595
FXUS01 KWBC 240818
PMDSPD
SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
359 AM EDT TUE SEP 24 2024
VALID 12Z TUE SEP 24 2024 - 12Z THU SEP 26 2024
...POTENTIAL TROPICAL CYCLONE NINE IS FORECAST TO PASS NOT TOO FAR
FROM THE FLORIDA KEYS WEDNESDAY NIGHT AS A HURRICANE BEFORE
SKIRTING UP THE WEST COAST OF FLORIDA BY THURSDAY MORNING...
...MUCH NEEDED RAINFALL FROM THE OHIO VALLEY INTO THE CENTRAL TO
SOUTHERN APPALACHIANS, UPPER TENNESSEE VALLEY AND MID-ATLANTIC...
...MUCH ABOVE AVERAGE TEMPERATURES CONTINUE ACROSS THE WEST INTO
THE NORTHERN PLAINS AND ACROSS THE GULF COAST INTO THE SOUTHEAST...
A RELATIVELY BENIGN MID- TO UPPER-LEVEL TROUGH THAT WILL LIKELY
BRING BENEFICIAL RAINFALL FOR THE EASTERN U.S. IS FORECAST TO
DEEPEN WHEN ANOTHER UPPER-LEVEL TROUGH OVER THE NORTHERN PLAINS
DROPS SOUTHEAST AND MERGES WITH THE LEAD TROUGH. THE RESULTING
TROUGH AMPLIFICATION WILL BE INSTRUMENTAL IN PULLING THE TROPICAL
MOISTURE AS WELL AS POTENTIAL CYCLONE NINE (PTC9) NORTHWARD INTO
THE EASTERN PORTION OF THE GULF OF MEXICO BY THE END OF THE
SHORT-RANGE FORECAST PERIOD ON THURSDAY MORNING.
THE INITIAL IMPACTS FROM THE LEAD TROUGH WILL BE IN THE FORM OF AN
EXPANDING AREA OF MODERATE TO HEAVY RAINFALL POTENTIAL FROM THE
MIDWEST INTO THE LOWER GREAT LAKES, OHIO VALLEY, UPPER TENNESSEE
VALLEY, CENTRAL TO SOUTHERN APPALACHIANS INTO THE MID-ATLANTIC
NEAR AND AHEAD OF A LOW PRESSURE WAVE. MUCH OF THESE AREAS ARE
CURRENTLY EXPERIENCING SEVERE TO EXCEPTIONAL DROUGHT CONDITIONS,
WITH THE EXPECTED 1 TO 1.5 INCH PLUS RAINFALL AMOUNT OVER THE NEXT
TWO DAYS BRINGING SOME RELIEF TO THESE DROUGHT CONDITIONS. WITH
THE DRY CONDITIONS ACROSS THESE AREAS, RIVER FLOODING WILL BE
UNLIKELY. HOWEVER, THERE IS STILL AT LEAST A MARGINAL RISK OF
ISOLATED FLASH FLOODING WITH THE EXPECTED HEAVY RAINFALL AMOUNTS,
ESPECIALLY IF THEY OCCUR OVER URBANIZED REGIONS.
AS THE ABOVE-MENTIONED AMPLIFYING PATTERN DEVELOPS OVER THE
NORTHERN PLAINS AND DIPS TOWARD THE DEEP SOUTH, PTC9 IS FORECAST
TO TRACK MORE TOWARD THE NORTH AND INTENSIFY RAPIDLY AS IT MOVES
ACROSS THE YUCATAN CHANNEL ON WEDNESDAY AND THEN PASS NOT TOO FAR
FROM THE FLORIDA KEYS WEDNESDAY NIGHT. THE FLORIDA KEYS CAN
EXPECT STRENGTHENING WINDS WITH MORE FREQUENT PASSAGES OF SQUALLY
DOWNPOURS WEDNESDAY NIGHT AS PTC9 IS FORECAST TO PASS TO THE WEST
AS A HURRICANE. COMPUTER MODELS INDICATE THAT THE CIRCULATION OF
PTC9 WILL EXPAND AS IT INTERACTS WITH THE DEEPENING UPPER TROUGH
IN THE DEEP SOUTH. GIVEN A MORE ROBUST CONVECTIVE STRUCTURE
CONCENTRATED MORE ON THE EAST SIDE OF THE STORM, THE WEST COAST OF
FLORIDA COULD BEGIN TO SEE MORE FREQUENT AND INTENSE SQUALLS WITH
WINDS FURTHER STRENGTHENING BY THURSDAY MORNING. PLEASE REFER TO
THE NATIONAL HURRICANE CENTER FOR THE LATEST UPDATES ON THIS
SYSTEM.
THE AMPLIFYING UPPER RIDGE ACROSS THE INTERIOR WEST WILL BE
SUPPORTING WIDESPREAD MUCH ABOVE AVERAGE TEMPERATURES OVER THE
NEXT FEW DAYS ACROSS NEARLY ALL OF THE WEST AND INTO THE NORTHERN
PLAINS. HIGH TEMPERATURES ACROSS THESE REGIONS ARE FORECAST TO BE
AS MUCH AS 10 TO 20 DEGREES ABOVE AVERAGE. ABOVE AVERAGE
TEMPERATURES ALSO LIKELY ACROSS THE GULF COAST AND INTO THE
SOUTHEAST. WHILE TEMPERATURES ARE FORECAST TO BE MUCH ABOVE
ACROSS THESE AREAS OVER THE NEXT FEW DAYS, THERE ARE NOT EXPECTED
TO BE MANY RECORD HIGHS. HOWEVER, MORE NUMEROUS RECORD HIGH
MORNING TEMPERATURES ARE POSSIBLE BOTH TODAY AND WEDNESDAY MORNING
ALONG THE WEST COAST AND FROM PORTIONS OF THE SOUTHERN
MID-ATLANTIC INTO THE SOUTHEAST AND FLORIDA.
KONG/ORAVEC
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