983  
FXUS02 KWBC 060648  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
147 AM EST THU JAN 6 2022  
 
VALID 12Z SUN JAN 9 2022 - 12Z THU JAN 13 2022  
   
..GENERAL PATTERN OVERVIEW
 
 
A DEEP UPPER LEVEL TROUGH COUPLED WITH AN ARCTIC SURFACE HIGH WILL  
BE PRESENT ACROSS THE NORTH-CENTRAL U.S. AND THEN THE EAST COAST  
THROUGH TUESDAY WITH AN AMPLIFIED UPPER LEVEL FLOW PATTERN IN  
PLACE, AND AN UPPER RIDGE OVER THE WEST COAST ON SUNDAY. A SPLIT  
FLOW PATTERN DEVELOPS OVER THE EASTERN PACIFIC AND THIS LEADS TO A  
POTENTIAL CLOSED LOW NEAR THE DESERT SOUTHWEST, AND PROGRESSIVE  
SHORTWAVE IMPULSES TRACKING FROM WESTERN CANADA TO THE GREAT LAKES  
THROUGH THE MIDDLE OF THE WEEK.  
   
..GUIDANCE/PREDICTABILITY ASSESSMENT
 
 
THE 00Z MODEL GUIDANCE SUITE AND ENSEMBLES CONTINUE TO AGREE QUITE  
WELL ON THE OVERALL SYNOPTIC SCALE PATTERN, PARTICULARLY THROUGH  
MONDAY. GOING IN EARLY NEXT WEEK, THE MODELS STILL HAVE A GOOD  
HANDLE ON THE DEEP TROUGH OVER THE EAST COAST REGION AND THE  
TIMING OF THE COLD FRONT PASSAGE. THEN MODELS AND ENSEMBLE  
MEMBERS CONTINUE TO VARY FOR SPECIFICS OF HOW EASTERN PACIFIC  
SHORTWAVE ENERGY MAY SPLIT AS IT NEARS THE WEST COAST. THESE  
DIFFERENCES ULTIMATELY AFFECT FLOW OVER/NEAR THE SOUTHWEST AS WELL  
AS LOCATIONS EAST OF THE ROCKIES, WITH NORTHERN STREAM FLOW  
DETERMINED IN PART BY HOW PACIFIC ENERGY GOES AROUND THE WESTERN  
U.S. RIDGE AND SOUTHERN TIER FLOW INFLUENCED BY THE PATTERN TO THE  
WEST.  
 
THE WPC FORECAST WAS BASED PRIMARILY ON A MULTI-DETERMINISTIC  
MODEL BLEND THROUGH TUESDAY, AND THEN GRADUALLY INCREASING USE OF  
THE ECENS AND GEFS MEANS THROUGH EARLY NEXT WEEK WHILE STILL  
KEEPING ABOUT 50 PERCENT OF A CMC/ECMWF/GFS BLEND..  
   
..HAZARDS/SENSIBLE WEATHER HIGHLIGHTS
 
 
GULF MOISTURE ADVECTING NORTHWARD AHEAD OF A DEVELOPING  
PLAINS/MIDWEST COLD FRONT WILL SUPPORT INCREASING COVERAGE OF  
SHOWERS AND THUNDERSTORMS FROM EASTERN TEXAS AND THE CENTRAL GULF  
COAST TO THE CENTRAL APPALACHIANS AND MID-ATLANTIC REGION THIS  
WEEKEND, WITH LIGHTER PRECIPITATION EXPECTED FARTHER NORTH. THERE  
WILL LIKELY BE SOME EMBEDDED HEAVIER RAINFALL ACROSS PORTIONS OF  
THE DEEP SOUTH WHERE CONVECTION IS PERSISTENT, AND SOME LOCALIZED  
FLOODING IS WITHIN THE REALM OF POSSIBILITY. AREAS FROM THE UPPER  
GREAT LAKES TO THE NORTHEAST COULD SEE WINTRY WEATHER, WITH THE  
BEST SNOWFALL PROSPECTS OVER MICHIGAN AND NORTHERN NEW YORK AS A  
RESULT OF LAKE EFFECT SNOW. FREEZING RAIN AND/OR SLEET MAY BE  
AMONG THE HAZARDS OVER AND NEAR PARTS OF THE NORTHERN HALF OF THE  
APPALACHIANS FOR A TIME AS MOISTURE OVERRUNS COLD AIR AT THE  
SURFACE. DRY CONDITIONS WILL LIKELY PREVAIL OVER A MAJORITY OF  
THE COUNTRY FOR MONDAY AND TUESDAY. EXCEPTIONS INCLUDE SOME  
SHOWERS AND MOUNTAIN SNOW OVER WESTERN WASHINGTON AND OREGON AS  
ONE OR MORE SYSTEMS CROSS THE REGION AND SOME PRECIPITATION OVER  
THE SOUTHWEST AND SOUTHERN PLAINS BY WEDNESDAY.  
 
THE NEXT BLAST OF ARCTIC AIR MAKES ITS PRESENCE KNOWN ACROSS THE  
NORTHERN PLAINS AND UPPER MIDWEST BY SUNDAY IN THE WAKE OF THE  
STRONG COLD FRONT, AND THIS COLD WEATHER WILL EVENTUALLY REACH THE  
EAST COAST IN MODIFIED FORM AS WELL, BRINGING HIGHS DOWN TO 10-25F  
BELOW NORMAL FROM THE MID-ATLANTIC THROUGH NEW ENGLAND ON TUESDAY  
FOR ONE OF THE COLDEST DAYS OF THE YEAR THUS FAR. IT SHOULD STILL  
BE RATHER MILD ACROSS THE SOUTHEAST U.S. AHEAD OF THE FRONT ON  
SUNDAY BEFORE A RETURN TO REALITY BY MONDAY. THE NORTHERN-CENTRAL  
PLAINS WILL TREND WARMER NEXT WEEK, REACHING 10-15F OR SO ABOVE  
NORMAL OVER SOME LOCATIONS BY TUESDAY-WEDNESDAY. SEASONABLY COLD  
CONDITIONS ARE LIKELY WEST OF THE CONTINENTAL DIVIDE WITH READINGS  
GENERALLY WITHIN 10 DEGREES OF CLIMATOLOGICAL AVERAGES.  
 
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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