911
FXUS01 KWBC 210801
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT FRI APR 21 2023
VALID 12Z FRI APR 21 2023 - 12Z SUN APR 23 2023
...SHOWERS AND THUNDERSTORMS CONTINUE EASTWARD ALONG A COLD FRONT
FROM THE MISSISSIPPI VALLEY TODAY TO THE EAST COAST THIS WEEKEND
WITH POSSIBLE SEVERE WEATHER AND ISOLATED FLASH FLOODING...
...MODERATE TO LOCALLY HEAVY SNOW ACROSS THE NORTHERN PLAINS AND
UPPER MIDWEST WILL GRADUALLY TAPER OFF THROUGH TODAY INTO
TONIGHT...
...MOUNTAIN SNOW AND COASTAL RAIN TODAY FOR THE NORTHERN/CENTRAL
ROCKIES AND PACIFIC NORTHWEST; TRANQUIL CONDITIONS FOR CALIFORNIA
AND THE SOUTHWEST...
A FRONTAL SYSTEM PUSHING EASTWARD BENEATH A DEEPENING UPPER-LEVEL
LOW WILL CONTINUE TO BRING WIDESPREAD SHOWERS AND THUNDERSTORMS
WITH THE RISK OF FLASH FLOODING AND SEVERE WEATHER FROM PORTIONS
OF THE OHIO/MISSISSIPPI VALLEYS FRIDAY TO THE EAST COAST ON
SATURDAY. THE HIGHEST CHANCE OF HEAVY RAIN IS FORECAST TO BE
EARLY TODAY FROM THE MID-MISSISSIPPI VALLEY AND DOWN TOWARD THE
LOUISIANA COAST WITH A SLIGHT RISK OF FLASH FLOODING AS A SQUALL
LINE PASSES THROUGH THE AREA WITH SEVERE THUNDERSTORMS POSSIBLE.
THE RAIN AND THUNDERSTORMS ARE FORECAST TO BE LESS INTENSE AS THE
FRONT BEGINS PUSHING EASTWARD AT A FASTER PACE. BY TONIGHT, A LOW
PRESSURE WAVE IS FORECAST TO DEVELOP QUICKLY ALONG THE FRONT OVER
THE OHIO VALLEY AND THEN TRACK NORTH ACROSS THE LOWER GREAT LAKES
ON SATURDAY. THE ADDED DYNAMICS ASSOCIATED WITH THE DEVELOPING
WAVE WILL PUSH A STRONG COLD FRONT FROM WEST TO EAST ACROSS THE
EAST COAST SATURDAY AND SATURDAY NIGHT. STRONG TO SEVERE
THUNDERSTORMS ARE EXPECTED TO PRECEDE AND ACCOMPANY THIS DYNAMIC
COLD FRONT. SUDDEN ONSET OF HEAVY RAIN ALONG WITH VERY GUSTY
WINDS ARE ALSO EXPECTED WITH THESE STORMS. HOWEVER, THE RELATIVE
QUICK MOTION OF THE STORMS SHOULD LIMIT THE THREAT OF FLASH
FLOODING ALTHOUGH ISOLATED FLASH FLOODING CANNOT BE RULED OUT.
MEANWHILE, THE WARMTH OVER THE EASTERN U.S. WILL REACH ITS PEAK
TODAY AS HIGH TEMPERATURES ARE FORECAST TO REACH INTO THE 80S FOR
MUCH OF THE EAST TODAY WITH A FEW LOCATIONS POSSIBLY REACH 90
DEGREES, WHICH WILL CHALLENGE SOME DAILY HIGH TEMPERATURE RECORDS.
INCREASED PRECIPITATION CHANCES AS THE COLD FRONT APPROACHES ON
SATURDAY WILL DROP TEMPERATURES INTO THE 70S FOR THE MID-ATLANTIC.
BY SUNDAY MORNING, MUCH COOLER AIR WILL ARRIVE FROM THE WEST AS
THE COLD FRONT BEGINS PUSHING OFF THE EAST COAST.
IN CONTRAST TO THE WARMTH IN THE EAST, MODERATE TO HEAVY SNOW IS
IN PROGRESS OVER THE NORTHERN PLAINS INTO THE UPPER MIDWEST ON THE
BACK SIDE OF AN OCCLUDED CYCLONE. THE SNOW SHOULD REACH PEAK
INTENSITY THIS MORNING FOLLOWED BY GRADUAL TAPERING OFF OF THE
SNOW THROUGH THE REST OF TODAY INTO TONIGHT AS THE LOW PRESSURE
SYSTEM WEAKENS. HIGH TEMPERATURES WILL REMAIN QUITE CHILLY AND
MUCH BELOW AVERAGE BEHIND THE COLD FRONT AND UNDER THE INFLUENCE
OF THE UPPER-LEVEL LOW, WITH HIGHS IN THE 30S AND 40S TODAY FOR
THE NORTHERN PLAINS SPREADING INTO THE GREAT LAKES AND PORTIONS OF
THE UPPER TO MIDDLE MISSISSIPPI VALLEY ON SATURDAY. HIGHS FROM
THE CENTRAL PLAINS TO THE LOWER OHIO VALLEY WILL DROP FROM THE 60S
FRIDAY INTO THE 50S ON SATURDAY.
FURTHER SOUTH, ONGOING SHOWERS AND THUNDERSTORMS IN EASTERN TEXAS
WILL END BY THIS EVENING AS THE COLD FRONT PUSHES OFF THE GULF
COAST. CONDITIONS ACROSS THE SOUTHERN PLAINS WILL TURN COOLER WITH
HIGHS GENERALLY IN THE 60S AND 70S TODAY AND SATURDAY OUTSIDE OF
THE RIO GRANDE VALLEY. MORNING LOWS FOR PORTIONS OF THE TEXAS
PANHANDLE AND OKLAHOMA WILL DIP AS LOW AS THE UPPER 30S. GUSTY
WINDS MIXING DOWN OVER THE SOUTHERN HIGH PLAINS COMBINED WITH LOW
RELATIVE HUMIDITY AND DRY ANTECEDENT CONDITIONS HAVE PROMPTED A
CRITICAL RISK FOR FIRE WEATHER PER THE STORM PREDICTION CENTER FOR
TODAY.
UPPER-LEVEL SHORTWAVE ENERGY PASSING OVER THE INTERMOUNTAIN WEST
WILL TRIGGER SNOW SHOWERS FOR PORTIONS OF THE NORTHERN AND CENTRAL
ROCKIES TODAY. SOME LOCALLY HEAVY ACCUMULATING SNOW WILL BE
POSSIBLE FOR HIGHER MOUNTAIN ELEVATIONS, PARTICULARLY IN THE
CENTRAL ROCKIES. A PACIFIC STORM SYSTEM WILL APPROACH THE PACIFIC
NORTHWEST LATER THURSDAY EVENING INCREASING CHANCES FOR LIGHT TO
MODERATE LOWER ELEVATION COASTAL/VALLEY RAIN AND HIGHER ELEVATION
SNOW HERE AS WELL. HIGHS WILL REMAIN COOL FOR THE NORTHERN/CENTRAL
ROCKIES FOLLOWING THE PASSAGE OF A COLD FRONT AND ON THE WESTERN
EDGE OF THE EXPANSIVE UPPER-LEVEL LOW, WITH HIGHS GENERALLY IN THE
40S AND 50S. AN UPPER-LEVEL RIDGE BUILDING OFF THE PACIFIC COAST
WILL LEAD TO TRANQUIL CONDITIONS AND NEAR-AVERAGE TEMPERATURES FOR
CALIFORNIA, THE SOUTHERN GREAT BASIN, AND THE DESERT SOUTHWEST.
HIGHS TODAY AND SATURDAY WILL RANGE BETWEEN THE 70S AND 80S FOR
MOST OF CALIFORNIA AND THE GREAT BASIN WITH 90S IN THE DESERT
SOUTHWEST.
KONG/PUTNAM
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