043
FXUS64 KHUN 051054
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
554 AM CDT SAT SEP 5 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 937 PM CDT FRI SEP 4 2026
- A HEAT ADVISORY REMAINS IN EFFECT THROUGH 8 PM SUNDAY DUE TO
MAJOR TO EXTREME HEATRISK, ALONG WITH AFTERNOON HEAT INDICES
RISING UP TO 105-109 DEGREES IN PORTIONS OF THE FORECAST AREA.
- A LOW CHANCE (30% OR LESS) OF THUNDERSTORMS ARE FORECAST
SATURDAY AFTERNOON INTO THE LATE EVENING, WITH A LOW CHANCE OF
SOME BECOMING SEVERE. DAMAGING WINDS WILL BE THE PRIMARY THREAT
IS ANY STRONG TO SEVERE STORMS.
NEAR TERM
(TODAY)
ISSUED AT 301 AM CDT SAT SEP 5 2026
CALM WINDS AND LOW DEW POINT DEPRESSIONS EARLY THIS MORNING HAS
LED TO PATCHY FOG DEVELOPMENT, PARTICULARLY IN SHELTERED VALLEYS.
AFTER DISSIPATING SHORTLY AFTER SUNRISE, DIURNAL CUMULUS FIELDS
WILL FORM IN THE LATE MORNING. EXTRA SYNOPTIC FORCING FOR ASCENT
WILL BE PRESENT DUE TO A STRONG CUT OFF LOW PRESSURE SYSTEM OVER
NEW ENGLAND PROPELLING A SHORTWAVE TROUGH ACROSS THE EASTERN
CONUS. AS A RESULT, THE UPPER LEVEL RIDGE AXIS WILL SLIDE
WESTWARD. THIS WILL NOT BE SUFFICIENT FOR A REPRIEVE FROM THE
HEAT, AND TEMPERATURES IN THE UPPER 90S, POTENTIALLY TOUCHING 100,
ARE EXPECTED THIS AFTERNOON BEFORE CONVECTION INITIATION.
THERMODYNAMIC SUPPORT WILL BE PRESENT FOR STRONG TO SEVERE STORMS,
WHICH HAVE A 20-30% CHANCE OF FORMING OVER ANY GIVEN LOCATION THIS
AFTERNOON DUE TO THE AFOREMENTIONED SHORTWAVE. LOW LEVEL LAPSE
RATES APPROACHING 10 C/KM AND SBCAPE VALUES OF 2500-3000 J/KG WILL
SUPPORT RAPIDLY GROWING UPDRAFTS. COUPLED WITH WEAK STEERING FLOW
AND PWATS OF 1.8", STRONG DOWNBURSTS WITH DAMAGING WINDS OF 60-70
MPH REPRESENT A REASONABLE WORST CASE SCENARIO THIS AFTERNOON.
HEAVY RAINFALL MAY ALSO LEAD TO BRIEF, LOCALIZED FLOODING THAT
SHOULD RAPIDLY DRAIN AS THE STORMS DISSIPATE. CONVECTIVE COVERAGE
WILL INCREASE AROUND 2 PM BUT SHOULD WANE AFTER SUNSET, UNLESS
OUTFLOW BOUNDARY INTERACTIONS LEAD TO AN ISOLATED STORM AS LATE AS
10 PM.
SHORT TERM
(SATURDAY NIGHT THROUGH MONDAY)
ISSUED AT 937 PM CDT FRI SEP 4 2026
THUNDERSTORMS SHOULD GRADUALLY COME TO AN END BY THE LATE EVENING
HOURS SATURDAY WITH THE LOSS OF DIURNAL SUPPORT. HOWEVER, SUB-
SEVERE THUNDERSTORMS WILL LIKELY REMAIN IN THE AREA THROUGH THE
EARLY MORNING HOURS- BRINGING ADDITIONAL HEAVY RAINFALL AS WELL AS
LIGHTNING WITH A LOW CHANCE OF GUSTY WINDS. WHILE OUR HEAT
ADVISORY WAS SLATED TO END SATURDAY NIGHT, IT HAS NOW BEEN
EXTENDED TO SUNDAY NIGHT AS THE TENNESSEE VALLEY REMAINS UNDER THE
INFLUENCE OF AN UPPER LEVEL RIDGE AND SUBSEQUENT ABOVE NORMAL
TEMPERATURES. HIGH TEMPERATURES ON SUNDAY ARE FORECAST TO REACH
THE UPPER 90S WITH HEAT INDICES UP TO 109 DEGREES. A COLD FRONT
SHOULD PUSH THROUGH THE AREA SUNDAY AFTERNOON, BRINGING SLIGHT RELIEF
FROM THE HEAT BY SUNDAY NIGHT AS LOW TEMPERATURES DROP INTO THE
UPPER 60S TO LOWER 70S (AS OPPOSED TO MID 70S THE PAST SEVERAL
NIGHTS). HIGHS ON MONDAY ARE STILL FORECAST TO REACH THE 90S,
HOWEVER, HEAT INDICES SHOULD BE CAPPED NEAR 100 DEGREES AS A
RELATIVELY DRIER AIRMASS SHIFTS SOUTHWARD INTO THE AREA. LOW
CHANCES (30% OR LESS) OF THUNDERSTORMS REMAIN IN RESPONSE TO
DIURNAL HEATING MONDAY AFTERNOON.
LONG TERM
(MONDAY NIGHT THROUGH FRIDAY)
ISSUED AT 937 PM CDT FRI SEP 4 2026
HEAT WILL PERSIST THROUGH THE LONG TERM AS WELL. THE VAST RIDGE OF
HIGH PRESSURE THAT IS CENTERED OVER THE SOUTHERN PLAINS AND MID MS
VALLEY WILL EXPAND EASTWARD TO ENCOMPASS THE REST OF THE SOUTHEAST
EARLY THIS WEEK. MID WEEK, A TROUGH WILL SWING THROUGH THE SOUTHERN
CANADIAN PRAIRIE PROVINCES DAMPENING THE RIDGE, AND SFC HIGH
PRESSURE WILL SET UP ALONG THE APPALACHIANS. THIS SET UP COULD CREATE
A CAD EXPANDING INTO NE AL AND PORTIONS OF SOUTHERN MIDDLE TN. IF
THIS COMES TO FRUITION, ADJUSTMENTS TO POPS (SLIGHT INCREASE) AND
TEMPS (SLIGHT DECREASE) WOULD BE NEEDED. REGARDLESS, IT LOOKS LIKE
TEMPS WILL REMAIN IN THE 90S THROUGHOUT THE WEEK, WHICH IS PAR FOR
THE COURSE THIS MONTH, BUT RUNNING A TAD HIGHER THAN SEASONAL NORMS
WHICH IS 87-88 DEGREES. HEAT INDEX VALUES WILL HOVER AROUND 100
DEGREES AND THE NWS HEAT RISK WILL BE A LEVEL 2 (MODERATE LEVEL) FOR
THE LARGE MAJORITY OF US. REMAIN HEAT SMART:
SLOW DOWN, COOL DOWN, STAY HYDRATED AND NEVER LEAVE PEOPLE OR PETS
IN VEHICLES.
AVIATION
(12Z TAFS)
ISSUED AT 554 AM CDT SAT SEP 5 2026
PATCHY FOG WILL DISSIPATE SHORTLY AFTER SUNRISE, AFTER WHICH CU
SHOULD DEVELOP LATE THIS MORNING. DESPITE LOW STORM COVERAGE, ANY
STORMS THAT DO FORM WILL BE CAPABLE OF STRONGER WINDS AND
DOWNBURSTS, SO TODAY WILL BE A DAY TO MONITOR FOR AWWS THROUGH THE
EVENING. WINDS BECOME CALM AGAIN OVERNIGHT WITH PATCHY FOG OVER
ANY AREAS THAT DO RECEIVE RAIN.
HUN WATCHES/WARNINGS/ADVISORIES
AL...HEAT ADVISORY UNTIL 8 PM CDT SUNDAY FOR ALZ001>010-016.
TN...HEAT ADVISORY UNTIL 8 PM CDT SUNDAY FOR TNZ076-096-097.
NEAR TERM...30
SHORT TERM....HC
LONG TERM....JMS
AVIATION...30
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