481
FXUS64 KHUN 180753
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
253 AM CDT FRI SEP 18 2026
..NEW NEAR TERM
KEY MESSAGES
UPDATED AT 930 PM CDT THU SEP 17 2026
- A HEAT ADVISORY IS IN EFFECT THROUGH 8 PM SATURDAY ACROSS ALL
OF SOUTHERN MIDDLE TENNESSEE AND NORTHERN ALABAMA.
- NWS HEAT RISK HIGHLIGHTS MODERATE (LEVEL 2/4) TO MAJOR (LEVEL
3/4) HEAT IMPACTS THROUGH THE WEEKEND ACROSS THE TENNESSEE
VALLEY. LOCALIZED EXTREME (LEVEL 4/4) IMPACTS MAY OCCUR IN
URBANIZED AREAS.
NEAR TERM
(TODAY)
ISSUED AT 252 AM CDT FRI SEP 18 2026
CURRENT TEMPS ARE SITTING IN THE LOWER 70S, WHICH IS RUNNING ABOUT
10 DEGREES ABOVE SEASONAL NORMS FOR MID SEPTEMBER. WITH THIS
RELENTLESS RIDGE, IT WILL BE ANOTHER RINSE AND REPEAT FORECAST...A
WARM START TO THE MORNING THAT WILL LEAD TO ANOTHER DANGEROUSLY
HOT DAY BY THIS AFTERNOON. HEAT ADVISORY FOR THE ENTIRE TN VALLEY
REMAINS IN EFFECT UNTIL 8PM SATURDAY.
GUIDANCE WENT A LITTLE BIT WARMER FOR TODAY, PUSHING THE SHOALS
AREA UP TO THE TRIPLE DIGITS, 100 DEGREES, FOR A FORECAST HIGH.
ENSEMBLE PROBABILITIES ARE NOT A SLAM DUNK THAT WE'LL REACH 100
THOUGH, SO WE WILL SEE. OTHERWISE, THE MID TO UPPER 90S ARE
EXPECTED ELSEWHERE. DEWPOINTS ARE EXPECTED TO MIX OUT AGAIN THIS
AFTERNOON, BUT ADJUSTED THE VALUES DOWN A LITTLE BIT BASED OFF OF
PREVIOUS OBSERVATIONAL TRENDS WITH BLENDING IN CONSSHORT. THE
MIXING WILL HELP HEAT INDEX VALUES REMAIN BELOW 106 DEGREES. WILL
NOTE THAT THE WBGT ARE STILL IN THE UPPER 80S, AND THE NWS
HEATRISK MAJOR LEVEL (LEVEL 3 OUT OF 4) EXPANDS FURTHER ACROSS THE
CWA WITH SOME METRO AREAS REACHING EXTREME (LEVEL 4 OF 4). SOME
CAMS SHOW A LOW CHANCE 15-20% OF A FEW SHOWERS/STORMS THIS
AFTERNOON, MAINLY ACROSS NE AL WITH GREATER CHANCES REMAINING OFF
TO OUR NORTHEAST.
IT MAY SOUND LIKE A BROKEN RECORD AT THIS POINT, HOWEVER BE HEAT
SMART: SLOW DOWN, COOL DOWN, STAY HYDRATED AND NEVER LEAVE PEOPLE
OR PETS IN VEHICLES.
SHORT TERM
(FRIDAY NIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 930 PM CDT THU SEP 17 2026
AS WE HEAD INTO THE WEEKEND THE UPPER LEVEL RIDGE BEGINS TO BREAK
DOWN AND RECEDE A BIT TO THE WEST. AT THE SAME TIME, A WEAK LOW
PRESSURE SYSTEM OFF THE EAST COAST OF FLORIDA BEGINS TO DRIFT TO
THE WEST. THIS WILL PRODUCE MORE FAVORABLE CONDITIONS FOR
AFTERNOON CONVECTION, ESPECIALLY EAST OF I-65. AT THIS TIME, NO
SEVERE STORMS ARE EXPECTED GIVEN THE WEAK SHEAR PROFILES. HOWEVER,
CANNOT RULE OUT A STRONG STORM OR TWO CAPABLE OF GUSTY WINDS AS
DCAPE VALUES RISE ABOVE 1000 J/KG. PRIOR TO ANY PRECIP,
TEMPERATURES WILL ONCE AGAIN WARM INTO THE MID TO UPPER 90S BOTH
SATURDAY AND SUNDAY. SHOWERS AND STORMS WILL DISSIPATE AFTER
SUNSET WITH THE LOSS OF DAYTIME HEATING RESULTING IN CALM
CONDITIONS OVERNIGHT. SOMETHING TO KEEP AN EYE ON IS THE LOW
CHANCES FOR EARLY MORNING FOG IN AREAS THAT RECEIVE RAINFALL
DURING THE DAY. OTHERWISE, MILD AND HUMID NIGHTS CONTINUE WITH
OVERNIGHT LOWS IN THE UPPER 60S TO LOWER 70S.
LONG TERM
(MONDAY THROUGH THURSDAY)
ISSUED AT 930 PM CDT THU SEP 17 2026
EXTENDED RANGE MODEL SOLUTIONS SUGGEST THAT A 500-MB RIDGE WILL
REMAIN POSITIONED ACROSS THE FORECAST AREA ON MONDAY. HOWEVER, AS WE
PROGRESS THROUGH THE REST OF THE PERIOD, IT IS BECOMING INCREASINGLY
LIKELY THE THE SOUTHERN EDGE OF THE MID-LATITUDE WESTERLIES WILL
DEVELOP SOUTHWARD INTO OUR REGION, WITH INDICATIONS OF A FLAT
SUBTROPICAL RIDGE LYING ACROSS THE NORTHERN GULF AND DEVELOPMENT OF
AN UPPER LOW (FROM PHASING OF 2-3 DISTINCT NORTHERN STREAM
SHORTWAVES) OVER THE GREAT LAKES. IN THE LOW-LEVELS, A WEAK AREA OF
LOW PRESSURE IS PREDICTED TO MIGRATE FROM THE MID-SOUTH INTO THE TN
VALLEY ON MONDAY, BEFORE DEGENERATING INTO A FRONTAL WAVE AS IT LIFTS
NORTHEASTWARD INTO THE UPPER OH VALLEY MONDAY NIGHT. ALTHOUGH THE
TRAILING COLD FRONT WILL MAKE ONLY GRADUAL SOUTHEASTWARD PROGRESSION
INTO THE OZARKS AND OH VALLEY BY EARLY TUESDAY MORNING, MESOSCALE
BOUNDARIES ORIGINATING FROM EXTENSIVE CONVECTION TO OUR NORTHWEST
SHOULD CONTRIBUTE TO A HIGHER COVERAGE OF THUNDERSTORMS ACROSS OUR
CWFA MONDAY AFTERNOON AND EVENING. AS SURFACE PRESSURES BEGIN TO RISE
WITHIN A HIGH MIGRATING EASTWARD ACROSS SOUTHERN ONTARIO/QUEBEC (AND
RENEWED CYCLOGENESIS TAKES PLACE OVER THE EASTERN GREAT LAKES), THE
COLD FRONT WILL ADVANCE FURTHER SOUTHEASTWARD ON TUESDAY, RESULTING
IN ANOTHER EPISODE OF CONVECTION DURING THE AFTERNOON/EVENING HOURS.
SUFFICIENT CAPE WILL EXIST TO SUPPORT A RISK FOR STRONG-LOCALLY
SEVERE THUNDERSTORMS BOTH PERIODS, ESPECIALLY GIVEN AN INCREASE IN
MID-LEVEL FLOW TO 15-25 KNOTS. AS THE COLD FRONT SHIFTS FURTHER
SOUTHEASTWARD THROUGH THE REGION WEDNESDAY, LIGHT-MODERATE NORTHERLY
FLOW WILL BEGIN TO ADVECT A SLIGHTLY COOLER/DRIER AIRMASS INTO THE
REGION, WITH HIGHS ON WEDNESDAY AND THURSDAY DROPPING BACK INTO THE
85-90F RANGE AND LOWS FALLING INTO THE L-M 60S.
AVIATION
(06Z TAFS)
ISSUED AT 1136 PM CDT THU SEP 17 2026
CONDITIONS WILL REMAIN VFR AT THE HSV/MSL TERMINALS THROUGHOUT
THE EARLY MORNING HOURS, FEATURING A FEW CU/CI AND CALM WINDS.
ALTHOUGH PATCHY BR/FG MAY INDEED DEVELOP NEAR LARGE BODIES OF
WATER IN THE 10-13Z TIMEFRAME, WE WILL MAINTAIN A PERSISTENCE
FORECAST AND REFRAIN FROM INTRODUCING MVFR VSBY REDUCTIONS IN THE
TAFS ATTM. A MORE SCATTERED DIURNAL CU FIELD WILL EVOLVE ONCE
AGAIN BY 16Z, WITH SOUTH-SOUTHWESTWARD PROPAGATING CONVECTIVE
OUTFLOW POSSIBLY RESULTING IN DEVELOPMENT OF WIDELY SCATTERED
SHRA/TSRA IN OUR REGION LATE FRI AFTN AND EVENING. HOWEVER, WITH
THIS ACTIVITY EXPECTED TO BE MORE CONCENTRATED TO THE N/E OF HSV,
WE WILL NOT MENTION PCPN IN THE FORECAST. PREVAILING SFC FLOW WILL
REMAIN AOB 5 KTS THRU THE PERIOD.
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...JMS
SHORT TERM....GH
LONG TERM....70
AVIATION...70
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