946  
FXUS07 KWBC 312020  
PMD30D  
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
300 PM EST TUE DEC 31 2024  
 
30-DAY OUTLOOK DISCUSSION FOR JANUARY 2025  
 
THE JANUARY 2025 MONTHLY TEMPERATURE AND PRECIPITATION OUTLOOKS ARE UPDATED  
WITH INPUT FROM THE CLIMATE PREDICTION CENTER (CPC) EXTENDED RANGE AND  
SUBSEASONAL OUTLOOKS, DYNAMICAL MODEL GUIDANCE FOR WEEK 2 AND WEEKS 3-4,  
BACKGROUND CLIMATE STATES SUCH AS THE MADDEN JULIAN OSCILLATION (MJO) AND EL  
NIñO SOUTHERN OSCILLATION (ENSO), RECENT CLIMATE FORECAST SYSTEM VERSION 2  
(CFSV2) MONTHLY FORECASTS OF TEMPERATURE AND PRECIPITATION, AND EXPERIMENTAL  
MONTHLY FORECASTS OF TEMPERATURE AND PRECIPITATION FROM EXTENDED RUNS OF THE  
GLOBAL ENSEMBLE FORECAST SYSTEM VERSION 12 (GEFSV12) AND THE EUROPEAN CENTRE  
FOR MEDIUM-RANGE WEATHER FORECASTS (ECMWF) MODELS. ENSO-NEUTRAL CONDITIONS ARE  
CURRENTLY PRESENT, HOWEVER, EQUATORIAL SEA SURFACE TEMPERATURES (SSTS) ARE  
NEAR-TO-BELOW AVERAGE IN THE CENTRAL AND EASTERN PACIFIC OCEAN, WITH THE LATEST  
WEEKLY NIñO3.4 SST DEPARTURE REACHING -1.1 DEGREES CELSIUS. WHILE ENSO-NEUTRAL  
CONDITIONS ARE PRESENT, THESE COLDER SSTS MAY LEAD TO SOME LA NIñA-LIKE IMPACTS  
IN THE ATMOSPHERE AND OVER THE U.S., THOUGH THE IMPACTS ARE MORE LIKELY TO BE  
WEAK AND TRANSIENT COMPARED TO THOSE DURING A STRONGER LA NIñA. PERHAPS MORE OF  
A PLAYER AND IN CONTRAST TO THE PREVIOUS MID-MONTH DISCUSSION, THE MJO HAS  
BECOME MORE COHERENT, AND HAS PROPAGATED FROM THE MARITIME CONTINENT INTO THE  
WESTERN PACIFIC. DYNAMICAL MODEL FORECASTS OF THE REALTIME MULTIVARIATE MJO  
(RMM) INDEX ARE IN AGREEMENT FAVORING CONTINUED EASTWARD PROGRESSION OF THE MJO  
SIGNAL OVER THE NEXT TWO WEEKS, WHICH TYPICALLY LEADS TO INCREASED TROUGHING  
OVER THE CENTRAL AND EASTERN CONTIGUOUS UNITED STATES (CONUS), CONSISTENT WITH  
A NEGATIVE ARCTIC OSCILLATION AND NORTH ATLANTIC OSCILLATION. OVERALL, THE MORE  
CERTAIN MJO FORECASTS AND SUBSEQUENT EASTERN CONUS TROUGHING WILL ALLOW FOR THE  
POTENTIAL FOR COOLER AIR FROM THE NORTH ENTERING THE EASTERN CONUS DURING  
JANUARY.  
 
MODELS AND TELECONNECTIONS, PARTICULARLY THE MJO AND ITS POTENTIAL PROGRESSION,  
WERE MORE UNCERTAIN DURING THE MID-MONTH RELEASE OF THE MONTHLY TEMPERATURE  
OUTLOOK. AS SUCH, THE FORECAST WAS BASED MAINLY ON DYNAMICAL MODELS SUCH AS THE  
NORTH AMERICAN MULTI-MODEL ENSEMBLE (NMME), THE POTENTIAL FOR LA NIñA-LIKE  
IMPACTS LEADING TO ABOVE NORMAL TEMPERATURES OVER MUCH OF THE SOUTHERN TIER,  
AND THE POTENTIAL FOR A WARM START TO JANUARY, THOUGH WE EXPECTED A TRANSIENT  
PATTERN THROUGHOUT THE MONTH. GIVEN THE UNCERTAINTY IN MODELS AND EXPECTED  
TRANSIENT PATTERN A LARGE AREA OF EQUAL CHANCES (EC) OF ABOVE, NEAR, AND BELOW  
NORMAL TEMPERATURES WAS FAVORED FOR MUCH OF THE CONUS. SHORT- (6-10 AND 8-14  
DAY) AND LONG-TERM (WEEKS 3-4) FORECASTS HAVE COME INTO AGREEMENT ON A FAIRLY  
PERSISTENT PATTERN OF 500-HPA RIDGING OVER THE WEST AND TROUGHING OVER THE  
EAST. THIS PATTERN IS EXPECTED TO BEGIN IN EARLY JANUARY AND PERSIST THROUGH  
NEAR THE END OF THE MONTH, THOUGH ECMWF FORECASTS SHOW SOME MODERATION OF THE  
PATTERN BY WEEK 4 (ENDING JANUARY 28TH). THIS PERSISTENT PATTERN IS A TYPICAL  
RESPONSE TO THE ACTIVE AND FORECAST MJO, AND THE TROUGHING WILL ALLOW FOR COLD  
AIR FROM THE NORTH TO OVERSPREAD THE EASTERN CONUS, AND AS SUCH A SWATH OF  
BELOW NORMAL TEMPERATURES ARE INDICATED FROM THE NORTHERN AND CENTRAL PLAINS TO  
THE SOUTHEAST. PROBABILITIES ARE HIGHER WHERE THERE IS STRONG MODEL AGREEMENT,  
AND ALIGNING WITH REGIONS WHERE EXTENDED RANGE AND WEEKS 3-4 FORECASTS FAVOR  
PERSISTENCE OF THE BELOW NORMAL TEMPERATURES. ABOVE NORMAL TEMPERATURES ARE  
FAVORED OVER THE CONUS FROM THE WEST COAST TO THE ROCKIES AND EXTENDING  
EASTWARD ACROSS MUCH OF THE SOUTHERN PLAINS AND FOR SOUTHERN ALASKA BENEATH  
FORECAST RIDGING THROUGHOUT MUCH OF THE MONTH OF JANUARY AND WHERE THERE WAS  
STRONG MODEL AGREEMENT. OVER ALASKA, THE ABOVE NORMAL TEMPERATURES TRANSITION  
TO EC OVER THE NORTH WHERE SOME MODELS FAVORED A WEAK TILT TOWARD BELOW NORMAL,  
HOWEVER, THIS IS HIGHLY DEPENDENT ON THE NORTHERN EXTENT OF THE RIDGE.  
INTERESTINGLY, THOUGH WE ARE SEEING COOLER SSTS IN THE NIñO3.4 REGION WHICH  
WOULD TYPICALLY SUPPORT BELOW NORMAL TEMPERATURES OVER ALASKA, MODELS HAVE AND  
CURRENTLY FAVOR ABOVE NORMAL TEMPERATURES. IT IS POSSIBLE THAT ALASKA MAY SEE  
THESE COOLER TEMPERATURES PARTICULARLY OVER THE SOUTH AS THE WINTER SEASON  
PROGRESSES, BUT HAVE A WARM START TO THE WINTER. ABOVE NORMAL TEMPERATURES ARE  
ALSO FAVORED OVER NORTHERN PARTS OF THE NORTHEAST AHEAD OF THE EXPECTED  
TROUGHING OVER THE EAST. FINALLY, EC IS INDICATED OVER THE GREAT LAKES, MUCH OF  
NEW YORK STATE, AND SOUTHERN NEW ENGLAND, GIVEN WEAK OR INCONSISTENT MODEL  
SIGNALS.  
 
DESPITE THE FORECASTED CHANGE IN PATTERN FOR JANUARY AND CHANGES TO THE MONTHLY  
TEMPERATURE OUTLOOK, THE MONTHLY PRECIPITATION OUTLOOK IS SIMILAR TO THE PRIOR  
RELEASED VERSION. RECENT PRECIPITATION FORECASTS STILL RESEMBLE A LA NIñA-LIKE  
RESPONSE IN THE MODELS OVER SOME OF THE KEY TELECONNECTION REGIONS. ABOVE  
NORMAL PRECIPITATION IS FAVORED OVER THE NORTHWEST AND NORTHERN PLAINS, WHICH  
IS A HALLMARK OF THE WINTER LA NIñA TELECONNECTION. BELOW NORMAL PRECIPITATION  
IS FAVORED OVER THE SOUTHWESTERN CONUS TO EASTERN TEXAS AND REACHING INTO PARTS  
OF THE LOWER MISSISSIPPI VALLEY, ALSO COINCIDENT WITH A LA NIñA-LIKE RESPONSE.  
ON THE OTHER HAND, PRECIPITATION IS MORE UNCERTAIN OVER MUCH OF THE EASTERN  
CONUS THAN PREVIOUSLY INDICATED IN THE MONTHLY PRECIPITATION OUTLOOK. ANOTHER  
LA NIñA-LIKE TELECONNECTION WOULD BE EXPECTED TO LEAD TO ABOVE NORMAL  
PRECIPITATION OVER THE GREAT LAKES STRETCHING INTO THE OHIO VALLEY, WITH BELOW  
NORMAL PRECIPITATION OVER THE SOUTHEAST, HOWEVER, THE DIFFERENCES IN THE  
ATMOSPHERIC PATTERN, MJO, AND INCONSISTENCIES IN MODEL FORECASTS FROM  
RUN-TO-RUN NOW SUPPORT EC OVER THE GREAT LAKES, MUCH OF THE EAST COAST, AND  
SOUTHEAST. ABOVE NORMAL PRECIPITATION IS FAVORED OVER PARTS OF NEW ENGLAND  
DOWNSTREAM OF THE FORECASTED TROUGH. FINALLY, OVER ALASKA, ABOVE NORMAL  
PRECIPITATION IS FAVORED OVER THE SOUTH TRANSITIONING TO BELOW NORMAL  
PRECIPITATION OVER THE NORTH, GIVEN MODEL AGREEMENT.  
 
******************************************************************************  
 
***** PREVIOUS MID-MONTH DISCUSSION BELOW *****  
 
******************************************************************************  
 
FOLLOWING A FEW MONTHS OF WEAKLY BELOW NORMAL SEA SURFACE TEMPERATURES (SSTS),  
SST DEPARTURES REACHED -0.6 DEGREES CELSIUS IN THE NIñO3.4 REGION OVER THE PAST  
WEEK. THE CURRENT EL NIñO SOUTHERN OSCILLATION (ENSO) ALERT SYSTEM STATUS IS A  
LA NIñA WATCH. THE EXTENDED PERIOD OF WEAKLY BELOW NORMAL SSTS AND RECENT DROP  
TO -0.6 DEGREES CELSIUS MAY LEAD TO SOME LA NIñA-LIKE IMPACTS OVER THE  
CONTIGUOUS UNITED STATES (CONUS) DURING JANUARY AND THE UPCOMING SEASON,  
HOWEVER, WE EXPECT THAT ANY IMPACTS MAY BE WEAK AND VARIABILITY TO BE HIGH,  
LEADING TO UNCERTAINTY IN SOME OF THE TYPICAL IMPACTS. THOUGH THE MADDEN-JULIAN  
OSCILLATION (MJO) HAS BEEN A SIGNIFICANT PLAYER IN THE TROPICS IN RECENT WEEKS  
AND DYNAMICAL MODELS DEPICT CONTINUED EASTWARD PROPAGATION OF THE MJO ENVELOPE  
WITH A SLOWED PHASE SPEED, THE EMERGING LA NIñA HAS THE POTENTIAL TO INTERFERE  
WITH PROPAGATION AND AMPLITUDE OF THE MJO. SHOULD THE MJO CONTINUE INTO  
JANUARY, THIS MAY LEAD TO COOLER THAN AVERAGE TEMPERATURES FOR THE NORTHERN  
PARTS OF THE CONUS AND NORTHEAST, BUT THE POTENTIAL INTERFERENCE FROM LA NIñA  
AND SLOW PHASE SPEED ADD TO THE UNCERTAINTY. IN ADDITION TO THE LARGE-SCALE  
DRIVERS OF LA NIñA AND THE MJO, COASTAL OR LOCAL SSTS, SEA ICE, AND SNOW COVER  
ARE TAKEN INTO ACCOUNT FOR THIS FORECAST WHERE APPROPRIATE. MONTHLY FORECASTS  
OF TEMPERATURE AND PRECIPITATION BY DYNAMICAL MODELS FROM THE NORTH AMERICAN  
MULTI-MODEL ENSEMBLE (NMME), COPERNICUS CLIMATE SUITE (C3S), AND CFSV2 WERE  
UTILIZED IN PREPARING THIS OUTLOOK. WEEK 3-4 PREDICTIONS FOR THE FIRST PART OF  
JANUARY FROM GEFSV12, ECMWF, AND CFSV2 AND THE EXPECTED TRANSITION IN THE  
ATMOSPHERIC PATTERN FROM THE WEEK 2 PERIOD WERE ALSO CONSIDERED.  
 
ENHANCED RIDGING IS FORECAST OVER MOST OF THE CONUS TOWARD THE END OF DECEMBER,  
LEADING TO THE POTENTIAL FOR ABOVE NORMAL TEMPERATURES TO END THE YEAR.  
HOWEVER, THIS STRONG RIDGING IS EXPECTED TO MODERATE BY THE BEGINNING OF  
JANUARY, GIVING WAY TO RIDGING OVER THE WEST AND NEUTRAL TO ABOVE NORMAL  
HEIGHTS OVER THE REMAINDER OF CONUS. WEEK 3-4 MODELS FORECASTING THE BEGINNING  
OF JANUARY FAVOR WEAK RIDGING OVER THE WEST AND TROUGHING OVER THE EAST, THOUGH  
THE POSITION, EXACT TIMING, AND STRENGTH OF THE PATTERN IS UNCERTAIN. GIVEN THE  
ATMOSPHERIC PATTERN LEADING INTO JANUARY AND THE FORECASTS FOR EARLY JANUARY,  
WE EXPECT A WARM START TO THE MONTH FOLLOWED BY A TRANSIENT PATTERN.  
UNCERTAINTY IS HIGH DUE TO THE POTENTIAL FOR THIS TRANSIENT PATTERN,  
PARTICULARLY FOR TEMPERATURES.  
 
THE JANUARY 2025 TEMPERATURE OUTLOOK FEATURES ABOVE NORMAL TEMPERATURES OVER  
THE SOUTHERN HALF OF THE WESTERN CONUS, SOUTHERN PLAINS, AND THE EAST COAST.  
THIS PATTERN IS FAIRLY TYPICAL OF LA NIñA, AND REFLECTS DYNAMICAL MODEL  
PREDICTIONS THAT FAVOR A LA NIñA LIKE RESPONSE FOR THE MONTH. HOWEVER, GIVEN  
THE EXPECTED TRANSIENT HEIGHT PATTERN DURING THE MONTH, PROBABILITIES ARE  
OVERALL LOW FOR TEMPERATURES. PROBABILITIES ARE ENHANCED OVER THE SOUTHERN  
PLAINS WHERE THERE WAS THE BEST AGREEMENT AMONG AVAILABLE TOOLS. SOME MODELS  
SUCH AS THE C3S SUITE AND CFSV2 FAVORED HIGHER PROBABILITIES OF ABOVE NORMAL  
TEMPERATURES OVER THE SOUTHWEST, HOWEVER, NMME AND STATISTICAL TOOLS THAT  
INCLUDE DECADAL TRENDS WHICH ARE BELOW NORMAL IN PARTS OF THE SOUTHWEST MORE  
STRONGLY FAVOR NEAR-NORMAL TEMPERATURES. GIVEN THIS DISCREPANCY, A WEAK TILT  
TOWARD ABOVE NORMAL TEMPERATURES IS FAVORED DESPITE SOME OF THE MODEL RESULTS  
SHOWING STRONGER PROBABILITIES IN THE REGION, WHICH ALSO ALIGNS WITH FORECAST  
BELOW NORMAL PRECIPITATION IN THE REGION. SIMILARLY, SOME MODELS INDICATE  
STRONGER PROBABILITIES FOR ABOVE NORMAL TEMPERATURES OVER THE EAST COAST  
RELATIVE TO THE OUTLOOK, BUT GIVEN WEEK 3-4 MODELS THAT TILT TOWARD BELOW  
NORMAL TEMPERATURES OVER THE EAST, PROBABILITIES ARE AGAIN WEAKENED. EQUAL  
CHANCES (EC) OF ABOVE, NEAR, AND BELOW NORMAL TEMPERATURES ARE FAVORED OVER THE  
NORTHERN TIER OF THE CONUS AND CENTRAL PLAINS WHERE TOOLS HAD WEAK OR UNCERTAIN  
SIGNALS, AND, MOREOVER, BOTH MJO AND LA NIñA MAY LEAD TO COLD AIR INTRUSIONS  
INTO THE REGION, THOUGH BOTH INFLUENCES ARE CURRENTLY SOMEWHAT UNCERTAIN. IN  
ADDITION, GIVEN THE FORECASTED WARM START TO THE MONTH OF JANUARY, IT IS  
UNCERTAIN IF PERIODS OF COLDER TEMPERATURES WILL BE STRONG OR LONG ENOUGH TO  
TILT THE PROBABILITY TO BELOW NORMAL OVER THE NORTHERN TIER. OVER ALASKA MOST  
MODELS FAVORED ABOVE NORMAL TEMPERATURES, PARTICULARLY CFSV2, AND AS SUCH A  
TILT TOWARD ABOVE NORMAL TEMPERATURES IS INDICATED IN THE OUTLOOK.  
 
DESPITE THE TRANSIENT PATTERN, PRECIPITATION SIGNALS WERE MORE CONSISTENT IN  
TOOLS THAN TEMPERATURES. WHILE SSTS IN THE NIñO3.4 REGION JUST RECENTLY DROPPED  
BELOW -0.6 CELSIUS, IT IS POSSIBLE THAT TOOLS ARE PICKING UP THE EXTENDED  
PERIOD OF WEAKLY BELOW NORMAL SSTS AND FORECASTS OF A WEAK LA NIñA AS MANY OF  
THE TOOLS ARE SHOWING A LA NIñA LIKE PRECIPITATION PATTERN OVER THE CONUS. FOR  
EXAMPLE, BOTH NMME AND C3S PROBABILISTIC MULTI-MODEL ENSEMBLE PROBABILISTIC  
FORECASTS SHOW A GENERAL PATTERN OF BELOW NORMAL PRECIPITATION OVER THE  
SOUTHERN TIER OF CONUS, AND ABOVE NORMAL PRECIPITATION OVER THE NORTHWEST AND  
GREAT LAKES AND INTERIOR SOUTHEAST, WHICH ARE HALLMARKS OF A LA NIñA PATTERN.  
THE JANUARY 2025 PRECIPITATION OUTLOOK THUS RESEMBLES A LA NIñA LIKE PATTERN,  
FEATURING ENHANCED PROBABILITIES OF ABOVE NORMAL PRECIPITATION OVER THE  
INTERMOUNTAIN WEST AND PARTS OF THE NORTHERN AND CENTRAL PLAINS, THE GREAT  
LAKES AND INTERIOR SOUTHEAST, AND A TILT TOWARD BELOW NORMAL PRECIPITATION FROM  
THE SOUTHWEST ALONG THE SOUTHERN CONUS AND PARTS OF THE COASTAL SOUTHEAST. OVER  
ALASKA, ABOVE NORMAL PRECIPITATION IS FAVORED FOR WESTERN AND NORTHERN PARTS OF  
THE STATE, WITH A SMALL AREA OF BELOW NORMAL PRECIPITATION OVER ITS SOUTHERN  
COAST. SOME UNCERTAINTY EXISTS ALONG THE WEST COAST WHERE EC IS INDICATED. NMME  
AND C3S FAVOR BELOW NORMAL PRECIPITATION OVER THE SOUTHERN WEST COAST AND ABOVE  
NORMAL PRECIPITATION OVER THE NORTHERN WEST COAST, WHILE CFSV2 TILTS TOWARD  
BELOW NORMAL OVER THE NORTHERN WEST COAST. GIVEN THE POTENTIAL FOR PERIODS OF  
ABOVE NORMAL PRECIPITATION OVER THE WEST COAST DURING WINTER MONTHS, EC IS  
FAVORED DESPITE SOME OF THE TOOLS LEANING TOWARD BELOW NORMAL. MODELS AND TOOLS  
ALSO HAD MIXED SIGNALS ALONG THE COASTAL NORTHEAST AND NEW ENGLAND, AND THERE  
IS POTENTIAL FOR VARIABILITY DURING THE MONTH DUE TO UNCERTAINTY IN STORM  
TRACKS, LEADING TO THE FAVORED REGION OF EC. FINALLY, OVER ALASKA, BELOW NORMAL  
PRECIPITATION IS FAVORED OVER ITS SOUTHERN COAST GIVEN LA NIñA TELECONNECTIONS,  
AND ABOVE NORMAL IS FAVORED OVER THE WESTERN AND NORTHERN PARTS OF THE STATE  
GIVEN LA NIñA TELECONNECTIONS, DYNAMICAL MODEL AGREEMENT, AND ABOVE NORMAL  
DECADAL TRENDS OVER THE NORTHERN COAST.  
 
FORECASTER: JOHNNA INFANTI  
 
THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1991 AND 2020, FOLLOWING  
THE WORLD METEOROLOGICAL ORGANIZATION CONVENTION OF USING THE MOST RECENT 3  
COMPLETE DECADES AS THE CLIMATE REFERENCE PERIOD. THE PROBABILITY ANOMALIES  
FOR TEMPERATURE AND PRECIPITATION BASED ON THESE NEW NORMALS BETTER REPRESENT  
SHORTER TERM CLIMATIC ANOMALIES THAN THE FORECASTS BASED ON OLDER NORMALS.  
 
THE NEXT MONTHLY OUTLOOK...FOR FEB ... WILL BE ISSUED ON THU JAN 16 2025  
 
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1991-2020 BASE PERIOD.  
 
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