588
FXUS64 KHUN 011035
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
435 AM CST SAT FEB 1 2025
..NEW NEAR TERM, SHORT TERM, LONG TERM
NEAR TERM
(TODAY)
ISSUED AT 435 AM CST SAT FEB 1 2025
NORTHWEST FLOW ALOFT WILL CONTINUE TO WEAKEN ACROSS THE TN VALLEY
THIS MORNING, IN THE WAKE OF A SHORTWAVE TROUGH DEPARTING TO THE
EAST. AT THE SURFACE, WINDS WILL GRADUALLY VEER TO NNW AND
STRENGTHEN AS THE LEADING EDGE OF A MODIFIED CANADIAN AIRMASS
(CENTERED ACROSS SOUTHERN ONTARIO) SPREADS SOUTHWARD INTO THE
REGION. HOWEVER, PRIOR TO ARRIVAL OF STRONGER MIXING AND A
SLIGHTLY DRIER BOUNDARY LAYER AIRMASS, THE COMBINATION OF TEMPS IN
THE U30S-L40S AND DEWPOINT DEPRESSIONS AT ZERO REMAIN FAVORABLE
FOR LOCALLY DENSE FOG (ESPECIALLY IN THE VALLEYS OF NORTHEAST
AL/SOUTHERN TN), AND AN SPS HAS BEEN ISSUED THROUGH 8 AM CST TO
ADDRESS THE RISK FOR SIGNIFICANT VISIBILITY REDUCTIONS IN THESE
AREAS.
OVER THE COURSE OF THE DAY, WINDS ALOFT WILL BACK TO THE WEST AND
SUBSIDE FURTHER AS OUR REGION WILL BE LOCATED BENEATH THE
NORTHERN EDGE OF A STRONG SUBTROPICAL RIDGE CENTERED ACROSS THE
GREATER ANTILLES AND ADJACENT PORTIONS OF THE SOUTHEASTERN
BAHAMAS. IN THE LOW-LEVELS, LIGHT NNW WINDS THIS MORNING WILL
SLOWLY VEER TO THE E AS THE HIGH TO OUR NORTH BUILDS SOUTHEASTWARD
INTO THE EASTERN GREAT LAKES. LIMITED MIXING IN THIS REGIME WILL
NOT HELP TO DISPERSE A BAND OF LOW STRATUS CLOUDS (CURRENTLY
DROPPING SOUTHWARD ALONG THE I-40 CORRIDOR), AND THUS WE EXPECT
CLOUDY SKIES FOR MUCH OF THE DAY WITH HIGHS RANGING FROM THE L50S
(NORTH) TO U50S (SOUTH).
SHORT TERM
(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 435 AM CST SAT FEB 1 2025
LATEST MODEL GUIDANCE SUGGESTS THAT UNAMPLIFIED W TO WNW FLOW
ALOFT WILL EXIST ACROSS THE TN VALLEY FOR THE DURATION OF THE
SHORT TERM PERIOD, AS THE SUBTROPICAL RIDGE (MENTIONED ABOVE)
GRADUALLY RETROGRADES WESTWARD ACROSS THE NORTHWESTERN CARIBBEAN
SEA. AT THE SURFACE, LIGHT SSE FLOW WILL RETURN TO THE REGION
LATER TONIGHT, WITHIN THE GRADIENT BETWEEN A COLD AIR DAMMING
EVENT IN THE LEE OF THE SOUTHERN APPALACHIANS AND A SURFACE LOW
TRACKING EASTWARD ALONG THE U.S-CANADIAN BORDER. PRESUMING THAT
LOW CLOUDS DISPERSE THIS EVENING (WHICH IS HIGHLY UNCERTAIN AT
THIS POINT AS SOME MODEL SOLUTIONS SUGGEST THEY MAY REMAIN INTACT
THROUGH MID-DAY SUNDAY), CONDITIONS WILL BE FAVORABLE FOR
RADIATIONAL COOLING (LOWS IN THE U30S-L40S) AND DEVELOPMENT OF
LOCALLY DENSE VALLEY FOG ACROSS OUR EASTERN ZONES.
AS THE HIGH TO OUR NORTHEAST DRIFTS EASTWARD INTO THE WESTERN
NORTH ATLANTIC ON SUNDAY/SUNDAY NIGHT, LOW-LEVEL FLOW WILL VEER TO
SSW AS THE NORTHERN STREAM SURFACE LOW PROGRESSES EASTWARD INTO
ONTARIO. THIS WILL ALLOW FOR A MODEST WARMING TREND ON SUNDAY
AFTERNOON AS HIGHS CLIMB BACK INTO THE L-M 60S, BUT LOWS ON MONDAY
MORNING WILL REMAIN IN THE L-M 40S. DURING THE PERIOD FROM
MONDAY-MONDAY NIGHT, PRESSURE FALLS IN THE LEE OF THE ROCKIES WILL
BECOME CONSOLIDATED ACROSS THE CENTRAL/SOUTHERN HIGH PLAINS, AS
AN ARCTIC AIRMASS EXPANDS SOUTHEASTWARD ACROSS MUCH OF THE NORTH-
CENTRAL CONUS. LIGHT-MODERATE SSW FLOW AT THE SURFACE WILL PERSIST
ACROSS OUR REGION, WITH AFTERNOON TEMPS RETURNING TO THE
U60S-L70S MONDAY AND LOWS ONLY FALLING INTO THE U40S-L50S TUESDAY
MORNING. CONDITIONS WILL REMAIN FAVORABLE FOR DEVELOPMENT OF
NOCTURNAL VALLEY FOG BOTH MONDAY AND TUESDAY MORNINGS.
LONG TERM
(TUESDAY THROUGH FRIDAY)
ISSUED AT 435 AM CST SAT FEB 1 2025
EXTENDED RANGE MODEL DATA STILL INDICATES THAT A MORE SUBSTANTIAL
INCREASE IN LOW-LEVEL MOISTURE WILL OCCUR ON TUESDAY, AS
PERSISTENT SSW FLOW WITHIN THE WARM SECTOR OF A DEVELOPING CYCLONE
ACROSS EASTERN CO FORCES DEWPOINTS BACK INTO THE U50S-L60S.
ALTHOUGH THIS WILL RESULT IN A GREATER COVERAGE OF LOW CLOUDS AND
PERHAPS SOME LIGHT SHOWERS, IT APPEARS AS IF HIGHER CHANCES FOR
SHOWERS AND SOME THUNDERSTORMS WILL NOT MATERIALIZE UNTIL EARLY
WEDNESDAY MORNING (AT THE EARLIEST). THIS IS THE TIMEFRAME WHEN A
CONFLUENCE AXIS (MARKING THE INTERFACE BETWEEN THE ARCTIC AIRMASS
TO OUR NORTH AND AN INCREASINGLY WARM/MOIST AIRMASS TO OUR SOUTH)
MAY DRIFT SOUTHWARD INTO THE FORECAST AREA BEFORE EVENTUALLY
STALLING.
THE BOUNDARY WILL BEGIN TO RETREAT NORTHWARD ON WEDNESDAY
EVENING, AS A WEAK SOUTHERN STREAM DISTURBANCE EJECTING
NORTHEASTWARD THROUGH THE CENTRAL PLAINS INDUCES DEVELOPMENT OF A
STRONGER FRONTAL WAVE TO OUR NORTHWEST. AS THIS LOW ACCELERATES
NORTHEASTWARD ON THURSDAY/THURSDAY NIGHT, THE TRAILING COLD FRONT
WILL INSTIGATE ANOTHER ROUND OF SHOWERS AND STORMS AS IT ADVANCES
SOUTHEASTWARD THROUGH OUR REGION (BEFORE STALLING TO OUR IMMEDIATE
SOUTHEAST ON FRIDAY). ALTHOUGH POOR LAPSE RATES ALOFT WILL LIMIT
CAPE TO AROUND 500 J/KG ON WEDNESDAY/THURSDAY (IN SPITE OF TEMPS
IN THE 70S/DEWPOINTS IN THE 60S), DEEP-LAYER SHEAR WILL BE IN THE
30-40 KNOT RANGE IF NOT A BIT HIGHER. THUS, WE WILL MONITOR TRENDS
IN INSTABILITY OVER THE COMING DAYS AS FAVORABLE SHEAR WOULD
SUPPORT SOME RISK FOR STRONG/SEVERE CONVECTION SHOULD THE
ATMOSPHERE BE MORE UNSTABLE.
AVIATION
(06Z TAFS)
ISSUED AT 1233 AM CST SAT FEB 1 2025
RECENT SATELLITE IMAGERY AND SFC OBSERVATIONS INDICATE THE
DEVELOPMENT OF PATCHY BR/FG ACROSS THE SOUTHEASTERN PORTION OF
NORTHERN AL EARLY THIS MORNING. THUS, WE HAVE INCLUDED A TEMPO
GROUP FOR IFR VSBY REDUCTIONS AT THE HSV TERMINAL THRU 10Z, WITH
EXPECTATIONS THAT AN APPROACHING COLD FRONT WILL RESULT IN
STRONGER MIXING AND MINOR DRY AIR ADVECTION BEYOND THIS POINT.
LOW/MVFR-LEVEL STRATUS CLOUDS WILL BUILD SOUTHEASTWARD INTO THE
REGION IN THE WAKE OF THE FRONT, WITH SCATTERING OF THIS CLOUD
DECK EXPECTED BY ~20Z.
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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