255
FXUS64 KHUN 210903 CCA
AFDHUN
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HUNTSVILLE AL
403 AM CDT TUE JUL 21 2026
..NEW NEAR TERM
KEY MESSAGES
UPDATED AT 402 AM CDT TUE JUL 21 2026
- A HEAT ADVISORY IS IN EFFECT FOR MOST OF THE TENNESSEE VALLEY
THROUGH 8 PM.
- MODERATE (LEVEL 2/4) TO MAJOR (LEVEL 3/4) HEAT RISK WILL BUILD
INTO THE TENNESSEE VALLEY THROUGH THE MIDDLE OF THE WEEK, WITH
PEAK HEAT INDEX VALUES BETWEEN 100 TO 109 DEGREES LIKELY IN
MOST LOCATIONS TODAY AND TUESDAY.
- DAILY THUNDERSTORM CHANCES WILL CONTINUE BEFORE ENDING LATER IN
THE DAY ON WEDNESDAY. A FEW STORMS COULD BECOME STRONG TO
MARGINALLY SEVERE THIS EVENING INTO EARLY WEDNESDAY MORNING.
GUSTY TO DAMAGING WINDS, FREQUENT LIGHTNING, AND LOCALLY HEAVY
RAINFALL WILL BE THE MAIN THREATS.
NEAR TERM
(TODAY)
ISSUED AT 402 AM CDT TUE JUL 21 2026
CLEAR SKIES CONTINUE TO BE IN PLACE ACROSS NORTHERN ALABAMA AND
SOUTHERN MIDDLE TENNESSEE. EXPECT THAT TO CONTINUE THROUGH
DAYBREAK. GIVEN CURRENT DEW POINT DEPRESSIONS, PATCHY FOG WILL
CONTINUE TO BE POSSIBLE THROUGH THE DAYBREAK HOURS. ADVECTION OF
LOWER DEWPOINTS FROM THE NE SHOULD HELP TO KEEP DENSE FOG FROM
FORMING THOUGH GIVEN UPSTREAM WEAK FLOW SEEN AT 1000 MB FROM THE
EAST OR SOUTHEAST.
EXPECT MORE SCATTERED CLOUDS TO FORM OVER THE AREA AFTER DAYBREAK.
THESE CLOUDS SHOULD NOT HAVE MUCH IMPACT ON AREA TEMPERATURES.
EXPECTING A WARMER DAY TODAY THAN YESTERDAY AS A RESULT WITH HIGH
TEMPERATURES CLIMBING INTO THE 92 TO 95 DEGREE RANGE IN MANY
LOCATIONS. WITH A FRONT PUSHING SOUTH TOWARDS THE AREA THIS
EVENING, HIGHER DEWPOINTS SHOULD BE FOCUSED OVER OUR AREA AGAIN
TODAY IN THE MID TO LATE AFTERNOON HOURS INTO THE EVENING HOURS.
THIS WILL DRIVE HEAT INDEX VALUES INTO THE 105 TO 109 DEGREE RANGE
IN MANY LOCATIONS AS WELL. THE EXCEPTION TO THIS LOOKS TO BE
DEKALB COUNTY AND PORTIONS OF JACKSON COUNTY. MODELS CONTINUE TO
KEEP THE AREA DRY THROUGH THE AFTERNOON HOURS. A HEAT ADVISORY
REMAINS IN EFFECT THROUGH 8 PM THIS EVENING.
SHORT TERM
(TUESDAY NIGHT THROUGH THURSDAY)
ISSUED AT 402 AM CDT TUE JUL 21 2026
AT SUNSET, STORMS WILL LIKELY BE ON THE HORIZON TO OUR NORTH
ALONG AN APPROACHING COLD FRONT. MODELS MAINTAIN A LATER ARRIVAL
OF STORMS, BETWEEN 9 PM - 12 AM. FORTUNATELY, THE LATER ARRIVAL
WILL ALLOW TIME FOR INSTABILITY TO ERODE, LEAVING ONLY A FEW
HUNDRED J/KG OF CAPE BY THE TIME STORMS GET HERE. MODELS DIVERGE
ON COVERAGE OF SHOWERS AND STORMS. SOME DISSIPATE STORMS AS THEY
ARRIVE AND OTHERS DRAG A BROKEN LINE OF STORMS THROUGH, DISSIPATING
AS THEY GO. WHAT IS CONSISTENT IS THE LACK OF SHEAR, MEANING
REGARDLESS OF THE ACTUAL COVERAGE OF STORMS, ANY STORMS THAT DO
MAKE IT THROUGH WILL OBTAIN ONLY A LOW SEVERE THREAT WITH THE
PRIMARY HAZARD BEING DAMAGING WINDS.
THE ACTUAL FRONT LOOKS TO PUSH THROUGH MOST OF THE AREA WEDNESDAY
MORNING. HOWEVER, SOME MODELS DO SHOW THE FRONT LINGERING OVER OR
JUST SOUTHEAST OF CULLMAN/MARSHALL/DEKALB COUNTIES INTO WEDNESDAY
AFTERNOON. AT THIS POINT, STORMS DO NOT LOOK SEVERE. THEN MOST
GUIDANCE PUSHES IT FULLY SOUTHEAST OF THE AREA. THIS WILL LEAVE
DRIER AND RELATIVELY COOLER TEMPERATURES IN ITS WAKE. TEMPS ON
WEDNESDAY WILL BE RELEGATED BACK TO THE LOW 90S DUE TO CLOUD COVER
AND POSSIBLE SCATTERED PRECIPITATION CHANCES. HIGH TEMPERATURES
SHOULD DROP EVEN FURTHER ON THURSDAY INTO THE HIGH 80S. DEW POINTS
WILL DROP THROUGH THE DAY ON WEDNESDAY WITH MID TO HIGH 60S DEW
POINTS IN PLACE BY THURSDAY MORNING. FROM LATE WEDNESDAY INTO
THURSDAY, THE AFORMENTIONED FRONT LOOKS TO STALL JUST TO OUR
SOUTH. THIS WILL KEEP SOME POST FRONTAL CLOUD COVER THROUGH THE
DAY ON THURSDAY AND ALSO SUPPORT LOW RAIN CHANCES (20-40%) IN FAR
SE PORTIONS OF OUR CWA. FORTUNATELY THREATS FOR BOTH SEVERE
WEATHER AND EXCESSIVE HEAT WILL REMAIN LOW. HOWEVER, REMAINING
WEATHER AWARE AND PRACTICING PROPER HEAT SAFETY ARE ALWAYS GOOD
SUMMER PRACTICES.
LONG TERM
(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 905 PM CDT MON JUL 20 2026
THE GENERAL UPPER LEVEL SETUP WILL CONSIST OF A RIDGING WEST AND
TROUGHING EAST PATTERN OVER THE GREATER NORTH AMERICAN DOMAIN. THIS
PATTERN WAS BEING KEPT IN PLACE BY OMEGA-STYLE UPPER BLOCKING OVER
THE NORTHERN PACIFIC BASIN. AT THE BEGINNING OF THE EXTENDED, UPPER
TROUGHING WILL BE IN PLACE OFF OF THE WEST COAST (THE EASTERN ANCHOR
OF THE UPPER BLOCK), WITH STRONG UPPER LEVEL RIDGING SITUATED OVER
THE SOUTHERN GREAT PLAINS. A PASSING UPPER LOW OVER THE CENTRAL
ONTARIO AND QUEBEC REGION WILL DEEPEN, AND HELP AMPLIFY UPPER
TROUGHING FROM THE EASTERN GREAT LAKES TO NORTHERN FLORIDA. THIS WILL
PLACE THE TENNESSEE VALLEY IN A WNW-ESE FLOW FROM THE LATE WEEK INTO
EARLY NEXT WEEK.
A NORTHWESTERLY UPPER LEVEL FLOW ACROSS THIS AREA, ESPECIALLY IF IT
IS DISTURBANCE LADEN, IS KNOWN FOR BRINGING SHOWERS AND THUNDERSTORMS
TO THE VALLEY. CONVECTION IN THESE REGIMES CAN BE ACCOMPANIED BY
STRONG WINDS. FOR THIS AREA, A FEW COMPLICATIONS TO THAT SIMPLISTIC
VIEW. FIRST, A COLD FRONT SHOULD BE SOUTH OF THE AREA BY LATE THU.
MOISTURE FROM TROPICAL STORM BERTHA SHOULD BE STREAMING BACK TO THE
NE, WITH SOME OF IT IMPACTING THE AREA FRI INTO SAT. ALONG WITH LOWER
LEVEL TROPICAL MOISTURE, SOME OF THE EXTENDED GUIDANCE WAS SUGGESTING
THAT UPPER LEVEL SUPPORT MOVING ACROSS THE AREA FROM LATE FRI INTO
SUN COULD BRING MORE THUNDERSTORMS TO THE AREA. IT IS WAY TOO EARLY
TO DISCERN IF THIS CONVECTION COULD BECOME MORE SIGNIFICANT, GIVEN
MUCH MODEL UNCERTAINTY THIS FAR OUT. WITH A MAIN SYNOPTIC FRONT TO
OUR SOUTH AND WITH SOME SHOWER/STORM CHANCES, DAILY HIGH/LOW
TEMPERATURES SHOULD TREND A BIT MILDER, WITH HIGHS FRI/SAT IN THE MID
80S TO AROUND 90. WARMER CONDITIONS LOOK RETURN FOR THE START OF THE
NEW WEEK, WITH HIGHS FROM THE UPPER 80S TO LOWER 90S SUN, AND LOW/MID
90S NEXT MON. LOWS THU NIGHT SHOULD RANGE IN THE MID/UPPER 60S, WITH
MAINLY LOWER 70S FOR THE FRI - SUN NIGHT PERIOD.
AVIATION
(06Z TAFS)
ISSUED AT 1224 AM CDT TUE JUL 21 2026
VFR CONDITIONS SHOULD CONTINUE A FEW MORE HOURS. HOWEVER, AROUND
08Z, WITH CLEAR SKIES AND LIGHT WINDS, EXPECT VSBYS TO BECOME MVFR
DUE TO PATCHY FOG DEVELOPMENT. SOME MODELS SHOW AN AXIS OF LOW
CLOUDS PUSHING NORTHWEST AND MAYBE OVER THE TERMINALS AROUND 9Z.
THIS COULD KEEP DENSE FOG FROM FORMING, BUT IT WILL DEPEND ON HOW
EXPANSIVE THIS LOW CLOUD DEVELOPMENT IS FROM WEST TO EAST. IF IT
IS A VERY THIN AXIS OF CLOUDS, THEN DENSE FOG STILL COULD DEVELOP.
LEFT DENSE FOG OUT OF THE TERMINALS FOR NOW, BUT MAY NEED TO BE
ADDED VIA AMENDMENTS.
HUN WATCHES/WARNINGS/ADVISORIES
AL...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR ALZ001>009-016.
TN...HEAT ADVISORY UNTIL 8 PM CDT THIS EVENING FOR TNZ076-096-097.
NEAR TERM...KTW
SHORT TERM....RAD
LONG TERM....RSB
AVIATION...KTW
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