Written by Sig Silber
It is the NOAA theory that the MJO will dominate the first half of January and El Nino will gradually take control. There are reasons to agree with this but also reasons to conclude that there may not really be an El Nino this Winter – that the major driver will remain the MJO. What we may be able to agree on is that the second half of January is likely to be quite different than the first half of January but that can be explained by the changing location or phase of the MJO or alternatively by the El Nino taking charge. Meteorological Winter lasts three months namely December/January/February so within two months we will know if El Nino managed to suppress the MJO. Can you bet on this in Vegas?
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First we will start with the January Update Issued today.
Although the general theme is a bit warmer and a bit wetter, it is important for readers to look at the maps for the month and the maps that we have in the article for first five days, Days 6 – 10, Days 8 – 14 and Week 3 – 4 as the pattern is expect to change during the month. Other than the full -month map, the other maps will auto-update so this article will remain useful throughout the month.
Now let us address the NOAA Update of the January, 2018 Forecast.
A note about terminology; the deviations from climatology/normal are color coded but also labeled “A” for more than (above) normal and “B” for less than (below) normal. The area designated EC means Equal Chances of being more or less than normal. In the Short Term forecasts, NOAA has switched from using EC to N for Normal. I believe this was a recommendation of a Focus Group. I find those new graphics harder to read especially if printed in black and white. For most purposes, EC and N can be considered to mean about the same thing. “N” implies a bit more certainty that the variation from Normal/Climatology will be small compared to “EC”.
First we will compare the NOAA Early Outlook for January, 2019 with the newly issued update.
Early Outlook Temperature
Updated Temperature Outlook
Early Outlook Precipitation
Updated Precipitation
Here is the unusually long NOAA Discussion that was released with the January Update.
30-DAY OUTLOOK DISCUSSION FOR JANUARY 2019
THE UPDATED TEMPERATURE AND PRECIPITATION OUTLOOKS FOR JANUARY 2019 ARE BASED PRIMARILY ON THE LATEST AVAILABLE DYNAMICAL MODEL GUIDANCE (SUCH AS THE GFS, CFS, AND ECMWF), WPC’S WEEK-1 PRECIPITATION OUTLOOK, CPC’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’S INDEX VALUES WERE MOSTLY NEGATIVE, WHICH FAVORED A SOMEWHAT COLDER PATTERN OVER THE CENTRAL AND EASTERN CONUS COMPARED TO TODAY.
THE UPDATED TEMPERATURE OUTLOOK FOR JANUARY 2019 PREDICTS ENHANCED ODDS OF BELOW NORMAL TEMPERATURES OVER MUCH OF NEW ENGLAND. IT IS THOUGHT THAT MORE WIDESPREAD COLD WILL BE IN PLACE ACROSS THE EASTERN CONUS DURING MID-LATE JANUARY, THOUGH IT MAY NOT OFFSET THE NEAR TO ABOVE NORMAL TEMPERATURES PREDICTED EARLY IN THE MONTH. THEREFORE, EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE NORMAL TEMPERATURES ARE CONSIDERED TO BE THE BEST BET ACROSS MOST OF THE EASTERN CONUS. THIS IS LARGELY BASED ON THE LAST 9 RUNS OF THE CFS MODEL; AND ON CPC’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
THE UPDATED PRECIPITATION OUTLOOK FOR JANUARY 2019 FAVORS UPPER-TERCILE (ABOVE NORMAL) PRECIPITATION FROM SOUTHERN CALIFORNIA EASTWARD ACROSS ARIZONA, NEW MEXICO, FAR WEST TEXAS, AND PARTS OF NEIGHBORING STATES. THIS IS SUPPORTED BY DETERMINISTIC GFS AND ECMWF MODEL OUTPUT, RECENT RUNS OF THE CFS, AND CPC’S OFFICIAL 6-10 DAY AND WEEK-2 PRECIPITATION OUTLOOKS. A SECOND AREA OF FAVORED UPPER-TERCILE PRECIPITATION IS INDICATED FOR THE LOWER MISSISSIPPI VALLEY, THE TENNESSEE VALLEY, THE SOUTHEAST, AND PARTS OF ADJACENT STATES. THIS SECOND AREA IS BASED ON CPC’S WEEK 3/4 PRECIPITATION OUTLOOK, AND 8 OF THE LAST 9 CFS RUNS. A THIRD AREA OF FAVORED UPPER-TERCILE PRECIPITATION IS DEPICTED OVER SOUTHWEST ALASKA, SUPPORTED BY NEARLY EVERY ONE OF THE LAST 9 CFS RUNS, AND CPC’S 6-10 DAY AND WEEK-2 PRECIPITATION OUTLOOKS. THESE THREE FORECAST AREAS ARE COINCIDENT WITH THE TYPICAL LOCATION OF WINTERTIME EL NINO STORM TRACKS. LOWER-TERCILE (BELOW NORMAL) PRECIPITATION IS FAVORED FOR THE PACIFIC NORTHWEST, NORTHERN AND CENTRAL PORTIONS OF THE INTERMOUNTAIN REGION AND THE ROCKIES, MOST OF THE NORTHERN AND CENTRAL GREAT PLAINS, THE NORTH-CENTRAL MISSISSIPPI VALLEY, THE OHIO VALLEY, AND THE GREAT LAKES REGION. THIS AREA OF FAVORED BELOW NORMAL PRECIPITATION HAS VARIOUS DEGREES OF SUPPORT FROM CPC’S PRECIPITATION OUTLOOKS SPANNING ALL TIME SCALES OUT TO ONE MONTH IN ADVANCE, AND IS SUPPORTED BY A MAJORITY OF THE MOST RECENT 9 CFS PRECIPITATION FORECASTS.
IN AREAS WHERE MODELS/TOOLS CONFLICT, OR CLIMATE INDICATIONS ARE VERY WEAK, EC IS FAVORED. THIS INCLUDES MOST OF ALASKA, AND A SIGNIFICANT FRACTION OF THE LOWER 48 STATES.
—– REASONING BEHIND 0.5-MONTH LEAD OUTLOOKS [Editor’s note: the prior Early Outlook forecast] FOR JANUARY IS SHOWN BELOW —–
THE MONTHLY TEMPERATURE AND PRECIPITATION OUTLOOKS ARE BASED ON DYNAMICAL MODELS (MONTHLY NMME SUITE OF FORECASTS WHICH INCLUDES THE CFS, THE IMME, AND THE WEEK 3/4 ECMWF AND CFS FORECASTS), STATISTICAL MODELS (SMLR, CCA, OCN, CAS), ENSO, THE MJO, SSTS NEAR THE U.S. COAST, CONSIDERATION OF BOTH THE NORTH PACIFIC OSCILLATION (NPO) AND ARCTIC OSCILLATION (AO), AND CLIMATOLOGY.
THE LATEST ENSO UPDATE INDICATES ENSO-NEUTRAL CONTINUED DURING NOVEMBER. DESPITE ABOVE AVERAGE SSTS AND SUBSURFACE TEMPERATURES ACROSS MOST OF THE TROPICAL PACIFIC, THERE IS NO CLEAR COUPLING BETWEEN ATMOSPHERIC CONVECTION AND THE ABOVE AVERAGE OCEAN TEMPERATURES. THE LONG TRANSITION FROM ENSO-NEUTRAL TO EL NINO IS EXPECTED TO FINALLY GIVE WAY TO EL NINO, AND THEN CONTINUE THROUGH THE NORTHERN HEMISPHERE WINTER (90% CHANCE) AND THROUGH SPRING (ABOUT A 60% CHANCE). THEREFORE, EL NINO IS EXPECTED TO PLAY A ROLE IN THE JANUARY 2019 TEMPERATURE AND PRECIPITATION PATTERNS.
THE MJO IS CURRENTLY ROBUST, WITH THE ENHANCED CONVECTIVE PHASE OVER THE MARITIME CONTINENT REGION (PHASES 4 AND 5). DURING THE NEXT FEW WEEKS, THIS ENHANCED PHASE IS FORECAST TO MOVE OUT OVER THE WESTERN PACIFIC (PHASES 6 AND 7). THE CONVECTIVE PHASE OVER THIS LATTER REGION IS OFTEN ASSOCIATED WITH ANOMALOUSLY COLD WEATHER OVER THE CENTRAL AND EASTERN CONUS, PERHAPS BY MID JANUARY 2019.
THE NORTH PACIFIC OSCILLATION (NPO) AND ITS RELATED WEST PACIFIC OSCILLATION (WPO) ARE CURRENTLY IN THEIR POSITIVE PHASE. THIS PHASE IS CHARACTERIZED BY BELOW NORMAL SEA-LEVEL PRESSURE AND MID-TROPOSPHERIC HEIGHTS OVER THE ALASKA DOMAIN, AND ABOVE NORMAL SEA-LEVEL PRESSURE AND MID-TROPOSPHERIC HEIGHTS OVER THE MID-LATITUDE CENTRAL AND EASTERN PACIFIC. THIS SETUP IS TYPICALLY ASSOCIATED WITH ANOMALOUS WARMTH OVER MUCH OF NORTH AMERICA, AS RELATIVELY MILD PACIFIC AIR OVERSPREADS A LARGE PORTION OF THE CONTINENT. HOWEVER, IT IS THOUGHT THAT BY MID TO LATE JANUARY 2019, THE PHASE OF THE NPO COULD REVERSE, WHICH FAVORS THE FORMATION OF CONTINENTAL ARCTIC AIR MASSES OVER WESTERN CANADA. FROM THERE, IT’S ONLY A MATTER OF TIME BEFORE THESE ARCTIC AIR MASSES ADVANCE SOUTHEASTWARD INTO THE CENTRAL AND EASTERN CONUS. THE ARCTIC OSCILLATION (AO) IS ANOTHER KEY PLAYER REGARDING U.S. WINTERTIME CLIMATE VARIABILITY. THE GFS ENSEMBLE MEAN PREDICTS THE AO WILL BE IN ITS NEGATIVE PHASE (ANOMALOUS COLD OVER MUCH OF THE EASTERN CONUS) FOR THE NEXT 7-10 DAYS. BEYOND THAT, THERE IS LARGE UNCERTAINTY IN THE PREDICTED PHASE OF THE AO, THOUGH A SLIGHT MAJORITY OF ENSEMBLE MEMBERS FAVOR THE NEGATIVE PHASE.
THE OFFICIAL JANUARY 2019 TEMPERATURE OUTLOOK FAVORS ABOVE NORMAL TEMPERATURES OVER ALASKA, THE WESTERN CONUS, AND SOUTHERN FLORIDA. THIS IS SUPPORTED BY THE NMME MODEL SUITE, THE IMME, MOST CFS MODEL RUNS DURING THE PAST NINE DAYS, AND TO SOME DEGREE THE SMLR TOOL. TEMPERATURE TRENDS DURING THE PAST 15 YEARS FOR THIS TIME OF YEAR SUPPORT ABOVE NORMAL TEMPERATURES ACROSS THE WEST. BELOW NORMAL TEMPERATURES ARE FAVORED OVER THE INTERIOR SOUTHEAST, SOUTHERN OHIO VALLEY, AND THE VIRGINIAS. THIS AGREES WELL WITH THE WEEK 3/4 TEMPERATURE FORECASTS FROM THE CFS AND ESPECIALLY THE ECMWF. SEVEN OF THE LAST NINE RUNS OF THE CFS PREDICT NEAR NORMAL TEMPERATURES ACROSS THIS SAME GENERAL REGION, WITH THE EXCEPTION OF THE LATEST TWO RUNS, WHICH INTRODUCE SOME ABNORMAL COLD TO THE EAST. A FEW OF THE INPUT MODELS TO THE NMME (NCAR, NASA, AND GFDL) ALSO FAVOR THIS RELATIVE COLD, BUT THE EXACT LOCATION IS UNCLEAR. THE CMC1 AND CMC2 CANADIAN MODELS PREDICT BELOW NORMAL TEMPERATURES FARTHER WEST OVER THE MIDDLE AND LOWER MISSISSIPPI VALLEY. ELSEWHERE, EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE NORMAL TEMPERATURES ARE FAVORED.
THE PRECIPITATION OUTLOOK FOR JANUARY 2019 FAVORS ABOVE NORMAL PRECIPITATION FROM THE SOUTHERN PLAINS EASTWARD ACROSS THE GULF COAST STATES, INCLUDING ALL OF FLORIDA. THIS WETNESS IS SUPPORTED BY A MAJORITY OF NMME INPUTS, AND IS WHAT WOULD BE EXPECTED WITH AN EL NINO AND ITS ASSOCIATED SOUTHERN TIER STORM TRACK. THE CALIBRATED VERSION OF THE NMME DEPICTS THE MOST FAVORED AREAS FOR RELATIVE WETNESS ARE THE SOUTHERN HIGH PLAINS AND THE EASTERN GULF COAST REGION. THE IMME, ON THE OTHER HAND, PREDICTS NEAR TO BELOW NORMAL PRECIPITATION ACROSS THE PREDICTED REGION (SOUTHERN PLAINS EASTWARD ACROSS THE GULF COAST STATES, INCLUDING ALL OF FLORIDA). THE CFS HAS BEEN CONSISTENT IN PREDICTING ABOVE NORMAL PRECIPITATION OVER MUCH OF TEXAS AND FLORIDA. ABOVE NORMAL PRECIPITATION IS ALSO FAVORED OVER THE SOUTHERN THIRD OF MAINLAND ALASKA, WHICH IS CONSISTENT WITH AN EL NINO, THOUGH THIS IS NOT PREDICTED BY ALL MODELS. BELOW NORMAL PRECIPITATION IS FAVORED OVER THE PACIFIC NORTHWEST, NORTHERN CALIFORNIA, THE NORTHERN AND PORTIONS OF THE CENTRAL INTERMOUNTAIN REGION, AND PARTS OF THE NORTHERN ROCKIES. THIS IS STRONGLY SUPPORTED BY THE NMME, THE IMME (ALTHOUGH SHIFTED SOUTHWARD TO INCLUDE WESTERN OREGON AND ALL OF CALIFORNIA), AND THE CFS MODEL TO VARIOUS DEGREES. ODDS FAVOR BELOW NORMAL PRECIPITATION OVER THE OHIO VALLEY AND SOUTHERN GREAT LAKES REGION, WHICH IS PARTLY ATTRIBUTED TO TYPICAL EL NINO IMPACTS, THE CAS, A MAJORITY OF THE PAST 9 CFS RUNS, AND THE IMME. ELSEWHERE, EQUAL CHANCES (EC) OF BELOW, NEAR, AND ABOVE NORMAL PRECIPITATION IS FAVORED.
Visual Consistency Testing.
It is useful to see how the month forecast fits with the set of shorter forecasts that we have. These will continue to update in this article day by day. This consistency testing also serves the purpose of showing how the next 25 days or so are forecast to play out so it segments the month forecast into four parts which cover most but not all of January.
First Temperature
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| The new monthly forecast is to the right. Does it appear to be reflective of the four parts of the month for which we have forecasts? → |
| ↑ ← The Week 3 – 4 forecast was updated Friday so it is reasonably current. The four parts seem to add up pretty well to the month forecast and we do not have the last week of the month shown in the top row. | |
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The new monthly forecast is to the right. Does it appear to be reflective of the four parts of the month for which we have forecasts? → |
| ↑ ← The current Week 3 – 4 forecast was updated pm Friday so it is reasonably current. For precipitation it is not clear if the four partial forecasts combined equal the month forecast. But we are missing the last week of January. | |
Sometimes it is useful to compare the three-month outlook to the forecast for the first of the three months. It shows how much the pattern changes over the three-month period.
One can mentally subtract the First-Month Outlook from the Three-month Outlook and create the Outlook for the last two months in the three-month period.
And with respect to drought. This was issued today.
Intermediate-Term Forecast
Now we focus on the next 25 days breaking it down mostly by Days 6 – 10, 8 – 14, and Weeks 3 – 4 but we also cover the short term. What we called the Visual Consistency Testing of the Monthly forecast also serves as a summary of the Intermediate-Term Forecast so we are not repeating that table what was shown earlier. .
Here is the recent history of the overall pattern for North America and the North Pacific.
Now we will 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 moisture entering CONUS from the Pacific and also impacting CONUS further south as the Jet Stream has been split.
Tonight, Monday December 31, 2018, as I am looking at the above graphic, you see the same pattern.
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 have been using was not updating o for the time being we are using 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.
And Now the Day One and Two CONUS Forecasts
Day One CONUS Forecast | Day Two CONUS Forecast |
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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. | |
| You see very definitive snow areas around mostly in the Southwest. | |
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.
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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 988 hPa and is centered in the Gulf of Alaska. 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. There is a trailing Aleutian Low with surface central pressure of 988 hPa so this is not an isolated event. We see a High over the Southern Rockies with surface central pressure of 1020 hPa and a larger ridge of high pressure northeast of this Four Corners High. Off of Newfoundland there is a Low with central surface pressure of 996 hPa. It covers a large area. There is an Arctic High with surface central pressure of 1024 hPa. It is not a very complex situation but there are always complications. One complication is the strength of the southern branch of the Polar Jet Stream. That is more of an MJO feature than an El Nino feature.
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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 |
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| You can see the current pattern here. The base of that trough will be impacting New Mexico on New Years Day. | There is a subsequent trough, not as perfectly created, shown here on Day 5. |
Putting the Jet Stream into Motion and Looking Forward a Few Days Also
To see how the pattern is projected to evolve, please click here. In addition to the shaded areas which show an interpretation of the Jet Stream, one can also see the wind vectors (arrows) at the 300 Mb level.
This longer animation shows how the jet stream is crossing the Pacific and when it reaches the U.S. West Coast is going every which way.
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.
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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.
| Surface 850MB | Mid Atmosphere 500 MB |
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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 December 31, 2018 was 3 out of 5
8 – 14 Day Temperature Outlook issued today (Note the NOAA Level of Confidence in the Forecast Released on December 31, 2018 was 3 out of 5).
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Looking further out.
Now – Precipitation
6 – 10 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 31, 2018 was 3 out of 5)
8 – 14 Day Precipitation Outlook Issued Today (Note the NOAA Level of Confidence in the Forecast Released on December 31, 2018 was 3 out of 5)
Looking further out.
Here is the 6 – 14 Day NOAA discussion released today December 31, 2018
6-10 DAY OUTLOOK FOR JAN 06 – 10 2019
THERE IS GENERALLY FAIR AGREEMENT AMONG TODAY’S MODEL RUNS IN REGARDS TO THE 500-HPA GEOPOTENTIAL HEIGHT PATTERN OVER THE 6-10 DAY PERIOD. RIDGING AND POSITIVE HEIGHT ANOMALIES ARE FORECAST OVER MUCH OF THE CONUS WITH THE 06Z GEFS ENSEMBLE MEAN BEING MORE AMPLIFIED THAN THE 00Z ECMWF ENSEMBLE MEAN. MODEL SIMULATIONS ALL SHOW POSITIVE HEIGHT ANOMALIES IN THE NORTH ATLANTIC CONSISTENT WITH A PREDICTED NEGATIVE PHASE OF THE NORTH ATLANTIC OSCILLATION. HOWEVER, KEY DIFFERENCES EXIST IN THE DEPICTION OF TROUGHING UPSTREAM. THE 06Z GEFS SHOWS A STRONGER TROUGH AXIS CENTERED NEAR NEW BRUNSWICK, CANADA THAN THE 00Z ECMWF ENSEMBLE MEAN AND THE 00Z CANADIAN ENSEMBLE MEAN. OF NOTE IS THAT THE CANADIAN ENSEMBLE MEAN PLACES THE NORTH ATLANTIC RIDGE AXIS THE FARTHEST EAST OF THE DYNAMICAL GUIDANCE AND THE GEFS FARTHEST WEST, WITH THE ECMWF IN BETWEEN THE GEFS AND THE CANADIAN. MOST WEIGHT IS GIVEN TO THE ECMWF SOLUTION AS THE NORTH ATLANTIC OSCILLATION IS FORECAST TO BE TRENDING MORE TOWARD A NEUTRAL PHASE SUPPORTING A MORE DE-AMPLIFIED PATTERN UPSTREAM. TROUGHING IS FORECAST OFF THE WEST COAST OF THE CONUS EXTENDING THROUGH ALASKA.
RIDGING OVER THE CONUS FAVORS WIDESPREAD ABOVE NORMAL TEMPERATURE PROBABILITIES, WITH PROBABILITIES NOT RAISED TOO HIGH GIVEN THE UNCERTAINTY IN REGARDS TO THE LEVEL OF AMPLIFICATION. THE GEFS SHOWS BELOW NORMAL TEMPERATURES FOR PARTS OF THE EAST WITH THE ECMWF BEING WARMER DUE TO MODELING DIFFERENCES IN THE NORTH ATLANTIC HEIGHT PATTERN DISCUSSED ABOVE. THE ECMWF DEPICTION OF THE NORTH ATLANTIC RIDGE STILL TELECONNECTS WITH BELOW NORMAL TEMPERATURE PROBABILITIES OVER NEW ENGLAND WHICH IS FAVORED IN TODAY’S FORECAST. BELOW NORMAL TEMPERATURES ARE FAVORED OVER MUCH OF ALASKA DUE TO FORECASTED TROUGHING. SOME MODERATION IS POSSIBLE OVER THE SOUTHEAST MAINLAND AND THE PANHANDLE LATE IN THE PERIOD.
HIGH CONFIDENCE EXISTS FOR ABOVE NORMAL PRECIPITATION OVER SOUTHERN CALIFORNIA AND THE DESERT SOUTHWEST AS SHORTWAVE ENERGY REACHES THE COAST AROUND JAN 6 AND 7 ALLOWING SOUTHERLY FLOW OF MOISTURE INTO THE REGION. OVER THE LAST FEW DAYS THERE HAS BEEN UNCERTAINTY AMONG THE DETERMINISTIC GUIDANCE IN REGARDS TO THIS ENERGY AFTER IT IMPACTS THE WEST AS TO WHETHER OR NOT IT WILL RESULT IN SURFACE CYCOLOGENESIS OVER THE PLAINS, WHICH WOULD RESULT IN HIGHER PROBABILITIES FOR ABOVE NORMAL PRECIPITATION. SURFACE HIGH PRESSURE FAVORS BELOW NORMAL TEMPERATURE PROBABILITIES ACROSS THE SOUTHEAST. WHILE THE GEFS SHOW A LARGE AREA OF BELOW NORMAL PRECIPITATION PROBABILITIES THROUGHOUT MUCH OF THE EASTERN CONUS, UNCERTAINTY IN REGARDS TO A POTENTIAL STORM SYSTEM IN THE MIDWEST SHIFTING TOWARD THE NORTHEAST NEAR THE END OF THE PERIOD PROMOTES A NEAR NORMAL FORECAST FOR NOW, WITH FUTURE FORECASTS ADJUSTING UPWARD OR DOWNWARD AS CONFIDENCE REGARDING THE AFOREMENTIONED STORM SYSTEM INCREASES. BELOW NORMAL PRECIPITATION PROBABILITIES ARE FAVORED FOR MUCH OF ALASKA EXCEPT FOR THE SOUTHERN MAINLAND, PANHANDLE, AND THE ALEUTIANS WHICH ARE FORECAST TO SEE IMPACTS FROM MULTIPLE WAVES OF LOW PRESSURE THROUGHOUT THE PERIOD.
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO FAIR AGREEMENT AMONG MODEL SOLUTIONS, OFFSET BY SOME DISAGREEMENT IN REGARDS TO THE PATTERN EVOLUTION LATE IN THE PERIOD.
8-14 DAY OUTLOOK FOR JAN 08 – 14 2019
AS IN THE 6-10 DAY PERIOD THERE IS SOME UNCERTAINTY IN REGARDS TO THE PATTERN EVOLUTION IN THE 8-14 DAY PERIOD. BOTH THE GEFS AND ECMWF ENSEMBLES WEAKEN THE BROAD RIDGE OVER THE CONUS, BUT SHOW SOME REDEVELOPMENT OVER THE WESTERN CONUS EXTENDING THROUGH EASTERN MAINLAND ALASKA LATER IN THE PERIOD. POSITIVE HEIGHT ANOMALIES ARE FORECAST TO BE LOWER TOWARD THE EAST COAST OF THE CONUS, WITH PERSISTENT POSITIVE HEIGHT ANOMALIES OVER THE NORTH ATLANTIC CONTINUING TO ADD UNCERTAINTY TO THE FORECAST.
ABOVE NORMAL TEMPERATURES ARE FAVORED FOR THE CENTRAL AND WESTERN CONUS, WITH SOME HIGHER PROBABILITIES ALONG THE WEST COAST AS RIDGING POSSIBLY BECOMES MORE AMPLIFIED LATE. ABOVE NORMAL TEMPERATURE PROBABILITIES ARE INTRODUCED INTO SOUTHEASTERN MAINLAND ALASKA AND THE PANHANDLE WHICH IS ALSO FORECAST TO COME UNDER THE INFLUENCE OF RIDGING. THE EASTERN CONUS IS FAVORED TO HAVE NEAR NORMAL TEMPERATURE PROBABILITIES WITH THE EXCEPTION OF NEW ENGLAND WHERE BELOW NORMAL PROBABILITIES ARE FAVORED.
ABOVE NORMAL PRECIPITATION PROBABILITIES ARE FORECAST FOR THE DESERT SOUTHWEST IN ASSOCIATION WITH SHORTWAVE ENERGY MOVING THROUGH EARLY IN WEEK-2. PROBABILITIES FOR ABOVE NORMAL PRECIPITATION ARE ALSO ELEVATED OVER THE PLAINS AS THIS ENERGY MOVES NORTHEASTWARD. AS HIGHLIGHTED IN THE 6-10 DAY OUTLOOK, THERE IS UNCERTAINTY AS TO WHETHER OR NOT THIS ENERGY WILL IMPACT THE NORTHEAST AND MID-ATLANTIC WITH THE GEFS REFORECAST FAVORING BELOW NORMAL PRECIPITATION AND THE ECMWF FAVORING ABOVE NORMAL. SURFACE HIGH PRESSURE FAVORS BELOW NORMAL PRECIPITATION PROBABILITIES OVER THE DEEP SOUTH. A FARTHER NORTH STORM TRACK OVER SOUTHERN ALASKA FAVORS MOVING THE ABOVE NORMAL PROBABILITIES FOR PRECIPITATION SLIGHTLY NORTH RELATIVE TO THE 6-10 DAY OUTLOOK, BUT BELOW NORMAL PRECIPITATION IS STILL FORECAST FOR MUCH OF THE MAINLAND.
FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: ABOUT AVERAGE, 3 OUT OF 5, DUE TO FAIR AGREEMENT AMONG MODEL SOLUTIONS IN REGARDS TO TEMPERATURES, WITH SOME DISAGREEMENT AMONG THE PRECIPITATION 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.
| Centered Day | ENSO Phase | PDO* | AMO* | Other Comments |
| Jan 3, 1951 | Neutral | – | + | |
| Dec 29, 1966 | Neural | – | – | |
| Dec 30, 1966 | Neutral | – | – | |
| Dec 31, 1971 | La Nina | – | – | |
| Dec 15, 1975 (2) | La Nina | – | – | |
| Dec 21, 1987 | El Nino | + | – | Modoki Type I |
| Dec 22, 1987 | El Nino | + | – | Modoki Type I |
| Dec 29, 1988 (2) | La Nina | – | – |
* 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 15 to January 3, 2019 is only 19 days which is fairly tight. 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 December 20. These analogs are describing historical weather that was centered on 3 days and 4 days ago (December 26 or December 27). So the analogs could be considered to be out of sync with respect to weather that we would normally be getting right now but we are getting weather that we would normally get a week earlier. .
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 two El Nino Analogs, three Neutral analogs and five La Nina Analogs. The pre-forecast analogs this week strongly favor McCabe Condition B which is “More wet than dry but Great Plains and Northeast are dry”.
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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.
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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.
Recent CONUS Weather
This is provided mainly to see the pattern in the weather that has occurred recently.
| And the 30 Days ending December 22, 2018 | And the 30 Days ending December 29, 2018 |
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| The precipitation pattern did not change much but the temperature anomaly switched form cold east to warm west….this is the west to east movement of large troughs/ | You can see the wetter pattern in the West and the shift to the east of the warm anomaly. |
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-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 daily SST anomalies. | ||||
| Mediterranean, Black Sea and Caspian Sea | Western Pacific | West of North America | North and East of North America | North Atlantic |
The Mediterranean. Black Sea and Caspian Sea are mostly Neutral | Warm south of Japan. | Fairly Neutral which is unusual | Mostly Neutral Warm Davis Strait. | Slightly warm north of Scandinavia. |
| 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 |
Slightly cool off West Africa extending out to sea. Warm south of South Africa Cool Gulf of Guinea | Neutral. | Cool to North and Northwest. Warm to the Southeast but offshore and beyond New Zealand. | Fairly Neutral | Warm off 30S Warm off 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.
| ———————————————— | A | B | C | D | E | —————– |
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
Global Warming in the News
Judith Curry sea-level study disputes climate-disaster predictions – Washington Times
F. Useful Reference Information
Understand How the Jet Stream Impacts Weather
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Standard Pressure Levels
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