861
FXUS64 KHUN 021900
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
200 PM CDT WED SEP 2 2026
..NEW NEAR TERM
KEY MESSAGES
UPDATED AT 1110 AM CDT WED SEP 2 2026
- A HEAT ADVISORY REMAINS IN EFFECT THROUGH 8 PM SATURDAY DUE TO
MAJOR TO EXTREME HEATRISK, ALONG WITH AFTERNOON HEAT INDICES
RISING UP TO 105-109 DEGREES IN PORTIONS OF THE FORECAST AREA.
NEAR TERM
(REST OF TODAY AND TONIGHT)
ISSUED AT 200 PM CDT WED SEP 2 2026
THERE HAVE BEEN NO SIGNIFICANT CHANGES TO NEAR TERM FORECAST
REASONING SINCE THE UPDATE EARLIER THIS MORNING, WITH CURRENT
TEMPERATURES SUGGESTING THAT HIGHS ARE ON TRACK TO REACH THE
94-98F RANGE FOR MOST VALLEY LOCATIONS. ALTHOUGH MIXING HAS LIKELY
CONTRIBUTED TO DEWPOINTS FALLING INTO THE M-U 60S ACROSS OUR
WESTERN FORECAST ZONES, MOST LOCATIONS WILL AT LEAST BRIEFLY
EXPERIENCE HI IN THE 100-105F RANGE (IF NOT A COUPLE OF DEGREES
WARMER) AND A HEAT ADVISORY REMAINS IN EFFECT. FINALLY, LATEST
HIGH-RESOLUTION MODEL DATA STILL SUGGESTS THAT A FEW SHOWERS AND
THUNDERSTORMS MAY DEVELOP LATER THIS AFTERNOON IN THE HIGHER
TERRAIN OF NORTHEAST AL/SOUTHERN MIDDLE TN, BUT THIS ACTIVITY
SHOULD DISSIPATE QUICKLY BETWEEN 0-2Z. MOSTLY CLEAR SKIES AND DRY
CONDITIONS ARE ANTICIPATED OVERNIGHT, AS TEMPS FALL INTO THE L-M
70S.
PREVIOUS DISCUSSION:
A STRONG MID-LEVEL HIGH WILL REMAIN CENTERED ACROSS EASTERN
TN/WESTERN NC FOR THE DURATION OF THE NEAR TERM PERIOD,
MAINTAINING SE FLOW ALOFT OF 5-15 KNOTS BETWEEN THE ANTICYCLONE
AND A BROAD TROUGH ACROSS THE EASTERN GULF. IN THE LOW-LEVELS, OUR
REGION WILL REMAIN UNDER THE INFLUENCE OF SURFACE HIGH PRESSURE
ACROSS THE SOUTHERN APPALACHIANS, WHICH WILL RESULT IN A LIGHT SE
WIND ACROSS WESTERN PORTIONS OF THE CWFA AND LIGHT/VARIABLE-CALM
FLOW ELSEWHERE.
ALTHOUGH THE RESULTANT DEEP-LAYER SE FLOW REGIME WILL SUSTAIN A
MOIST AND UNSTABLE AIRMASS (FEATURING PWAT VALUES IN THE 1.7-1.9"
RANGE AND CAPE OF 1750-2250 J/KG), WITH NO CLEAR EVIDENCE OF A
LIFTING MECHANISM WE EXPECT DRY CONDITIONS TO PREVAIL FOR MOST OF
THE REGION. THAT SAID, GENTLE OROGRAPHIC ASCENT IN THE MORE RUGGED
TERRAIN OF NORTHEAST AL/SOUTHERN MIDDLE TN MAY INITIATE THE
DEVELOPMENT OF A FEW SHOWERS AND THUNDERSTORMS THIS AFTERNOON, BUT
POPS EVEN IN THIS REGION REMAIN AROUND 10%. WITH ONLY A
SCATTERED, HIGH-BASED CUMULUS FIELD ANTICIPATED TODAY, CURRENT
TEMPERATURES APPEAR ON TRACK TO RANGE FROM 90-94F IN ELEVATED
TERRAIN TO 94-98F IN THE VALLEY (WITH URBAN HEAT ISLANDS PERHAPS
REACHING 98-100F). ALTHOUGH EFFICIENT BOUNDARY LAYER MIXING MAY
FORCE DEWPOINTS INTO THE MID 60S FOR MUCH OF THE REGION, WE WILL
MAKE NO CHANGES TO THE CURRENT HEAT ADVISORY TO HIGHLIGHT HEAT
INDEX IN THE 102-106F RANGE (PERHAPS 106-110F IN URBAN LOCATIONS).
ANY AFTERNOON CONVECTION THAT MANAGES TO DEVELOP LATER TODAY WILL
DISSIPATE QUICKLY BETWEEN 0-2Z, WITH MOSTLY CLEAR SKIES AND DRY
CONDITIONS EXPECTED OVERNIGHT. LOWS WILL BE IN THE 72-76F RANGE,
WITH CALM WINDS SUPPORTING DEVELOPMENT OF PATCHY, EARLY-MORNING
FOG (PARTICULARLY IN THE VALLEYS OF NORTHEAST AL).
SHORT TERM
(THURSDAY THROUGH FRIDAY NIGHT)
ISSUED AT 1110 AM CDT WED SEP 2 2026
LATEST SHORT RANGE MODEL GUIDANCE SUGGESTS THAT A MID-LEVEL HIGH
WILL REMAIN CENTERED TO THE IMMEDIATE NORTHEAST OF THE TN VALLEY
ON THURSDAY/THURSDAY NIGHT, AS A BROAD TROUGH TO OUR SOUTH BEGINS
TO RETROGRADE SLOWLY WESTWARD INTO THE CENTRAL/WESTERN GULF. AS A
LOWER-AMPLITUDE EASTERLY WAVE TRACKS WESTWARD ACROSS THE NORTHERN
FL PENINSULA AND INTO THE NORTHEASTERN GULF (IN THE FLOW BETWEEN
THE HIGH TO ITS NORTHEAST AND TROUGH TO ITS SOUTHWEST), A RELATED
SURFACE TROUGH WILL LIKELY FOCUS A GREATER COVERAGE OF SHOWERS AND
THUNDERSTORMS ACROSS NORTH FL AND ADJACENT PORTIONS OF THE
NORTHEAST GULF COAST TOMORROW, WITH SOME INDICATION THAT A SUBTLE
LOW-LEVEL CONFLUENCE AXIS MAY RESULT IN A SLIGHT INCREASE IN THE
COVERAGE OF AFTERNOON SHOWERS AND THUNDERSTORMS ACROSS OUR REGION,
AS WELL. DUE TO SOME LOOSE AGREEMENT IN THE LOCATION OF THIS
FEATURE IN VARIOUS MEMBERS OF THE HREF, WE HAVE INCREASED POPS
INTO THE 10-20% RANGE FOR MUCH OF NORTHWEST AL/SOUTHERN MIDDLE TN.
REGARDLESS OF STORM COVERAGE, DCAPE IN THE 1200-1400 J/KG RANGE
COUPLED WITH STEEP LOW-LEVEL LAPSE RATES SUGGEST THAT LOCALLY
DAMAGING DOWNBURST WINDS COULD OCCUR WITH THE STRONGEST CELLS. FOR
LOCATIONS THAT DO NOT EXPERIENCE A COOLING SHOWER OR
THUNDERSTORM, IT WILL BE ANOTHER HOT/HUMID DAY FEATURING HIGHS IN
THE M-U 90S AND SIMILAR HEAT INDEX VALUES (COMPARED TO TODAY).
DURING THE PERIOD FROM FRIDAY-FRIDAY NIGHT, THE MID-LEVEL HIGH TO
OUR NORTHEAST IS PREDICTED TO WEAKEN CONSIDERABLY AS RIDGING
ALOFT BECOMES ESTABLISHED ACROSS THE SOUTHERN GREAT PLAINS. DUE TO
THE MORE FAVORABLE ENVIRONMENT FOR UPDRAFT GROWTH IN THIS
SCENARIO, A SIMILAR COVERAGE OF AFTERNOON SHOWERS AND
THUNDERSTORMS MAY OCCUR ON FRIDAY (ESPECIALLY AS PWAT VALUES COULD
INCREASE TO AROUND 2" BY THIS POINT). HOWEVER, POPS WILL BE LEFT
IN THE 10-20% RANGE UNTIL DETAILS REGARDING A FORCING MECHANISM
BECOME MORE CLEAR. HIGH TEMPERATURES WILL ONCE AGAIN REACH THE M-U
90S (WITH SIMILAR HEAT INDEX VALUES) AND HEAT ADVISORY WILL
REMAIN IN EFFECT THROUGH THE PERIOD.
LONG TERM
(SATURDAY THROUGH TUESDAY)
ISSUED AT 813 PM CDT TUE SEP 1 2026
THE UPPER LEVEL RIDGE OVER MUCH OF THE CENTRAL AND SOUTHEASTERN
US WILL PERSIST INTO THIS WEEKEND; HOWEVER, IT LOOKS LIKE AN UPPER
TROUGH TRIES TO DIG SOUTH OVER THE NORTHEAST, POTENTIALLY
BREAKING DOWN THE RIDGE OVER THE APPALACHIANS, OHIO VALLEY, AND
TENNESSEE VALLEY SOMEWHAT DURING THIS TIME. THIS MAY BE SHORT-
LIVED, SINCE SYNOPTIC GUIDANCE SUGGESTS THAT THE RIDGE WILL BUILD
BACK OVER THE SOUTHEAST THROUGH EARLY NEXT WEEK. AT THE SURFACE,
HIGH PRESSURE OVER THE APPALACHIANS MAY BE OVERTAKEN BY A BACKDOOR
COLD FRONT SLATED TO MOVE INTO THE REGION FROM THE NORTHEAST BY
SUNDAY. SOME GUIDANCE HINTS THAT THIS FEATURE MAY BRING ENOUGH
MOISTURE AND LIFT WITH IT TO PRODUCE AT LEAST A LOW CHANCE OF
SHOWERS AND STORMS THIS WEEKEND, BUT THESE TRENDS WILL BE
MONITORED. BY EARLY NEXT WEEK, SURFACE HIGH PRESSURE BUILDS BACK
OVER THE APPALACHIANS AS THE UPPER RIDGE TAKES HOLD OVER THE
REGION ONCE AGAIN.
OVERALL, THE HOT AND HUMID CONDITIONS ARE EXPECTED TO CONTINUE
THROUGH THE LONG TERM PERIOD. EXPECT HIGHS IN THE MID TO UPPER 90S
THROUGH THE WEEKEND WITH NOT MUCH RELIEF AT NIGHT AS LOWS MERELY
DIP INTO THE UPPER 60S TO LOWER 70S. THESE TEMPERATURES, ALONG
WITH DEW POINTS IN THE LOWER TO MID 70S, WILL RESULT IN HEAT
INDICES IN THE 100-106 DEGREE RANGE ALONG WITH WBGTS IN THE MID TO
UPPER 80S (SOME SPOTS AROUND 90 DEGREES) AND MODERATE TO MAJOR
HEATRISK (LEVELS 2 AND 3 OF 4) FOR MOST OF NORTH ALABAMA AND
SOUTHERN MIDDLE TENNESSEE. BY EARLY NEXT WEEK, THE AFOREMENTIONED
BACKDOOR FRONT MAY TEMPER THE HEAT AND HUMIDITY SLIGHTLY. HIGHS IN
THE LOWER TO MID 90S WITH DEW POINTS IN THE UPPER 60S TO LOWER
70S ARE ANTICIPATED, KEEPING THE HEATRISK IN THE MODERATE RISK
CATEGORY, HEAT INDICES GENERALLY BETWEEN 98-103 DEGREES, AND WBGTS
SOLIDLY IN THE 83-87 DEGREE RANGE. ULTIMATELY, THE CURRENT HEAT
ADVISORY RUNS THROUGH SATURDAY EVENING; HOWEVER, WE WILL BE
MONITORING IF A FURTHER EXTENSION INTO SUNDAY BECOMES NECESSARY.
REMEMBER TO PRACTICE HEAT SAFETY, ESPECIALLY IF YOU WORK OUTSIDE
OR HAVE OUTDOOR ACTIVITIES! STAY HYDRATED, TAKE PLENTY OF BREAKS
IN THE SHADE, AND NEVER LEAVE PEOPLE OR PETS IN VEHICLES!
AVIATION
(18Z TAFS)
ISSUED AT 1245 PM CDT WED SEP 2 2026
VFR CONDITIONS WILL CONTINUE AT THE HSV/MSL TERMINALS THIS
FORECAST PERIOD, FEATURING FEW-SCT HIGH-BASED CU DURING THE
DIURNAL WARMING CYCLE AND MOSTLY CLEAR SKIES OVERNIGHT. ALTHOUGH
ISOLATED SHRA/TSRA MAY DEVELOP THIS AFTN IN THE HIGHER TERRAIN TO
THE N/E OF HSV, ANTICIPATED COVERAGE IS FAR TOO LOW TO INCLUDE IN
THE FORECAST. WITH LGT SE FLOW EXPECTED TO BECOME CALM OVERNIGHT,
PATCHY BR/FG MAY FORM DURING THE PREDAWN HOURS IN VALLEYS AND NEAR
LARGE BODIES OF WATER, BUT VSBY REDUCTIONS ARE NOT EXPECTED TO
IMPACT EITHER TERMINAL AT THIS POINT.
HUN WATCHES/WARNINGS/ADVISORIES
AL...HEAT ADVISORY UNTIL 8 PM CDT SATURDAY FOR ALZ001>010-016.
TN...HEAT ADVISORY UNTIL 8 PM CDT SATURDAY FOR TNZ076-096-097.
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...26
AVIATION...70/DD
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