758
FXUS64 KHUN 041951
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
251 PM CDT TUE AUG 4 2026
..NEW NEAR TERM
KEY MESSAGES
UPDATED AT 1056 AM CDT TUE AUG 4 2026
- CHANCES FOR SHOWERS AND THUNDERSTORMS WILL RANGE FROM 10-20%
(WEST) TO 50-60% (EAST) FROM TODAY-THURSDAY. LIGHTNING, HEAVY
RAINFALL AND BRIEF STRONG WIND GUSTS WILL BE THE GREATEST
IMPACTS FROM THE STORMS.
- MAINLY AFTERNOON/EVENING SHOWERS AND STORMS WILL CONTINUE EACH
DAY FROM FRIDAY-TUESDAY, WITH RAIN CHANCES IN THE 20-40% RANGE
(40-60% RANGE ON SATURDAY).
- NWS HEAT RISK HIGHLIGHTS MODERATE (LEVEL 2 OF 4) HEAT IMPACTS
ACROSS THE TENNESSEE VALLEY BEGINNING THURSDAY. THESE VALUES
WILL INCREASE TO MAJOR (LEVEL 3 OF 4) FOR PARTS OF THE AREA ON
MONDAY/TUESDAY.
NEAR TERM
(REST OF TODAY AND TONIGHT)
ISSUED AT 251 PM CDT TUE AUG 4 2026
THERE HAVE BEEN NO SIGNIFICANT CHANGES TO NEAR TERM FORECAST
REASONING SINCE THE UPDATE EARLIER THIS MORNING. CURRENT THINKING
IS THAT THE COVERAGE OF ONGOING MODERATE-HEAVY SHOWER ACTIVITY
WILL CONTINUE TO GRADUALLY INCREASE THROUGH 4-5 PM, WITH A GROWING
RISK FOR THUNDERSTORMS DURING THIS TIMEFRAME AS WELL. HOWEVER,
SIMILAR TO YESTERDAY, CELLS WOULD LIKELY NEED TO SUSTAIN A 40-50
DBZ CORE IN THE 16-18 KFT AGL LAYER FOR LIGHTNING TO BE A
CONSIDERABLE THREAT, AND THIS HAS NOT HAPPENED THUS FAR TODAY. IT
STILL APPEARS AS IF AT LEAST ISOLATED SHOWERS (AND PERHAPS A FEW
THUNDERSTORMS) WILL PERSIST IN THE VICINITY OF A SLOW-MOVING
SURFACE TROUGH THROUGH 0-2Z BEFORE DISSIPATING LATER THIS EVENING.
AS SKIES CLEAR, LIGHT/VARIABLE WINDS WILL SUPPORT THE DEVELOPMENT
OF PATCHY BUT LOCALLY DENSE FOG (PARTICULARLY IN LOCATIONS THAT
RECEIVE WETTING RAINFALL TODAY) AS TEMPS FALL INTO THE U60S-L70S.
PREVIOUS DISCUSSION:
AN AREA OF LOW PRESSURE AT THE SURFACE WILL TRAVEL WESTWARD
ACROSS SOUTHERN PORTIONS OF GA/AL/MS TODAY AND TONIGHT, AS THE
PARENT CUTOFF UPPER CYCLONE DRIFTS NORTHWARD ACROSS GA AND
GRADUALLY WEAKENS. AS THIS OCCURS, A WELL-DEFINED SURFACE
TROUGH/STREAMLINE CONFLUENCE AXIS (EXTENDING NORTHWARD OFF THE
LOW) WILL ENTER NORTHEASTERN AL LATER THIS MORNING, BEFORE
PROGRESSING VERY SLOWLY WESTWARD FOR THE REMAINDER OF THE DAY AND
NIGHT. IN THE PRESENCE OF AN OTHERWISE UNFAVORABLE ENVIRONMENT FOR
LIFT ALOFT, LOW-LEVEL CONVERGENCE IN THE VICINITY OF THE TROUGH
(AND IN THE PRESENCE OF A MOIST BOUNDARY LAYER WARMING INTO THE
M-U 80S), COMBINED WITH MLCAPE OF 1000-2000 J/KG WILL BE
SUFFICIENT FOR THE DEVELOPMENT OF BOTH SHOWERS AND THUNDERSTORMS,
INITIALLY BEGINNING IN THE EAST BETWEEN 15-17Z. WITH DEEP-LAYER
NNE FLOW OF 10-20 KNOTS EXPECTED TO PERSIST IN THE CIRCULATION
AROUND THE CUTOFF LOW, CONVECTIVE CELLS WILL BE MOVING SOUTH-
SOUTHWESTWARD AT A DECENT PACE AND THIS SHOULD LIMIT THE OVERALL
RISK FOR FLASH FLOODING. HOWEVER, LIGHTNING AND HEAVY RAINFALL CAN
BE EXPECTED, ALONG WITH BRIEF STRONG WIND GUSTS UP TO 40 MPH.
IN SIMILAR FASHION TO YESTERDAY EVENING, ISOLATED SHOWERS AND
THUNDERSTORMS ARE EXPECTED TO CONTINUE FOR A SHORT PERIOD AFTER 0Z
(ESPECIALLY IN THE VICINITY OF THE SURFACE TROUGH), BUT SHOULD
DISSIPATE BETWEEN 2-4Z. AS SKIES CLEAR LATE THIS EVENING,
CONDITIONS WILL ONCE AGAIN BECOME FAVORABLE FOR THE DEVELOPMENT OF
PATCHY FOG (SOME OF WHICH COULD BE LOCALLY DENSE IN LOCATIONS
THAT EXPERIENCE WETTING RAINFALL LATER TODAY). OVERNIGHT LOWS WILL
BE SIMILAR TO THOSE OBSERVED THE PAST COUPLE OF NIGHTS
(U60S-L70S).
SHORT TERM
(WEDNESDAY THROUGH THURSDAY NIGHT)
ISSUED AT 1056 AM CDT TUE AUG 4 2026
OVER THE COURSE OF THE SHORT TERM PERIOD, A CUTOFF UPPER LOW
(INITIALLY SITUATED TO THE IMMEDIATE EAST OF THE CWFA) WILL OPEN
INTO A HIGHLY SHEARED TROUGH AS THE NORTHERN PORTION OF THE WAVE
BECOMES ABSORBED IN THE POLAR WESTERLIES WHILE THE SOUTHERN
PORTION LINGERS ACROSS THE CENTRAL/SOUTHERN APPALACHIANS. IN THE
LOW-LEVELS, AN INCREASINGLY DIFFUSE SURFACE TROUGH/WIND SHIFT AXIS
WILL EXIST ACROSS THE CENTRAL OR WESTERN PORTION OF THE FORECAST
AREA ON WEDNESDAY, AND SHOULD ONCE AGAIN INITIATE DEVELOPMENT OF
DEEP/MOIST CONVECTION BY LATE MORNING (WITH ADDITIONAL SHOWERS AND
THUNDERSTORMS FOCUSED ALONG CONVECTIVE OUTFLOW BOUNDARIES AND IN
PREFERRED REGIONS OF OROGRAPHIC ASCENT ACROSS NORTHEAST
AL/SOUTHERN MIDDLE TN LATER IN THE AFTERNOON). SHEAR WILL REMAIN
VERY WEAK TOMORROW, AND WITH SIMILAR VALUES OF MLCAPE (1000-2000
J/KG) AND PWAT (1.8-2"), WE EXPECT LIGHTNING, LOCALLY HEAVY
RAINFALL AND BRIEF STRONG WINDS TO BE THE GREATEST IMPACTS.
HOWEVER, DUE TO THE DECAYING NATURE OF THE CUTOFF LOW, STEERING
FLOW WILL BACK TO THE NW AND DIMINISH, RESULTING IN SLOWER CELL
MOTIONS TO THE SOUTHEAST. PRESENT INDICATIONS ARE THAT THIS
ACTIVITY WILL DISSIPATE BY 2-4Z, WITH PATCHY FOG EXPECTED DURING
THE EARLY MORNING HOURS THURSDAY AS TEMPS FALL INTO THE U60S-L70S.
DURING THE TIMEFRAME FROM THURSDAY-THURSDAY NIGHT, ENVIRONMENTAL
CONDITIONS WILL BECOME LESS CONDUCIVE FOR CONVECTION AS A MID-
LEVEL RIDGE BUILDS ACROSS MUCH OF THE GULF COAST AND A BERMUDA
HIGH EXPANDS SOUTHWESTWARD IN THE LOW-LEVELS (RESULTING IN A LIGHT
PREVAILING FLOW FROM THE SSE). NEVERTHELESS, AT LEAST WIDELY
SCATTERED AFTERNOON THUNDERSTORMS ARE EXPECTED IN OUR REGION ON
THURSDAY (PERHAPS MOST CONCENTRATED IN THE ELEVATED TERRAIN OF THE
EAST), BUT OVERALL COVERAGE SHOULD BE LOWER (ESPECIALLY AS
SLIGHTLY DRIER AIR MAY SPILL SOUTHWESTWARD FROM THE APPALACHIANS).
DUE TO A LOWER COVERAGE OF AFTERNOON CLOUDS/PRECIPITATION, HIGHS
WILL RETURN TO THE U80S-L90S, WITH OVERNIGHT LOWS RISING INTO THE
L-M 70S FRIDAY MORNING.
LONG TERM
(FRIDAY THROUGH MONDAY)
ISSUED AT 930 PM CDT MON AUG 3 2026
ON FRIDAY, THE RIDGE TO OUR WEST WILL EXPAND AND PROVIDE AN
INCREASE IN HEAT CONCERNS THAT WILL PERSIST THROUGH THE WEEKEND.
OTHERWISE, THERE'S A LOW TO MEDIUM CHANCES (20-40%) FOR DIURNAL
SHOWERS AND THUNDERSTORMS WITH THE GREATEST COVERAGE EAST OF I-65.
THIS WEEKEND, MOISTURE WILL WRAP AROUND THE WESTERN SIDE OF THE
SUBTROPICAL RIDGE OUT IN THE ATLANTIC AND BRING AN INCREASE IN
RAINFALL, LOW TO MEDIUM (30-60%) CHANCES SATURDAY THROUGH MONDAY.
HIGHEST COVERAGE WILL AGAIN BE EAST OF I-65. HIGHS WILL BE IN THE
UPPER 80S TO LOWER 90S FRIDAY THROUGH MONDAY BUT HEAT INDEX VALUES
WILL PUSH ABOVE 100 DEGREES. AT THIS TIME, VALUES REMAIN JUST
BELOW HEAT ADVISORY CRITERIA HOWEVER TRENDS WILL BE MONITORED.
REGARDLESS, PRACTICE HEAT SAFETY!
AVIATION
(18Z TAFS)
ISSUED AT 1251 PM CDT TUE AUG 4 2026
VFR CONDITIONS CURRENTLY EXIST AT THE HSV/MSL TERMINALS,
FEATURING SCT-BKN CU CON BENEATH A BKN LAYER OF AC. OVER THE
COURSE OF THE AFTN, A SUBTLE SFC TROUGH/WIND SHIFT AXIS WILL SHIFT
SLOWLY WESTWARD ACROSS EASTERN/CENTRAL PORTIONS OF NORTH AL,
FOCUSING THE DEVELOPMENT OF SHRA/TSRA. AT THIS POINT,
PROBABILITIES FOR DIRECT IMPACTS AT BOTH TERMINALS APPEAR LOW (BUT
COMPARATIVELY HIGHER AT HSV) AND FOR THIS REASON WE HAVE INCLUDED
A PROB30 GROUP IN TAFHSV FROM 18-23Z (HIGHLIGHTING THE TIMEFRAME
WHEN AWWS FOR LIGHTNING MAY BE REQUIRED). LINGERING EVENING
CONVECTION SHOULD DISSIPATE BY 2-4Z, WITH CLEARING SKIES AND
LGT/VRBL FLOW EXPECTED TO SUPPORT DEVELOPMENT OF PATCHY BR/FG.
HOWEVER, DUE TO UNCERTAINTIES IN RAINFALL COVERAGE INVOF THE
TERMINALS, WE WILL NOT INCLUDE MVFR VSBY REDUCTIONS ATTM. A SCT-
BKN CU FIELD WILL REDEVELOP BY THE END OF THE PERIOD, AND ALTHOUGH
SHRA/TSRA MAY EVOLVE ONCE AGAIN PRIOR TO 18Z, CONFIDENCE IN
COVERAGE IS NOT HIGH ENOUGH TO INCLUDE AT THIS POINT.
HUN WATCHES/WARNINGS/ADVISORIES
AL...NONE.
TN...NONE.
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...JMS
AVIATION...70/DD
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