622  
FXUS02 KWBC 230700  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
159 AM EST SUN JAN 23 2022  
 
VALID 12Z WED JAN 26 2022 - 12Z SUN JAN 30 2022  
   
..OVERVIEW
 
 
MODELS AND ENSEMBLE MEANS GENERALLY AGREE UPON THE IDEA OF BROAD  
MEAN TROUGHING ALOFT OVER MUCH OF THE LOWER 48 AS OF WEDNESDAY  
TRANSITIONING MORE TO THE EASTERN HALF OF THE COUNTRY AS A MEAN  
RIDGE OVER THE EASTERN PACIFIC MOVES INTO THE WESTERN U.S. BEST  
CONSENSUS OF GUIDANCE HAS A PACIFIC SHORTWAVE BRIEFLY SUPPRESSING  
THE WESTERN RIDGE AROUND SATURDAY FOLLOWED BY A REBOUND OF THE  
RIDGE, AHEAD OF TROUGHING OVER THE FAR NORTHEASTERN PACIFIC. THE  
STRONGEST SYSTEM OF THE PERIOD WILL LIKELY BE LOW PRESSURE  
EXPECTED TO DEVELOP OVER THE WESTERN ATLANTIC AROUND THE END OF  
THE WEEK THROUGH THE WEEKEND, IN RESPONSE TO A STRONG SHORTWAVE  
TROUGH APPROACHING AND CROSSING THE EAST COAST. DETAILS REMAIN  
TOO UNCERTAIN TO RESOLVE EXACTLY WHAT THE SYSTEM'S EFFECTS WILL BE  
OVER THE EAST. FARTHER WEST, A COUPLE CLIPPER SYSTEMS WITH FAIRLY  
LIGHT PRECIPITATION WILL TRACK OVER THE NORTHERN TIER WHILE THE  
LATE WEEK/WEEKEND PATTERN SHOULD BRING AT LEAST A MODEST INCREASE  
OF MOISTURE TO THE NORTHWEST. FOR TEMPERATURES THE EAST WILL BE  
BELOW NORMAL MOST OF THE PERIOD WHILE MUCH OF THE WEST THROUGH  
PORTIONS OF THE PLAINS WILL BE ABOVE NORMAL.  
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
WITHIN THE FAIRLY AGREEABLE MEAN PATTERN, THE MOST PROMINENT  
FORECAST UNCERTAINTIES HAVE BEEN WITH THE EASTERN PACIFIC/WESTERN  
U.S. EVOLUTION AS SHORTWAVE ENERGY APPROACHES THE UPPER RIDGE THAT  
REACHES THE WEST ALONG WITH EXPECTED WESTERN ATLANTIC DEVELOPMENT  
AS AN AMPLIFIED TROUGH REACHES THE EAST LATE IN THE WEEK. MODEL  
AND ENSEMBLE SPREAD REMAINS CONSIDERABLE FOR THE PACIFIC/WEST  
AREA, WITH RECENT GFS RUNS AND 12Z CMC HOLDING ONTO A STRONGER  
RIDGE VERSUS THE PAST COUPLE ECMWF RUNS. HOWEVER THE 18Z AND NEW  
00Z GFS RUNS HAVE ADJUSTED MUCH CLOSER TO THE 12Z ECMWF AND THE  
ENSEMBLE MEANS. THE 00Z CMC HAS ALSO TRENDED TOWARD THIS  
IMPROVING CLUSTER. THIS LEAVES THE 00Z UKMET THAT DIVERGES FROM  
MOST OTHER GUIDANCE FOR VARIOUS ASPECTS OF THE EASTERN  
PACIFIC/NORTHWESTERN NORTH AMERICAN PATTERN. PERHAPS WITH THE AID  
OF THIS BETTER WESTERN AGREEMENT, THE 00Z MODELS HAVE TRENDED  
SOMEWHAT CLOSER FOR THE LATE WEEK/WEEKEND ATLANTIC DEVELOPMENT.  
IN PARTICULAR THE 00Z GFS HAS GONE AWAY FROM THE 12Z/18Z RUNS  
WHOSE SLOWER/SHARPER/ELONGATED UPPER TROUGH HAD PRODUCED A FARTHER  
SOUTHWEST STORM THAN A GREAT MAJORITY OF GEFS/ECMWF/CMC ENSEMBLE  
MEMBERS. THE 00Z GFS/CMC AND LATEST ENSEMBLE MEANS ARE NOW  
SIMILAR IN SHOWING LOW PRESSURE SOMEWHAT EAST OF THE MID-ATLANTIC  
COAST EARLY SATURDAY AND THEN TRACKING INTO OR SOUTH OF THE  
CANADIAN MARITIMES BY EARLY SUNDAY. THE SUPPORTING SHORTWAVE  
ENERGY IS CURRENTLY OVER THE NORTH PACIFIC AND IS NOT SCHEDULED TO  
ROUND THE EAST PACIFIC RIDGE UNTIL AROUND TUESDAY, PLUS GUIDANCE  
IS STILL VARYING WITH THE WESTERN RIDGE/PACIFIC ENERGY HEADING  
INTO IT, SO IT WILL LIKELY TAKE A WHILE TO GAIN MUCH MORE  
CONFIDENCE IN A PARTICULAR SCENARIO.  
 
THE FORECAST HAS BEEN FAIRLY CONSISTENT IN CONCEPT FOR TWO  
FRONTS/WAVES EXPECTED TO DROP INTO THE NORTHERN TIER DURING THE  
PERIOD, THE FIRST AROUND THURSDAY AND ANOTHER DURING THE WEEKEND.  
THERE ARE STILL SOME TYPICAL DETAIL DIFFERENCES AND RUN-TO-RUN  
ADJUSTMENTS THAT ARE BEST RESOLVED BY A BLEND APPROACH.  
MODELS/MEANS SHOW BETTER THAN AVERAGE AGREEMENT FOR THE UPPER  
TROUGHING AND SURFACE SYSTEM OVER THE NORTHEASTERN PACIFIC BY THE  
END OF THE PERIOD.  
 
AN EARLY PERIOD 12Z/18Z MODEL BLEND TRENDED TOWARD 50-60 PERCENT  
TOTAL WEIGHT OF THE 18Z GEFS/12Z ECMWF MEANS BY DAYS 6-7  
SATURDAY-SUNDAY TO REFLECT THE CONSISTENT AND INTERMEDIATE  
SOLUTION FOR ATLANTIC DEVELOPMENT IN THE MEANS (MINIMIZING 12Z/18Z  
GFS INFLUENCE) AND TO ACCOUNT FOR ONGOING UNCERTAINTY WITH DETAILS  
OVER THE WEST LATE WEEK INTO THE WEEKEND.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
A MID-LATE WEEK WAVE/FRONTAL SYSTEM SHOULD SPREAD AN AREA OF  
MOSTLY LIGHT SNOW ACROSS PARTS OF THE NORTHERN PLAINS AND GREAT  
LAKES/NORTHEAST, FOLLOWED BY ANOTHER SYSTEM ALSO ACCOMPANIED BY  
MOSTLY LIGHT SNOW NEXT WEEKEND. THE SOUTHERN HIGH PLAINS MAY SEE  
A LITTLE LIGHT PRECIPITATION WEDNESDAY. CONFIDENCE IS STILL NOT  
GREAT FOR EXACTLY HOW LATE WEEK/WEEKEND ATLANTIC STORM DEVELOPMENT  
WILL AFFECT AREAS NEAR THE EAST COAST. THE MOST LIKELY EVOLUTION  
WOULD LEAD TO SOME POTENTIAL FOR SNOW AND BRISK TO STRONG WINDS  
OVER NEW ENGLAND WITH LESSER PROBABILITY FOR SIGNIFICANT EFFECTS  
FARTHER SOUTH. TYPICAL GUIDANCE ERRORS AT THIS TIME FRAME STILL  
ALLOW FOR SIGNIFICANT CHANGES TO THE CURRENT FORECAST.  
APPROACHING PACIFIC SHORTWAVE ENERGY AND THEN FLOW AHEAD OF A  
DEVELOPING NORTHEASTERN PACIFIC UPPER TROUGH MAY BRING LIGHT TO  
LOCALLY MODERATE RAIN AND MOUNTAIN SNOW INTO THE PACIFIC NORTHWEST  
DURING FRIDAY-SUNDAY, WITH A LITTLE SNOW POSSIBLY EXTENDING INTO  
THE NORTHERN ROCKIES.  
 
WITHIN THE CHILLY PATTERN OVER THE EASTERN HALF OF THE COUNTRY,  
COLDEST ANOMALIES SHOULD EXTEND FROM THE MIDWEST/UPPER MISSISSIPPI  
VALLEY THROUGH THE GREAT LAKES WEDNESDAY INTO EARLY THURSDAY WITH  
READINGS 15-25F BELOW NORMAL AND LOCALLY COLDER IN PARTS OF THE  
MIDWEST EARLY WEDNESDAY. SOMEWHAT LESS EXTREME COLD ANOMALIES  
WILL SPREAD THROUGH THE SOUTHERN PLAINS/SOUTH AND THE EAST DURING  
THAT TIME. REINFORCING COLD AIR SHOULD LEAD TO DECENT COVERAGE OF  
5-15F BELOW NORMAL TEMPERATURES OVER THE EAST NEXT WEEKEND.  
MOSTLY ABOVE NORMAL READINGS WILL PREVAIL FROM THE WEST THROUGH  
THE NORTHERN HALF OF THE PLAINS. SOME SCATTERED PLUS 10-15F  
ANOMALIES WILL BE POSSIBLE OVER AND NEAR THE GREAT BASIN AND THE  
NORTHERN PLAINS SHOULD HAVE ONE OR MORE DAYS 10-20F ABOVE NORMAL.  
SOME OF THE POSITIVE ANOMALIES SHOULD REACH INTO THE SOUTHERN  
PLAINS BY THE WEEKEND.  
 
RAUSCH  
 
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC  
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP  
 
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,  
QUANTITATIVE PRECIPITATION, WINTER WEATHER OUTLOOK PROBABILITIES  
AND HEAT INDICES ARE AT:  
 
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML  
 

 
 

 
 
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