January 7, 2019 – Intermediate-Term Weather Report – Transitions Abound

Written by Sig Silber

It is a strange situation with the analogs corresponding to the end of prior El Nino events, while the potential incipient El Nino has been fading for weeks. The MJO is pausing. The large Pacific storm offshore seems to be hesitating for almost a week before coming ashore. Most but not all parts of CONUS will be warmer than climatology. It seems as if the Weather is trying to make up its mind with respect to the last two weeks of January and the beginning of February. The forecast for the next 10 days or so is fairly reliable but beyond that it is too soon to have a high level of confidence.  

Please share this article – Go to very top of page, right hand side for social media buttons.

From NOAA Climate Prediction Center

The enhanced phase of a robust MJO signal is currently located in Phase 8 (primarily central and eastern Pacific), and a Kelvin wave is near the Brazilian coast.

Most dynamical models agree on very limited eastward propagation of a rapidly weakening MJO signal during Week-1. During Week-2, there is large disagreement on where a new subseasonal signal may re-emerge. The GEFS and Canadian point to a strengthening signal over the West Pacific; the ECMWF model maintains more eastward propagation throughout the period, hinting at the enhanced phase emerging over the Indian Ocean and propagating to the Maritime Continent.

Two major uncertainties regarding the MJO forecast for the next two weeks include a) how long will the convection remain stationary near and west of the Date Line, and b) differences between Week-2 RMM forecasts. The enhanced phase crossing over the Pacific favors a transition to a colder pattern over central and eastern North America during mid January. This transition has been forecast by subseasonal climate forecasts initialized over the past couple of weeks.

In our Monday night Weekly Intermediate-Term Weather and Climate Report, we mostly cover Days 6 – 14 and Weeks 3 – 4 which depending on when you read this article covers to about Day 25. We cover Days  1- 5 also but in most cases readers will want to consult their local NWS Office for more detailed information that impacts them in the short term. However, we plan to start publishing a Report that will continually update and provide easy access to products from the NOAA Storm Prediction Center and other parts of NOAA. This will make it easy to see if there are special situations that need to be considered by those living in the areas covered or planning to travel there. It is not intended to replace reliance on the local NWS Offices but will be an easy way to find out if and where that is needed. The first report may be published Wednesday night.  .

Here is the recent history of the overall pattern for North America and the North Pacific.

Summary of the Forecast

We now provide our usual summary first for temperature and then for precipitation of small images of the four 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.

Sometimes it is useful to see the evolution of the forecasts from the 1 – 5 Day, 6 – 10 Day (which NOAA considers to be Week-1 of their intermediate forecast) , 8 – 14 Day (which NOAA considers to be Week-2) and Week 3 and 4 (which after being issued overlap with Week-2). I do not have comparable maps for the Day 1 – 5 forecast in the same format as the three maps we generally work with. What I am showing for temperature is the Day 3 Maximum Temperature and for precipitation the five-day precipitation: the latter being fairly similar in format to the subsequent set of the maps I present each week but showing absolute QPF (inches of precipitation) not QPF deviation from Normal.

First Temperature

This shows magnitude rather than probability of being higher or lower than Normal and shows the middle day of the five ay period.	The pattern is now mostly zonal (west to east versus meridional north to south to north). But the pattern is moving east very slowly.		The transition from the 8 -14 day forecast shown above to the week 3/4 forecast seems feasibly only because the discussion released with the forecast is convincing.

And then Precipitation

The five day QPF is shown above. The units are different than the other maps i.e. in units of precipitation (inches) not probabilities of exceeding or being less than climatology.	After Day 5, it is generally wet.		The transition from the 8 -14 day forecast shown above to the week 3/4 forecast seems feasible based on reading the discussion issued with the map. It is a big change from the Week – 1, 2 forecast.

A. Now we will begin with our regular approach and focus 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 moderate moisture entering CONUS from the Pacific and also impacting CONUS further south as the Jet Stream has been split.

Tonight, Monday January 7, 2018, as I am looking at the above graphic, you see the same pattern. But notice the gap between the moisture currently entering from the Pacific and the next storm.

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.

The graphic we had been using was not updating so for the time being we added another version which is updating. It does not cover all of CONUS but it does provide a very good view of what is happening in the Pacific and the North American West Coast. But the original graphic we were using is not working so we are using both.

And this graphic is now working again.

And Now the Day One and Two CONUS Forecasts

Day One CONUS Forecast	Day Two CONUS Forecast
These graphics update and can be clicked on to enlarge but my brief comments are only applicable to what I see on Monday night prior to publishing.
Snow looks pretty sparse for the next two days as of Monday Night.

Additional useful forecasts are available from our Severe Weather Report which this week can be found here and always can be located via this directory.

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.

The below makes it easier to focus on a particular day.  The best way to read them is from left to right on the first row and then from left to right in the row below it.

include(“/home4/aleta/public_html/pages/weather/modules/Weather_Map_by_Day_Matrix.htm”); ?>

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 forecast 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.

The Aleutian Low is quite strong with surface central pressure of 976hPa and is mostly centered over the Central Aleutians but also extends down off the West Coast of North America. The Hawaiian High has surface central pressure of 1020 hPa and is far out to sea allowing the Aleutian Low to create troughs that enter CONUS far south.  We see a complex High for the Eastern CONUS but extending west to the Southern Rockies with surface central pressure of 1032 hPa. There is an Arctic High with surface central pressure of 1032 hPa. Further to the east there is a Hudson Bay Low with surface central pressure of 1012 hPa and off shore there is a weak Low with surface central pressure of 1012 hPa. It does not look like I would expect given the NOAA precipitation forecast.

include(“/home4/aleta/public_html/pages/weather/modules/Air_Pressure_Map_by_Day_Matrix.htm”); ?>

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
You can see the current pattern here. One trough impacts the Southwest the other just barely the Northeast.	Looks like a gap in the action until the trough off the Pacific Coast arrives.

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. 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. It is quite complicated. Read from left to right first  row and then left to right on the  second row. 

include (“/home4/aleta/public_html/pages/weather/modules/500_Millibar_by_Day_Matrix.htm”); ?>

We are showing both the situation on the surface and at mid-atmosphere 500 mb and the view is different so sometimes it is useful to simply be able to compare them.

Here is the seven-day cumulative precipitation forecast. More information in how to interpret this graphic 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 January 7, 2019 was 4 out of 5

8 – 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on January 7, 2019 was 2 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 January 7, 2019 was 4 out of 5)

8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on January 7, 2019 was 2 out of 5)

Looking further out.

Here is the 6 – 14 Day NOAA discussion released today January 7, 2019

6-10 DAY OUTLOOK FOR JAN 13 – 17 2019

THE ENSEMBLE MEANS ARE IN GOOD AGREEMENT IN PREDICTING MEAN 500-HPA TROUGHS OVER THE ALEUTIANS AND OFFSHORE OF THE WEST COAST OF NORTH AMERICA DURING THE 6-10 DAY PERIOD. DOWNSTREAM, SPLIT-FLOW IS GENERALLY FORECAST ACROSS WESTERN NORTH AMERICA WITH RIDGING ANTICIPATED FROM THE NORTHWESTERN CONUS TO THE MAINLAND ALASKA WHERE AN ACTIVE SOUTHERN STREAM IS PREDICTED. FARTHER TO THE SOUTH OVER THE SOUTHWESTERN CONUS. GENERALLY LOW AMPLITUDE FLOW IS FORECAST FOR MUCH OF THE CENTRAL AND EASTERN CONUS. THE MANUAL BLEND FOR THE 6-10 DAY PERIOD AVERAGE INDICATES POSITIVE 500-HPA HEIGHT ANOMALIES FOR MUCH OF THE CONUS AND NEGATIVE ANOMALIES OVER THE PACIFIC COAST OF THE WESTERN CONUS AND SOUTHWESTERN ALASKA.  

PACIFIC FLOW AND NEAR TO ABOVE NORMAL 500-HPA HEIGHTS FAVOR ABOVE NORMAL TEMPERATURES ACROSS MUCH OF THE CONUS. THE HIGHEST ODDS FOR ABOVE-NORMAL TEMPERATURES ARE FORECAST ACROSS THE CENTRAL U.S., ASSOCIATED WITH LARGE POSITIVE HEIGHT ANOMALIES DURING THE PERIOD. BELOW NORMAL TEMPERATURE PROBABILITIES ARE FAVORED FOR THE FAR NORTHEAST DUE TO A TROUGH OVER THE ATLANTIC. ABOVE NORMAL TEMPERATURES ARE FAVORED FOR MUCH OF SOUTHEASTERN ALASKA AND THE ALASKA PANHANDLE EAST OF A TROUGH PREDICTED NEAR THE ALEUTIANS. DYNAMICAL MODEL GUIDANCE SUPPORTS INCREASED CHANCES OF BELOW NORMAL TEMPERATURES FOR PARTS OF NORTHWESTERN MAINLAND ALASKA AND THE ALEUTIANS.  

THE UPPER-LEVEL TROUGH OFFSHORE OF THE WEST COAST AND A POTENTIALLY ACTIVE SOUTHERN STREAM INCREASE CHANCES FOR ABOVE NORMAL PRECIPITATION ACROSS THE WESTERN AND MUCH OF CENTRAL CONUS. TELECONNECTIONS FROM THE NEGATIVE HEIGHT ANOMALY CENTER ASSOCIATED WITH THE TROUGH STRONGLY FAVOR ABOVE NORMAL PRECIPITATION FOR MUCH OF CALIFORNIA. INCREASED CHANCES OF ABOVE NORMAL PRECIPITATION ARE INDICATED ACROSS MUCH OF THE SOUTHEASTERN CONUS DUE TO ACTIVE STORMS IN THE SOUTHERN STREAM. FORECAST RIDGING LEADS TO FAVORED NEAR TO BELOW NORMAL PRECIPITATION ACROSS THE NORTHERN ROCKIES EXTENDING TO THE NORTHERN HIGH PLAINS. BELOW NORMAL PRECIPITATION IS ALSO LIKELY FOR THE GREAT LAKES REGION AND THE NORTHEAST IN ASSOCIATION WITH THE ABOVE NORMAL 500-HPA HEIGHTS. MODEL SOLUTIONS INDICATE A 500-HPA TROUGH CENTERED NEAR THE ALEUTIANS WITH BROAD CYCLONIC FLOW, INCREASING CHANCES OF ABOVE NORMAL PRECIPITATION ACROSS THE ALEUTIANS, WESTERN MAINLAND ALASKA, THE SOUTH COAST OF MAINLAND ALASKA, AND THE ALASKA PANHANDLE.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOVE AVERAGE, 4 OUT OF 5, DUE TO GOOD AGREEMENT AMONG 500-HPA HEIGHT PATTERN AND TEMPERATURE AND PRECIPITATION TOOLS.

 8-14 DAY OUTLOOK FOR JAN 15 – 21 2019 

THE ENSEMBLE MEAN SOLUTIONS GENERALLY PREDICT AN AMPLIFIED 500-HPA PATTERN ACROSS WESTERN NORTH AMERICA. A MEAN TROUGH IN THE NORTHEASTERN PACIFIC IS FORECAST WHILE STRONG RIDGING IS PREDICTED FROM THE NORTHWESTERN CONUS TO THE ALASKA PANHANDLE AND INTO MAINLAND ALASKA. CYCLONIC FLOW IS ANTICIPATED FARTHER TO THE EAST ACROSS MUCH OF THE NORTH-CENTRAL AND NORTHEASTERN CONUS. THE 500-HPA BLEND INDICATES WEAK ABOVE NORMAL HEIGHTS OVER MUCH OF THE CONUS AND MUCH OF ALASKA EXCEPT PARTS OF SOUTHWESTERN ALASKA AND THE ALEUTIANS AND THE FLORIDA PENINSULA. 

ENHANCED PROBABILITIES OF NEAR TO ABOVE NORMAL TEMPERATURES ARE INDICATED FOR THE CONUS IN ASSOCIATION WITH THE LOW AMPLITUDE FLOW AND WEAK ABOVE NORMAL HEIGHTS PREDICTED ACROSS MUCH OF THE FORECAST DOMAIN. ENHANCED ODDS OF ABOVE NORMAL TEMPERATURES ARE FAVORED FOR SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA PANHANDLE DUE TO 500-HPA RIDGING AND ABOVE NORMAL HEIGHTS THERE.

 THE TROUGH PREDICTED NEAR CALIFORNIA COAST YIELDS INCREASED CHANCES FOR ABOVE NORMAL PRECIPITATION FOR THE WESTERN CONUS. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED FARTHER TO THE EAST ACROSS MUCH OF THE CENTRAL CONUS NORTHEASTWARD TO THE GREAT LAKES REGION AND NORTHEAST UNDERNEATH PREDICTED MEAN CYCLONIC FLOW. A TILT IN THE ODDS FOR NEAR TO BELOW NORMAL PRECIPITATION IS INDICATED FOR PARTS OF THE NORTHERN HIGH PLAINS DUE TO THE RIDGING. ENHANCED ODDS FOR ABOVE NORMAL PRECIPITATION ARE INDICATED ACROSS SOUTHERN ALASKA DUE TO THE AMPLIFIED UPPER-LEVEL TROUGH CENTERED OVER THE ALEUTIANS. 

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: BELOW AVERAGE, 2 OUT OF 5, DUE TO RELATIVELY HIGH MODEL SPREAD AND DISAGREEMENTS AMONG THE SURFACE TOOLS.

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

Analogs to the NOAA 6 – 14 Day 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.

* I assign values that are consistent with the trend so I am doing some subjective smoothing with respect to the Phases of the AMO and PDO shown in this table. (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 December 17 to January 16, 2019 is 30 days which is much wider than last week. I have not calculated the centroid of this distribution which would be the better way to look at things but the midpoint, which is a lot easier to calculate, and fairly accurate if the dates are reasonably evenly distributed, is about January 1. These analogs are describing historical weather that was centered on 3 days and 4 days ago (January 2 or January 3). So the analogs could be considered to be pretty much in of sync with respect to weather that we would normally be getting right now.

For more information on Analogs see discussion in the GEI Weather Page Glossary. 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 are eight El Nino Analogs, zero Neutral analogs and two La Nina Analogs. The pre-forecast analogs this week strongly favor McCabe Condition D which is “Southwest Drought  extending  to the North and also the Great Lakes. This is the most drought-prone combination of Ocean Phases”.  This totally contradicts the forecast and leaves me with low confidence in the NOAA forecast.

include(“/home4/aleta/public_html/pages/weather/modules/McCabe_background_information.htm”); ?>

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.

Some Indices of Possible Interest: We should always remember that the forecast is driven by many factors some of which are conflicting in terms of their impacts. Please pay more attention to the graphics than my commentary which does not update on a regular basis once the article is published. The indices will continue to update. I provide these indices as they are important guidelines to the weather. It is in a way looking at the factors that are impacting the weather. There were developed  because weather forecasters found them to be useful.

include (“/home4/aleta/public_html/pages/weather/modules/AO_NAO_PNA_MJO_Background_Information.htm”); ?>

We provided additional information in the introduction to this Article.

Madden Julian Oscillation (MJO)

The MJO is an area of convective activity along the Equator which circles the globe generally in 30 to 60 days. The location of the convective activity not only impacts the Equator but also the middle latitudes. Most people are not familiar with the MJO but at certain times it plays an important role Worldwide re weather and for CONUS.

There are a lot of models and I try to read the results from all of them. For access to a variety of models, I refer readers here. This weekly report summarizes things. Here is another useful source of information.

First we look at two models that I find very helpful. On the GFS graphic , the light gray shading shows the tracks which fit with 90% of the forecasts and the dark gray shading shows a smaller area that fits with 50% of the forecasts The large dot is the current location.

It is sometimes useful to look at the recent history of the MJO.

Here is another way  of looking at this information through time with a Hovmoeller graphic.

Then the first of the two indices we typically present.

This shows the recent history.  MJO is now in Phase 5.  It has not moved.

And then a forecast.

Remember we are interested in how the MJO impacts CONUS weather during early January. So I have displayed the DJF information this week.  Over the next two weeks, Phases 6 and 7 may be experienced.

Temperature

Precipitation

Recent CONUS Weather

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

And the 30 Days ending December 29, 2018	And the 30 Days ending January 5, 2018
You can see the wetter pattern in the West and the shift to the east of the warm anomaly.	Drier in the Southwest and more intense re temperature along the Northern Tier.
Remember, these maps are a 30 average so the most distant seven days are removed and the most recent seven days are added.

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

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-to late-January (with respect to the forecast we should have returned from the set of positions shown below for July to the Winter Pattern. For CONUS, the seasonal repositioning of the Bermuda High and the Pacific High are very significant.

World Forecasts

1. Today (Source: University of Maine)

2. Short-term set for day six but can be adjusted (BOM – Australia)

3. 8 – 14 Day (NOAA/Canada/Mexico Experimental NAEFS))

4 Tropical  Activity

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

And now precipitation

Additional Maps showing different weather variables can be found here.

2. 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

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

Now Precipitation

3. And now we have experimental 8 – 14 Day World forecasts from the NAEFS Model.

First Temperature

Then Precipitation

4. Tropical Hazards.

C. ENSO SUMMARY of Current Status. Our full report was published on December 13 with the  Drought Report and it can be accessed here. 

Current Status of ENSO

This section is organized into three parts.

1. Current Sea Surface Temperatures (SST)

2. Current Nino 3.4 Readings

3. The Surface Air Pressure Pattern that confirms the state of ENSO.

1. Current and Recent Sea Surface Temperatures (SST)

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.

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

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.

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

First the categorization of the current Monthly Average SST anomalies.
Mediterranean, Black Sea and Caspian Sea	Western Pacific	West of North America	North and East of North America	North Atlantic
Mediterranean and Black Sea warm, Caspian Sea cool	Warm	Warm especially in Gulf of Alaska	Great Lakes cool Cool north of Cape Hatteras Warm around Florida	Not shown in this map
Equator	Looks like El Nino but Barely
Africa	West of Australia	North, South and East of Australia	West of South America	East of South America
Warm off Kenya extending beyond Madagascar	Cool	Warm SE and beyond New Zealand	Neutral	Warm 20S Warm 40S 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.

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. NOAA considers Nino 3.4 shown in the graphic as the best indicator of Equatorial Surface Temperature Anomalies associated with different phases of ENSO. There is a duration requirement to be a recorded El Nino or La Nina but to have El Nino Conditions the Nino 3.4 index needs to be +0.5C or warmer and to have La Nina Conditions the Nino 3.4 Index needs to be -0.5C or cooler.

This graphic brings the Nino 3.4 up to date and is easy to read.

Here is a daily version

Starting with Surface Conditions.

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

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

This may help put the above graphics in focus.

Updated ONI History

3. The Surface Air Pressure that Confirms the Nino 3.4 Index

And of course Queensland Australia is the official keeper of the SOI measurements.

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).

D. Putting it all Together.

At this time, La Nina Conditions along the Equator have come to an end and we are solidly into ENSO Neutral and possibly entering into El Nino Conditions. But the drivers of a transition to El Nino are not solidly in place. In fact this is almost unprecedented in terms of the lateness of the arrival of a potential El Nino. If an El Nino it will be where the Peak Value of the Nino 3.4 Index will be achieved early on and will be in decline the rest of the time which has different impacts than an El Nino with a stable Nino 3.4 Index.

E. Relevant Recent Articles and Reports

Weather in the News

Nothing to Report

Global Warming in the News

Nothing to Report

F. Useful Reference Information

Understand How the Jet Stream Impacts Weather

include(“/home4/aleta/public_html/pages/weather/modules/Jet_Streak_Four_Quadrant_Analysis.htm”); ?>

include(“/home4/aleta/public_html/pages/weather/modules/MJO_and_ENSO_Interaction_Matrix.htm”); ?>

Standard Pressure Levels

include(“/home4/aleta/public_html/pages/weather/modules/Standard_Pressure_surfaces.htm”); ?> include(“/home4/aleta/public_html/pages/weather/modules/Table_of_Contents_for_Part_II.htm”); ?>