288  
FXUS02 KWBC 180650  
PMDEPD  
 
EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
248 AM EDT MON APR 18 2022  
 
VALID 12Z THU APR 21 2022 - 12Z MON APR 25 2022  
 
***ADDITIONAL SNOW AND COLD WEATHER LIKELY FOR PORTIONS OF THE  
NORTHERN PLAINS THIS WEEKEND, AND HEAVY SNOW IN THE SIERRA ON  
THURSDAY***  
 
   
..WEATHER PATTERN OVERVIEW
 
 
A QUASI-ZONAL FLOW PATTERN ALOFT WILL INITIALLY BE IN PLACE ACROSS  
MUCH OF THE CENTRAL AND SOUTHERN U.S. ON THURSDAY, WITH A NORTHERN  
STREAM SHORTWAVE AND SURFACE LOW CROSSING NORTH OF THE GREAT  
LAKES. THE PATTERN BECOMES MORE AMPLIFIED BY FRIDAY AND INTO THE  
WEEKEND AS A LARGE SYNOPTIC SCALE TROUGH FROM THE PACIFIC MOVES  
INLAND ACROSS THE INTERMOUNTAIN WEST, AND THIS WILL SPUR SURFACE  
CYCLOGENESIS ACROSS THE PLAINS BY FRIDAY NIGHT WITH SHOWERS AND  
STORMS DEVELOPING AHEAD OF THE TRAILING FRONT. MEANWHILE, A  
DOWNSTREAM RIDGE AXIS BUILDS ACROSS THE EASTERN U.S. AND RESULTS  
IN A CONSIDERABLE WARMING TREND FOR THE WEEKEND.  
   
..MODEL GUIDANCE EVALUATION
 
 
THE 00Z MODEL GUIDANCE SUITE APPEARS TO HAVE ABOVE AVERAGE  
AGREEMENT ON THE MAIN SYNOPTIC SCALE FEATURES THROUGH THURSDAY  
NIGHT, WITH JUST SOME MINOR DIFFERENCES IN COLD FRONT TIMING  
ACROSS THE GREAT LAKES AND NORTHEAST. SIMILAR TO YESTERDAY, THE  
THE GFS REMAINS MORE PROGRESSIVE WITH THE AXIS OF THE MAIN TROUGH  
AXIS ACROSS THE CENTRAL/NORTHERN PLAINS, AND DEFINITELY STRONGER  
BY 12Z SATURDAY COMPARED TO THE MODEL CONSENSUS. MEANWHILE, THE  
00Z CMC/ECMWF ARE IN CLOSER AGREEMENT AND DEPICT A CLOSED LOW  
EVOLVING OVER THE DAKOTAS BY EARLY SUNDAY, AND THIS ALSO HAS  
SUPPORT FROM THE 00Z UKMET. THE GFS/GEFS IS ALSO FARTHER EAST  
WITH THE DOWNSTREAM UPPER RIDGE AXIS OVER THE EASTERN U.S., WHICH  
WOULD HAVE IMPLICATIONS FOR THE TEMPERATURE FORECASTS. BY EARLY  
NEXT WEEK, THE MODELS ARE IN GOOD AGREEMENT ON THE DEPICTION OF  
ANOTHER STORM SYSTEM OVER THE NORTHEAST PACIFIC OCEAN, BUT  
CONSIDERABLE MODEL SPREAD IS APPARENT ACROSS THE ROCKIES AND  
WESTERN HIGH PLAINS IN THE WAKE OF THE DEPARTING SURFACE LOW OVER  
THE NORTH-CENTRAL U.S. A NEARLY MULTI-DETERMINISTIC MODEL BLEND  
WAS INCORPORATED AS A STARTING POINT FOR THURSDAY, AND THEN MORE  
OF THE ECMWF/ECENS WAS USED GOING FORWARD INTO THE WEEKEND ALONG  
WITH SOME OF THE CMC AND GEFS MEAN.  
   
..SENSIBLE WEATHER/THREATS
 
 
IN THE PRECIPITATION DEPARTMENT, MODERATE TO HEAVY RAIN ALONG WITH  
HEAVY SNOW IN THE SIERRA WILL LIKELY BE ONGOING ON THURSDAY AS THE  
DEEP UPPER TROUGH MOVES INLAND. THIS SPRING EVENT WILL DELIVER  
SOME HIGHLY BENEFICIAL PRECIPITATION TO DROUGHT-STRICKEN AREAS OF  
CALIFORNIA, WITH THE POTENTIAL FOR 1-2+ INCHES OF RAIN IN SOME  
AREAS OF CENTRAL AND NORTHERN CALIFORNIA, AND 1-3 FEET OF SNOW FOR  
THE HIGHER ELEVATIONS OF THE SIERRA.  
 
ANOTHER ROUND OF ORGANIZED SHOWERS AND STORMS ARE EXPECTED TO  
DEVELOP ACROSS THE CENTRAL U.S. AND EXTENDING NORTHWARD TO THE  
GREAT LAKES FOR THE END OF THE WEEK AS GULF MOISTURE IS ADVECTED  
NORTHWARD AHEAD OF THE ORGANIZING STORM SYSTEM OVER THE CENTRAL  
PLAINS. ADDITIONAL MODERATE TO HEAVY SNOW IS ALSO EXPECTED FOR  
PORTIONS OF THE NORTHERN ROCKIES FOR FRIDAY AND INTO THE WEEKEND,  
WITH AN INCREASING THREAT FOR ACCUMULATING SNOW ACROSS THE DAKOTAS  
AND EASTERN MONTANA/WYOMING NEXT WEEKEND, POTENTIALLY AFFECTING  
THE SAME AREAS THAT WERE HAMMERED BY THE RECENT BLIZZARD.  
 
IN TERMS OF TEMPERATURES, A MAJOR WARMING TREND IS FORECAST FOR  
MUCH OF THE EASTERN HALF OF THE NATION GOING INTO THE WEEKEND,  
ALONG WITH INCREASING HUMIDITY LEVELS, IN RESPONSE TO DEEP  
SOUTHERLY FLOW AHEAD OF THE CENTRAL U.S. STORM SYSTEM. ONE OF THE  
CAVEATS IN THE TEMPERATURE FORECAST WILL BE THE PRESENCE OF A BACK  
DOOR COLD FRONT NEAR THE MID-ATLANTIC AND NORTHEAST U.S. THIS  
WEEKEND, WITH POTENTIALLY A BIG CONTRAST OVER A RELATIVELY SHORT  
DISTANCE, SO FUTURE CHANGES IN THE FORECAST ARE LIKELY. IT WILL  
LIKELY REMAIN UNCOMFORTABLY COLD FROM MONTANA TO NORTH DAKOTA AND  
NORTHERN MINNESOTA WITH HIGHS RUNNING 15-25 DEGREES BELOW NORMAL.  
 
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, EXPERIMENTAL EXCESSIVE RAINFALL  
OUTLOOK, 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/#PAGE=ERO  
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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