613
FXUS64 KHUN 201819
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
119 PM CDT MON JUL 20 2026
..NEW NEAR TERM
KEY MESSAGES
UPDATED AT 936 AM CDT MON JUL 20 2026
- A HEAT ADVISORY WILL BE IN EFFECT FOR MOST OF THE TENNESSEE
VALLEY FROM 10 AM TODAY THROUGH TUESDAY AT 7 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 INTO EARLY THIS WEEK.
A FEW STORMS COULD BECOME STRONG TO MARGINALLY SEVERE TUESDAY
EVENING/NIGHT. GUSTY TO DAMAGING WINDS, FREQUENT LIGHTNING, AND
LOCALLY HEAVY RAINFALL WILL BE THE MAIN THREATS.
NEAR TERM
(TONIGHT)
ISSUED AT 119 PM CDT MON JUL 20 2026
MODERATE (LEVEL 2/4) TO MAJOR (LEVEL 3/4) HEAT RISK WILL CONTINUE
THIS AFTERNOON WITH PEAK HEAT INDEX VALUES BETWEEN 100-109 DEGREES
AND INTO THE OVERNIGHT HOURS WITH LOWS REMAINING ABOVE 75 DEGREES
IN MOST LOCATIONS. A HEAT ADVISORY REMAINS IN EFFECT THIS
AFTERNOON/EVENING, OVERNIGHT, AND THROUGH 8 PM TUESDAY. A CU
FIELD OVER THE AREA HAS JUST NOW BEGUN TO LOOK MORE AGITATED AND
THINK AT LEAST A 30-40% CHANCE FOR DIURNALLY DRIVEN STORMS IS STILL
PLAUSIBLE ALONG A FEW RESIDUAL OUTFLOW BOUNDARIES THAT REMAIN IN
PLACE. MLCAPE VALUES AROUND 2000-2500 J/KG AND LAPSE RATES AROUND
7-8 C/KM WILL SUPPORT AT LEAST A FEW LOCALLY STRONG STORMS, WITH
GUSTY WINDS AND LOCALLY HEAVY DOWNPOURS THE PRIMARY THREAT. ANY
CONVECTION THAT DOES FORM WILL WANE AFTER SUNSET, WITH PATCHY FOG
LIKELY TO DEVELOP IN LOCATIONS THAT DO RECEIVE RAINFALL.
SHORT TERM
(TUESDAY THROUGH WEDNESDAY)
ISSUED AT 936 AM CDT MON JUL 20 2026
MAJOR (LEVEL 3/4) HEAT IMPACTS WILL DEVELOP ACROSS MUCH OF THE
TENNESSEE VALLEY ON TUESDAY AS HIGH PRESSURE (AND THE SUBSEQUENT
HEAT DOME) BUILDS EAST INTO THE TENNESSEE VALLEY. THIS WILL
PROMOTE MOSTLY SUNNY AND VERY WARM CONDITIONS ACROSS THE REGION ON
TUESDAY, WITH SOUTHERLY FLOW HELPING TO PUSH HIGH TEMPERATURES
INTO THE MID 90S IN MOST LOCATIONS. COMBINED WITH DEWPOINTS IN THE
MID TO UPPER 70S, THIS WILL CREATE HEAT INDEX VALUES BETWEEN
105-110 DEGREES ACROSS MUCH OF THE REGION AND A HEAT ADVISORY
REMAINS IN EFFECT THROUGH 8 PM TUESDAY.
SPEAKING OF THUNDERSTORM CHANCES, ONE OF THE REASONS THAT WE'RE SO
CONFIDENT IN THE HEAT RISK ON TUESDAY IS THAT WE SHOULD BE LARGELY
DEVOID OF STORMS AND CLOUD COVER DURING THE DAY. THE MAIN FOCUS
FOR THESE STORMS WILL BE A COLD FRONT IN THE OHIO VALLEY AND
STORMS AREN'T EXPECTED TO INITIATE ON IT UNTIL THE VERY LATE
AFTERNOON AND EVENING. LATEST GUIDANCE, ESPECIALLY THE HI-RES KEEP
POPS VERY LOW DURING THE AFTERNOON AND MUCH OF THE EVENING
(10-20%), WITH THE LINE OF STORMS NOT MAKING IT IN UNTIL AROUND
MIDNIGHT. AT THIS POINT, THE THREAT SHOULD BE CONSIDERABLY LOWER
GIVEN THE LIMITED INSTABILITY. STILL, SPC HAS NORTHERN PORTIONS
OF THE REGION CLIPPED BY A MARGINAL RISK (LEVEL 1/5) TO HIGHLIGHT
THE LOW-END THREAT FOR A COUPLE STRONG TO MARGINALLY SEVERE WIND
GUSTS IN THE LATE EVENING AND OVERNIGHT TIMEFRAME. THESE STORMS
WILL CONTINUE TO WEAKEN AS THEY MOVE THROUGH THE AREA LATE
TUESDAY, WITH GUSTY WINDS/HEAVY DOWNPOURS THE MAIN THREAT.
FOR WEDNESDAY, THE ACTUAL COLD FRONT SHOULD BE PUSHING THROUGH THE
REGION FROM THE LATE MORNING THROUGH THE AFTERNOON. THE STORM
ENVIRONMENT SHOULD BE FAIRLY WORKED OVER THANKS TO THE OVERNIGHT
CONVECTION, BUT A LOW-MEDIUM (30-60) CHANCE FOR SHOWERS AND A FEW
STORMS WILL EXIST THROUGH THE AFTERNOON. THE CLOUDS/RAIN CHANCES
SHOULD LOWER HIGHS A TOUCH INTO THE UPPER 80S TO LOWER 90S, BUT
HEAT INDEX VALUES COULD STILL REACH OR JUST EXCEED TO THE 100
DEGREE MARK ACROSS MUCH OF THE AREA.
LONG TERM
(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 1014 PM CDT SUN JUL 19 2026
THE PASSAGE OF A COLD FRONT ON WEDNESDAY WILL MARK THE START OF
THE LONG TERM FORECAST WITH SLIGHTLY LOWER TEMPS AND DEW POINTS.
HIGHS THROUGH THE LONG TERM PERIOD WILL BE RELEGATED TO THE LOW
90S WITH DEW POINTS DROPPING BACK TO THE HIGH 60S TO LOW 70S. THE
PASSAGE OF THE COLD FRONT WILL MARK A PATTERN CHANGE WITH A
TROUGHING EAST/RIDGING WEST REGIME SETTING UP THROUGH THE LONG
TERM FORECAST. AS SUCH, WE WILL FIND OURSELVES SOLIDLY IN NW FLOW
AS WE HEAD INTO THE WEEKEND AND INTO EARLY NEXT WEEK. THIS WILL
KEEP MEDIUM RAIN CHANCES IN THE FORECAST AS SEVERAL SHORTWAVES
RIPPLE ALONG THE BASE OF THE TROUGH. THIS SET UP DOES FAVOR MCSS
DROPPING SOUTH ALONG THE BASE OF THE TROUGH, POTENTIALLY INTO OUR
AREA. AS THE SET UP DRAWS NEARER, WE WILL CONTINUE TO EVALUATE MCS
POTENTIAL AND ANY INCREASED THREATS FOR SEVERE WEATHER OR
FLOODING.
AVIATION
(18Z TAFS)
ISSUED AT 1221 PM CDT MON JUL 20 2026
VFR CONDITIONS WILL BE THE PREDOMINANT FLIGHT CATEGORY AT EACH
TERMINAL THROUGH THE PERIOD. THE ONE CAVEAT MAY BE IF A TSRA
IMPACTS EITHER TERMINAL BETWEEN 19-23Z WHEN LOCALIZED MVFR
CONDITIONS DUE TO REDUCED VISIBILITIES AND CEILINGS MAY OCCUR.
HUN WATCHES/WARNINGS/ADVISORIES
AL...HEAT ADVISORY UNTIL 8 PM CDT TUESDAY FOR ALZ001>009-016.
TN...HEAT ADVISORY UNTIL 8 PM CDT TUESDAY FOR TNZ076-096-097.
NEAR TERM...AMP.24
SHORT TERM....AMP
LONG TERM....RAD
AVIATION...AMP
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