850  
FXUS02 KWBC 031900  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
159 PM EST MON JAN 03 2022  
 
VALID 12Z THU JAN 06 2022 - 12Z MON JAN 10 2022  
 
...ADDITIONAL ROUNDS OF HEAVY COASTAL RAIN AND MOUNTAIN SNOW FOR  
THE NORTHWEST...  
 
...MUCH BELOW NORMAL TEMPERATURES FOR THE NORTH-CENTRAL U.S. AND  
ACCUMULATING SNOW FROM THE APPALACHIANS TO THE NORTHEAST LATE  
WEEK...  
 
   
..GENERAL PATTERN OVERVIEW
 
 
THE UPPER LEVEL PATTERN OVER THE CONUS DURING THE MEDIUM RANGE  
PERIOD SHOULD REMAIN FAIRLY AMPLIFIED BUT ALSO PROGRESSIVE.  
TROUGHING SWEEPING THROUGH THE EAST THURSDAY INTO FRIDAY SHOULD  
GIVE WAY TO A BRIEF PERIOD OF UPPER RIDGING THIS WEEKEND AS AN  
ARCTIC AIR MASS SETTLES INTO THE NORTH-CENTRAL U.S. IN THE WAKE OF  
THE STRONG COLD FRONT. MEANWHILE, A STRONG ATMOSPHERIC RIVER MAY  
BRING ANOTHER ROUND OF HEAVY RAIN AND MOUNTAIN SNOWS TO THE  
NORTHWEST LATE THIS WEEK WITH THE UPPER TROUGH SLIDING EASTWARD  
INTO THE CENTRAL U.S. AND EVENTUALLY THE GREAT LAKES/NORTHEAST AND  
RIDGING BEGINNING TO BUILD AGAIN OVER THE WEST. ANOTHER TROUGH MAY  
APPROACH THE WEST COAST BY NEXT MONDAY.  
 
   
..GUIDANCE ASSESSMENT AND UNCERTAINTY
 
 
THE LATEST MODEL GUIDANCE CONTINUES TO SHOW FAIRLY GOOD SYNOPTIC  
SCALE AGREEMENT THROUGH AT LEAST SATURDAY, WITH SOME LINGERING  
MESOSCALE TIMING AND AMPLITUDE DIFFERENCES WITH INDIVIDUAL  
SHORTWAVES. REGARDING THE EARLY PERIOD EAST COAST LOW, THE 06Z/12Z  
GFS CONTINUES TO BE FASTER/MORE OFFSHORE WITH THE TRACK WHILE THE  
BULK OF THE REST OF THE GUIDANCE SUGGESTS SOMETHING CLOSER TO THE  
COAST AND A MORE IMPACTFUL WINTER STORM FROM THE LOWER OHIO VALLEY  
INTO THE NORTHEAST. BY SUNDAY, THE 06Z GFS WAS CONSIDERABLY  
STRONGER WITH A CUT OFF UPPER LOW OVER THE SOUTHWEST, WHICH DID  
NOT HAVE MUCH ENSEMBLE SUPPORT, BUT IT APPEARS THE 12Z HAS BACKED  
OFF SOMEWHAT WITH THAT. BY DAY 7, THERE ARE ALSO SOME TIMING  
DIFFERENCES WITH THE NEXT SYSTEM MOVING TOWARDS THE WEST COAST.  
 
THE WPC FORECAST WAS BASED PRIMARILY ON A MULTI-DETERMINISTIC  
MODEL BLEND THROUGH SATURDAY. AFTER THIS, THE GFS WAS DROPPED DUE  
TO THE ISSUES IN THE WEST DESCRIBED ABOVE, AND CONTRIBUTIONS FROM  
THE ENSEMBLE MEANS WERE INCREASED TO ACCOUNT FOR GROWING LATE  
PERIOD UNCERTAINTIES. THIS APPROACH PROVIDED A RELATIVELY  
CONSISTENT FORECAST COMPARED TO THE PREVIOUS WPC BLEND.  
 
   
..SENSIBLE WEATHER
 
 
THERE WILL BE MULTIPLE PACIFIC STORM SYSTEMS THAT WILL AFFECT THE  
PACIFIC NORTHWEST AND INLAND ACROSS PORTIONS OF THE GREAT BASIN  
AND THE NORTHERN ROCKIES. THIS WILL RESULT IN HEAVY RAIN AND HEAVY  
MOUNTAIN SNOW FOR THURSDAY AND FRIDAY, WITH A LIKELY ATMOSPHERIC  
RIVER EVENT FOR NORTHERN OREGON AND SOUTHWEST WASHINGTON DURING  
THIS TIME. A DRYING TREND SHOULD COMMENCE IN TIME FOR THE WEEKEND  
ACROSS MUCH OF THE WEST AS HIGH PRESSURE BUILDS BACK INTO THE  
REGION. MEANWHILE, AN AREA OF ACCUMULATING SNOW IS POSSIBLE NORTH  
AND WEST OF A LOW PRESSURE SYSTEM TRACKING ACROSS THE MID-ATLANTIC  
AND DEEPENING OFF THE NORTHEAST COAST THURSDAY-FRIDAY. THE LATEST  
GUIDANCE SHOWS THE BEST POTENTIAL FOR AT LEAST A COUPLE OF INCHES  
ACROSS THE CENTRAL APPALACHIANS/LOWER OHIO VALLEY INTO THE  
NORTHERN MID-ATLANTIC AND NEW ENGLAND. MORE SHOWERS AND STORMS ARE  
LIKELY TO MAKE A RETURN TO THE GULF COAST REGION AND INTO THE  
TENNESSEE VALLEY BY SUNDAY AHEAD OF THE NEXT FRONT.  
 
TEMPERATURES ARE EXPECTED TO BE MUCH BELOW NORMAL 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. SUBZERO HIGHS ARE ONCE AGAIN  
LIKELY FOR PORTIONS OF EASTERN MONTANA, NORTH DAKOTA, AND NORTHERN  
MINNESOTA, AND HIGHS IN THE TEENS SETTLING AS FAR SOUTH AS KANSAS  
ON THURSDAY. SOME MODERATION OF THE SEVERE COLD MAY COME ACROSS  
THIS REGION ON SATURDAY AHEAD OF THE NEXT ARCTIC SURGE INTO THE  
NORTHERN TIER STATES ON SUNDAY, WHICH IS NOT EXPECTED TO BE AS  
INTENSE AS THE EARLIER ARCTIC BLAST. ELSEWHERE, SEASONABLY COLD  
CONDITIONS ARE EXPECTED WEST OF THE CONTINENTAL DIVIDE WITH  
READINGS GENERALLY WITHIN 10 DEGREES OF CLIMATOLOGICAL AVERAGES,  
AND MILD ACROSS THE SOUTHERN PLAINS AND DEEP SOUTH WITH HIGHS  
RUNNING 5 TO 15 DEGREES ABOVE AVERAGE THIS WEEKEND.  
 
SANTORELLI/HAMRICK  
 
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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