207
FXUS01 KWBC 262000
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT THU SEP 26 2024
VALID 00Z FRI SEP 27 2024 - 00Z SUN SEP 29 2024
...HELENE IS FORECAST TO MAKE LANDFALL AS A MAJOR HURRICANE LATER
THURSDAY EVENING AND BRING LIFE-THREATENING IMPACTS TO FLORIDA AND
THE SOUTHEAST THROUGH EARLY SATURDAY...
...RARE HIGH RISKS OF EXCESSIVE RAINFALL ARE IN PLACE FOR PARTS OF
THE FLORIDA PANHANDLE WHERE HELENE WILL MAKE LANDFALL, AND FOR THE
SOUTHERN APPALACHIANS 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, NOW A MAJOR HURRICANE, IS MOVING NORTHWARD
THROUGH THE GULF OF MEXICO THIS AFTERNOON AND FORECAST TO MAKE
LANDFALL LATER THIS (THURSDAY) EVENING IN THE FLORIDA BIG BEND
REGION. BECAUSE HELENE IS A LARGE SYSTEM AND WILL INITIALLY MOVE
INLAND QUICKLY, DAMAGING AND LIFE-THREATENING HURRICANE-FORCE
WINDS, ESPECIALLY IN GUSTS, WILL PENETRATE WELL INLAND OVER
PORTIONS OF THE FLORIDA PANHANDLE/BIG BEND REGION AND INTO
SOUTHWESTERN GEORGIA LATE THURSDAY AND THURSDAY NIGHT WHERE
HURRICANE WARNINGS ARE IN EFFECT. STRONG, TROPICAL-STORM FORCE
WIND GUSTS ARE ALSO LIKELY FARTHER NORTH ACROSS PORTIONS OF
NORTHERN GEORGIA AND THE CAROLINAS LATE THURSDAY AND INTO THE DAY
FRIDAY, PARTICULARLY OVER THE HIGHER TERRAIN OF THE SOUTHERN
APPALACHIANS. ADDITIONALLY, CATASTROPHIC AND DEADLY STORM SURGE IS
EXPECTED ALONG PORTIONS OF THE FLORIDA BIG BEND COAST, WHERE
INUNDATION COULD REACH AS HIGH AS 20 FEET ABOVE GROUND LEVEL,
ALONG WITH DESTRUCTIVE WAVES. THERE IS ALSO A DANGER OF
LIFE-THREATENING STORM SURGE ALONG THE REMAINDER OF THE WEST COAST
OF THE FLORIDA PENINSULA. 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 BRING CATASTROPHIC AND LIFE-THREATENING EXTREME
RAINFALL AND FLOODING THREATS. BEGINNING AHEAD OF HELENE ITSELF,
TROPICAL MOISTURE IS BEING PULLED NORTH INTO THE SOUTHEAST TO
SOUTHERN APPALACHIANS AHEAD OF A SLOW-MOVING UPPER TROUGH/LOW AND
SURFACE FRONT, CURRENTLY CAUSING RAINFALL AND FLOODING THAT WILL
CONTINUE THROUGH THE NEXT COUPLE OF DAYS AS HELENE MOVES INLAND.
HEAVY TO EXTREME RAINFALL FROM YESTERDAY HAS ALREADY LED TO WET
ANTECEDENT CONDITIONS IN PLACES WHERE HELENE WILL TRACK,
CONTRIBUTING TO THE SIGNIFICANCE OF THE FLOODING THREAT WITH THIS
SYSTEM. A RARE HIGH RISK (LEVEL 4/4) IS IN PLACE IN WPC'S
EXCESSIVE RAINFALL OUTLOOK (ERO) THROUGH FRIDAY MORNING ACROSS
PORTIONS OF THE FLORIDA PANHANDLE/BIG BEND REGION, GEORGIA, AND
INTO THE SOUTHERN APPALACHIANS. THIS THREAT WILL EXTEND INTO AT
LEAST MID-DAY FRIDAY FOR THE SOUTHERN APPALACHIANS WHERE UPSLOPE
FLOW SHOULD INCREASE RAIN TOTALS AND VARYING TERRAIN IS LIKELY TO
LEAD TO LANDSLIDES. CATASTROPHIC AND LIFE-THREATENING FLASH AND
URBAN FLOODING, INCLUDING NUMEROUS SIGNIFICANT LANDSLIDES IN THE
APPALACHIANS, IS EXPECTED. A MUCH BROADER SLIGHT RISK (LEVEL 2/4)
IS IN EFFECT OVER MUCH OF THE SOUTHEAST AND EXTENDING NORTHWARD
INTO THE CENTRAL APPALACHIANS AND WEST THROUGH THE TENNESSEE AND
OHIO VALLEYS INTO THE MID-SOUTH WHERE MORE SCATTERED FLASH
FLOODING IS EXPECTED THROUGH FRIDAY. A MORE TARGETED SLIGHT RISK
CONTINUES INTO SATURDAY OVER THE OHIO VALLEY WHERE AREAS OF
HEAVIER RAINFALL AND SCATTERED FLASH FLOODING MAY CONTINUE AS THE
FORECAST EXTRATROPICAL HELENE AND THE UPPER-LOW INTERACT OVER THE
REGION. OVERALL, HELENE IS FORECAST TO PRODUCE TOTAL RAIN
ACCUMULATIONS OF 6 TO 12 INCHES OVER PORTIONS OF THE SOUTHEAST,
WITH ISOLATED TOTALS OF 20 INCHES OR MORE INTO THE SOUTHERN
APPALACHIANS. WIDESPREAD SIGNIFICANT RIVER FLOODING AND ISOLATED
MAJOR RIVER FLOODING ARE LIKELY. 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, FROM THE FLORIDA PENINSULA NORTH INTO THE CAROLINAS
THROUGH EARLY FRIDAY, CONTINUING IN THE CAROLINAS THROUGH EARLY
SATURDAY.
ELSEWHERE, SHOWERS AND STORMS ARE ALSO POSSIBLE FARTHER NORTH IN
THE EASTERN U.S. ALONG THE NORTHERN PART OF THE FRONTAL SYSTEM FOR
PORTIONS OF NEW ENGLAND THOUGH FRIDAY, AND AS TROPICAL MOISTURE
INTERACTS WITH THE FRONT OVER THE MID-ATLANTIC THROUGH SATURDAY. 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. MUCH OF THE INTERIOR
WEST INCLUDING THE CENTRAL CALIFORNIA VALLEYS AND GREAT BASIN WILL
SEE HIGHS INTO THE LOW 90S. HIGHS INTO THE MID- TO UPPER 80S AND
EVEN THE LOW 90S ARE FORECAST FOR THE NORTHERN PLAINS, WITH LOW
80S STRETCHING INTO THE UPPER MIDWEST. RECORD WARM TEMPERATURES
ARE POSSIBLE FOR BOTH MORNING LOWS AND AFTERNOON HIGHS.
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