111  
FXUS02 KWBC 202015  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
315 PM EST THU JAN 20 2022  
 
VALID 12Z SUN JAN 23 2022 - 12Z THU JAN 27 2022  
 
18Z UPDATE: THE 12Z MODEL SUITE IS IN EXCELLENT AGREEMENT ON THE  
OVERALL SYNOPTIC SCALE PATTERN THROUGH ABOUT EARLY TUESDAY, WITH  
BROAD CYCLONIC FLOW ALOFT WITH A DEEP TROUGH ANCHORED OVER THE  
CENTRAL-EASTERN U.S., AND A RIDGE OFF THE WEST COAST. A SHORTWAVE  
TROUGH TRACKING AROUND THE EASTERN PERIPHERY OF THAT RIDGE SINKS  
SOUTHWARD ACROSS THE INTERMOUNTAIN WEST, WITH THE PAST FEW RUNS OF  
THE GFS BEING QUITE AMPLIFIED BY WEDNESDAY WITH THIS FEATURE, AND  
THE OVERNIGHT RUN WAS AN OUTLIER SOLUTION COMPARED TO THE ENSEMBLE  
SPAGHETTI PLOTS. THEREFORE, THE GFS WAS WEIGHTED LESS FOR THE  
SECOND HALF OF THE FORECAST PERIOD. IN TERMS OF QPF, THERE WAS A  
SLIGHT INCREASE IN RAINFALL TOTALS FOR THE CENTRAL GULF COAST  
REGION, AND A SLIGHT DECREASE ACROSS THE MID SOUTH. OTHERWISE,  
THE MAJORITY OF THE FORECAST REMAINS ON TRACK AND THE PREVIOUS  
DISCUSSION IS APPENDED BELOW FOR REFERENCE. /HAMRICK  
 
   
..PATTERN OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
MODELS AND ENSEMBLES ARE IN GOOD AGREEMENT WITH THE AMPLIFIED MEAN  
FLOW OVER THE LOWER 48 HIGHLIGHTED BY AN UPPER RIDGE OFF/ALONG THE  
WEST COAST AND AN UPPER TROUGH OVER THE CENTRAL TO EASTERN U.S..  
GUIDANCE NOW OFFERS MORE CHARACTERISTIC RUN TO RUN CONTINUITY  
ISSUES WITH EMBEDDED SYSTEMS WITHIN THE LARGER SCALE FLOW OVER  
TIME IN A PATTERN WITH SEEMINGLY NEAR NORMAL FORECAST  
PREDICTABILITY.  
 
ACCORDINGLY, THE EARLIER ISSUED WPC MEDIUM RANGE PRODUCT SUITE WAS  
MAINLY DERIVED FROM A COMPOSITE OF THE THE REASONABLY WELL  
CLUSTERED SOLUTIONS OF THE 18 UTC GFS AND 12 UTC  
ECMWF/UKMET/CANADIAN ALONG WITH THE 01 UTC NATIONAL BLEND OF  
MODELS FOR DAYS 3/4 (SUNDAY/MONDAY). TRANSITIONED TO A COMPOSITE  
OF THE COMPATIBLE 18 UTC GEFS AND 12 UTC ECMWF ENSEMBLE MEANS  
ALONG WITH THE NBM FOR DAYS 5-7 (TUESDAY-NEXT THURSDAY). THIS  
ALONG WITH SOME APPLIED MANUAL ADJUSTMENTS CONSISTENT WITH  
UNCERTAINTY MAINTAINS DECENT WPC PRODUCT CONTINUITY THAT ALSO  
REMAINS GENERALLY IN LINE WITH A SIMILAR COMPOSITE PLAN FROM NEWER  
00 UTC GUIDANCE.  
   
..WEATHER HIGHLIGHTS/THREATS
 
 
A WEEKEND SOUTHERN STREAM SOUTHWEST U.S/NORTHERN MEXICO CLOSED LOW  
OFFERS SOME SNOW POTENTIAL FOR THE SOUTHERN ROCKIES/HIGH PLAINS.  
THE SYSTEM WILL EJECT EASTWARD ACROSS THE U.S. SOUTHERN TIER EARLY  
NEXT WEEK AND WAVE GENESIS ON A LINGERING TRAILING FRONT OVER THE  
GULF OF MEXICO WILL INDUCE LEAD MOISTURE RETURN FROM THE GULF OF  
MEXICO TO FUEL A MODERATE SWATH OF PRECIPITATION WITHIN A COOLED  
AIRMASS FROM TEXAS EASTWARD ACROSS THE GULF COAST/SOUTHEAST. THIS  
MAY INCLUDE SOME SNOW/ICE ON THE NORTHERN PERIPHERY OF  
PRECIPITATION.  
 
THE NEXT IN A SERIES OF ARCTIC BLASTS WILL AGAIN SPREAD FAR SOUTH  
OVER THE CENTRAL AND EASTERN U.S. MONDAY-NEXT THURSDAY AS ANOTHER  
MEAN FLOW REINFORCING UPPER TROUGH DIGS SOUTHEASTWARD FROM CANADA.  
TRANSITORY FRONTAL ENHANCED UPSLOPE SNOWS WILL DIG THROUGH THE  
COOLING ROCKIES AND ADJACENT HIGH PLAINS. NORTHERN STREAM UPPER  
SYSTEM PASSAGE AND FRONTAL LOW GENESIS ON THE LEADING EDGE OF  
ARCTIC AIR STARTING MONDAY SHOULD SUPPORT A WINDY SNOW SWATH FROM  
THE DAKOTAS THROUGH THE UPPER MIDWEST/GREAT LAKES. LOW DEVELOPMENT  
THROUGH THE GREAT LAKES/NORTHEAST TUESDAY INTO WEDNESDAY AND  
TRAILING COLD FRONTAL PASSAGE ACROSS THE EAST FAVORS LINGERING  
LAKE EFFECT ALONG WITH SOME THREAT OF PLOW-ABLE SNOWS FROM THE  
APPALACHIANS THROUGH THE NORTHEAST. SYSTEM EVOLUTION BECOMES  
COMPLEX OFFSHORE AND INTO THE CANADIAN MARITIME BY MIDWEEK AS THE  
AFOREMENTIONED SOUTHERN STREAM SYSTEM PHASES/LIFTS ON THE LEAD  
PERIPHERY OF THE AMPLIFIED NORTHERN STREAM UPPER TROUGH.  
 
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  
 
HAZARDS:  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE SOUTHERN  
PLAINS AND THE SOUTHWEST, SUN-MON,  
JAN 23-JAN 24.  
- MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE  
NORTHERN/CENTRAL PLAINS, THE UPPER/MIDDLE  
MISSISSIPPI VALLEY, AND THE GREAT LAKES, SUN, JAN 23 AND TUE-WED,  
JAN 25-JAN 26.  
- HEAVY PRECIPITATION ACROSS PORTIONS OF THE ALASKA PANHANDLE AND  
MAINLAND ALASKA, SUN-MON, JAN  
23-JAN 24.  
- HIGH WINDS ACROSS PORTIONS OF THE ALASKA PANHANDLE AND MAINLAND  
ALASKA, MON, JAN 24.  
 
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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