556
FXUS01 KWBC 200749
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
349 AM EDT WED SEP 20 2023
VALID 12Z WED SEP 20 2023 - 12Z FRI SEP 22 2023
...MUCH COOLER, FALL-LIKE TEMPERATURES AND LOCALLY HEAVY RAINFALL
FOR THE WEST...
...ABOVE AVERAGE HEAT FORECAST FROM THE PLAINS TO THE GREAT LAKES
THROUGH THURSDAY...
...CHANCES FOR HEAVY RAIN AND SEVERE THUNDERSTORMS CONTINUE FOR
THE SOUTHERN PLAINS...
A DEEP UPPER-LEVEL LOW DROPPING SOUTHWARD OVER THE WEST FROM
CANADA WILL PROVIDE QUITE THE COOL DOWN OVER THE NEXT COUPLE OF
DAYS. THE LOW WILL HELP TO DRIVE A QUASI-STATIONARY FRONT
LINGERING OVER THE INTERMOUNTAIN WEST FURTHER SOUTHWARD, BRINGING
MUCH BELOW AVERAGE, FALL-LIKE TEMPERATURES. HIGHS IN THE UPPER 50S
AND LOW 60S IN THE PACIFIC NORTHWEST AND NORTHERN ROCKIES ON
WEDNESDAY WILL SPREAD INTO THE GREAT BASIN BY THURSDAY. HIGHS
ALONG THE PACIFIC COAST WILL BE MUCH BELOW AVERAGE TOO, WITH 60S
INTO SOUTHERN CALIFORNIA. CONDITIONS WILL REMAIN A BIT MORE
SEASONABLE IN THE DESERT SOUTHWEST, WITH MOSTLY 90S EXPECTED. IN
ADDITION TO THE COOLER TEMPERATURES, ENHANCED LIFT FROM THE
APPROACHING UPPER-LOW AS WELL AS MOISTURE POOLING ALONG AND BEHIND
THE FRONTAL BOUNDARY WILL LEAD TO INCREASING SHOWER AND
THUNDERSTORM CHANCES ACROSS THE INTERMOUNTAIN WEST WEDNESDAY INTO
THURSDAY. SOME MORE WIDESPREAD, LOCALLY HEAVY RAINFALL AND
INCREASINGLY WET ANTECEDENT CONDITIONS MAY LEAD TO A HIGHER RISK
FOR AN ISOLATED CHANCE OF FLASH FLOODING FOR PORTIONS OF THE GREAT
BASIN INTO THE NORTHERN ROCKIES ON THURSDAY.
TO THE EAST, MUCH ABOVE AVERAGE TEMPERATURES WILL CONTINUE FOR THE
PLAINS AND SPREAD INTO THE GREAT LAKES AS AN AMPLIFYING PATTERN
HELPS TO REINVIGORATE UPPER-LEVEL RIDGING OVER THE CENTRAL U.S.
FORECAST HIGHS IN THE UPPER 70S TO MID-80S WILL BE 10-20 DEGREES
ABOVE AVERAGE FOR PORTIONS OF THE NORTHERN PLAINS/UPPER GREAT
LAKES. HIGHS IN THE MID- TO UPPER 90S IN TEXAS ARE SIMILARLY ABOVE
AVERAGE FOR LATE SUMMER. WHILE NOT QUITE AS ANOMALOUS, HIGHS IN
THE MID- TO UPPER 80S FOR LOCATIONS IN THE CENTRAL AND SOUTHERN
PLAINS ARE STILL QUITE WARM. MEANWHILE, THUNDERSTORM CHANCES WILL
CONTINUE ALONG A LINGERING QUASI-STATIONARY FRONT DRAPED FROM THE
SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY WEDNESDAY INTO
THURSDAY WITH BOTH LOCALLY HEAVY RAINFALL AND SOME INSTANCES OF
DAMAGING WINDS/LARGE HAIL POSSIBLE. AN UPPER-LEVEL SHORTWAVE
APPROACHING THE REGION LATER THURSDAY SHOULD HELP TO ENHANCE STORM
DEVELOPMENT/COVERAGE, LEADING TO A HIGHER RISK OF MORE WIDESPREAD
HEAVY RAINFALL AND SOME SCATTERED INSTANCES OF FLASH FLOODING FOR
PORTIONS OF SOUTHEASTERN OKLAHOMA INTO NORTHEASTERN TEXAS, WITH A
SLIGHT RISK OF EXCESSIVE RAINFALL (LEVEL 2/4) IN PLACE. INCREASING
LIFT AHEAD OF THE DEEPENING UPPER-LOW OVER THE WEST SHOULD LEAD TO
INCREASED SHOWER AND THUNDERSTORM CHANCES ALONG A QUASI-STATIONARY
FRONT OVER THE NORTHERN PLAINS THURSDAY WITH SOME LOCALLY HEAVY
RAINFALL POSSIBLE HERE AS WELL.
ELSEWHERE, CONDITIONS WILL REMAIN RELATIVELY DRY WITH SEASONABLE
TEMPERATURES FOR MOST OF THE EASTERN U.S. FORECAST HIGHS WEDNESDAY
AND THURSDAY WILL BE IN THE 60S AND 70S FOR NEW ENGLAND, 70S AND
80S FOR THE MID-ATLANTIC, AND 80S FOR THE SOUTHEAST INTO FLORIDA.
A LINGERING FRONTAL BOUNDARY OVER THE FLORIDA PENINSULA WILL
CONTINUE TO LEAD TO DAILY THUNDERSTORM CHANCES, WITH SOME LOCALLY
HEAVY DOWNPOURS AND ISOLATED FLASH FLOODING POSSIBLE. RAIN CHANCES
MAY BEGIN TO INCREASE LATE THURSDAY NORTHWARD ALONG THE GEORGIA
AND CAROLINA COASTS AS AN AREA OF LOW PRESSURE/FRONTAL SYSTEM
BEGINS TO ORGANIZE JUST OFF THE COAST.
PUTNAM
GRAPHICS AVAILABLE AT
HTTPS://WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page