991
FXUS64 KHUN 191117
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
617 AM CDT SAT SEP 19 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 242 AM CDT SAT SEP 19 2026
- CONDITIONS WILL BE FAVORABLE FOR STRONG-SEVERE THUNDERSTORMS
EACH AFTERNOON FROM TODAY-TUESDAY, WITH THE GREATEST SPATIAL
COVERAGE OF STORMS EXPECTED TO OCCUR ON MONDAY AND TUESDAY.
LOCALLY DAMAGING DOWNBURST WINDS, FREQUENT LIGHTNING AND HEAVY
RAINFALL WILL BE THE MAIN STORM IMPACTS.
- HOT TEMPERATURES WILL CONTINUE FROM TODAY-MONDAY, WITH HIGHS IN
THE MID-UPPER 90S IN THE VALLEY. A HEAT ADVISORY REMAINS IN
EFFECT THROUGH 8 PM CDT TODAY.
- A SLIGHTLY COOLER AND DRIER AIRMASS WILL ARRIVE LATE IN THE
FORECAST PERIOD, WITH HIGHS DROPPING BACK INTO THE 80S ON
THURSDAY/FRIDAY.
NEAR TERM
(TODAY)
ISSUED AT 242 AM CDT SAT SEP 19 2026
ANOTHER HOT DAY EXPECTED ACROSS THE TN VALLEY. WE WILL RUN ABOUT
10 DEGREES ABOVE SEASONABLE DAYTIME HIGHS OF THE MID 80S. HEAT
ADVISORY REMAINS IN EFFECT UNTIL 8PM THIS EVENING. THE TN VALLEY
IS STATIONED BETWEEN AN UPPER LEVEL RIDGE CENTERED ACROSS THE
SOUTHERN PLAINS, AN UPPER LOW MEANDERING ACROSS FL AND A
DISTURBANCE SLIDING THROUGH THE MIDWEST. THE SFC COLD FRONT
SINKING SOUTHWARD FROM THE OH VALLEY, SADLY, WILL NOT MAKE IT TO
US.
THE FRONT DEVELOPED CONVECTION OFF TO OUR NORTHEAST LAST NIGHT
AND OUTFLOW BOUNDARIES FROM THAT SHOULD HELP IGNITE STORMS FOR US
AROUND LUNCHTIME IN NE AL AND SOUTHERN MIDDLE TN. THE OUTFLOW
FROM THOSE STORMS WILL TRAVEL WESTWARD AND CREATE ADDITIONAL
DEVELOPMENT. IN SPC'S LATEST DAY 1, THEY PULLED BACK ON THE
MARGINAL OUTLOOK FOR THE FORECAST AREA, LEAVING A SLIVER IN
JACKSON AND DEKALB COUNTIES, HOWEVER THERMODYNAMICS STILL SUPPORT
DOWNBURSTS OCCURRING WITHIN AND OUTSIDE OF THE OUTLOOK AREA THIS
AFTERNOON AND EVENING. FORECAST SOUNDINGS SUGGEST MLCAPE CAN BE AS
HIGH AS 1500-2000 J/KG, WITH PWATS IN THE 1.6-1.8" AND STEEP LOW-
LEVEL LAPSE RATES, WHICH COULD SUPPORT A RISK FOR LOCALLY
DAMAGING DOWNBURSTS AND FREQUENT LIGHTNING WITH THIS ACTIVITY.
OUTSIDE OF ANY CONVECTION, DAYTIME HIGHS WILL REACH THE LOWER 90S
IN THE ELEVATED TERRAIN AND THE MID TO UPPER 90S ELSEWHERE. HEAT
INDEX VALUES WILL REACH UP TO 105 DEGREES.
SHORT TERM
(SATURDAY NIGHT THROUGH MONDAY NIGHT)
ISSUED AT 1057 PM CDT FRI SEP 18 2026
SHORT RANGE MODEL CONSENSUS SUGGESTS THAT A WEAKENING MID-LEVEL
RIDGE WILL EXTEND FROM THE NORTHWESTERN GULF COAST INTO THE TN
VALLEY FROM SATURDAY NIGHT-SUNDAY NIGHT. IN THE LOW-LEVELS, A
LIGHT S-SE FLOW WILL RETURN TO THE REGION ON SATURDAY NIGHT AS AN
AREA OF LOW PRESSURE SHIFTS EASTWARD FROM NORTHERN IL INTO THE
SOUTHEASTERN GREAT LAKES, AND SUBTLE CONVERGENCE AT THE ONSET OF
THIS REGIME COULD RESULT IN SHOWERS AND THUNDERSTORMS CONTINUING A
BIT LATER INTO THE EVENING HOURS TOMORROW (PARTICULARLY ACROSS
OUR SOUTHEASTERN COUNTIES). OTHERWISE, WE EXPECT ANOTHER HOT DAY
ON SUNDAY, WITH TEMPERATURES WARMING QUICKLY AFTER SUNRISE AND
PEAKING IN THE M-U 90S IN LOWER ELEVATIONS SUNDAY AFTERNOON.
ALTHOUGH AFTERNOON THUNDERSTORM COVERAGE MAY BE A LIT LOWER
(COMPARED TO SATURDAY) DUE TO LACK OF A DISCERNIBLE CONVERGENCE
AXIS AT THE SURFACE, AT LEAST ISOLATED STORM ARE EXPECTED TO
DEVELOP DURING THE AFTERNOON HOURS (PARTICULARLY IN REGIONS OF
TERRAIN-INDUCED LIFT), AND THERMODYNAMIC PROFILES WILL ONCE AGAIN
SUPPORT A RISK FOR LOCALLY DAMAGING DOWNBURST WINDS AND FREQUENT
LIGHTNING WITH THE MOST INTENSE CELLS.
FOR THE LATTER PORTION OF THE SHORT TERM PERIOD, A LOW-AMPLITUDE
MID-LEVEL WAVE IN THE SOUTHERN STREAM (PROGRESSING EASTWARD OVER
THE RED RIVER VALLEY ON SUNDAY AND SUNDAY NIGHT) IS EXPECTED TO
GRADUALLY DECAY ACROSS THE NORTHERN PART OF THE TN VALLEY ON
MONDAY AND MONDAY NIGHT. AS THIS OCCURS (AND A SLIGHTLY MORE
AMPLIFIED NORTHERN STREAM TROUGH DIGS EAST-SOUTHEASTWARD INTO THE
MID-MS VALLEY), W-SW FLOW ALOFT WILL INCREASE INTO THE 10-15 KNOT
RANGE. IN THE LOW-LEVELS, WEAK CYCLOGENESIS (IN RESPONSE TO THE
LOWER-LATITUDE DISTURBANCE) IS PREDICTED IN THE VICINITY OF THE
EASTERN OZARK PLATEAU ON SUNDAY/SUNDAY NIGHT, WITH THE LOW
EXPECTED TO SHIFT SLOWLY EASTWARD INTO MIDDLE TN ON MONDAY BEFORE
OPENING INTO A TROUGH MONDAY NIGHT. LIFT PROVIDED BY THE SHORTWAVE
(COUPLED WITH STRONGER LOW-LEVEL CONFLUENCE IN THE VICINITY OF
THE LOW) WILL SUPPORT A HIGHER COVERAGE OF SHOWERS AND
THUNDERSTORMS REGION-WIDE MONDAY AFTERNOON (AND CONTINUING WELL
INTO MONDAY NIGHT). DUE TO THE INCREASE IN DEEP-LAYER FLOW, STORMS
WILL BE MOVING AT HIGHER SPEEDS (FROM WSW TO ENE) AND MAY BE
STRONG-LOCALLY SEVERE (ESPECIALLY DURING THE AFTERNOON-EARLY
EVENING HOURS).
LONG TERM
(TUESDAY THROUGH FRIDAY)
ISSUED AT 1057 PM CDT FRI SEP 18 2026
LATEST EXTENDED RANGE FORECAST DATA SUGGEST THAT A WEAK NORTHERN
STREAM TROUGH WILL ADVANCE SLOWLY EASTWARD FROM THE MID-MS VALLEY
INTO THE NORTHERN MID-ATLANTIC STATES NEXT WEEK, AS IT WILL LIKELY
BE BLOCKED BY RIDGING TO ITS NORTH. AT THE SURFACE, A TROUGH
(INITIALLY EXTENDING FROM CENTRAL PARTS OF MS/AL NORTH-
NORTHEASTWARD INTO THE UPPER OH VALLEY) IS PREDICTED TO REMAIN
NEARLY STATIONARY ON TUESDAY, AND WILL LIKELY FOCUS DEVELOPMENT OF
ADDITIONAL SHOWERS AND THUNDERSTORMS ACROSS OUR REGION BOTH
DURING THE DAY AND AT NIGHT. IN SIMILAR FASHION TO MONDAY, A FEW
STRONG-SEVERE THUNDERSTORMS MAY OCCUR DURING THE AFTERNOON AND
EVENING HOURS, AIDED BY HIGH CAPE AND INCREASING W-NW FLOW ALOFT.
ALTHOUGH THERE IS SOME UNCERTAINTY REGARDING PRECISELY WHEN THIS
WILL OCCUR, THE SURFACE TROUGH IS EXPECTED TO SHIFT SLOWLY
SOUTHEASTWARD AT SOME POINT WEDNESDAY/THURSDAY, ALLOWING A
COOLER/DRIER AIRMASS (ORIGINATING FROM AN ANTICYCLONE ACROSS
SOUTHERN QC) TO SPREAD SOUTHEASTWARD INTO THE REGION. THIS COUPLED
WITH 20-30 KNOT W-NW FLOW ALOFT AND DRY ADVECTION THROUGH THE
DEPTH OF THE TROPOSPHERIC COLUMN WILL ALLOW RAIN CHANCES TO
DECREASE CONSIDERABLY ON THURSDAY/FRIDAY. AFTERNOON HIGHS WILL
FALL BACK INTO THE L-M 80S BY THE END OF THE WORK WEEK, WITH
OVERNIGHT LOWS THURSDAY NIGHT/FRIDAY MORNING IN THE U50S-L60S.
AVIATION
(12Z TAFS)
ISSUED AT 617 AM CDT SAT SEP 19 2026
LOW CHANCES OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AROUND
19-01Z AT BOTH TERMINALS. STORMS WILL BE CAPABLE OF PRODUCING
LIGHTNING AND STRONG TO DAMAGING WIND GUSTS, ALONG WITH A
VIS REDUCTION TO MVFR.
HUN WATCHES/WARNINGS/ADVISORIES
AL...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR ALZ001>010-016.
TN...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR TNZ076-096-097.
NEAR TERM...JMS
SHORT TERM....70
LONG TERM....70
AVIATION...JMS
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