722
FXUS01 KWBC 270757
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 AM EDT WED SEP 27 2023
VALID 12Z WED SEP 27 2023 - 12Z FRI SEP 29 2023
...SEVERE THUNDERSTORMS AND LOCALLY HEAVY RAIN POSSIBLE ACROSS
PORTIONS OF THE OHIO VALLEY TODAY...
...WET WEATHER TO CONTINUE ACROSS MUCH OF FLORIDA AND INTO THE
COASTAL SOUTHEAST, AS WELL AS THE PACIFIC NORTHWEST...
...MUCH ABOVE AVERAGE TEMPERATURES EXPECTED TO BUILD OVER THE
CENTRAL U.S. BY THE END OF THE WEEK...
A SLOW-MOVING LOW PRESSURE SYSTEM OVER THE MIDWEST AND ASSOCIATED
FRONTAL BOUNDARIES ARE FORECAST TO SLIDE EASTWARD INTO THE OHIO
VALLEY TODAY, WHILE SPREADING SCATTERED THUNDERSTORM CHANCES INTO
THE REGION. SOME STORMS COULD BECOME STRONG ENOUGH TO PRODUCE HAIL
AND DAMAGING WIND GUSTS. THE STORM PREDICTION CENTER HAS ISSUED A
SLIGHT RISK (LEVEL 2/5) FOR SEVERE WEATHER ACROSS AN AREA WITH THE
GREATEST CHANCES FOR POTENTIALLY ROBUST THUNDERSTORMS. THIS
INCLUDES FAR SOUTHEAST ILLINOIS, SOUTHERN INDIANA, AND
WESTERN/CENTRAL KENTUCKY. LOCALLY HEAVY RAIN MAY ALSO ACCOMPANY
THUNDERSTORMS AND LEAD TO ISOLATED INSTANCES OF FLASH FLOODING.
THIS SYSTEM IS EXPECTED TO WEAKEN AND LINGER OVER THE OHIO VALLEY
ON THURSDAY, WITH ADDITIONAL CHANCES FOR SCATTERED THUNDERSTORMS.
ANOTHER REGION WHERE AUTUMN THUNDERSTORMS WILL BE COMMON, BUT
LASTING FOR SEVERAL DAYS THIS WEEK, IS FLORIDA AND THE NEARBY
SOUTHEAST COASTLINE. A GRADUALLY SINKING COLD FRONT AND AREA OF
LOW PRESSURE LINGERING OFF THE SOUTHEAST COAST WILL ALLOW FOR
DAILY CHANCES FOR NUMEROUS THUNDERSTORMS. THE MAIN WEATHER HAZARD
IS EXPECTED TO BE ASSOCIATED WITH HEAVY RAIN AND CHANCES FOR URBAN
FLOODING. AMPLE ATMOSPHERIC MOISTURE IN PLACE WILL ALLOW FOR
THUNDERSTORMS TO CONTAIN INTENSE RAINFALL RATES THAT COULD LEAD TO
RAPID WATER RISES WHERE RAINFALL RUNOFF IS IMPEDED. A MARGINAL
RISK (LEVEL 1/4) FOR EXCESSIVE RAINFALL HAS BEEN ISSUED FOR THE
SUNSHINE STATE BETWEEN TODAY AND FRIDAY. RESIDENTS AND VISITORS
ARE REMINDED TO NEVER DRIVE THROUGH FLOODED ROADWAYS.
UNSETTLED WEATHER IS ALSO IN STORE FOR THE PACIFIC NORTHWEST AS A
MARCH OF LOW PRESSURE SYSTEMS CONTINUE THROUGH THE END OF THE WEEK
AND PRODUCE AN EARLY TASTE OF THE REGION'S RAINY SEASON. THE FIRST
SYSTEM TO IMPACT WASHINGTON AND OREGON WILL MOVE ONSHORE THIS
MORNING AND SPREAD MODERATE TO LOCALLY HEAVY SHOWER ACTIVITY
INLAND. ANOTHER WEAKER SYSTEM WILL APPROACH THE NORTHWEST ON
THURSDAY AND CONTINUE RAINFALL CHANCES THROUGH AT LEAST FRIDAY
INTO NORTHERN CALIFORNIA. THE FEW INCHES OF RAINFALL EXPECTED
ACROSS PARTS OF WASHINGTON AND NORTHWEST OREGON ARE EXPECTED TO BE
MOSTLY BENEFICIAL AS THE AREA DEALS WITH ONGOING DROUGHT
CONDITIONS. BELOW AVERAGE TEMPERATURES ARE ALSO IN THE FORECAST,
WITH HIGHS INTO 60S DUE TO RAINFALL AND ASSOCIATED CLOUD COVER.
BELOW AVERAGE TEMPERATURES ARE ALSO ANTICIPATED TO REMAIN LOCKED
IN PLACE OVER THE MID-ATLANTIC AND NEW ENGLAND AS THE FINAL DAYS
OF SEPTEMBER LOOM. THE COMBINATION OF A STRONG HIGH PRESSURE
SYSTEM OVER SOUTHERN QUEBEC AND LOW PRESSURE OFF THE SOUTHEAST
COAST WILL CONTINUE PERSISTENT MOIST EASTERLY FLOW OFF THE
ATLANTIC OCEAN INTO THE REGION. LIGHT RAIN AND DRIZZLE MAY BECOME
MORE WIDESPREAD BY THE END OF THE WEEK, WITH HIGH TEMPERATURES
REMAINING IN THE 60S AND LOW 70S. IN CONTRAST, WELL ABOVE
TEMPERATURES ARE FORECAST THROUGHOUT A MAJORITY OF THE NATION
BETWEEN THE EAST AND WEST COASTS. HIGHS INTO THE 80S AND 90S ARE
EXPECTED TO STRETCH FROM THE DESERT SOUTHWEST TO THE MIDWEST AND
MID-SOUTH. THIS WOULD EQUATE TO AROUND 10 TO 20 DEGREES ABOVE
AVERAGE THROUGHOUT THE CENTRAL PLAINS AND NEIGHBORING UPPER/MIDDLE
MISSISSIPPI VALLEYS.
SNELL
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