956
FXUS64 KHUN 130544
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1244 AM CDT THU AUG 13 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1114 PM CDT WED AUG 12 2026
- CLUSTERS OF THUNDERSTORMS WILL CONTINUE TO SPREAD SOUTHEASTWARD
ACROSS THE TN VALLEY LATE THIS EVENING BEFORE DISSIPATING.
STRONG WINDS, EXCESSIVE LIGHTNING AND TORRENTIAL DOWNPOURS WILL
ACCOMPANY THE MOST INTENSE CELLS.
- THE COVERAGE OF AFTERNOON/EARLY EVENING THUNDERSTORMS IS
EXPECTED TO PROGRESSIVELY DECREASE FROM THURSDAY-SUNDAY, BUT A
FEW STORMS WILL BE POSSIBLE EACH DAY (ESPECIALLY IN THE EAST).
CONDITIONS WILL REMAIN FAVORABLE FOR LOCALLY DAMAGING DOWNBURST
WINDS WITH THIS ACTIVITY.
- A HEAT ADVISORY REMAINS IN EFFECT FOR THE ENTIRE FORECAST AREA
THROUGH SUNDAY, WITH EXTENSIONS LIKELY INTO THE MIDDLE OF NEXT
WEEK.
NEAR TERM
(THIS EVENING THROUGH THURSDAY)
ISSUED AT 1114 PM CDT WED AUG 12 2026
OVER THE COURSE OF THE NEAR TERM PERIOD, THE CENTER OF A
SUBTROPICAL HIGH IN THE MID-LEVELS WILL MIGRATE SLOWLY NORTHWARD
ACROSS THE EASTERN GULF. ALTHOUGH THIS WILL INITIALLY SUSTAIN NW
FLOW ALOFT OF 15-25 KNOTS ACROSS THE TN VALLEY, HIGH-LEVEL WINDS
WILL BEGIN TO WEAKEN TOMORROW, AS RIDGING ALOFT BECOMES MORE
AMPLIFIED FROM THE CENTRAL GULF COAST NORTHWARD INTO THE LOWER OH
VALLEY. AT THE SURFACE, LIGHT-MODERATE SW FLOW WILL PREVAIL
BETWEEN LOW PRESSURE ACROSS WESTERN KS AND A NARROW RIDGE LYING
ACROSS THE NORTHERN GULF. HOWEVER, A REMNANT OUTFLOW BOUNDARY
(ORIGINALLY GENERATED BY A LARGE MCS TO OUR NORTHEAST YESTERDAY
EVENING) CURRENTLY EXTENDS FROM SOUTHWESTERN TN THROUGH NORTHERN
AL/GA AND INTO WESTERN SC. BASED ON CURRENT RADAR DATA, IT IS
BECOMING APPARENT THAT CLUSTERS OF THUNDERSTORMS WILL CONTINUE TO
INITIATE IN THE GENERAL VICINITY OF THIS FEATURE, AIDED BY A
WESTERLY LOW-LEVEL JET OF 15-25 KNOTS AND A SUBTLE MID-LEVEL WAVE
CROSSING THE REGION. AS CELLS MATURE, THEY WILL SPREAD EAST-
SOUTHEASTWARD, AND ALTHOUGH THERE IS NO CLEAR INDICATION REGARDING
WHEN THIS REGIME WILL END, IT IS LIKELY TO PERSIST THROUGH AT
LEAST 4-6Z.
OF SECONDARY CONCERN IS A SEPARATE SMALL CLUSTER OF THUNDERSTORMS
CURRENTLY DROPPING SOUTHEASTWARD ACROSS SOUTHERN IL/WESTERN KY.
ALTHOUGH THIS FEATURE IS PREDICTED TO DECAY AS IT ADVANCES FURTHER
SOUTHEASTWARD INTO WESTERN/MIDDLE TN AFTER MIDNIGHT, OUTFLOW
COULD REGENERATE SHOWERS AND SOME THUNDERSTORMS IN OUR REGION ONCE
AGAIN PRIOR TO SUNRISE. FOR AT LEAST THE NEXT COUPLE OF HOURS,
BOTH MUCAPE (1500-2000 J/KG) AND DCAPE (1000-1250 J/KG) WILL
SUPPORT A LIMITED RISK FOR LOCALLY DAMAGING DOWNBURST WINDS (UP TO
60 MPH), EXCESSIVE LIGHTNING AND PERHAPS EVEN SOME SMALL HAIL
WITH THE MOST INTENSE CORES. ADDITIONALLY, FLASH FLOODING WILL BE
A CONCERN DUE TO PWAT VALUES IN THE 1.8-2" RANGE, SLOW STORM
MOTIONS AND THE POTENTIAL FOR BACKBUILDING CONVECTION. PRESUMING
THAT THE COVERAGE OF PRECIPITATION DIMINISHES DURING THE EARLY
MORNING HOURS, PATCHY, LOCALLY DENSE FOG WILL BE POSSIBLE IN
LOCATIONS THAT HAVE RECEIVED WETTING RAINFALL, AS TEMPS SLOWLY
FALL INTO THE L-M 70S.
AS THE PREVIOUSLY MENTIONED SUBTROPICAL RIDGE BEGINS TO ASSERT
MORE OF AN INFLUENCE ACROSS OUR CWFA TOMORROW, WE EXPECT MOSTLY
SUNNY SKIES TO EXIST FOR THE MAJORITY OF THE DAY, PERMITTING
AFTERNOON TEMPS TO RISE WELL INTO THE L-M 90S FOR THE ENTIRE
VALLEY. WITH FORECAST SOUNDINGS NOT CONDUCIVE FOR DEEP MIXING,
DEWPOINTS SHOULD REMAIN IN THE U60S-M70S, RESULTING IN APPARENT
TEMPS OF 102-108F, AND A HEAT ADVISORY REMAINS IN EFFECT. ALTHOUGH
CONDITIONS APPEAR LESS FAVORABLE FOR CONVECTION TOMORROW, A FEW
THUNDERSTORMS MAY DEVELOP BY MID-LATE AFTERNOON BOTH IN THE
VICINITY OF THE ORIGINAL OUTFLOW BOUNDARY (LIKELY POSITIONED FROM
SOUTHWESTERN TN THROUGH NORTHERN MS AND CENTRAL AL) AS WELL AS IN
THE VICINITY OF A SECONDARY MESOSCALE BOUNDARY (LIKELY POSITIONED
FROM EASTERN KY SOUTHWARD INTO NORTHERN GA). WHILE IT IS ENTIRELY
POSSIBLE THAT NEITHER FEATURE WILL LEAD TO STORM DEVELOPMENT IN
OUR REGION, HIGH CAPE/DCAPE AND STEEP LOW-LEVEL LAPSE RATES WILL
SUPPORT LOCALLY DAMAGING DOWNBURST WINDS ONCE AGAIN.
SHORT TERM
(THURSDAY NIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 1114 PM CDT WED AUG 12 2026
SHORT TERM MODEL DATA CONTINUES TO SUGGEST THAT A STRENGTHENING
SUBTROPICAL HIGH IN THE MID-LEVELS WILL EXPAND AS IT BUILDS
NORTHWARD THROUGH THE FIRST HALF OF THE WEEKEND (WITH THE RIDGE
LIKELY TO EXTEND FROM EASTERN PARTS OF THE SOUTHERN PLAINS TO THE
SOUTHEASTERN ATLANTIC COAST BY 12Z SUNDAY). WITH THE BUILDING
RIDGE EXPECTED TO BEGIN DEFLECTING STORM CLUSTERS TO THE NORTH OF
OUR REGION AS EARLY AS THURSDAY NIGHT, CHANCES FOR SHOWERS AND
THUNDERSTORMS WILL REMAIN RATHER LOW THROUGH THE PERIOD, AS BROAD
SCALE SUBSIDENCE AND WEAK STEERING CURRENTS WILL DOMINATE THE
LOCAL SYNOPTIC PATTERN. THAT SAID, INTENSE HEATING ALONG THE
HIGHER TERRAIN OF NORTHEAST AL ON FRIDAY MAY STILL INITIATE A FEW
AFTERNOON THUNDERSTORMS WHICH COULD PRODUCE LOCALLY DAMAGING
DOWNBURST WINDS GIVEN A FAVORABLE THERMODYNAMIC ENVIRONMENT.
DURING THE TIMEFRAME FROM FRIDAY NIGHT-SATURDAY NIGHT, THERE ARE
INDICATIONS THAT A LOW-AMPLITUDE EASTERLY WAVE MAY UNDERCUT THE
RIDGE AND SHIFT WESTWARD ALONG THE NORTHERN GULF COAST, WHICH MAY
ALSO PROVIDE SUPPORT FOR ISOLATED THUNDERSTORMS (PARTICULARLY
ACROSS PORTIONS OF NORTHEAST AL, WHERE OUTFLOW FROM MORE EXTENSIVE
CONVECTION ACROSS NORTH GA/CENTRAL AL MAY ENTER THE REGION).
WITH THE GENERAL LACK OF CLOUD COVER AND CONVECTIVE IMPACTS,
AFTERNOON TEMPERATURES WILL CONTINUE TO RISE (REACHING THE M-U 90S
IN THE LOWER ELEVATIONS BOTH FRIDAY AND SATURDAY). ALTHOUGH THERE
ARE SOME INDICATIONS THAT A DEEPER MIXING LAYER MAY LOWER
AFTERNOON DEWPOINTS INTO THE MID 60S ACROSS PARTS OF NORTHWEST AL
(ESPECIALLY BY SATURDAY), HEAT INDEX BOTH DAYS WILL REMAIN IN THE
104-110F RANGE (PERHAPS 110-112F IN URBAN LOCATIONS), AND THE HEAT
ADVISORY WILL CONTINUE THROUGH THE UPCOMING WEEKEND, AS OVERNIGHT
LOWS IN THE M-U 70S WILL ONLY COMPOUND IMPACTS.
LONG TERM
(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 1114 PM CDT WED AUG 12 2026
GLOBAL MODELS CONTINUE TO INDICATE THAT AN INTENSE MID-LEVEL
SUBTROPICAL HIGH (INITIALLY CENTERED ACROSS THE GULF COAST STATES)
WILL RETROGRADE WESTWARD INTO AZ/NM EARLY IN THE EXTENDED PERIOD,
AS A NORTHERN STREAM SHORTWAVE TROUGH DIGS SOUTHEASTWARD ACROSS
THE CANADIAN PRAIRIE. THIS EVOLUTION WILL ALLOW WNW FLOW ALOFT OF
10-20 KNOTS TO BECOME ESTABLISHED ACROSS THE REGION ONCE AGAIN BY
MONDAY, PERHAPS ALLOWING A WEAK COLD FRONT TO DROP SOUTHWARD INTO
THE REGION AT SOME POINT MONDAY NIGHT OR TUESDAY. PRIOR TO THE
ARRIVAL OF THE FRONT, VERY HOT AFTERNOON TEMPERATURES WILL EXIST
ON BOTH SUNDAY AND MONDAY, WITH SOME LOCATIONS LIKELY TO REACH OR
EXCEED 100F BOTH AFTERNOONS. ALTHOUGH FORECAST SOUNDINGS SUGGEST
INCREASINGLY FAVORABLE PROFILES FOR DEEP MIXING (WHICH COULD
RESULT IN DEWPOINTS PERHAPS MIXING OUT INTO THE L-M 60S ACROSS
LARGE PORTIONS OF THE FORECAST AREA BOTH DAYS), APPARENT TEMPS
SOLIDLY IN THE 105-110F RANGE SUGGEST THAT THE CURRENT HEAT
ADVISORY WILL NEED TO BE EXTENDED INTO MONDAY.
SHOULD THE WEAK COLD FRONT (MENTIONED ABOVE) INDEED ENTER THE
REGION ON MONDAY NIGHT OR TUESDAY, IT WOULD LIKELY BE ACCOMPANIED
BY A BROKEN BAND OF CONVECTION THAT MAY STRUGGLE TO SURVIVE AS IT
ENTERS A WELL-MIXED AIRMASS (WITH LOWER MOISTURE CONTENT AND CAPE
COMPARED TO WHAT WE ARE EXPERIENCING CURRENTLY). HOWEVER, THERE IS
A HIGH DEGREE OF UNCERTAINTY REGARDING THIS SCENARIO, AND FOR
THIS REASON WE WILL ONLY ADVERTISE A LOW (10-30% POP) WITH
AFTERNOON TEMPS MERELY DROPPING BACK INTO THE L-M 90S.
AVIATION
(06Z TAFS)
ISSUED AT 1244 AM CDT THU AUG 13 2026
AFTER AN INCREASE IN TSRA NEAR A LINGERING OUTFLOW BOUNDARY
YESTERDAY EVENING, IT NOW APPEARS AS IF CONVECTION IS DIMINISHING
IN BOTH COVERAGE AND INTENSITY. HOWEVER, BASED ON CURRENT RADAR
DATA, WE WILL INCLUDE A 2-HR TEMPO GROUP FOR MVFR VSBY REDUCTIONS
IN SHRA AT HSV, FOLLOWED BY A SEPARATE TEMPO GROUP AT BOTH
TERMINALS FROM 9-13Z (FOR MVFR VSBY REDUCTIONS IN BR/FG). SW FLOW
WILL INCREASE TO 5-10 KTS ONCE AGAIN BY 15Z, WITH DEVELOPMENT OF A
SCATTERED CU FIELD EXPECTED AROUND THIS TIME, AS WELL. ALTHOUGH A
FEW STORMS MAY OCCUR IN OUR GENERAL REGION ONCE AGAIN DURING THE
MID-LATE AFTN HOURS, THE THREAT FOR IMPACTS AT THE TERMINALS IS
TOO LOW TO MENTION IN THE FORECAST ATTM. SKIES WILL BECOME MOSTLY
CLEAR THIS EVENING, WITH A LGT WSW FLOW CONTINUING THRU 6Z FRIDAY.
CLIMATE
ISSUED AT 157 PM CDT WED AUG 12 2026
THE CLIMATE PREDICTION CENTER HAS INCLUDED MUCH OF NORTHERN
ALABAMA IN A HIGH RISK FOR MUCH ABOVE NORMAL TEMPERATURES AND MUCH
OF SOUTHERN MIDDLE TENNESSEE AND FAR NORTHEAST ALABAMA IN A
MODERATE RISK FOR MUCH ABOVE NORMAL TEMPERATURES ON AUGUST 20TH
AND 21ST.
ALL OF NORTHERN ALABAMA AND SOUTHERN MIDDLE TENNESSEE IS ALSO
INCLUDED IN A MODERATE RISK FOR MUCH ABOVE NORMAL TEMPERATURES
AUGUST 22ND AND 23RD.
THEREFORE, THERE IS A 40-60% CHANCE IN THE MODERATE RISK
LOCATIONS AND A 60-80% CHANCE FOR THOSE IN THE HIGH RISK AREAS FOR
TEMPERATURES ABOVE 95 TO 97 DEGREES F AND HEAT INDEX VALUES ABOVE
105 TO 110 DEGREES F DURING THIS PERIOD.
MORE INFORMATION ON THE CPC U.S. HAZARDS OUTLOOK CAN BE FOUND AT:
HTTPS://WWW.CPC.NCEP.NOAA.GOV/PRODUCTS/PREDICTIONS/THREATS/THREATS.PHP
HUN WATCHES/WARNINGS/ADVISORIES
AL...HEAT ADVISORY UNTIL 7 PM CDT SUNDAY FOR ALZ001>010-016.
TN...HEAT ADVISORY UNTIL 7 PM CDT SUNDAY FOR TNZ076-096-097.
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...70/DD
AVIATION...70/DD
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