706
FXUS64 KHUN 270409
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1109 PM CDT SUN JUL 26 2026
..NEW NEAR TERM, SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 1109 PM CDT SUN JUL 26 2026
- A HEAT ADVISORY REMAINS IN EFFECT FOR AREAS ALONG AND WEST OF
I-65 THROUGH 7 PM TUESDAY.
- CLUSTERS OF THUNDERSTORMS WILL SHIFT SOUTHWARD DURING THE EARLY
MORNING HOURS MONDAY, WITH POTENTIAL REDEVELOPMENT OF STORMS IN
THE SOUTHWEST DURING THE AFTERNOON. LOCALLY DAMAGING WINDS,
FREQUENT LIGHTNING AND HEAVY RAINFALL WILL ACCOMPANY THIS
ACTIVITY.
- A COLD FRONT WILL BRING ADDITIONAL THUNDERSTORMS TO THE REGION
TUESDAY AFTERNOON/EVENING, WITH COVERAGE HIGHEST IN THE EAST. A
A FEW STRONG-SEVERE STORMS MAY OCCUR DURING THIS TIMEFRAME.
- A DRIER AIRMASS WILL ENCOMPASS THE REGION FROM WEDNESDAY-
FRIDAY, BUT CHANCES FOR SHOWERS AND SOME THUNDERSTORMS WILL
INCREASE ONCE AGAIN THIS WEEKEND.
NEAR TERM
(THIS EVENING THROUGH MONDAY)
ISSUED AT 1109 PM CDT SUN JUL 26 2026
THE PRIMARY FEATURE OF INTEREST THIS EVENING IS A LARGE MCS THAT
IS CURRENTLY PROPAGATING SOUTHWARD ACROSS WESTERN/MIDDLE TN.
ALTHOUGH THUNDERSTORMS ORIGINALLY INITIATED ALONG THE NORTHERN
PORTION OF A SYNOPTIC SCALE STREAMLINE CONFLUENCE AXIS (EXTENDING
FROM THE LOWER-OH VALLEY INTO NORTHERN GA), THE BROADER COMPLEX
HAS NOW TURNED SOUTHWARD AND SHOULD CONTINUE TO TRAVEL ALONG THE
EASTERN EDGE OF AN INSTABILITY AXIS. GIVEN THE COMBINATION OF COLD
POOL-INDUCED ACCELERATION AND NNW FLOW ALOFT OF 15-25 KNOTS, THE
SYSTEM IS EXPECTED TO ENTER THE NORTHERN ZONES OF OUR CWFA AROUND
4Z AND SHOULD SPREAD QUICKLY ACROSS THE REGION (EXITING BY 6-7Z).
FORTUNATELY, RADAR DATA SUGGESTS THAT STORMS WILL CONTINUE TO
WEAKEN AS LOW-LEVEL LAPSE RATES WILL BECOME LESS FAVORABLE WITH
TIME. HOWEVER, WITH MUCAPE REMAINING IN THE 2000-2500 J/KG RANGE,
INSTANCES OF BRIEF WIND GUSTS UP TO 40-50 KNOTS CAN STILL BE
EXPECTED, ALONG WITH FREQUENT LIGHTNING AND HEAVY RAINFALL.
ADDITIONAL THUNDERSTORMS HAVE RECENTLY REDEVELOPED IN THE VICINITY
OF A TRAILING OUTFLOW BOUNDARY FROM THE INITIAL MCS ACROSS
SOUTHERN IL/IN, AND THIS ACTIVITY MAY ALSO SPREAD SOUTHWARD INTO
THE TN VALLEY (ARRIVING CLOSER TO 12Z MONDAY). HOWEVER, THIS
ACTIVITY (SHOULD IT CONTINUE TO TRACK SOUTHWARD) WILL ENCOUNTER A
PRE-ESXITING COLD POOL, AND SHOULD ALSO BE SUB-SEVERE UPON
ENTERING OUR FORECAST AREA.
PRESENT INDICATIONS ARE THAT LINGERING NOCTURNAL THUNDERSTORMS
WILL LIKELY END IN OUR REGION BY 13-15Z, WITH THICK LAYERS OF
CONVECTIVE DEBRIS CLOUDS EXPECTED TO GRADUALLY DISSIPATE OVER THE
COURSE OF THE MORNING. EVEN WITH LIMITED AIRMASS RECOVERY THROUGH
EARLY AFTERNOON, STRONG BOUNDARY LAYER WARMING AFTER 16-18Z WILL
ALLOW TEMPERATURES TO QUICKLY RISE BACK INTO THE U80S-L90S.
FURTHERMORE, LIGHT SOUTHWESTERLY FLOW WILL RESUME DURING THE
AFTERNOON HOURS AS A PROMINENT NORTHERN STREAM SHORTWAVE TROUGH
AND DEEPENING SURFACE LOW SHIFT INTO THE WESTERN GREAT LAKES, AND
THIS WILL MAINTAIN DEWPOINTS IN THE U70S-L80S. THUS, WE FEEL
CONFIDENT THAT HEAT ADVISORY CRITERIA WILL BE ACHIEVED ONCE AGAIN
TOMORROW. REGARDING THE POTENTIAL FOR REDEVELOPMENT OF
THUNDERSTORMS DURING THE AFTERNOON, THERE ARE INDICATIONS THAT
THIS COULD OCCUR IN THE VICINITY OF A MESOSCALE BOUNDARY LEFT
BEHIND FROM THE MORNING MCS. CURRENT THINKING IS THAT THIS FEATURE
WILL BE POSITIONED FROM NORTHEASTERN MS/NORTHWESTERN AL INTO
CENTRAL AL, WITH STORMS EXPECTED TO SPREAD SOUTH-SOUTHWESTWARD AND
AWAY FROM THE REGION DURING THE EVENING. REGARDLESS, CAPE WILL BE
SUFFICIENTLY HIGH (3000-3500 J/KG) ACROSS THIS PORTION OF THE
FORECAST AREA TO SUPPORT A RISK FOR LOCALLY DAMAGING WINDS WITH
THE STRONGER CELLS.
SHORT TERM
(MONDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 1109 PM CDT SUN JUL 26 2026
OVER THE COURSE OF THE SHORT TERM PERIOD, AN INTENSIFYING MID-
LEVEL SHORTWAVE TROUGH IN THE NORTHERN STREAM IS PREDICTED TO
TRAVEL ACROSS THE EASTERN GREAT LAKES BEFORE EVOLVING INTO A
CLOSED LOW OVER THE NORTHERN MID-ATLANTIC STATES THAT WILL DRIFT
SLOWLY EAST-SOUTHEASTWARD THROUGH WEDNESDAY. IN THE LOW-LEVELS, A
SURFACE LOW RELATED TO THE SHORTWAVE TROUGH IS EXPECTED TO
GRADUALLY DEEPEN ACROSS NY/PA, WITH A COLD FRONT ATTACHED TO THE
LOW EXPECTED TO MAKE STEADY SOUTHEASTWARD PROGRESS ON MONDAY NIGHT
AND TUESDAY. SOUTHWESTERLY FLOW IN THE LOW-LEVELS WILL BEGIN TO
STRENGTHEN ON MONDAY NIGHT, AND ALTHOUGH LATEST GUIDANCE FROM THE
CAMS INDICATES THAT ANOTHER MCS WILL TRACK SOUTH-SOUTHEASTWARD
FROM THE LOWER GREAT LAKES INTO EASTERN KY/TN, AT THIS POINT IT
APPEARS AS IF THIS SYSTEM WILL BYPASS OUR FORECAST AREA TO THE
NORTHEAST.
HOWEVER, CHANCES FOR THUNDERSTORMS SHOULD BEGIN TO INCREASE IN
OUR CWFA BY MID/LATE TUESDAY AFTERNOON (AND CONTINUE THROUGH THE
EVENING HOURS) AS A PREFRONTAL TROUGH/WIND SHIFT AXIS BEGINS TO
ENTER THE REGION FROM THE NORTH. ALTHOUGH THE COVERAGE OF
CONVECTION SHOULD BE HIGHER TO OUR NORTH/EAST (WHERE DEEP-LAYER
ASCENT WILL BE AUGMENTED BY THE SHORTWAVE TROUGH), IT SEEMS
REASONABLE TO BELIEVE THAT AT LEAST SCATTERED STORMS WILL DEVELOP
AS FAR SOUTHWEST AS NORTHERN AL. VERY HOT TEMPERATURES (M-U 90S)
AND HIGH DEWPOINTS (U70S-L80S) WILL EXIST AHEAD OF THE WIND SHIFT
AXIS, WARRANTING ANOTHER HEAT ADVISORY AND YIELDING HIGH CAPE OF
3000-3500 J/KG. THIS LEVEL OF INSTABILITY, COUPLED WITH AN
INCREASE IN NNW FLOW ALOFT TO 20-30 KNOTS, SUGGESTS THAT DAMAGING
WINDS AND FREQUENT LIGHTNING WILL BE POSSIBLE WITH THE STRONGEST
CELLS. LIGHT NORTHERLY FLOW IN THE WAKE OF THE FRONT WILL BEGIN TO
ADVECT A DRIER CONTINENTAL AIRMASS INTO THE REGION DURING THE DAY
ON WEDNESDAY, WITH ONLY A LOW CHANCE FOR A FEW SHOWERS SOUTH OF
THE TN RIVER BEFORE THIS OCCURS.
LONG TERM
(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 1109 PM CDT SUN JUL 26 2026
EXTENDED RANGE GUIDANCE FROM THE LASTEST SUITE OF GLOBAL MODELS
CONTINUES TO INDICATE THAT OUR FORECAST AREA WILL REMAIN UNDER THE
INFLUENCE OF MODERATELY STRONG NNW FLOW ALOFT AND DRY NORTHERLY
FLOW AT THE SURFACE FROM WEDNESDAY NIGHT-FRIDAY. WITH DEWPOINTS
FALLING INTO THE 60S, OVERNIGHT LOWS WILL RESPOND BY DROPPING TO
MORE COMFORTABLE LEVELS (M-U 60S), WITH AFTERNOON HIGHS REMAINING
IN THE U80S-L90S. HOWEVER, IT APPEARS AS IF DEEP-LAYER MOISTURE
WILL QUICKLY RETURN TO THE REGION AT SOME POINT FRIDAY
NIGHT/SATURDAY MORNING AS A COMPACT SURFACE LOW SHIFTS EASTWARD
FROM THE SOUTHERN PLAINS INTO THE LOWER-MS VALLEY. ALTHOUGH STRONG
LOW-LEVEL WARM/MOIST ADVECTION AHEAD OF THE LOW WILL CONTRIBUTE
TO AN INCREASE IN THE COVERAGE OF CONVECTION ACROSS OUR REGION,
CURRENT THINKING IS THAT INSTABILITY WILL REMAIN LOW (AT LEAST
COMPARED TO THE PAST COUPLE OF WEEKS) AND SHOULD LIMIT THE OVERALL
COVERAGE OF THUNDERSTORMS. THAT SAID, THE LOW-LEVEL JET WILL
LIKELY INCREASE CONSIDERABLY AHEAD OF THIS SYSTEM, AND MAY YIELD
AT LEAST A LIMITED RISK FOR STORM ORGANIZATION ON FRIDAY
NIGHT/SATURDAY. BY SUNDAY, THE SURFACE LOW IS EXPECTED TO WEAKEN
AND TRANSITION INTO A BROAD TROUGH ACROSS THE GULF COAST STATES,
WHICH SHOULD LEAD TO A GRADUAL DECREASE IN THE COVERAGE OF
PRECIPITATION ACROSS OUR REGION.
AVIATION
(00Z TAFS)
ISSUED AT 655 PM CDT SUN JUL 26 2026
CONDITIONS WILL REMAIN VFR AT THE HSV/MSL TERMINALS THIS EVENING,
WITH AN INCREASING COVERAGE OF MID/HIGH-LEVEL CLOUDS EXPECTED
ALONG WITH A LIGHT W FLOW. DURING THE EARLY MORNING HOURS ON
MONDAY, A COMPLEX OF THUNDERSTORMS (CURRENTLY DEVELOPING IN THE
LOWER OH VALLEY VICINITY) IS PREDICTED TO SPREAD SOUTHWARD THROUGH
THE TN VALLEY, WITH CONVECTIVE IMPACTS (INCLUDING WIND GUSTS TO
40KTS, FREQUENT LIGHTNING AND HEAVY RAIN) EXPECTED AT BOTH
AIRPORTS FOR AT LEAST A PORTION OF THE TIMEFRAME BTWN 9-13Z. IN
THE WAKE OF THIS SYSTEM, BKN-OVC DEBRIS CLOUDS WILL PERSIST FOR
MUCH OF THE MORNING BEFORE DISSIPATING DURING THE EARLY AFTN. A
SECOND ROUND OF TSRA IS LIKELY TO EVOLVE LATE IN THE PERIOD
(20-24Z) ALONG A TRAILING MESOSCALE OUTFLOW OR DIFFERENTIAL
HEATING BOUNDARY LEFT BEHIND BY THE MORNING MCS, WITH THIS
ACTIVITY MORE LIKELY TO IMPACT MSL THAN HSV.
HUN WATCHES/WARNINGS/ADVISORIES
AL...HEAT ADVISORY UNTIL 7 PM CDT TUESDAY FOR ALZ001>007-016.
TN...HEAT ADVISORY UNTIL 7 PM CDT TUESDAY FOR TNZ076-096.
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...70/DD
AVIATION...70/DD
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