176
FXUS64 KHUN 071120
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
620 AM CDT TUE OCT 7 2025
..NEW AVIATION
NEAR TERM
(TODAY)
ISSUED AT 332 AM CDT TUE OCT 7 2025
THE PREVIOUS DISCUSSION REMAINS ON TRACK WITH MINOR TWEAKS (A
SLIGHT DECREASE) TO THE WIND SPEEDS THROUGH THIS MORNING DUE TO
CURRENT TRENDS. AS SHOWERS CONTINUE TO WORK THEIR WAY EASTWARD
THROUGH THE TENNESSEE VALLEY THIS MORNING, LOW CHANCES OF
LIGHTNING DEVELOPMENT EXIST. OUR PRIMARY CONCERN TODAY WILL BE
MONITORING HEAVY RAINFALL AND THE SUBSEQUENT LOW CHANCE FOR FLASH
FLOODING CONCERNS. THE WEATHER PREDICTION CENTER HAS PORTIONS OF
NW AL IN A MARGINAL (RISK LEVEL 1 OF 4) EXCESSIVE RAINFALL OUTLOOK
THROUGH WEDNESDAY MORNING FOR RAINFALL EXCEEDING FLASH FLOOD
GUIDANCE. WHILE SHEAR CONTINUES TO LOOK LIMITED, SOME INSTABILITY
IS FORECAST TO BE PRESENT THIS AFTERNOON- PRIMARILY ALONG AND WEST
OF THE I-65 CORRIDOR. THEREFORE, A LOW CHANCE OF A STORM
PRODUCING GUSTY WINDS UP TO 40 MPH THIS AFTERNOON CANNOT BE RULED
OUT. CLOUD COVER AND SHOWERS/THUNDERSTORMS THIS AFTERNOON SHOULD
LIMIT HIGHS IN THE UPPER 70S TO MID 80S.
PREVIOUS DISCUSSION:
IN THE MID/UPPER-LEVELS, WEST-SOUTHWESTERLY FLOW OF 15-25 KNOTS
WILL PERSIST ACROSS THE TN VALLEY OVERNIGHT, AS OUR REGION WILL
REMAIN ALONG THE NORTHERN RIM OF A SUBTROPICAL RIDGE EXPANDING
SOUTHWESTWARD FROM THE SOUTHEASTERN ATLANTIC COAST INTO THE
NORTHERN GULF. AT THE SURFACE, ESE WINDS WILL VEER TO SSE OVER THE
COURSE OF THE NIGHT AS A RIDGE (CENTERED OFF THE NORTHERN MID-
ATLANTIC COAST) SHIFTS EASTWARD AND A WEAK AREA OF LOW PRESSURE
DEVELOPS ACROSS EASTERN AR IN RESPONSE TO THE NORTHEASTWARD MOTION
OF A REMNANT MID-LEVEL TROUGH (PREVIOUSLY ALONG THE NORTHWEST GULF
COAST) AROUND THE EXPANDING SUBTROPICAL RIDGE.
A SOUTH-SOUTHEASTERLY LOW-LEVEL JET OF 15-25 KNOTS IS CURRENTLY
IN PLACE ACROSS THE REGION, AND WILL SUSTAIN POCKETS OF VERY LIGHT
RAIN FOR MUCH OF THE REGION THROUGH 6Z. HOWEVER, THE LLJ WILL
VEER TO SOUTHWEST AND STRENGTHEN INTO THE 25-35 KNOT RANGE BETWEEN
6-12Z DUE TO THE MOVEMENT OF THE REMNANT MID-LEVEL TROUGH, WITH
THE RELATED INCREASE IN LOW-LEVEL WARM ADVECTION EXPECTED TO
RESULT IN AN AXIS OF SURFACE PRESSURE FALLS TO OUR WEST THAT WILL
FOCUS RENEWED DEVELOPMENT OF SHOWERS AND SOME THUNDERSTORMS EARLY
TUESDAY MORNING. THIS ACTIVITY WILL SPREAD SLOWLY EASTWARD THROUGH
SUNRISE (LIKELY REACHING THE I-65 CORRIDOR BY 12Z), WITH
LIGHTNING AND LOCALLY HEAVY RAINFALL THE PRIMARY CONCERNS AS PWAT
VALUES WILL REMAIN IN THE 1.7-1.9" RANGE BUT WITH CAPE BELOW 500
J/KG. OTHERWISE, THE COMBINATION OF ABUNDANT CLOUDS AND ELEVATED
WINDS WILL CONTRIBUTE TO ANOTHER WARM/MUGGY NIGHT, WITH LOWS IN
THE 65-70F RANGE.
LATEST FORECAST DATA SUGGESTS THAT THE BAND OF SHOWERS AND
THUNDERSTORMS MENTIONED IN THE PARAGRAPH ABOVE WILL CONTINUE TO
SPREAD EASTWARD AFTER SUNRISE, WITH REDEVELOPMENT OF ADDITIONAL
(BUT MORE SCATTERED) CONVECTION POSSIBLE IN THE WAKE OF THIS
FEATURE AND PRIOR TO THE ARRIVAL OF A PREFRONTAL WIND SHIFT AXIS
IN NORTHWEST AL BETWEEN 22-0Z. PRESUMING THAT PARTIAL CLEARING
TAKES PLACE BEGINNING LATE TOMORROW MORNING, TEMPS IN THE L-M 80S
WITH DEWPOINTS IN THE M-U 60S MAY SUPPORT CAPE IN THE 1000-1250
J/KG RANGE ACROSS THE WEST, WHICH WILL LEAD TO AN INCREASING RISK
FOR LIGHTNING AND THUNDER. HOWEVER, IT STILL APPEARS AS IF BOTH
DEEP-LAYER AND LOW-LEVEL SHEAR WILL REMAIN TOO WEAK TO RAISE
CONCERN FOR ORGANIZED STORM CLUSTERS.
SHORT TERM
(TUESDAY NIGHT THROUGH THURSDAY NIGHT)
ISSUED AT 1040 PM CDT MON OCT 6 2025
A FINAL/BROKEN LINE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE TO
PROGRESS SOUTHEASTWARD ACROSS THE LOCAL FORECAST AREA TOMORROW
EVENING IN CONJUNCTION WITH A PREFRONTAL WIND SHIFT AXIS. HOWEVER,
WITH LIMITED DEEP-LAYER FORCING FOR ASCENT, BOTH COVERAGE AND
INTENSITY SHOULD DECREASE CONSIDERABLY BETWEEN 0-3Z. THAT SAID,
THE SURFACE CONFLUENCE AXIS WILL BE MOVING RATHER SLOWLY, AND
COULD SUPPORT DEVELOPMENT OF ADDITIONAL SHOWERS ACROSS MAINLY THE
SOUTHEASTERN PORTION OF THE FORECAST AREA BETWEEN 3-9Z BEFORE
FINALLY EXITING OUR REGION PRIOR TO SUNRISE ON WEDNESDAY.
NORTH-NORTHEASTERLY GRADIENT WINDS WILL INCREASE ACROSS THE
REGION ON WEDNESDAY AS A HIGH DEVELOPS EASTWARD FROM THE UPPER MS
VALLEY INTO THE GREAT LAKES, BUT THE ADVECTION OF DRIER AIR INTO
THE TN VALLEY WILL BE A GRADUAL PROCESS, WITH ABUNDANT LOW STRATUS
CLOUDS AND EVEN SOME POCKETS OF LIGHT RAIN POSSIBLE FOR MUCH OF
THE DAY. THIS REGIME WILL CONTINUE ON WEDNESDAY NIGHT AND INTO THE
DAY ON THURSDAY, AS ELEVATED LIFT WILL STRENGTHEN WITH THE
APPROACH OF A TROUGH AND LOW-LEVEL LIFT WILL STRENGTHEN WITH THE
ONSET OF COLD AIR DAMMING IN THE LEE OF THE SOUTHERN APPALACHIANS.
EASTERLY FLOW WILL BEGIN TO ADVECT AN EVEN DRIER AIRMASS
(FEATURING DEWPOINTS IN THE 40S) INTO THE REGION THURSDAY NIGHT,
BUT ABUNDANT CLOUDS WILL REMAIN IN PLACE FOR MUCH OF THE NIGHT
EVEN AS THE THREAT FOR PRECIPITATION DIMINISHES. HIGHS WILL FALL
INTO THE M-U 70S ON WEDNESDAY AND L-M 70S ON THURSDAY, WITH LOWS
ALSO FALLING INTO THE L-M 50S.
LONG TERM
(FRIDAY THROUGH MONDAY)
ISSUED AT 1040 PM CDT MON OCT 6 2025
DATA FROM THE LATEST SUITE OF GLOBAL MODELS CONTINUES TO SUGGEST
THAT A MID-LEVEL TROUGH (INITIALLY ACROSS GA/SC) WILL EVOLVE INTO
A RATHER DEEP CLOSED LOW AS IT DRIFTS NORTHEASTWARD IN THE GENERAL
VICINITY OF THE SOUTHEASTERN ATLANTIC COAST OVER THE COURSE OF
THE LONG TERM PERIOD. ALTHOUGH THIS DEVELOPMENT WILL OCCUR IN
RESPONSE TO AN INTENSE HIGH-LEVEL SPEED MAX DIGGING SOUTH-
SOUTHEASTWARD THROUGH OUR REGION THIS WEEKEND, IT STILL APPEARS AS
IF OUR FORECAST AREA WILL REMAIN ON THE DRY/WESTERN SIDE OF THE
LOW, WITH LITTLE TO NO OPPORTUNITY FOR ADDITIONAL RAINFALL (ASIDE
FROM A FEW AFTERNOON SHOWERS ALONG THE CUMBERLAND PLATEAU ON
FRIDAY). HIGHS WILL SLOWLY WARM FROM THE L-M 70S ON FRIDAY INTO
THE U70S-L80S BY MONDAY, WITH PLEASANTLY COOL OVERNIGHT LOWS IN
THE U40S-L50S.
AVIATION
(12Z TAFS)
ISSUED AT 619 AM CDT TUE OCT 7 2025
MVFR CONDITIONS ARE FORECAST THROUGH MOST OF THE TAF PERIOD AT
BOTH KMSL AND KHSV AS INCREASED CHANCES OF SHOWERS/THUNDERSTORMS
ARE POSSIBLE TODAY INTO THIS EVENING. LOWERED CLOUD CEILINGS WILL
PERSISTS WEDNESDAY MORNING, POTENTIALLY CAUSING IFR CONDITIONS.
VFR CONDITIONS SHOULD RETURN TO BOTH SITES BY WEDNESDAY
AFTERNOON.
HUN WATCHES/WARNINGS/ADVISORIES
AL...NONE.
TN...NONE.
NEAR TERM...HC
SHORT TERM....70
LONG TERM....70
AVIATION...HC
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