452  
FXUS07 KWBC 211333  
PMD30D  
PROGNOSTIC DISCUSSION FOR MONTHLY OUTLOOK  
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD  
830 AM EST THU JAN 21 2021  
 
30-DAY OUTLOOK DISCUSSION FOR FEBRUARY 2021  
 
THE FEBRUARY 2021 TEMPERATURE AND PRECIPITATION OUTLOOKS ARE BASED ON WEEKS 3  
TO 4 FORECASTS FROM THE CFS AND ECMWF MODELS, THE NORTH AMERICAN MULTI-MODEL  
ENSEMBLE (NMME), TYPICAL INFLUENCES FROM THE ONGOING LA NIA, AND DECADAL  
TRENDS. BELOW AVERAGE SEA SURFACE TEMPERATURES (SSTS) ACROSS THE EQUATORIAL  
PACIFIC ALONG WITH A STRONG COUPLING WITH THE ATMOSPHERE REPRESENT LA NIA  
CONDITIONS. ALTHOUGH DYNAMICAL MODELS DEPICT A STRENGTHENING MADDEN-JULIAN  
OSCILLATION (MJ0) DURING LATE JANUARY INTO EARLY FEBRUARY, LA NIA IS LIKELY TO  
BE THE MAJOR TROPICAL FORCING DUE TO THE WELL-ESTABLISHED ANOMALOUS ENHANCED  
(SUPPRESSED) CONVECTION OVER THE MARITIME CONTINENT (EQUATORIAL CENTRAL  
PACIFIC).  
 
 
 
DESPITE HIGH LATITUDE BLOCKING WITH A PERSISTENT NEGATIVE ARCTIC OSCILLATION  
(AO), 30-DAY TEMPERATURES SINCE MID-DECEMBER HAVE AVERAGED ABOVE NORMAL FOR  
NEARLY ALL OF THE CONUS. THIS MILD TEMPERATURE PATTERN WAS DUE IN PART TO  
ENHANCED PACIFIC FLOW OVERSPREADING THE HIGHER LATITUDES OF NORTH AMERICA AND  
CROSS POLAR FLOW GENERALLY LIMITED TO THE EASTERN HEMISPHERE. WEEK-2 MODEL  
GUIDANCE (JAN 28-FEB 3) REMAINS CONSISTENT THAT AN AMPLIFIED AND FULL-LATITUDE  
500-HPA RIDGE BECOMES CENTERED OVER THE ALEUTIANS AND EXTENDS POLEWARD. THE  
WEEK 3-4 ECMWF MODEL INDICATES THIS ANOMALOUS RIDGING PERSISTING THROUGH AT  
LEAST EARLY FEBRUARY, WHICH IS LIKELY TO PROMOTE CROSS POLAR FLOW AND RESULT IN  
BELOW NORMAL TEMPERATURES ACROSS PARTS OF ALASKA. BASED ON GOOD MODEL  
CONTINUITY WITH THIS FEATURE AND SUPPORT FROM A NUMBER OF INPUTS TO THE NMME,  
BELOW NORMAL TEMPERATURES ARE FAVORED FOR SOUTHEASTERN MAINLAND ALASKA AND THE  
ALASKA PANHANDLE. ALTHOUGH THE SOURCE REGION IS EXPECTED TO BECOME MORE  
FAVORABLE FOR ARCTIC AIR TO SHIFT SOUTH ACROSS THE WESTERN AND NORTH-CENTRAL  
CONUS DURING THE NEXT MONTH, THE NMME SUPPORTS EQUAL CHANCES (EC) OF BELOW,  
NEAR, OR ABOVE NORMAL TEMPERATURES FOR MUCH OF THE WEST AND NORTHERN GREAT  
PLAINS. SPARSE SNOW COVER ACROSS THE CANADIAN PRAIRIES AND NORTHERN GREAT  
PLAINS MAY BE A LIMITING FACTOR TO ANOMALOUSLY COLD TEMPERATURES HEADING INTO  
FEBRUARY. BELOW NORMAL TEMPERATURES ARE SLIGHTLY FAVORED FOR PARTS OF THE  
PACIFIC NORTHWEST AND NORTHERN ROCKIES, DUE TO THE PREDICTED CLOSE PROXIMITY OF  
ANOMALOUS COLD DURING THE FIRST HALF OF FEBRUARY AND THIS IS ALSO CONSISTENT  
WITH LA NIA COMPOSITES.  
 
 
 
THE LARGEST PROBABILITIES (ABOVE 50 PERCENT) OF ABOVE NORMAL TEMPERATURES ARE  
FORECAST FROM THE RIO GRANDE VALLEY EASTWARD TO THE GULF COAST, BASED ON THE  
WEEK 3-4 MODEL GUIDANCE, CALIBRATED NMME, AND LA NIA COMPOSITES. ALTHOUGH A  
HIGH LATITUDE BLOCK OVER THE DAVIS STRAIT AND NEGATIVE PHASE OF THE NAO ARE  
FORECAST TO PROMOTE PERIODS OF BELOW NORMAL TEMPERATURES ALONG THE EAST COAST  
DURING THE REMAINDER OF JANUARY, THE GFS ENSEMBLE MEMBERS DEPICT A TRANSITION  
TO A NEUTRAL OR EVEN POSITIVE PHASE OF THE NAO BY THE BEGINNING OF FEBRUARY. AS  
THE NEGATIVE NAO DIMINISHES DURING THE NEXT TWO WEEKS, LA NIA IS EXPECTED TO  
BECOME A MORE DOMINANT FACTOR WHICH INCREASES PROBABILITIES OF ABOVE NORMAL  
TEMPERATURES ACROSS THE SOUTHEAST. ABOVE NORMAL TEMPERATURES ARE ONLY SLIGHTLY  
FAVORED FOR THE NORTHEAST, GREAT LAKES, AND UPPER MISSISSIPPI VALLEY DUE TO  
LOWER FORECAST CONFIDENCE AND THE POTENTIAL FOR A VARIABLE TEMPERATURE PATTERN  
DURING FEBRUARY. IT REMAINS UNCLEAR WHEN OR EVEN IF THE RECENT STRATOSPHERIC  
WARMING EVENT WOULD INFLUENCE TEMPERATURES ACROSS THE CONUS AND THIS WILL BE  
REASSESSED FOR THE UPDATED OUTLOOK RELEASED ON JANUARY 31.  
 
 
 
THE PRECIPITATION OUTLOOK FOR FEBRUARY IS CONSISTENT WITH LA NIA COMPOSITES  
AND SUPPORTED BY THE NMME. BELOW NORMAL PRECIPITATION IS MOST LIKELY ACROSS THE  
SOUTHERN TIER OF THE CONUS, WHILE ABOVE NORMAL PRECIPITATION IS FAVORED FROM  
THE PACIFIC NORTHWEST EASTWARD TO THE UPPER AND MIDDLE MISSISSIPPI VALLEY AND  
GREAT LAKES. ELEVATED PROBABILITIES OF BELOW NORMAL PRECIPITATION, FORECAST FOR  
SOUTHEASTERN MAINLAND ALASKA AND THE ALASKA PANHANDLE, ARE CONSISTENT WITH  
BELOW NORMAL TEMPERATURES FAVORED FOR THESE AREAS. A MAJORITY OF INPUTS TO THE  
NMME SUPPORT INCREASED PROBABILITIES OF ABOVE NORMAL PRECIPITATION ACROSS THE  
ALEUTIANS. PROBABILITIES THROUGHOUT THE FORECAST DOMAIN ARE TEMPERED DUE TO  
LARGE UNCERTAINTIES DURING THIS MONTHLY OUTLOOK TIME RANGE.  
 
FORECASTER: BRAD PUGH  
 
THE CLIMATIC NORMALS ARE BASED ON CONDITIONS BETWEEN 1981 AND 2010, 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.  
 
AN UPDATED MONTHLY OUTLOOK... FOR FEB WILL BE ISSUED ON SUN JANUARY 31 2021  
 
THESE OUTLOOKS ARE BASED ON DEPARTURES FROM THE 1981-2010 BASE PERIOD.  

 
 
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