031
FXUS64 KHUN 011440
AFDHUN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HUNTSVILLE AL
840 AM CST SAT FEB 1 2025
..NEW NEAR TERM
NEAR TERM
(REST OF TODAY)
ISSUED AT 840 AM CST SAT FEB 1 2025
LOCALLY DENSE FOG IS GRADUALLY STARTING TO DIMINISH/LIFT OVER THE
CENTRAL TN VALLEY WITH THE ONSET OF THE DAYTIME HRS. LINGERING
FOG SHOULD GIVE WAY TO SOME LOW STRATUS THAT IS WORKING ITS WAY
SOUTH ACROSS MID TN VALLEY LATER THIS MORNING, AS THE FLOW PATTERN
OUT OF THE WNW TRANSITIONS MORE TO A ZONAL FLOW REGIME. EMBEDDED
MOISTURE BELOW A STRONG CAP AROUND THE H85 LEVEL SHOULD HELP
MAINTAIN THE LOW STRATUS FOR MUCH OF THE DAY, AS AFTERNOON HIGHS
STRUGGLE TO SURPASS THE MID 50S/NEAR 60F. IN ANY CASE, NO MAJOR
CHANGES ARE NEEDED TO THE ONGOING FORECAST OTHER THAN SOME MINOR
ADJUSTMENTS TO THE GRIDS BASED ON THE CURRENT TRENDS.
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
(12Z TAFS)
ISSUED AT 612 AM CST SAT FEB 1 2025
LOCALLY DENSE FG (PRODUCING VLIFR CIG/VSBY) WILL PERSIST AT THE
HSV TERMINAL THRU 14Z, ALTHOUGH WITH FLUCTUATIONS IN VSBY LIKELY
AS DIURNAL MIXING INCREASES AND THE FOG BEGINS TO DISPERSE WE WILL
ONLY INCLUDE THESE CONDS IN A TEMPO GROUP. TO THE NORTH OF THE
AL-TN BORDER, A VAST AREA OF POSTFRONTAL STRATUS WILL CONTINUE TO
SPREAD SOUTHWARD, PROVIDING AN EXTENDED PERIOD OF MVFR CIGS BTWN
1500-2500 FT THAT WILL CONTINUE FOR MUCH OF THE DAY AND INTO THE
EARLY EVENING HOURS. AT THIS POINT, WE HAVE INDICATED DISPERSION
OF THE STRATUS AND REDEVELOPMENT OF BR/FG AT 4Z, AS THE LOCAL
AIRMASS WILL REMAIN FAIRLY MOIST AND WINDS WILL BE LIGHT AND FROM
THE SSE. HOWEVER, THERE IS AT LEAST A LOW PROBABILITY THAT THE
STRATUS LAYER WILL REMAIN INTACT THRU THE END OF THE TAF PERIOD.
HUN WATCHES/WARNINGS/ADVISORIES
AL...NONE.
TN...NONE.
NEAR TERM...09
SHORT TERM....70
LONG TERM....70
AVIATION...70
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