440
FXUS01 KWBC 050739
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
338 AM EDT THU SEP 05 2024
VALID 12Z THU SEP 05 2024 - 12Z SAT SEP 07 2024
...VERY HEAVY RAIN AND THE THREAT FOR SCATTERED TO NUMEROUS
INSTANCES OF FLASH FLOODING CONTINUES FOR THE GULF COAST STATES
THE NEXT COUPLE OF DAYS...
...DANGEROUS HEAT WAVE INTENSIFIES OVER THE SOUTHWEST AND WEST
COAST...
HEAVY RAIN AND FLASH FLOODING REMAIN IN THE FORECAST ALONG THE
GULF COAST AS A STATIONARY FRONT AND COASTAL LOW DRIVE MULTIPLE
DAYS OF WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE REGION.
THE ELONGATED AREA OF LOW PRESSURE AND FRONT FROM THE
NORTH-CENTRAL TO WESTERN GULF WILL KEEP THE GREATEST FOCUS FOR
REPEATED ROUNDS OF STORMS MOVING ONSHORE OVER THE CENTRAL GULF
COAST AND UPPER TEXAS GULF COAST TODAY (THURSDAY), POTENTIALLY
SPREADING A BIT FURTHER NORTHWARD INTO THE LOWER MISSISSIPPI
VALLEY. VERY MOIST GULF AIR CONTINUES TO CONTRIBUTE TO VERY
EFFICIENT DOWNPOURS WITH THESE STORMS, APPROACHING 2-3" PER HOUR
IN SOME CASES, EXACERBATING THE THREAT FOR HEAVY TOTALS AND FLASH
FLOODING. THERE IS NOW A MODERATE RISK (LEVEL 3/4) OF EXCESSIVE
RAINFALL FOR SOUTHEASTERN LOUISIANA WHERE PRIOR DAYS RAINFALL HAS
LEAD TO VERY WET ANTECEDENT CONDITIONS AND BRINGS A LOCALLY
GREATER THREAT FOR SCATTERED TO NUMEROUS INSTANCES OF FLASH
FLOODING, ESPECIALLY FOR THE URBAN AREAS AROUND GREATER NEW
ORLEANS. A BROADER SLIGHT RISK (LEVEL 2/4) IS IN PLACE ACROSS THE
REGION FOR ADDITIONAL SCATTERED INSTANCES OF FLASH FLOODING. AN
APPROACHING UPPER-LEVEL WAVE WILL HELP TO SHIFT THE FOCUS FOR
HEAVY RAINFALL A BIT EASTWARD ON FRIDAY AS THE FRONT BEGINS TO
MEANDER AWAY FROM THE WESTERN GULF AND LIFT NORTHWARD INTO
SOUTHERN GEORGIA, LEADING TO DECREASING RAIN CHANCES FURTHER WEST.
ANOTHER SLIGHT RISK OF EXCESSIVE RAINFALL EXTENDS FROM THE CENTRAL
GULF COAST EASTWARD THROUGH THE FLORIDA PANHANDLE INTO SOUTHERN
GEORGIA WHERE A SIMILAR THREAT FOR INTENSE HEAVY DOWNPOURS WITH
REPEATED ROUNDS OF STORMS WILL LEAD TO SEVERAL INCHES OF RAIN, AND
THE POTENTIAL FOR SCATTERED INSTANCES OF FLASH FLOODING.
TEMPERATURES WILL REMAIN WELL BELOW AVERAGE ACROSS THE REGION
NORTH OF THE FRONTAL BOUNDARY AND IN THE PRESENCE OF WIDESPREAD
RAIN AND CLOUD COVER WITH MOSTLY UPPER 70S AND LOW 80S. SOME
LOCATIONS MAY ONLY REACH INTO THE LOW 70S FRIDAY. ON THE OTHER
HAND, IT WILL BE HOT SOUTH OF THE FRONT ACROSS THE FLORIDA
PENINSULA, WITH HIGHS IN THE LOW 90S. A HEAT ADVISORY IS IN PLACE
FOR SOUTH FLORIDA WHERE THE COMBINATION OF HEAT AND HUMIDITY WILL
LEAD TO HEAT INDICES IN THE 105-110 DEGREE RANGE.
A DANGEROUS HEAT WAVE WILL INTENSIFY OVER THE SOUTHWEST AND WEST
COAST THE NEXT COUPLE OF DAYS WITH A STRONG UPPER-LEVEL RIDGE NOW
SETTLED OVER THE REGION. FORECAST HIGH TEMPERATURES THURSDAY AND
FRIDAY RANGE FROM THE 110S FOR THE DESERT SOUTHWEST, LOW 100S TO
NEAR 110 FOR SOUTHERN CALIFORNIA, MID-100S FOR THE CENTRAL
CALIFORNIA VALLEYS, AND THE 90S TO LOW 100S FOR CENTRAL/NORTHERN
CALIFORNIA AND INTO THE PACIFIC NORTHWEST. SEVERAL
RECORD-TYING/BREAKING HIGHS ARE POSSIBLE ACROSS THE PACIFIC
NORTHWEST. WIDESPREAD HEAT-RELATED WARNINGS AND ADVISORIES ARE IN
PLACE GIVEN THE HEIGHTENED THREAT FOR HEAT-RELATED ILLNESS TO
ANYONE WITHOUT EFFICIENT AIR CONDITIONING OR ADEQUATE HYDRATION.
WHILE NOT QUITE AS HOT, HIGHS WILL BE WELL ABOVE AVERAGE AND
POTENTIALLY UNCOMFORTABLE EVEN FOR SOME IMMEDIATE COASTAL
LOCATIONS WITH TEMPERATURES REACHING INTO THE 80S.
ELSEWHERE, A BROAD AREA OF SHOWERS AND THUNDERSTORMS IS EXPECTED
AHEAD OF A PAIR OF COLD FRONTS PASSING THROUGH THE UPPER
MIDWEST/GREAT LAKES, CENTRAL PLAINS, AND CENTRAL/SOUTHERN HIGH
PLAINS AND ADJACENT ROCKIES. THE GREATEST CHANCE FOR SOME MODERATE
TO LOCALLY HEAVY RAINFALL WILL BE UNDER THE INFLUENCE OF AN
UPPER-LEVEL TROUGH OVER THE UPPER MIDWEST/GREAT LAKES, AND WHERE
UPSLOPE FLOW ENHANCES STORMS OVER THE SOUTHERN ROCKIES. A FEW
ISOLATED INSTANCES OF FLASH FLOODING WILL BE POSSIBLE IN THE
SOUTHERN ROCKIES GIVEN RECENT RAINS AND SOME MORE SENSITIVE BURN
SCARS. STORM CHANCES WITH MODERATE TO LOCALLY HEAVY RAINFALL WILL
CONTINUE AHEAD OF THE FRONT AS IT PUSHES EASTWARD THROUGH THE
GREAT LAKES OVERNIGHT THURSDAY AND INTO THE LOWER GREAT
LAKES/UPPER OHIO VALLEY ON FRIDAY. SOME STORMS MAY BEGIN TO SPREAD
INTO THE NORTHEAST AND MID-ATLANTIC BY EARLY SATURDAY MORNING.
TEMPERATURE-WISE, THE PASSING COLD FRONT WILL BRING WELL BELOW
AVERAGE, FALL-LIKE TEMPERATURES TO THE NORTHERN PLAINS AND UPPER
MIDWEST THURSDAY, WITH HIGHS IN THE 60S TO LOW 70S. TEMPERATURES
WILL BE RATHER CHILLY FOR THE UPPER GREAT LAKES BY FRIDAY AS HIGHS
DROP INTO THE 50S. CONDITIONS WILL BE MUCH WARMER AHEAD OF THE
FRONT THURSDAY OVER THE MIDWEST AND OHIO VALLEY WITH HIGHS IN THE
MID-80S TO LOW 90S. THE APPROACHING FRONT WILL BRING TEMPERATURES
DOWN INTO THE 70S FOR PORTIONS OF THE MIDWEST FRIDAY. MILD
CONDITIONS WILL CONTINUE FOR MUCH OF THE EAST COAST THROUGH FRIDAY
WITH HIGHS IN THE UPPER 70S TO LOW 80S.
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