458  
FXUS02 KWBC 021853  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
152 PM EST SUN JAN 02 2022  
 
VALID 12Z WED JAN 05 2022 - 12Z SUN JAN 09 2022  
 
...ARCTIC AIR SETS STAGE FOR MULTIPLE HEAVY SNOW THREATS FROM THE  
GREAT LAKES AND OH/TN VALLEYS/APPALACHIANS TO THE  
MID-ATLANTIC/NORTHEAST...  
 
...ADDITIONAL ROUNDS OF HEAVY COASTAL RAIN AND MOUNTAIN FOCUSING  
SNOW FROM THE NORTHWEST/NORTHERN CALIFORNIA THROUGH THE  
NORTH-CENTRAL GREAT BASIN/ROCKIES/HIGH PLAINS...  
 
   
..GUIDANCE ASSESSMENT AND UNCERTAINTY
 
 
MODEL AND ENSEMBLE FORECAST SPREAD AND UNCERTAINTY REMAINS LOWER  
THAN NORMAL FOR THE MOST PART THROUGH MEDIUM RANGE TIME SCALES. A  
COMPOSITE OF REASONABLY WELL CLUSTERED MASS FIELD GUIDANCE FROM  
THE 06 UTC GFS/GEFS MEAN, THE 00 UTC ECMWF/ECMWF ENSEMBLE  
MEAN/UKMET/CANADIAN ALONG WITH THE 13 UTC NATIONAL BLEND OF MODELS  
SEEMS TO OFFER A GOOD BASIS FOR THE WPC PRODUCT SUITE FOR DAYS 3/4  
(WED/THU). OPTED TO INCREASE WPC BLEND WEIGHT EMPHASIS ON THE  
ENSEMBLE MEANS INTO DAYS 5-7 (FRI/NEXT WEEKEND) TO MAINTAIN MAX  
WPC CONTINUITY. THE COMPOSITE TENDS TO MITIGATE LINGERING EMBEDDED  
SYSTEM TIMING/STRENGTH DIFFERENCES AND RUN TO RUN VARIABLE LOWER  
ATMOSPHERIC TEMPERATURE PROFILES. IT SHOULD BE NOTED THAT BY  
THU/FRI WITH THE SOUTHERN TO EASTERN U.S./COASTAL SYSTEM, THE  
PLAUSIBLE BUT LESS LIKELY 00/06/12 UTC GFS AND A MINORITY AMOUNT  
OF GEFS/ECMWF ENSEMBLE MEMBERS ARE MORE SUPPRESSED BY THE COLD  
AIRMASS IN THE WAKE OF A MIDWEEK DEEP GREAT LAKES LOW THAN THE  
00/12 UTC ECMWF/UKMET/CANADIAN RUNS, WITH A FARTHER OFFSHORE TRACK  
OF THE SOUTHERN BASED COASTAL LOW/STORM.  
   
..PATTERN OVERVIEW AND WEATHER/HAZARD HIGHLIGHTS
 
 
THE UPPER LEVEL FLOW PATTERN OVER THE NATION WILL BE RATHER  
AMPLIFIED THROUGH THE END OF THE WEEK WITH A LARGE SCALE TROUGH  
OVER THE EAST-CENTRAL U.S. AND A BROAD RIDGE OVER THE WEST COAST,  
BEFORE TRANSITIONING TO A MORE QUASI-ZONAL FLOW BY NEXT WEEKEND.  
 
A DEEPENING STORM WILL TRACK INTO THE GREAT LAKES AND EASTERN  
CANADA WED/THU. ARCTIC AIR WILL DIG ACROSS THE CENTRAL THEN  
EASTERN U.S. BEHIND THE WINDY AND PRECIPITATION FOCUSING LOW TO  
INCLUDE A THREAT OF PLOWABLE SNOW FROM THE GREAT LAKES/OHIO VALLEY  
TO THE NORTHEAST. ANOTHER QUICKLY DEVELOPING HEAVY SNOW/ICE THREAT  
WITH SOME AFOREMENTIONED UNCERTAINTY IS ON TAP UNDERNEATH THU INTO  
FRI FROM THE TN/OH VALLEYS THROUGH THE APPALACHIANS/MID-ATLANTIC  
TO THE NORTHEAST BY FRONTAL LOW/COASTAL STORM GENESIS.  
 
MEANWHILE, MULTIPLE PACIFIC SYSTEMS WITH MODERATE ATMOSPHERIC  
RIVER BLUEPRINTS WILL MEANWHILE TAKE AIM AT THE PACIFIC  
NORTHWEST/NORTHERN CA THIS WEEK, THAT WILL FUEL MULTI-DAY COASTAL  
RAINFALL AND TERRAIN/MOUNTAIN ENHANCING SNOWS. ENERGIES WILL WORK  
INLAND ACROSS A SNOWY NORTH-CENTRAL GREAT BASIN/ROCKIES/HIGH  
PLAINS WHERE LIFT WILL BE FURTHER ENHANCED BY POST-FRONTAL  
UPSLOPE. DOWNSTREAM BY NEXT WEEKEND, RETURN FLOW FROM THE GULF OF  
MEXICO IS ALSO EXPECTED TO FUEL AN EMERGING ENHANCED RAINFALL AREA  
INLAND OVER THE GULF COAST STATES/TN VALLEY IN ADVANCE OF YET  
ANOTHER ARCTIC FRONTAL SURGE DOWN THROUGH THE CENTRAL TO  
EAST-CENTRAL U.S..  
 
TEMPERATURES ARE EXPECTED TO BE FRIGID ACROSS THE CENTRAL/NORTHERN  
PLAINS TO THE UPPER MIDWEST THROUGH THE END OF THE WEEK WITH A  
LARGE SURFACE HIGH OF ARCTIC ORIGIN GOVERNING THE WEATHER PATTERN  
FOR THIS REGION. HIGHS IN THE DOUBLE DIGITS BELOW ZERO ARE ONCE  
AGAIN LIKELY FOR PORTIONS OF EASTERN MONTANA AND INTO NORTH  
DAKOTA, AND HIGHS IN THE TEENS SETTLING AS FAR SOUTH AS SOUTHERN  
KANSAS ON THURSDAY. SOME ABATEMENT IN THE SEVERE COLD MAY COME TO  
PASS ACROSS THIS REGION AHEAD OF THE NEXT ARCTIC SURGE NEXT  
WEEKEND. ELSEWHERE, SEASONABLY COLD CONDITIONS ARE EXPECTED WEST  
OF THE CONTINENTAL DIVIDE WITH READINGS GENERALLY WITHIN 10  
DEGREES OF CLIMATOLOGICAL AVERAGES, AND COLD NEXT WEEKEND OVER THE  
EAST WITH HIGHS 10+ DEGREES BELOW NORMAL.  
 
HAMRICK/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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