585  
FXUS02 KWBC 200701  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
200 AM EST SUN FEB 20 2022  
 
VALID 12Z WED FEB 23 2022 - 12Z SUN FEB 27 2022  
 
...HEAVY TO EXCESSIVE RAINFALL THREAT FROM THE LOWER  
MISSISSIPPI/TENNESSEE VALLEYS TO THE MID-ATLANTIC ALONG WITH A  
HEAVY SNOW/ICE THREAT FROM THE SOUTHERN PLAINS TO THE NORTHEAST  
WEDNESDAY-FRIDAY...  
 
   
..PATTERN OVERVIEW
 
 
EXPECT AN ACTIVE MID-WINTER PATTERN THIS WEEK AS COLD CANADIAN  
HIGH PRESSURE DIGS ACROSS MUCH OF THE LOWER 48 STATES. UPPER LEVEL  
TROUGHS WILL DIG THROUGH THE WEST, WITH EJECTING ENERGIES AND  
INDUCED FRONTAL WAVES PROGRESSING DOWNSTREAM THEN OVERTOP A  
WARMING SOUTHEAST/EAST UPPER RIDGE. THE MAIN UPPER TROUGH SHOULD  
SHIFT EASTWARD INTO THE CENTRAL PLAINS AND MIDWEST BY LATER WEEK  
AS AMPLIFIED RIDGING BUILDS FROM THE EAST PACIFIC INTO THE WEST  
COAST. THIS AMPLIFIED PATTERN FAVORS A HEAVY TO EXCESSIVE RAINFALL  
THREAT FROM THE LOWER MISSISSIPPI/TENNESSEE VALLEYS TO THE  
MID-ATLANTIC ALONG WITH A HEAVY SNOW AND ICE THREAT FROM THE  
SOUTHERN PLAINS TO THE NORTHEAST WEDNESDAY INTO FRIDAY ON THE  
COOLED NORTHERN PERIPHERY OF THE EXPANDING PRECIPITATION SHIELD  
WITH THE TAPPING OF DEEPER MOISTURE FROM THE GULF OF MEXICO AND  
EVENTUALLY TO A LESSER EXTENT FROM THE WESTERN ATLANTIC.  
 
   
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
 
 
MODELS AND ENSEMBLES OFFER SIMILAR MID-LARGER SCALE FLOW  
EVOLUTIONS IN A PATTERN WITH ABOVE NORMAL OVERALL PREDICTABILITY.  
A COMPOSITE OF THE 18 UTC GFS AND 12 UTC ECMWF/UKMET/CANADIAN  
ALONG WITH THE 01 UTC NATIONAL BLEND OF MODELS (NBM) SEEMS TO  
PROVIDE A GOOD FORECAST BASIS FOR DAYS 3-5 (WEDNESDAY-FRIDAY).  
COMPOSITE BLENDING OF THESE DECENTLY CLUSTERED MODELS TENDS TO  
MITIGATE SMALLER SCALE SYSTEM VARIANCES CONSISTENT WITH  
PREDICTABILITY. THIS SOLUTION IS SUPPORTED BY A COMPOSITE OF 00  
UTC GUIDANCE, GEFS/NAEFS/ECMWF ENSEMBLES AND MAINTAINS GOOD WPC  
PRODUCT CONTINUITY. THE WPC PRODUCT SUITE INTO DAYS 6/7 (NEXT  
WEEKEND) WAS MAINLY DERIVED FROM THE 12 UTC ECMWF ENSEMBLE MEAN  
THAT MORE CONSISTENTLY MAINTAINS THE LIKELY SLOW TO DE-AMPLFY  
UPPER FLOW PATTERN.  
 
   
..WEATHER HIGHLIGHTS/THREATS
 
 
MODERATE TO HEAVY MOUNTAIN SNOWS ARE LIKELY MIDWEEK FOR THE  
SOUTH-CENTRAL GREAT BASIN/ROCKIES WITH APPROACH/PASSAGE OF POTENT  
UPPER TROUGH ENERGY AND AS ENHANCED BY UPSLOPE FETCH. AMPLE UPPER  
ENERGIES WORKING DOWNSTREAM FROM THE WEST WILL ALSO ACT TO INDUCE  
WAVES ALONG A LEAD FRONT AND TAP DEEPENING MOISTURE FROM THE GULF  
OF MEXICO. THIS IS EXPECTED TO FUEL A HEAVY TO EXCESSIVE RAINFALL  
AND CONVECTION THREAT FROM THE LOWER MISSISSIPPI/TENNESSEE VALLEYS  
TO THE MID-ATLANTIC, MAINLY WEDNESDAY/THURSDAY. WAVE ORGANIZATION  
AND REDEVELOPMENT SHOULD ALSO SUPPORT THE SPREAD OF A POTENTIALLY  
SIGNIFICANT HEAVY SNOW/ICE THREAT FROM PARTS OF THE SOUTHERN  
PLAINS AND MID-MISSISSIPPI/OHIO VALLEYS TO A COLD AIR DAMMED  
NORTHERN MID-ATLANTIC AND NORTHEAST WEDNESDAY-FRIDAY.  
 
THE COLD HIGH PRESSURE SURGE WILL SPREAD MUCH BELOW TEMPERATURES  
ACROSS MUCH OF THE WESTERN AND CENTRAL U.S. BY MID-LATE WEEK TO  
INCLUDE WIDESPREAD RECORD COLD VALUES, ESPECIALLY FRIGID FROM THE  
NORTHERN HIGH PLAINS TO THE NORTHERN/CENTRAL PLAINS WHERE DAYTIME  
HIGHS AND OVERNIGHT LOWS COULD BE 30-40+ DEGREES BELOW NORMAL.  
THIS VERY COLD AIR WILL SPREAD, BUT GRADUALLY MODIFY LATER WEEK  
ACROSS THE MIDWEST/EAST. MEANWHILE, MUCH ABOVE NORMAL PRE-FRONTAL  
TEMPERATURES ARE EXPECTED ACROSS THE SOUTHEAST/EAST WITH SOME  
RECORD WARMTH LIKELY, ESPECIALLY OVERNIGHT MINS WITH UPPER LEVEL  
RIDGING AND ENHANCED PRE-FRONTAL MOISTURE INTO THE REGION.  
 
SCHICHTEL  
 
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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