022
FXUS64 KHUN 190357
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1057 PM CDT FRI SEP 18 2026
..NEW NEAR TERM, SHORT TERM, LONG TERM
KEY MESSAGES
UPDATED AT 1057 PM CDT FRI SEP 18 2026
- CONDITIONS WILL BE FAVORABLE FOR STRONG-SEVERE THUNDERSTORMS
EACH AFTERNOON FROM SATURDAY-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 SATURDAY-MONDAY, WITH HIGHS
IN THE MID-UPPER 90S IN THE VALLEY. A HEAT ADVISORY REMAINS IN
EFFECT THROUGH 8 PM CDT SATURDAY.
- 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
(THIS EVENING THROUGH SATURDAY)
ISSUED AT 1057 PM CDT FRI SEP 18 2026
IN THE MID/UPPER-LEVELS, A WEAKENING SUBTROPICAL HIGH WILL REMAIN
CENTERED ACROSS NORTHEASTERN TX THROUGHOUT THE NEAR TERM PERIOD,
WITH A RIDGE AXIS EXTENDING EAST-NORTHEASTWARD INTO VA/NC. DUE TO
THE ORIENTATION OF THE RIDGE ALOFT, N-NE FLOW OF 10-15 KNOTS WILL
BE MAINTAINED ACROSS THE TN VALLEY THIS EVENING AND OVERNIGHT,
BEFORE VEERING SLIGHTLY TO N-NW TOMORROW. AT THE SURFACE, A HIGH
(INITIALLY ACROSS EASTERN OT/WESTERN QC) WILL MIGRATE
SOUTHEASTWARD INTO NEW ENGLAND BY THE END OF THE PERIOD, WITH LOW-
LEVEL RIDGING EXPECTED TO PERSIST TO THE EAST OF THE APPALACHIANS.
HOWEVER, OUR REGION WILL REMAIN WITHIN A RELAXED PRESSURE
GRADIENT AND CALM-LIGHT/VARIABLE FLOW THROUGH THE FIRST HALF OF
THE WEEKEND.
ALTHOUGH A SOUTHWARD DRIFTING COLD FRONT RESULTED IN EXTENSIVE
CONVECTION EARLIER TODAY FROM THE CENTRAL OH VALLEY EAST-
SOUTHEASTWARD INTO THE SOUTHERN MID-ATLANTIC STATES, LINGERING
CLUSTERS OF SHOWERS AND THUNDERSTORMS (MAINTAINED BY OUTFLOW
BOUNDARIES) APPEAR TO BE WEAKENING AT THIS POINT, AND FOR THIS
REASON ADDITIONAL DEVELOPMENT OF CONVECTION ACROSS OUR
EASTERN/SOUTHEASTERN ZONES LATE THIS EVENING-EARLY SATURDAY
MORNING APPEARS UNLIKELY. THUS, WE EXPECT MOSTLY CLEAR SKIES AND
CALM WINDS TO ALLOW TEMPERATURES TO FALL INTO THE U60S-L70S, WITH
BRIEF DEVELOPMENT OF PATCHY MIST/FOG POSSIBLE IMMEDIATELY BEFORE
SUNRISE NEAR LARGE BODIES OF WATER.
TEMPERATURES WILL BEGIN TO RISE QUICKLY AFTER SUNRISE TOMORROW,
WITH DEVELOPMENT OF A SLIGHTLY MORE CONGESTED CUMULUS FIELD
(COMPARED TO PREVIOUS DAYS) EXPECTED BY LATE MORNING. CURRENT
THINKING IS THAT A REMNANT OUTFLOW BOUNDARY (ORIGINATING FROM
CONVECTION THIS EVENING TO OUR NORTH/EAST) WILL INITIATE
DEVELOPMENT OF SCATTERED THUNDERSTORMS IN OUR CWFA TOMORROW
AFTERNOON, INITIALLY BEGINNING IN THE HIGHER TERRAIN OF THE EAST
BETWEEN 17-19Z. ADDITIONAL CELLS WILL DEVELOP THROUGHOUT THE
AFTERNOON ALONG MESOSCALE BOUNDARIES AND SPREAD SOUTH-
SOUTHEASTWARD, WITH A HIGHER COVERAGE ANTICIPATED (PARTICULARLY
OVER THE EASTERN PORTION OF THE FORECAST AREA). MLCAPE AS HIGH AS
1500-2000 J/KG, COUPLED WITH PWATS IN THE 1.6-1.8" RANGE AND STEEP
LOW-LEVEL LAPSE RATES WILL SUPPORT A RISK FOR LOCALLY DAMAGING
DOWNBURSTS AND FREQUENT LIGHTNING WITH THIS ACTIVITY. PRIOR TO
CONVECTIVE IMPACTS, HIGHS WILL REACH THE M-U 90S (VALLEY) AND L90S
(ELEVATED TERRAIN), AND A HEAT ADVISORY REMAINS IN EFFECT THROUGH
8 PM CDT.
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
(00Z TAFS)
ISSUED AT 728 PM CDT FRI SEP 18 2026
VFR CONDITIONS ARE EXPECTED TO EXIST AT THE TERMINALS OVERNIGHT,
FEATURING A FEW HIGH-BASED CU (BENEATH HIGHER-LVL CONVECTIVE
DEBRIS CLOUDS) AND CALM WINDS. ALTHOUGH THERE IS STILL A LOW
CHANCE THAT OUTFLOW (FROM CLUSTERS OF TSRA CURRENTLY ACROSS
EASTERN TN AND WESTERN PARTS OF NC/SC) MAY INITIATE RENEWED
DEVELOPMENT OF A FEW THUNDERSTORMS IN OUR REGION LATER THIS
EVENING, THIS WOULD LIKELY BE CONFINED TO THE S/E OF THE HSV
TERMINAL. OTHERWISE, SUFFICIENTLY CLEAR SKIES AND CALM WINDS MAY
SUPPORT DEVELOPMENT OF PATCHY BR/FG IN A FEW LOCATIONS BTWN
10-13Z. DIURNAL CU WILL DEVELOP ONCE AGAIN BY 16Z, WITH WEAKENING
INFLUENCE FROM AN UPPER-LVL RIDGE PERHAPS RESULTING IN A SLIGHTLY
GREATER COVERAGE OF TERRAIN/OUTFLOW-INDUCED CONVECTION DURING THE
MID/LATE AFTN HOURS (COMPARED TO TODAY). THUS, A PROB30 GROUP HAS
BEEN INCLUDED AT BOTH TERMINALS FROM 20-24Z TO INDICATE THE MOST
LIKELY TIMEFRAME FOR IMPACTS FROM TSRA (INCLUDING POTENTIAL
ISSUANCE OF AWWS FOR LIGHTNING AND STRONG WIND GUSTS).
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...70/DD
SHORT TERM...70/DD
LONG TERM...70/DD
AVIATION...70/DD
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