (positive) in the eastern (western) tropical Indian Ocean. We may observe co-occurrence of a positive Indian Ocean Dipole and an El Niño-like state in the latter half of 2018; this is just as we observed in 1997 and 2015.

Regional forecast:

On a seasonal scale, most part of the globe will experience a warmer-than-normal condition in summer, while some parts of northern central Russia, India, Southeast Asia, northern Australia, Mexico, and South American Continent will experience a cooler-than-normal condition. In fall, most part of the globe will be a warmer-than-normal condition, while some parts of northern Europe, U. K., East Africa, southern India, Indonesia, the Philippines, western US, eastern Canada, and northern Brazil will experience a relatively cold condition

As regards to the seasonally averaged rainfall, a wetter-than-normal condition is predicted for most parts of India, southern West Africa, western U.S. and northern parts of South American Continent, while Indonesia, eastern China, North/South Korea, some parts of Europe, central U.S., southern Mexico, and Australia will experience a drier-than-normal condition during boreal summer. In fall, we expect a drier-than-normal condition in Northern Europe, northern India, southern China, Indonesia, and Australia will be drier than normal partly due to the expected positive Indian Ocean Dipole.

Most part of Japan will experience warmer and relatively wetter-than-normal conditions in summer. Monthly prediction (not sown) suggests an active rainy season (Baiu) in June. In fall, most part of Japan will experience warmer and relatively drier-than-normal conditions.

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

And the ENSO Outlook Discussion Issued on June 5, 2018

El Niño–Southern Oscillation neutral, but tropical Pacific Ocean warming

The El Niño–Southern Oscillation (ENSO) remains neutral—neither El Niño nor La Niña. Climate model consensus indicates that ENSO will continue in a neutral phase for at least the southern hemisphere winter.

Key indicators of ENSO are mostly near average. Sea surface temperatures (SSTs) are close to the long-term average across the tropical Pacific Ocean, with Nino3.4 positive for the first time since mid-August 2017. Waters beneath the surface are slightly warmer than average. In the atmosphere, the Southern Oscillation Index (SOI) and trade winds are both within the neutral range.

All but one of the eight surveyed international climate models indicate that Pacific Ocean sea surface temperatures (SSTs) will warm slowly over the coming months. Only one model expects central Pacific SSTs to reach El Niño threshold values during winter, however three of the eight models anticipate that an El Niño is likely to develop by the end of the southern hemisphere spring.

During El Niño, rainfall in eastern Australian is typically below average during winter and spring. A neutral ENSO phase has little effect on Australian climate.

Indian Ocean IOD (It updates every two weeks)

Indian Ocean Dipole Outlook  Discussion Issued June 3, 2018

The Indian Ocean Dipole (IOD) is currently neutral, with most climate models indicating a neutral pattern is likely to persist through the southern winter. However, there is a lot of variation amongst models in their outlooks, with one (of six models) forecasting a positive IOD to develop in winter, and another predicting a negative IOD during spring. The accuracy of IOD event forecasts is lower at this time of the year.  The weekly index value to 3 June was −0.34 °C.

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

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

D. Putting it all Together.

At this time La Nina Conditions along the Equator have come to an end. The actual impacts on Worldwide weather lag the change in conditions along the Equator so we may have impacts from this transitioning La Nina for a short period of time but these impacts seem to be tailing off quite dramatically.

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 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. 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 and it is probably three or more years out.

E. Relevant Recent Articles and Reports

Weather in the News  

Nothing to Report

Weather Research in the News

Nothing to Report

Global Warming in the News

Nothing to Report

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

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

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

2. Medium Frequency Cycles such as ENSO and IOD

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

4. Computer Models and Methodologies

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

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

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

1. Introduction

2. Climate Impacts of Global Warming

3. Economic Impacts of Global Warming

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

H. Useful Background Information

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

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

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

Click for Source

Interaction between the MJO and ENSO

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

History of ENSO Events as measured by the ONI

The new SON reading of -0.4 is no longer La Nina Reading. Not all Meteorological Agencies Worldwide will necessarily accept this La Nina to be legitimately declared but most will. 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. It would apply to the states that are at the apex of the trough.

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.]

Here is a time sequence animation. You may have to click on them to get the animation going.

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.