721
FXUS64 KHUN 202149
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
449 PM CDT WED MAY 20 2026
..NEW AVIATION
KEY MESSAGES
ISSUED AT 152 PM CDT WED MAY 20 2026
- MEDIUM TO HIGH CHANCES (60-90%) OF SHOWERS AND THUNDERSTORMS
ARE FORECAST TODAY THROUGH EARLY NEXT WEEK. NO SEVERE WEATHER
IS FORECAST.
- LOCALLY HEAVY DOWNPOURS AND FREQUENT LIGHTNING MAY ACCOMPANY
ALL THUNDERSTORMS AND THOSE WITH OUTDOORS PLANS OR EVENTS
SHOULD MONITOR THE FORECAST.
NEAR TERM
(REST OF TODAY AND TONIGHT)
ISSUED AT 152 PM CDT WED MAY 20 2026
THE APPROACHING SURFACE FRONT HAS SLOWLY MOVED EAST TODAY AND
CURRENTLY STRETCHES FROM SOUTHEASTERN OHIO THROUGH THE NASHVILLE,
TN AREA INTO NW ALABAMA. FORCING ALONG AND AHEAD OF THIS FEATURE
IS PRODUCING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS. SHEAR
IS NOT VERY IMPRESSIVE. 2-6 KM AND MID LEVEL LAPSE RATES ARE NOT
TOO IMPRESSIVE (2-6 KM ONLY 6 TO 6.5 DEGREES/KM). DCAPE VALUES ARE
STILL VERY MEAGER (ONLY 300 TO 600 J/KG). HOWEVER, SBCAPE HAS
INCREASED TO BETWEEN 1000 AND 2500 J/KG AND LOW LEVEL LAPSE RATES
ARE AROUND -8 IN SPC ANALYSIS. THUS, SOME STRONGER STORMS
PRODUCING DOWNBURST WINDS BETWEEN 30 AND 55 MPH CANNOT BE RULED
OUT THIS AFTERNOON. HOWEVER, GIVEN WEAK NATURE OF 0-3 KM SHEAR,
NOT EXPECTING AN AREA OF ORGANIZED SEVERE THUNDERSTORM
DEVELOPMENT. THE STORM PREDICTION CENTER HAS PLACED THE AREA UNDER
A MESOSCALE DISCUSSION FOR A POSSIBLE SEVERE THUNDERSTORM WATCH,
BUT THIS IS VERY UNLIKELY (ONLY 20% CHANCE OR LESS OF A WATCH).
FREQUENT LIGHTNING, HEAVY DOWNPOURS AND SOME SMALL HAIL CANNOT BE
RULED OUT IN THE STRONGEST STORMS.
IT LOOKS LIKE STRONGEST AND MOST PERSISTENT FORCING WILL REMAIN
MOSTLY IN TENNESSEE NE INTO THE SOUTHERN OHIO VALLEY. ONE QUARTER
TO AROUND HALF AN INCH IN SOUTHERN MIDDLE TENNESSEE LOOKS REASONABLE
FOR RAINFALL AMOUNTS THROUGH TONIGHT. THE MAJORITY OF GUIDANCE
PUSHES THE FRONT SOUTH OF THE TENNESSEE RIVER LATE TONIGHT INTO
THE DAYBREAK ON THURSDAY. WE SHOULD LOSE INSTABILITY OVERNIGHT
BEHIND THE FRONT. SOME POST-FRONTAL FORCING WILL LIKELY PRODUCE
SOME LINGERING LIGHT TO MODERATE RAIN OVER THE AREA.
SHORT TERM
(THURSDAY THROUGH SATURDAY)
ISSUED AT 1120 AM CDT WED MAY 20 2026
DURING THE DAY ON THURSDAY, GUIDANCE PUSHES THE FRONT BACK TO THE
NORTHWEST. SHEAR REMAINS WEAK NEAR AND ALONG THIS FRONTAL BOUNDARY.
INSTABILITY IS FORECAST TO AGAIN CLIMB INTO THE 1000 TO 2000 J/KG
RANGE, MAYBE SLIGHTLY HIGHER. AGAIN LAPSE RATES AND DCAPE VALUES
LOOK FAIRLY MEAGER. OVERALL FORCING SHOULD BE BETTER, BUT SEVERE
THUNDERSTORMS DO NOT LOOK POSSIBLE. GENERAL TO STRONG THUNDERSTORM
ACTIVITY IS LIKELY THOUGH PRODUCING FREQUENT LIGHTNING, HEAVY
DOWNPOURS, AND GUSTY WINDS TO AROUND 45 MPH.
THE FRONTAL BOUNDARY CONTINUES TO MORE QUICKLY MOVE NORTHWARD
THURSDAY NIGHT INTO THE DAY ON FRIDAY. AT THE SAME TIME, MODELS
FORM A PRE-FRONTAL TROUGH AXIS THAT EXTENDS WSW FROM THE MID-
ATLANTIC THROUGH NORTHERN GEORGIA INTO CENTRAL MISSISSIPPI.
30 KNOTS OF 0-3 KM SHEAR IS FORECAST BY SEVERAL MODELS BY THE
LATE AFTERNOON INTO THE EARLY EVENING HOURS ALONG THIS FEATURE.
SBCAPE VALUES CLIMB IN THE AFTERNOON INTO THE 1000 TO 2500 J/KG
RANGE IN SEVERAL MODELS. LUCKILY, LAPSE RATES LOOK FAIRLY POOR
(5.0 TO 6.0 DEGREES/KM). DCAPE VALUES REMAIN LESS THAN 500 J/KG AS
WELL. ALL IN ALL, THERE MAY BE JUST ENOUGH SHEAR FOR A LOW END
ORGANIZED SEVERE THUNDERSTORM THREAT PRODUCING DAMAGING WINDS.
SOME ENHANCED FORCING ASSOCIATED WITH AN UPPER LEVEL DISTURBANCE
MOVING ALONG THE PRE-FRONTAL TROUGH AXIS COULD PROVIDE THE SPARK
FOR A MORE ORGANIZED CLUSTER OF STORMS ALONG WITH THE MINIMAL
SHEAR. GIVEN FORCING AND HIGH PWAT VALUES BETWEEN 1.5 AND 1.7
INCHES, THIS COULD PRODUCE BETWEEN 0.5 AND 1.0 INCHES OF
ADDITIONAL RAINFALL OVER THE AREA. SOME LOCALLY HEAVIER AMOUNTS
CAN'T BE RULED OUT GIVEN FORCING AND SOME POSSIBLE BRIEF TRAINING
OF STORMS.
THIS PRE-FRONTAL TROUGH AXIS DOESN'T MOVE MUCH FRIDAY NIGHT INTO
SATURDAY. HOWEVER, WE MAY HAVE A SLIGHT BREAK FROM HEAVIER
RAINFALL. THE BASE OF THE SHORTWAVE TROUGH AXIS LOOKS TOO FAR
SOUTH FOR MUCH CONVECTION TO DEVELOP DESPITE A GOOD AMOUNT OF
INSTABILITY DEVELOPING IN THE AFTERNOON. IT LOOKS LIKE WE WILL BE
UNDER THE INFLUENCE OF MORE SUBSIDENCE. HOWEVER, WIDESPREAD CLOUD
COVER AND MAYBE SOME SHOWERS WILL LIKELY KEEP HIGHS IN THE UPPER
70S TO LOWER 80S.
LONG TERM
(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 1120 AM CDT WED MAY 20 2026
THE POSITION OF THE PRE-FRONTAL TROUGH AXIS CHANGES LITTLE THROUGH
EARLY NEXT WEEK. OCCASIONAL DISTURBANCES CONTINUE TO MOVE EAST
ACROSS IT AT TIMES THROUGHOUT THAT PERIOD. INSTABILITY BUILDS EACH
DAY IN THE AFTERNOON TO BETWEEN 1000 AND 3000 J/KG. NOT SEEING
SHEAR INCREASE, BUT FLOODING WILL LIKELY BECOME AN ISSUE IF IT
ALREADY ISN'T BY THE WEEKEND. AT THIS TIME, IT LOOKS LIKE THERE IS
ENOUGH OF A BREAK GIVEN THE PRIMARILY DIURNAL NATURE OF THE
CONVECTION TO KEEP A MORE SERIOUS FLASH FLOODING/FLOODING THREAT
FROM MATERIALIZING. HOWEVER, SOME LOW END FLASH FLOODING OR MINOR
RIVER FLOODING IS NOT OUT OF THE QUESTION THROUGH THAT PERIOD.
OVERALL, DAYTIME HIGHS WILL REMAIN BELOW NORMAL (UPPER 70S/LOWER
80S) DUE TO CLOUD COVER AND AFTERNOON CONVECTION. OVERNIGHT LOWS
WILL REMAIN FAIRLY WARM AND HUMID ONLY DROPPING INTO THE LOWER TO
MID 60S.
AVIATION
(00Z TAFS)
ISSUED AT 450 PM CDT WED MAY 20 2026
A LOW TO MEDIUM CHANCE OF SHRA AND PERHAPS A TSRA CONTINUE TONIGHT
INTO THURSDAY. HOWEVER, CONFIDENCE IN TIMING AND LOCATION REMAIN
UNCERTAIN, SO HAVE OPTED TO KEEP VCSH AT BOTH KHSV AND KMSL FOR
NOW, BUT AMENDMENTS MAY BE NECESSARY. LOWER CEILINGS BELOW 010AGL
(IFR) ARE FORECAST TO DEVELOP BY 08Z, AND RISE INTO THE 010-025AGL
RANGE (MVFR) BY 15Z, THEN REACH ABOVE 030AGL (VFR) BY NLT 20Z.
PREVAILING WIND WILL BE LIGHT AND VARIABLE TONIGHT, THEN BECOME
SOUTHERLY AT 6KT OR LESS AFTER 15Z.
HUN WATCHES/WARNINGS/ADVISORIES
AL...NONE.
TN...NONE.
NEAR TERM...KTW
SHORT TERM....KTW
LONG TERM....KTW
AVIATION...17
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