797
FXUS01 KWBC 251955
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
354 PM EDT WED SEP 25 2024
VALID 00Z THU SEP 26 2024 - 00Z SAT SEP 28 2024
...HELENE IS FORECAST TO RAPIDLY INTENSIFY TO A MAJOR HURRICANE IN
THE GULF AND BRING LIFE-THREATENING IMPACTS TO FLORIDA AND THE
SOUTHEAST THROUGH FRIDAY...
...A RARE HIGH RISK OF EXCESSIVE RAINFALL IS IN PLACE FOR THE
SOUTHERN APPALACHIANS THROUGH THURSDAY NIGHT WHERE CATASTROPHIC
FLASH FLOODING AND LANDSLIDES ARE EXPECTED...
...ABOVE AVERAGE TEMPERATURES AND SUMMER-LIKE WARMTH FORECAST TO
STRETCH FROM THE SOUTHWEST TO NORTHERN PLAINS...
HURRICANE HELENE IS CURRENTLY ENTERING THE SOUTHEASTERN GULF OF
MEXICO THIS AFTERNOON AND IS FORECAST TO BECOME A MAJOR HURRICANE
ON THURSDAY BEFORE MAKING LANDFALL OVER THE FLORIDA PANHANDLE
SOMETIME THURSDAY EVENING. A HURRICANE WARNING IS IN EFFECT OVER
THE FLORIDA BIG BEND AND EXTENDING INLAND INTO SOUTHWEST GEORGIA
FOR DAMAGING HURRICANE-FORCE WINDS. THE DAMAGING WIND THREAT IS
ALSO EXPECTED TO STRETCH EVEN FURTHER INLAND TOWARDS THE SOUTHERN
APPALACHIANS AND MUCH OF GEORGIA AS THE STORM RACES NORTHWARD
THROUGH FRIDAY, WITH TROPICAL STORM WATCHES POSTED. HELENE WILL
GROW IN SIZE AS IT STRENGTHENS, SPREADING ITS IMPACTS TO MUCH OF
FLORIDA AND THE SOUTHEAST. THERE IS A DANGER OF LIFE-THREATENING
STORM SURGE ALONG THE ENTIRE WEST COAST OF THE FLORIDA PENINSULA,
CENTRAL AND EASTERN SECTIONS OF THE FLORIDA PANHANDLE (INCLUDING
THE FLORIDA BIG BEND). THE HIGHEST INUNDATION LEVELS ARE EXPECTED
ALONG THE COAST OF THE FLORIDA BIG BEND. PREPARE NOW AND HEED
INSTRUCTIONS FROM LOCAL OFFICIALS ABOUT EVACUATIONS IN THESE
AREAS. PLEASE REFER TO THE NATIONAL HURRICANE CENTER FOR THE
LATEST UPDATES ON THE TRACK AND TIMING OF HELENE.
HELENE WILL ALSO CAUSE SIGNIFICANT RAINFALL AND FLOODING THREATS.
EVEN AHEAD OF HELENE ITSELF, TROPICAL MOISTURE WILL BE PULLED
NORTH INTO THE SOUTHEAST TO SOUTHERN APPALACHIANS THROUGH TONIGHT
AHEAD OF A SLOW-MOVING UPPER TROUGH/LOW. THIS MOISTURE WILL POOL
ALONG AND AHEAD OF A STALLING FRONT AT THE SURFACE AND LEAD TO
EXCESSIVE RAINFALL. A RARE HIGH RISK (LEVEL 4/4) IS IN PLACE IN
WPC'S EXCESSIVE RAINFALL OUTLOOK (ERO) ACROSS PORTIONS OF GEORGIA
INTO THE SOUTHERN APPALACHIANS TONIGHT, IN ADDITION SLIGHT RISKS
(LEVEL 2/4) OF FLASH FLOODING HAVE BEEN ISSUED IN PARTS OF THE
FLORIDA PENINSULA AND WEST COAST OF FLORIDA AS HELENE APPROACHES.
TODAY'S RAINFALL IS FORECAST TO CREATE NUMEROUS INSTANCES OF FLASH
FLOODING WHILE ALSO LEADING TO WET ANTECEDENT CONDITIONS THAT
SHOULD LIKELY OVERLAP HEAVY RAIN ALONG HELENE'S TRACK
THURSDAY-FRIDAY. THUS A HIGH RISK OF EXCESSIVE RAINFALL IS ALSO
DELINEATED ON THURSDAY ACROSS THE SOUTHERN APPALACHIANS WHERE
UPSLOPE FLOW SHOULD INCREASE RAIN TOTALS AND VARYING TERRAIN COULD
LEAD TO LANDSLIDES. ADDITIONALLY, A SEPARATE AREA OF EXTREME
RAINFALL IS ALSO LIKELY NEAR THE CORE OF THE STORM AS IT PASSES
OVER THE FLORIDA PANHANDLE, WHERE A SEPARATE HIGH RISK OF
EXCESSIVE RAINFALL IS IN EFFECT. OVERALL, 6 TO 12 INCHES OF RAIN
WITH ISOLATED TOTALS AROUND 18 INCHES IS FORECAST OVER THE
SOUTHEAST AND SOUTHERN APPALACHIANS. CATASTROPHIC AND
LIFE-THREATENING FLASH AND URBAN FLOODING, INCLUDING LANDSLIDES,
IS EXPECTED ACROSS PORTIONS OF THE SOUTHERN APPALACHIANS THROUGH
FRIDAY. CONSIDERABLE TO LOCALLY CATASTROPHIC FLASH AND URBAN
FLOODING IS LIKELY FOR NORTHWESTERN AND NORTHERN FLORIDA AND THE
SOUTHEAST THROUGH FRIDAY. WIDESPREAD MINOR TO MODERATE RIVER
FLOODING IS LIKELY, AND ISOLATED MAJOR RIVER FLOODING IS POSSIBLE.
ANOTHER WEATHER HAZARD ASSOCIATED WITH HELENE TO MONITOR IS THE
TORNADO THREAT, ESPECIALLY ON THE EASTERN SIDE OF THE TRACK. THE
STORM PREDICTION CENTER IS INDICATING A SLIGHT TO ENHANCED RISK OF
SEVERE WEATHER, PRIMARILY FOR TORNADOES, ON THURSDAY INTO THURSDAY
NIGHT FOR PARTS OF NORTHERN FLORIDA INTO GEORGIA AND SOUTH
CAROLINA.
ELSEWHERE, SHOWERS AND STORMS ARE ALSO POSSIBLE FARTHER NORTH IN
THE EASTERN U.S. ALONG THE NORTHERN PART OF THE FRONTAL SYSTEM
OVER THE NEXT COUPLE OF DAYS. A COUPLE OF FRONTS PASSING THROUGH
THE NORTHWEST SHOULD LEAD TO SOME PRECIPITATION THERE AND GUSTY
WINDS. MEANWHILE THE REST OF THE WESTERN U.S. STRETCHING INTO THE
NORTH-CENTRAL U.S. CAN EXPECT DRY CONDITIONS WITH WARMER THAN
AVERAGE TEMPERATURES. THE DESERT SOUTHWEST WILL SEE HIGHS WELL
INTO THE 100S AND LOW 110S, WHICH HAS PROMPTED EXCESSIVE HEAT
WARNINGS FROM SOUTH-CENTRAL ARIZONA INTO THE HIGH DESERTS OF
SOUTHERN CALIFORNIA. HIGH INTO THE 90S ARE POSSIBLE IN THE
NORTHERN HIGH PLAINS, WITH 80S STRETCHING INTO THE UPPER MIDWEST
THROUGH THE END OF THE WEEK. SOME RECORD WARM TEMPERATURES ARE
POSSIBLE FOR BOTH MORNING LOWS AND AFTERNOON HIGHS.
SNELL
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