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
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