405
FXUS64 KHUN 301904
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
204 PM CDT TUE JUN 30 2026
..NEW NEAR TERM
KEY MESSAGES
UPDATED AT 1135 AM CDT TUE JUN 30 2026
- AN EXTREME HEAT WARNING IS IN EFFECT FOR ALL COUNTIES IN
NORTHERN AL AND SOUTHERN MIDDLE TN THROUGH 7 PM WEDNESDAY DUE
TO A COMBINATION OF AFTERNOON TEMPERATURES IN THE MID-UPPER 90S
AND HEAT INDEX UP TO 112F. A HEAT ADVISORY REMAINS IN EFFECT
FROM 7 PM WEDNESDAY - 7 PM THURSDAY.
- THERE IS A LOW (10-20%) CHANCE FOR AFTERNOON THUNDERSTORMS
ACROSS NORTHEAST AL TODAY, WITH CHANCES INCREASING TO 20-40%
REGION-WIDE TOMORROW AND THURSDAY. CONDITIONS WILL BE FAVORABLE
FOR LOCALLY DAMAGING WINDS (55-65 MPH), EXCESSIVE LIGHTNING
AND PERHAPS SMALL HAIL WITH THIS ACTIVITY.
NEAR TERM
(REST OF TODAY AND TONIGHT)
ISSUED AT 204 PM CDT TUE JUN 30 2026
THERE HAVE BEEN NO SIGNIFICANT CHANGES TO NEAR TERM FORECAST
REASONING SINCE THE UPDATE EARLIER THIS MORNING, WITH CURRENT
TEMPERATURES AND DEWPOINTS ON TRACK TO REACH EXTREME HEAT WARNING
CRITERIA ACROSS PORTIONS OF THE FORECAST AREA. LATEST CAMS ALSO
SUGGEST THAT A FEW SHOWERS AND THUNDERSTORMS (10-20% COVERAGE) MAY
OCCUR IN THE HIGHER TERRAIN OF NORTHEAST AL LATE THIS AFTERNOON,
WITH ANY SUSTAINED UPDRAFTS CAPABLE OF PRODUCING STRONG DOWNBURST
WINDS AND FREQUENT LIGHTNING. ANY LINGERING STORMS SHOULD
DISSIPATE BY 2Z (IF NOT SOONER), WITH A VERY WARM NIGHT IN STORE
(FEATURING LOWS IN THE M-U 70S).
PREVIOUS DISCUSSION:
IN THE MID/UPPER-LEVELS, THE CENTER OF A STRONG ANTICYCLONE WILL
SHIFT SLOWLY EAST-NORTHEASTWARD INTO EASTERN KY/TN OVER THE COURSE
OF THE NEAR TERM PERIOD, MAINTAINING A LIGHT ESE FLOW OF 10-20
KNOTS ACROSS THE LOCAL FORECAST AREA. AT THE SURFACE, A NARROW
RIDGE OF HIGH PRESSURE (INITIALLY POSITIONED ACROSS THE CENTRAL
APPALACHIANS) WILL SPREAD EAST-NORTHEASTWARD OFF THE NORTHERN MID-
ATLANTIC COAST AS A WEAK AREA OF LOW PRESSURE (LOCATED WELL EAST
OF THE SOUTHEASTERN ATLANTIC COAST) BEGINS TO DRIFT WESTWARD.
ALTHOUGH (AT LEAST FOR TODAY) THERE IS NO EVIDENCE OF A MID-LEVEL
WAVE TRANSLATING AROUND THE SOUTHEASTERN PERIPHERY OF THE RIDGE
THAT WOULD ENHANCE DEVELOPMENT OF AFTERNOON THUNDERSTORMS, A
SUBTLE LOW-LEVEL CONFLUENCE AXIS (INITIATED BY NORTHEASTERLY FLOW
ACROSS THE CAROLINAS) WILL ASSIST IN CONVECTIVE DEVELOPMENT BY
EARLY THIS AFTERNOON FROM NORTHWEST GA SOUTHWARD INTO SOUTHEASTERN
AL (WITH ADDITIONAL CELLS LIKELY TO DEVELOP IN THE HIGHER TERRAIN
TO OUR NORTH/EAST). STORM COVERAGE APPEARS AS IF IT WILL BE
HIGHEST ACROSS SOUTHERN AL AND ADJACENT PORTIONS OF THE FL
PANHANDLE (WHERE BROAD SCALE SUBSIDENCE ASSOCIATED WITH THE RIDGE
ALOFT WILL BE COMPARATIVELY WEAKER). HOWEVER, WE WILL RETAIN A LOW
(10-20%) FOR OUR NORTHEAST AL ZONES. AFTER THUNDERSTORMS MATURE,
THEY WILL DRIFT SLOWLY WEST-NORTHWESTWARD WITH TIME, AND WILL BE
OCCURRING WITHIN A WEAKLY SHEARED BY HIGHLY FAVORABLE
THERMODYNAMIC ENVIRONMENT (FEATURING VERY STEEP LAPSE RATES IN THE
BOUNDARY LAYER, MLCAPE OF 2500-3500 J/KG AND DCAPE OF 1000-1500
J/KG) TO SUPPORT A RISK FOR LOCALLY DAMAGING DOWNBURST WINDS UP TO
55-65 MPH, EXCESSIVE CG LIGHTNING STRIKES AND PERHAPS SOME SMALL
HAIL. OTHERWISE, TEMPERATURES APPEAR ON TRACK TO REACH THE M-U 90S
FOR MOST OF THE FORECAST AREA (LOWER 90S ATOP THE CUMBERLAND
PLATEAU), WITH AFTERNOON HI IN THE 108-112F FOR A LARGE PORTION OF
THE REGION. THUS, WE WILL BE UPGRADING OUR HEAT ADVISORY TO AN
EXTREME HEAT WARNING THAT WILL RUN THROUGH 7 PM WEDNESDAY.
ANY THUNDERSTORMS IN THE SOUTHEASTERN PORTION OF THE FORECAST
AREA WILL BEGIN TO DIMINISH IN COVERAGE/INTENSITY QUICKLY AFTER
SUNSET THIS EVENING, AND SHOULD DISSIPATE ENTIRELY BY 2-4Z (IF NOT
SOONER). AFTER A PERIOD OF MOSTLY CLEAR SKIES LATE THIS EVENING
AND EARLY WEDNESDAY MORNING, A LAYER OF MID-LEVEL ALTOCU WILL
DEVELOP DURING THE PREDAWN HOURS, RESULTING IN VERY WARM OVERNIGHT
LOWS IN THE M-U 70S (AND NO RELIEF FROM THE HEAT). PATCHY FOG
WILL BE POSSIBLE IN AGRICULTURAL AREAS AND IN LOCATIONS THAT
EXPERIENCE WETTING RAINFALL AROUND SUNRISE.
SHORT TERM
(WEDNESDAY THROUGH THURSDAY NIGHT)
ISSUED AT 1135 AM CDT TUE JUN 30 2026
LATEST MODEL GUIDANCE SUGGESTS THAT THE CENTER OF A STRONG MID-
LEVEL HIGH TO OUR NORTHEAST WILL MIGRATE EASTWARD ACROSS THE
CENTRAL/SOUTHERN APPALACHIANS AND INTO VA/NC BY THE END OF THE
PERIOD. ALTHOUGH THIS CONFIGURATION WILL SUSTAIN ESE FLOW OF ONLY
10-20 KNOTS ALOFT, A NOTABLE MID-LEVEL VORTICITY MAXIMA IS
PREDICTED TO TRAVEL ANTICYCLONICALLY AROUND THE RIDGE AND ACROSS
THE NORTHERN GULF COAST STATES TOMORROW, PROVIDING ADDITIONAL
SUPPORT FOR THUNDERSTORMS THAT SHOULD BEGIN TO DEVELOP BY LATE
MORNING IN THE VICINITY OF A LENGTHY OUTFLOW BOUNDARY EXTENDING
FROM THE ARKLAMISS VICINITY INTO NORTHERN GA/SOUTHWESTERN NC.
ALTHOUGH THERE IS STILL SOME UNCERTAINTY REGARDING STORM COVERAGE
AND TIMING IN OUR SPECIFIC FORECAST AREA, WE ARE BECOMING
INCREASINGLY CONVINCED THAT COVERAGE WILL BE FAIRLY HIGH
(PARTICULARLY FROM MID-LATE AFTERNOON). WITH EVEN LESS MIXING OF
LOW-LEVEL MOISTURE PREDICTED TO OCCUR TOMORROW, DEWPOINTS IN THE
MID 70S WILL SUPPORT VERY HIGH CAPE (3000-4000 J/KG), WHICH
COUPLED WITH STEEP LOW-LEVEL LAPSE RATES AND PWAT VALUES AROUND 2"
WILL BE EXTREMELY CONDUCIVE FOR DAMAGING DOWNBURST WINDS (UP TO
65 MPH), EXCESSIVE LIGHTNING AND SMALL HAIL. STORMS WILL AGAIN
PROGRESS SLOWLY WEST-NORTHWESTWARD (PROPELLED BY OUTFLOW), ENDING
IN THE NORTHWEST BETWEEN 0-2Z. ALTHOUGH TIMING AND LOCATION OF
INITIAL CONVECTIVE DEVELOPMENT CASTS A BIT OF UNCERTAINTY ON THE
EXTREME HEAT WARNING FOR TOMORROW, WE FEEL FAIRLY CONFIDENT THAT
CRITERIA (GENERATED BY TEMPS IN THE M-U 90S AND DEWPOINTS IN THE
MID 70S) WILL BE ACHIEVED IMMEDIATELY PRIOR TO CONVECTIVE IMPACTS,
BUT SHOULD END BY 7 PM AS RAIN-COOLED AIR BEGINS TO OVERSPREAD
THE REGION.
A SIMILAR CONVECTIVE SCENARIO (FEATURING IDENTICAL THERMODYNAMIC
PROFILES AND AN ATTENDANT RISK FOR SEVERE DOWNBURST WINDS) IS
LIKELY TO UNFOLD ON THURSDAY, AS ANOTHER SUBTLE MID-LEVEL WAVE
WILL TRACK WESTWARD ACROSS THE LOCAL AREA DURING THE AFTERNOON
HOURS IN THE FLOW BETWEEN THE SUBTROPICAL HIGH TO OUR NORTHEAST
AND A BROAD SCALE EASTERLY WAVE TRANSLATING ACROSS THE FL
PENINSULA AND INTO THE EASTERN GULF. ALTHOUGH THERE MAY EVENTUALLY
BE A NEED TO UPGRADE THE HEAT ADVISORY TO AN EXCESSIVE HEAT
WARNING FOR THIS DAY AS WELL, CONFIDENCE IS NOT SUFFICIENTLY HIGH
AT THIS POINT.
LONG TERM
(FRIDAY THROUGH MONDAY)
ISSUED AT 1040 PM CDT MON JUN 29 2026
THE APEX OF THE UPPER LEVEL RIDGE WILL SHIFT OVER THE EASTERN
SEABOARD BY FRIDAY AND ALSO START TO FLATTEN AS RIPPLES OF
SHORTWAVES PROGRESS OVER THE MIDWEST, GREAT LAKES, AND UPPER OHIO
VALLEY REGIONS. SOME GLOBAL GUIDANCE SUGGESTS THAT A FEW OF THESE
SHORTWAVES WILL DIG TOWARDS THE SOUTHEAST LATE IN THE WEEKEND AND
INTO EARLY NEXT WEEK. MEANWHILE, SURFACE HIGH PRESSURE WILL
PERSIST OVER THE APPALACHIANS DOWN THROUGH THE ARKLAMISS REGION
THROUGH SUNDAY; HOWEVER, A COLD FRONT MAY APPROACH THE TENNESSEE
VALLEY BY EARLY NEXT WEEK, PUSHING THE HIGH PRESSURE TO THE
SOUTHEAST.
OVERALL, EXPECT A DIURNAL PATTERN TO SET UP BY LATE WEEK, WITH
DAILY CHANCES OF SHOWERS AND STORMS (GENERALLY 20-40%) IN THE
AFTERNOON AND EVENING. WITH THE CONTINUED WARM AND HUMID
CONDITIONS, ALONG WITH DCAPE VALUES NEAR OR JUST OVER 1000 J/KG,
WE'LL BE KEEPING AN EYE ON DOWNBURST POTENTIAL DURING THIS TIME AS
WELL. BY SUNDAY, AND ESPECIALLY MONDAY, SHOWER AND STORM CHANCES
THEN INCREASE AS THE AFOREMENTIONED COLD FRONT APPROACHES THE
REGION. WHILE THERE LOOKS TO BE MORE THAN ENOUGH INSTABILITY FOR
STORMS, BULK SHEAR VALUES ARE FAIRLY WEAK (10 KNOTS OR LESS).
THEREFORE, SEVERE WEATHER IS NOT ANTICIPATED SUNDAY OR MONDAY AT
THIS TIME.
AS FOR TEMPERATURES, FRIDAY AND SATURDAY WILL CONTINUE TO BE VERY
WARM WITH HIGHS IN THE LOWER TO UPPER 90S ALONG WITH HEAT INDEX
VALUES IN THE 98-106 DEGREE RANGE. NWS HEATRISK LOOKS TO MAINLY BE
IN THE MAJOR CATEGORY (LEVEL 3 OF 4) BY LATE WEEK, BUT WBGTS
REMAIN IN THE UPPER 80S TO AROUND 90. THEREFORE, HEAT PRODUCTS MAY
NEED TO BE EXTENDED INTO THE FIRST PART OF THE WEEKEND TO ACCOUNT
FOR THE LINGERING HEAT. MAKE SURE TO TAKE PRECAUTIONS FOR THE
DANGEROUS HEAT! WEAR LIGHT-COLORED, LOOSE-FITTING CLOTHING, STAY
HYDRATED, AND TAKE FREQUENT BREAKS IN THE SHADE IF YOU WORK
OUTSIDE OR HAVE OUTDOOR ACTIVITIES! LOOK BEFORE YOU LOCK - NEVER
LEAVE PEOPLE OR PETS IN VEHICLES! BY SUNDAY AND MONDAY, THE
INCREASED PRECIPITATION CHANCES WILL RESULT IN AN EVER SO SLIGHT
COOLDOWN, WITH HIGHS TOPPING OUT IN THE LOWER TO MID 90S ON SUNDAY
AND IN THE UPPER 80S TO LOWER 90S ON MONDAY.
AVIATION
(18Z TAFS)
ISSUED AT 1259 PM CDT TUE JUN 30 2026
CONDITIONS WILL REMAIN VFR AT THE HSV/MSL TERMINALS FOR THE
DURATION OF THE VALID TAF PERIOD, WITH ISOLATED THUNDERSTORM
ACTIVITY ACROSS OUR REGION THIS AFTERNOON CONFINED TO PORTIONS OF
NORTHEAST AL. AS THE DIURNALLY-ENHANCED CU FIELD BEGINS TO
DISSIPATE SHORTLY BEFORE 0Z, SKIES WILL BECOME MOSTLY CLEAR FOR
SEVERAL HOURS THIS EVENING BEFORE A BROKEN LAYER OF AC DEVELOPS
PRIOR TO SUNRISE. ALTHOUGH THIS SHOULD REDUCE CONCERN FOR
DEVELOPMENT OF LGT BR/FG, MINOR VSBY REDUCTIONS MAY STILL BRIEFLY
OCCUR AT BOTH TERMINALS BTWN 9-12Z. CU WILL REDEVELOP BY THE END
OF THE FORECAST PERIOD, WITH AN INCREASING RISK FOR TSRA BEGINNING
JUST BEYOND 18Z. SFC WINDS WILL RANGE FROM NW AT 5 KTS DURING THE
DAYLIGHT HOURS TO CALM AT NIGHT.
HUN WATCHES/WARNINGS/ADVISORIES
AL...EXTREME HEAT WARNING UNTIL 7 PM CDT WEDNESDAY FOR ALZ001>010-016.
HEAT ADVISORY FROM 7 PM WEDNESDAY TO 7 PM CDT THURSDAY FOR
ALZ001>010-016.
TN...EXTREME HEAT WARNING UNTIL 7 PM CDT WEDNESDAY FOR TNZ076-096-097.
HEAT ADVISORY FROM 7 PM WEDNESDAY TO 7 PM CDT THURSDAY FOR
TNZ076-096-097.
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...26
AVIATION...70/DD
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