293  
FXUS01 KWBC 220821  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
420 AM EDT THU APR 22 2021  
 
VALID 12Z THU APR 22 2021 - 12Z SAT APR 24 2021  
 
...SNOW LINGERS OVER NORTHERN MAINE INTO FRIDAY AS ANOTHER SHOT OF  
COLD AIR AND SNOW MOVES INTO THE NORTHERN ROCKIES AND HIGH  
PLAINS...  
 
...RECORD COLD TEMPERATURES TODAY ACROSS THE CENTRAL TO EASTERN  
U.S. WILL MODERATE ON FRIDAY...  
 
...A COMPLEX LOW PRESSURE SYSTEM WILL BEGIN TO BRING A THREAT OF  
HEAVY RAIN AND SEVERE THUNDERSTORMS ACROSS THE DEEP SOUTH ON  
FRIDAY...  
 
...FIRE WEATHER THREAT INCREASING ACROSS THE DESERT SOUTHWEST TO  
THE SOUTHERN HIGH PLAINS...  
 
THE INTENSIFYING LOW PRESSURE SYSTEM THAT RECENTLY BROUGHT WET  
SNOW ACROSS THE OHIO VALLEY TO THE INTERIOR NORTHEAST IS BEGINNING  
TO MOVE INTO SOUTHEASTERN CANADA. HOWEVER, IT FORWARD MOTION IS  
BEING SLOWED DOWN BY A BLOCKY WEATHER PATTERN ACROSS MUCH OF  
CANADA. THE SYSTEM WILL CONTINUE TO INTENSIFY OVER THE CANADIAN  
MARITIMES TODAY AS IT ROTATES SNOW BACK TOWARD NORTHERN MAINE  
WHERE A FOOT OF ACCUMULATION IS STILL POSSIBLE NEAR THE CANADIAN  
BORDER. THE CIRCULATION OF THE LOW WILL ALSO EXPAND IN SIZE AS IT  
PULLS MORE COLD AIR ACROSS THE GREAT LAKES AND DOWN INTO THE EAST  
COAST. IN FACT, SOME LAKE-ENHANCED SNOW IS EXPECTED TODAY  
DOWNWIND OF THE GREAT LAKES. WINDS WILL REMAIN STRONG AND GUSTY  
ACROSS MUCH OF THE NORTHEAST INTO THE MID-ATLANTIC TODAY AND THEY  
WILL BE SLOW TO SUBSIDE ON SATURDAY.  
 
A LARGE DOME OF UNSEASONABLY COLD AIR WILL EXPAND EASTWARD INTO  
MUCH OF THE EASTERN U.S. UNDER A LARGE AREA OF HIGH PRESSURE  
CENTERED OVER THE MID-MISSISSIPPI VALLEY. FREEZE WARNINGS AND  
FROST ADVISORIES REMAIN IN EFFECT ACROSS MULTIPLE STATES FROM THE  
CENTRAL PLAINS EASTWARD TO THE APPALACHIANS AND NORTHERN  
MID-ATLANTIC WHERE NUMEROUS DAILY RECORD LOW TEMPERATURES ARE  
FORECAST TO BE TIED OR BROKEN. BY FRIDAY, THE COLD AIRMASS WILL  
MODERATE AS IT DRIFTS EAST, ALTHOUGH LOW TEMPERATURES WILL STILL  
BE AROUND 10 DEGREES BELOW NORMAL IN THE CENTRAL U.S., WITH LOWS  
HOVERING IN THE MID-30'S TO 40'S.  
 
IN THE WESTERN U.S., A LOW PRESSURE SYSTEM WILL BRING LINGERING  
LIGHT SNOW ACROSS THE CENTRAL ROCKIES FOR THE NEXT FEW DAYS AS  
ANOTHER DOME OF COLD AIR FROM WESTERN CANADA IS POISED TO SURGE  
INTO THE NORTHERN ROCKIES/HIGH PLAINS. TEMPERATURES WILL ONCE  
AGAIN TUMBLE, ALONG WITH A QUICK BURST OF SNOW, AS THE ASSOCIATED  
COLD FRONT PASSES THROUGH MUCH OF MONTANA BY THIS EVENING. THE  
HIGHER ELEVATIONS WILL ONCE AGAIN RECEIVE THE HEAVIEST SNOWFALL  
AMOUNTS, WITH 6 TO 12 INCHES POSSIBLE. THE SNOW SHOULD THEN MOVE  
FURTHER SOUTH INTO WYOMING BY FRIDAY MORNING WHERE 3 TO 4 INCHES,  
WITH UP TO 6 IN THE MOUNTAINS, IS FORECAST.  
 
MEANWHILE, LITTLE IMPROVEMENT OF FIRE WEATHER CONDITIONS IS IN  
STORE FOR THE DESERT SOUTHWEST WHERE CRITICAL FIRE WEATHER RISK IS  
IN PLACE OVER THE REGION. THE MAIN AREA OF CONCERN WILL BE FROM  
FAR EASTERN ARIZONA THROUGH NEW MEXICO AND INTO THE TEXAS  
PANHANDLE. A DEEPENING LOW PRESSURE SYSTEM WILL COUPLE WITH DRY  
CONDITIONS TO PROMOTE CRITICAL RISK OF FIRE WEATHER ACROSS THE  
REGION INTO SATURDAY. MOREOVER, PORTIONS OF NORTHERN PLAINS AND  
INTERIOR NORTHWEST SHOULD BE ON THE ALERT FOR ELEVATED TO CRITICAL  
FIRE WEATHER RISK TODAY.  
 
ATTENTION WILL TURN TO THE SOUTHERN PLAINS FRIDAY MORNING AS A  
COMPLEX FRONTAL LOW PRESSURE SYSTEM DEVELOPS OVER THE AREA.  
WIDESPREAD SHOWERS AND THUNDERSTORMS ARE LIKELY AS A WARM FRONT  
LIFTS NORTH. THE UNSTABLE AIRMASS WILL PROMOTE THE DEVELOPMENT OF  
HEAVY RAIN AND SEVERE THUNDERSTORMS WHICH WILL LIKELY EXPAND  
EASTWARD ACROSS THE DEEP SOUTH LATE FRIDAY INTO EARLY SATURDAY.  
ACCORDINGLY, A SLIGHT RISK OF EXCESSIVE RAINFALL AND SEVERE  
WEATHER HAVE BEEN ISSUED BY THE WEATHER PREDICTION CENTER AND  
STORM PREDICTION CENTER, RESPECTIVELY.  
 
LAST BUT NOT LEAST, PRECIPITATION ASSOCIATED WITH A DEEPENING  
UPPER LOW IS FORECAST TO REACH THE PACIFIC NORTHWEST AND NORTHERN  
CALIFORNIA FRIDAY NIGHT.  
 
KONG/ASHERMAN  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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