559
FXUS64 KHUN 110303
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
1003 PM CDT WED SEP 10 2025
..NEW NEAR TERM, SHORT TERM, LONG TERM
NEAR TERM
(THIS EVENING THROUGH THURSDAY)
ISSUED AT 1003 PM CDT WED SEP 10 2025
IN THE MID/UPPER-LEVELS, NORTHWEST FLOW OF 15-25 KNOTS WILL
PERSIST ACROSS THE TN VALLEY OVERNIGHT, IN THE WAKE OF A SHORTWAVE
TROUGH THAT CROSSED THE REGION EARLIER TODAY. ALTHOUGH THIS HAS
CONTRIBUTED TO CLEAR SKIES THIS EVENING, MID-LEVEL ASCENT WILL
GRADUALLY STRENGTHEN ACROSS THE REGION EARLY TOMORROW MORNING AS A
WELL-DEFINED VORT MAX (INITIALLY ACROSS NORTHERN IL) DIGS
SOUTHEASTWARD INTO THE LOWER OH VALLEY. THIS WILL RESULT IN AN
INCREASING COVERAGE OF ALTOSTRATUS CLOUDS, WHICH WILL BOTH KEEP
TEMPERATURES WARMER (60-65F RANGE) COMPARED TO PREVIOUS NIGHTS AND
REDUCE CONCERN FOR FOG DEVELOPMENT IN SPITE OF LIGHT/VARIABLE
WINDS AND DEWPOINTS ALSO IN THE L-M 60S. RECENT VERSIONS OF BOTH
THE GLOBAL MODELS AND HIGHER RESOLUTION CAMS HAVE BEEN QUITE
INCONSISTENT REGARDING THE POTENTIAL DEVELOPMENT OF PRECIPITATION
IN THIS REGIME. HOWEVER, WITH WEAK VERTICAL MOTIONS EXPECTED TO
SLOWLY MOISTEN THE SUBCLOUD LAYER, IT WOULD NOT BE OUT OF THE
QUESTION TO SEE A FEW LIGHT SHOWERS DEVELOP TO OUR NORTH AFTER
MIDNIGHT, WHICH COULD SPREAD SOUTH-SOUTHEASTWARD INTO AND ACROSS
OUR FORECAST AREA BETWEEN 8-14Z. WE WILL INCLUDE A VERY LOW POP
FOR THIS SCENARIO, WHICH MAY ONLY AMOUNT TO A FEW SPRINKLES OF
RAIN AND TRACE AMOUNTS OF PRECIPITATION FOR A FEW LOCATIONS.
PRESENT INDICATIONS ARE THAT THE MID-LEVEL STRATUS LAYER WILL
BEGIN TO ERODE LATE TOMORROW MORNING, WITH A PERIOD OF UNIMPEDED
INSOLATION PERMITTING TEMPERATURES TO WARM INTO THE U80S-L90S BY
EARLY AFTERNOON. AS THE VORT MAX (INITIALLY OVER THE LOWER OH
VALLEY) DIGS FURTHER SOUTHEASTWARD INTO THE SOUTHERN APPALACHIANS,
A POCKET OF COLDER AIR ALOFT WILL SUPPORT CAPE IN THE 1000-1500
J/KG RANGE (PERHAPS A BIT HIGHER IN SOME LOCATIONS). AS A SUBTLE
SURFACE WIND SHIFT AXIS BEGINS TO TRACK SOUTHWESTWARD TOMORROW
AFTERNOON, THIS SHOULD INITIATE THE DEVELOPMENT OF WIDELY
SCATTERED SHOWERS (AND PERHAPS A FEW THUNDERSTORMS) NEAR OR
IMMEDIATELY NORTH OF OUR FORECAST AREA (MIDDLE TN) EARLY TOMORROW
AFTERNOON AS PWAT VALUES WILL BE IN THE 1-1.2" RANGE. WITH FLOW
ALOFT PREDICTED TO VEER TO NNW AND INCREASE INTO THE 20-30 KNOT
RANGE, THIS ACTIVITY WILL TRAVEL SOUTHWARD, POTENTIALLY IMPACTING
OUR CWFA DURING THE LATE AFTERNOON/EARLY EVENING HOURS BEFORE
SLOWLY DISSIPATING AND SPREADING FURTHER SOUTHWARD LATE TOMORROW
EVENING. LIGHTNING AND PERHAPS A BRIEF WIND GUST UP TO 30-40 MPH
WILL BE THE MAIN CONCERN WITH ANY THUNDERSTORMS, BUT AS WE
MENTIONED YESTERDAY, A SHALLOW LAYER OF WARM AIR ALOFT MAY LIMIT
UPDRAFT GROWTH AND THE OVERALL RISK FOR LIGHTNING/THUNDER.
SHORT TERM
(THURSDAY NIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 1003 PM CDT WED SEP 10 2025
OVER THE COURSE OF THE SHORT TERM PERIOD, A MID-LEVEL VORT MAX
(INITIALLY ACROSS THE SOUTHERN APPALACHIANS) WILL DIG FURTHER
SOUTHEASTWARD, EVENTUALLY DEEPENING INTO A PARTIALLY CLOSED
CYCLONE ALONG THE COAST OF SC BY SATURDAY NIGHT. IN RESPONSE TO
THIS AND THE ORIENTATION OF A HIGHLY AMPLIFIED 500-MB RIDGE
(EXTENDING FROM THE SOUTHERN PLAINS INTO THE CANADIAN PRAIRIE
PROVINCES), MID/HIGH-LEVEL WINDS WILL VEER TO NNE AND GRADUALLY
FALL BACK INTO THE 15-25 KNOT RANGE, RESULTING IN DRYING PROFILES
ALOFT. FOLLOWING THE DEPARTURE OF ANY EVENING SHOWERS OR
THUNDERSTORMS TOMORROW, A SLIGHTLY DRIER AND MORE STABLE LOW-
LEVEL AIRMASS WILL BE ADVECTED INTO THE REGION WITHIN A LIGHT NE
FLOW REGIME ALONG THE SOUTHERN PERIPHERY OF A CANADIAN SURFACE
HIGH CENTERED WELL TO OUR NORTHEAST, AND THIS WILL YIELD A
PRECIPITATION-FREE FORECAST FOR THE ENTIRE PERIOD. DUE TO THE DRY
NATURE OF THE AIRMASS AND ABSENCE OF THERMAL ADVECTION ACROSS OUR
REGION, HIGHS WILL WARM A DEGREE OR SO EACH DAY (REACHING THE MID
90S ACROSS THE WEST BY SATURDAY). OVERNIGHT LOWS WILL REMAIN IN
THE L-M 60S, BUT MAY BE A FEW DEGREES COOLER SATURDAY MORNING.
LONG TERM
(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 1003 PM CDT WED SEP 10 2025
FORECAST DATA FROM THE LATEST SUITE OF GLOBAL MODELS SUGGESTS
THAT A WEAKENING SUBTROPICAL HIGH ACROSS TX WILL RETROGRADE
WESTWARD INTO THE SOUTHERN ROCKIES/SOUTHWESTERN CONUS AND ADJACENT
PORTIONS OF NORTHERN MEXICO OVER THE COURSE OF THE LONG TERM
PERIOD. HOWEVER, A SLOW-MOVING LONGWAVE TROUGH OVER THE NORTHERN
ROCKIES WILL MAINTAIN A NARROW BUT AMPLIFIED 500-MB RIDGE
EXTENDING NORTHEASTWARD FROM THE DEPARTING HIGH INTO THE GREAT
LAKES AND SOUTHERN CANADA. ALTHOUGH THE RIDGE AXIS IS PREDICTED TO
BE ORIENTED WELL TO OUR NORTHWEST, IT WILL EFFECTIVELY DEFLECT
CONVECTIVE CLOUDS AND PRECIPITATION (ASSOCIATED WITH SEVERAL
SMALLER SCALE WAVES EJECTING OUT OF THE NORTHERN ROCKIES TROUGH),
WITH ABUNDANT INSOLATION AND GENERAL LACK OF CLOUDS CONTRIBUTING
TO AN EXTENDED PERIOD OF HOT/DRY WEATHER. HIGHS EACH DAY FROM
SUNDAY-WEDNESDAY WILL RANGE FROM THE U80S-L90S/E TO L-M 90S/W, BUT
WITH DEWPOINTS IN THE U50S-L60S, HI VALUES WILL BE NEAR OR ONLY A
DEGREE OR SO WARMER THAN AMBIENT AIR TEMPERATURES. OVERNIGHT LOWS
WILL REMAIN IN THE L-M 60S.
AVIATION
(00Z TAFS)
ISSUED AT 731 PM CDT WED SEP 10 2025
VFR/SKC CONDITIONS WILL PERSIST AT THE HSV/MSL TERMINALS THROUGH
LATE THIS EVENING. HOWEVER, LIFT RELATED TO AN UPPER-AIR
DISTURBANCE DROPPING SOUTH-SOUTHEASTWARD INTO THE LOWER OH VALLEY
WILL LEAD TO AN INCREASING COVERAGE OF MID-LEVEL CLOUDS BY 5Z THAT
WILL TRANSITION INTO A SCT CU FIELD BY 16Z. ALTHOUGH LATEST MODEL
GUIDANCE OFFERS A WIDE VARIETY OF SOLUTIONS REGARDING THE
POTENTIAL COVERAGE OF LIGHT PRECIPITATION (ASSOCIATED WITH THE
SAME MECHANISM) EARLY TOMORROW MORNING, IT IS CERTAINLY POSSIBLE
THAT SOME VERY LGT SHRA OR SPRINKLES MAY OCCUR AT OR IN THE
VICINITY OF THE TERMINALS BTWN 10-14Z. A SLIGHTLY GREATER RISK FOR
SHOWERS (AND PERHAPS A FEW TSRA) WILL OCCUR TOMORROW AFTN,
BEGINNING AROUND 20Z. DUE TO UNCERTAINTIES REGARDING THE SPATIAL
COVERAGE OF CONVECTION WE HAVE NOT MENTIONED ANYTHING IN THE TAFS
AT THIS POINT, BUT A PROB30 GROUP MAY EVENTUALLY BE WARRANTED FROM
20-2Z.
HUN WATCHES/WARNINGS/ADVISORIES
AL...NONE.
TN...NONE.
NEAR TERM...70/DD
SHORT TERM...70/DD
LONG TERM...70/DD
AVIATION...70/DD
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