608  
FXUS02 KWBC 030655  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
154 AM EST MON JAN 3 2022  
 
VALID 12Z THU JAN 6 2022 - 12Z MON JAN 10 2022  
 
***ADDITIONAL ROUNDS OF HEAVY COASTAL RAIN AND MOUNTAIN SNOW FOR  
THE NORTHWESTERN STATES***  
 
***FRIGID AIR MASS FOR THE NORTH-CENTRAL U.S. AND POTENTIAL SNOW  
FOR INLAND PORTIONS OF THE EAST COAST REGION LATE IN THE WEEK***  
 
   
..GENERAL PATTERN OVERVIEW
 
 
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 THE WEEKEND.  
AN ORGANIZED LOW PRESSURE SYSTEM IS EXPECTED NEAR THE EAST COAST  
TO CLOSE OUT THE WEEK, AND ANOTHER LOW AFFECTS THE GREAT LAKES BY  
SATURDAY NIGHT INTO SUNDAY. AN ARCTIC AIR MASS WILL SETTLE  
SOUTHWARD ACROSS MUCH OF THE NORTH-CENTRAL U.S. IN THE WAKE OF THE  
STRONG COLD FRONT.  
   
..GUIDANCE ASSESSMENT AND UNCERTAINTY
 
 
THE 00Z MODEL GUIDANCE SUITE IS IN VERY GOOD SYNOPTIC SCALE  
AGREEMENT THROUGH SATURDAY WITH SOME MESOSCALE TIMING AND  
AMPLITUDE DIFFERENCES WITH THE INDIVIDUAL SHORTWAVE PASSAGES. ONE  
OF THE MAIN DIFFERENCES IS WITH THE 00Z GFS BY DEPICTING A MORE  
OFFSHORE TRACK WITH THE EAST COAST LOW AND THUS MUCH LESS  
IMPACTFUL FOR THE NORTHEAST, AND THIS WAS ALSO THE CASE WITH  
YESTERDAY'S GFS RUN. BY SUNDAY, THE GFS BECOMES CONSIDERABLY  
STRONGER WITH A POTENTIAL CLOSED LOW OVER THE WEST COAST REGION,  
WHICH DOES NOT HAVE MUCH ENSEMBLE SUPPORT. THE GREATEST  
DIFFERENCES BY DAY 7 ARE APPARENT THIS SAME GENERAL REGION, WHILST  
THE TROUGH OVER THE EAST HAS GOOD MODEL AGREEMENT.  
 
THE WPC FORECAST WAS BASED PRIMARILY ON A MULTI-DETERMINISTIC  
MODEL BLEND THROUGH FRIDAY, AND THEN GRADUALLY INCREASING USE OF  
THE ECENS AND GEFS MEANS THROUGH NEXT WEEKEND AND INTO MONDAY.  
   
..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 POTENTIAL  
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, WIDESPREAD LIGHT TO  
MODERATE PRECIPITATION IS LIKELY ACROSS THE EASTERN THIRD OF THE  
U.S. IN ASSOCIATION WITH THE EAST COAST LOW ON FRIDAY, WITH HEAVY  
SNOW POSSIBLE FOR PORTIONS OF THE APPALACHIANS. MORE SHOWERS AND  
STORMS ARE LIKELY TO MAKE A RETURN TO THE GULF COAST REGION BY  
SUNDAY AHEAD OF THE NEXT FRONT.  
 
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. 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 ABATEMENT IN THE SEVERE COLD MAY COME TO PASS ACROSS THIS  
REGION ON SATURDAY AHEAD OF THE NEXT ARCTIC SURGE 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.  
 
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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