399
FXUS64 KHUN 231933
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
233 PM CDT THU JUL 23 2026
..NEW NEAR TERM
KEY MESSAGES
UPDATED AT 1020 AM CDT THU JUL 23 2026
- FLOOD WATCH IN EFFECT FOR AREAS EAST OF I-65 THROUGH 7 PM
FRIDAY.
- LOW TO MEDIUM CHANCES OF SHOWERS AND STORMS TODAY; WILL
INCREASE TO MEDIUM TO HIGH CHANCES BY FRIDAY AND SATURDAY.
- HEAT RISK INCREASES TO MODERATE RISK (LEVEL 2 OUT OF 4)
SUNDAY/MONDAY AND THEN MAJOR (LEVEL 3 OUT OF 4) ON TUESDAY
NEAR TERM
(TONIGHT)
ISSUED AT 233 PM CDT THU JUL 23 2026
THERE HAVE BEEN NO SIGNIFICANT CHANGES TO THE FORECAST SINCE THE
MORNING UPDATE. SHOWERS HAVE REMAINED QUITE LOW IN COVERAGE WITH
LIMITED VERTICAL GROWTH. THUNDERSTORM CHANCES FOR THE REST OF THE
DAY ARE QUITE LOW GIVEN RECENT RADAR TRENDS. THICK CLOUD COVER
OVERHEAD HAS LIMITED HEATING WITH TEMPERATURES IN THE LOW TO MID
70S ACROSS SOUTHERN MIDDLE TN, UPPER 70S ALONG AND NORTH OF THE TN
RIVER, AND LOW TO MID 80S SOUTH WHERE SOME BREAKS IN THE CLOUDS
HAVE ALLOWED PEEKS OF SUNSHINE THROUGH.
PREVIOUS DISCUSSION:
SFC OBSERVATIONS THIS MORNING SHOW A STALLED BOUNDARY SITTING
ACROSS THE TENNESSEE VALLEY WITH A COOLER AND DRIER AIRMASS
SITTING JUST TO OUR NORTH ACROSS MIDDLE TENNESSEE. SATELLITE
IMAGERY HAS THICK CLOUD COVER STRETCHING ALONG THE BOUNDARY. CAMS
SHOW SHOWERS AND STORMS DEVELOPING ALONG A DIFFERENTIAL HEATING
BOUNDARY ALONG THE SOUTHERN FRIDGE OF THE CLOUD COVER AS WE HEAT
UP LATER TODAY, WHICH IS ROUGHLY ALONG AND SOUTH OF THE TENNESSEE
RIVER. WHILE NO SEVERE STORMS ARE FORECAST THIS AFTERNOON, PWATS
ARE BETWEEN 2-2.2 INCHES AND CORFIDI UP-SHEAR VECTORS ARE AROUND
10 KTS. THIS WOULD SUGGEST FAVORABLE CONDITIONS FOR BACK BUILDING
STORMS WITH HIGH RAIN RATES RESULTING IN LOCALIZED FLASH
FLOODING. AS A RESULT, A FLOOD WARNING REMAINS IN EFFECT THROUGH
7PM FRIDAY. FURTHER NORTH, LIGHT RAIN IS EXPECTED ON AND OFF
THROUGHOUT THE DAY. CLOUD COVER AND PRECIP TODAY WILL KEEP US A
BIT COOLER THAN PREVIOUS DAYS WITH AFTERNOON HIGHS ONLY RISING
INTO THE LOWER 80S NORTH OF THE TENNESSEE RIVER AND MID TO UPPER
80S SOUTH.
SHOWERS DIMINISH THIS EVENING WITH THE LOSS OF DAYTIME HEATING.
GIVEN THE VERY MOIST CONDITIONS CANNOT FULLY RULE OUT AT LEAST A
LOW/MEDIUM CHANCE FOR PRECIP OVERNIGHT, BUT COVERAGE SHOULD BE
QUITE ISOLATED. PERSISTENT CLOUD COVER WILL ALSO LIMIT ANY FOG
DEVELOPMENT BY TOMORROW MORNING.
SHORT TERM
(FRIDAY THROUGH SATURDAY)
ISSUED AT 1020 AM CDT THU JUL 23 2026
UPPER LEVEL RIDGING TO OUR WEST CONTINUES TO BE DOMINANT AS WE
HEAD THROUGH THE SHORT TERM PERIOD. THIS KEEPS NORTHWEST FLOW
ALOFT OVER THE TENNESSEE VALLEY. A SUBTLE SHORTWAVE EJECTS THROUGH
THE LOCAL FORECAST AREA ON FRIDAY AND COMBINED WITH THE STALLED
BOUNDARY OVER NORTHERN ALABAMA LEADS TO MEDIUM TO HIGH CHANCES
FOR SHOWERS AND STORMS. THE LATEST TRENDS IN THE MORNING CAM RUNS
HAVE PUSHED THE BOUNDARY FURTHER TO THE SOUTH. THIS WOULD SHIFT
THE MOST FAVORABLE AXIS FOR HEAVY RAINFALL SOUTH OF THE TENNESSEE
RIVER AND PERHAPS EVEN INTO PORTIONS OF CENTRAL ALABAMA. IF THIS
WAS TO OCCUR, THE FLOODING RISK WOULD DECREASE ACROSS NORTHERN
ALABAMA. HOWEVER, AS WE HAVE SEEN IN THE PAST SMALL MESOSCALE
FEATURES CAN SHIFT WHERE THE HEAVIEST RAINFALL OCCURS, THEREFORE
IT IS STILL IMPORTANT TO KEEP AN EYE ON THE LATEST FORECAST AND
PREPARE FOR FLASH FLOODING.
RIDING ALONG THE NORTHWEST FLOW, ANOTHER SHORTWAVE PUSHES THROUGH
THE AREA ON SATURDAY. THIS WILL ONCE AGAIN PROVIDE MEDIUM CHANCES
FOR SHOWERS AND STORMS, ESPECIALLY DURING THE PEAK HEATING HOURS.
CONFIDENCE IN COVERAGE OF STORMS IS STILL QUITE LOW WITH PERHAPS
THE MOST FAVORABLE AREA BEING ACROSS NORTHWEST ALABAMA. THEREFORE,
AT THIS TIME THERE IS NO PLAN TO EXTEND THE FLOOD WARNING.
LONG TERM
(SATURDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 923 PM CDT WED JUL 22 2026
A RIDGE DOMINATED UPPER LEVEL PATTERN WILL PREVAIL ACROSS MUCH OF
THE LOWER-48 AS WE HEAD INTO NEXT WEEK. FORECASTS OF 500MB HEIGHTS
LATE SAT INDICATED STRONG UPPER RIDGING SPRAWLED FROM THE DESERT SW,
SOUTHERN ROCKIES, AND THE HIGH PLAINS FROM WYOMING TO THE BIG BEND. A
DEEP UPPER LOW OVER THE HUDSON BAY WAS PRODUCING TROUGHING WHICH
EXTENDED SOUTHWARD ALONG THE EAST COAST. THIS FIRMLY PLACES THE
GREATER TENNESSEE VALLEY IN A NW FLOW ALOFT, WHICH APPEARS WILL
CONTINUE INTO THE MIDDLE OF NEXT WEEK. A NUMBER OF PASSING UPPER
LEVEL DISTURBANCE WITHIN THIS STREAM WILL HELP CONTRIBUTE TO
CONVECTION IMPACTING THE AREA EARLY IN THE PERIOD. EXACT TIMING AND
PLACEMENT OF THEM IS RATHER DIFFICULT, SO AM DEPENDING UPON ENSEMBLE
AND BLEND GUIDANCE VERSUS DETERMINISTIC OUTPUT.
AT THE SURFACE, A FRONTAL BOUNDARY NOW MOVING IN A NW-SE MANNER
ACROSS THE AREA SHOULD RETURN AS A WARM FRONT LATE FRI INTO SAT. THIS
WILL BRING ADDITIONAL LOWER LEVEL MOISTURE FROM THE GULF OF AMERICA
FURTHER INLAND. OUTPUT FROM THE NBM HAS PRECIPITABLE WATER AMOUNTS OF
OVER 2" ACROSS THE FORECAST FROM SAT EVENING INTO SUN MORNING. WITH
PASSING UPPER LEVEL SUPPORT, THERE WILL BE GOOD CHANCES FOR NUMEROUS
SHOWERS AND THUNDERSTORMS TO IMPACT THE TENNESSEE VALLEY. SOME OF THE
STORMS COULD BECOME STRONG. OF GREATER WORRY IS RAINFALL OUTPUT IN
SUCH A HUMID ENVIRONMENT. EXCESSIVE RAINFALL AND A POTENTIAL OF
FLOODING CANNOT BE RULED OUT; WHICH WILL BE DEPENDENT UPON HOW MUCH
RAINFALL OCCURS BEFOREHAND. THE FRONTAL BOUNDARY PER DESI AND NBM
GUIDANCE SHOULD MOVE SOUTHWARD AGAIN LATE SUN INTO MON, WITH SHOWER
ACTIVITY ENDING FOR THE START OF A NEW WORK WEEK.
DAILY TEMPERATURES INTO THE MIDDLE OF NEXT WEEK APPEAR WILL BE ON THE
RISE, IN PART THANKS TO THE STRONG UPPER RIDGE JUST TO OUR WEST. AS
SHOWER ACTIVITY ENDS ON SUN, THE HEAT WILL RETURN. HIGHS TO START A
NEW WEEK SHOULD RANGE FROM THE MID/UPPER 80S TO THE LOWER 90S WEST.
EVEN WARMER CONDITIONS ARE EXPECTED FOR THE MON-WED TIMEFRAME, WITH
HIGHS ALL THREE DAYS MAINLY IN THE LOW/MID 90S, AND LOWS IN THE
LOW/MID 70S. HEAT INDEX VALUES ON SUN SHOULD RANGE FROM THE MID/UPPER
90S EAST TO 107 IN THE MORE URBANIZED SPOTS. ANOTHER NEED FOR HEAT
ADVISORIES MAYBE NEEDED SUN, BUT APPEAR MORE LIKELY NEXT MON/TUE,
WITH VALUES RANGING FROM THE UPPER 90S TO 109 IN THE HOTTEST SPOTS.
THEY COULD BE SOME RELIEF BY THE MIDWEEK, AS ANOTHER FRONTAL BOUNDARY
MOVES ACROSS THE AREA FROM THE NORTH. THIS BOUNDARY WILL ALSO BRING
LOWER END RAIN CHANCES BACK TO PARTS OF THE VALLEY.
AVIATION
(18Z TAFS)
ISSUED AT 1215 PM CDT THU JUL 23 2026
LOW CLOUDS WILL CONTINUE TO PERSIST ACROSS NORTHERN AL THROUGH THE
TAF PERIOD. CIGS WILL LIKELY BOUNCE BETWEEN HIGH END MVFR TO LOW
VFR THROUGH THE AFTERNOON AND EVENING HOURS. SOME LIGHT SHOWERS
ARE ALSO EXPECTED AT HSV WITH LOWER CHANCES FURTHER WEST AT MSL.
CIGS DROP DOWN TO MVFR OVERNIGHT AND REMAIN THAT WAY THROUGH
TOMORROW MORNING. THUNDERSTORM CHANCES INCREASE LATE TOMORROW
MORNING AND AFTERNOON. UNCERTAIN ON EXACT TIMING AND COVERAGE SO
FOR NOW KEPT WITHIN A PROB 30 GROUP.
HUN WATCHES/WARNINGS/ADVISORIES
AL...FLOOD WATCH THROUGH FRIDAY EVENING FOR ALZ006>010-016.
TN...FLOOD WATCH THROUGH FRIDAY EVENING FOR TNZ076-096-097.
NEAR TERM...GH
SHORT TERM....GH
LONG TERM....RSB
AVIATION...GH
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