770
FXUS62 KCAE 151952
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
252 PM EST SAT FEB 15 2025
SYNOPSIS
A STRONG COLD FRONT WILL MOVE THROUGH THE REGION SUNDAY MORNING.
WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED ALONG
AND AHEAD OF THE FRONT. STRONG GUSTY WINDS ARE EXPECTED THROUGH
THE DAY. THE WINDS WILL SLOWLY SUBSIDE SUNDAY NIGHT AS THE
PRESSURE GRADIENT RELAXES. A COOL AND DRY AIR MASS WILL SETTLE
OVER THE AREA THROUGH TUESDAY. A LOW PRESSURE SYSTEM WILL MOVE
INTO THE SOUTHEASTERN STATES MID WEEK WITH WINTRY PRECIPITATION
POSSIBLE ACROSS THE NORTHERN MIDLANDS. A COLD AND DRY AIR MASS
WILL BUILD INTO THE AREA LATE WEEK WITH BELOW NORMAL
TEMPERATURES CONTINUING INTO NEXT WEEKEND.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- INCREASING MOISTURE WITH SCATTERED SHOWERS THIS EVENING AHEAD
OF THE APPROACHING FRONT.
WITH BROAD 500MB RIDGING ALOFT AND OFFSHORE SURFACE HIGH PRESSURE,
SOME WEAK IN-SITU WEDGE CONDITIONS STARTED TO DEVELOP THIS MORNING
ACROSS THE AREA AS INCREASING MOISTURE AND ISENTROPIC LIFT MOVED IN.
MOISTURE WILL CONTINUE TO INCREASE THROUGHOUT THE EVENING AS SURFACE
WINDS CONTINUE OUT OF THE SOUTHEAST, WITH STRENGTHENING SOUTHERLIES
ABOVE AND RISING PWAT'S. THE ASSOCIATED TEMP AND MOISTURE GRADIENT
WILL STEADILY PUSH NORTHWARD OVERNIGHT AND A SURGE OF PWAT'S OVER
1.5" WILL CAUSE SOME SCATTERED SHOWERS AND LOW STRATUS THAT WILL
LAST INTO SUNDAY MORNING AHEAD OF THE FRONT. THERE IS GOOD CONSENSUS
IN THE HREF MEMBERS FOR THE MOST WIDESPREAD SHOWER ACTIVITY
GENERALLY FROM 6PM THROUGH MIDNIGHT ACROSS THE MIDLANDS AND COASTAL
PLAIN. TEMPS WILL GENERALLY RISE THROUGH THE OVERNIGHT PERIOD AND
INTO SUNDAY MORNING AHEAD OF THE RAPIDLY APPROACHING FRONT AND
CONVECTION FROM THE WEST.
SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/
KEY MESSAGE(S):
- WINDY CONDITIONS AND SOME STRONG-SEVERE THUNDERSTORMS ARE
LIKELY BETWEEN 8AM AND NOON. BREEZY CONDITIONS WILL LINGER
THROUGH THE AFTERNOON.
BY 6AM SUNDAY, A STRONG FRONT WILL BE APPROACHING THE AREA FROM THE
WEST. A WIDE SWATH OF STRONG SOUTH-SOUTHWESTERLY 850MB WINDS WILL
PROCEED THE FRONT ITSELF, WITH GUIDANCE CONSISTENTLY SHOWING 60+
KNOTS THROUGHOUT SUNDAY MORNING. CONSEQUENTLY, THE GRADIENT SURFACE
WINDS WILL STEADILY STRENGTHEN THROUGHOUT EARLY SUNDAY MORNING AHEAD
OF THE CONVECTIVE LINE ITSELF. WINDS 25-35 MPH ARE LIKELY AHEAD OF
THE LINE, BUT DUE TO THE NEUTRAL STABILITY, THE STRONGEST 850MB
WINDS WILL LIKELY NOT MIX DOWN WITHOUT FORCING. DESPITE EXTREME LOW
LEVEL SHEAR, THE SEVERE-TORNADO THREAT IS RELATIVELY LOW FROM THIS
CONVECTIVE LINE, AS THERE IS LITTLE IF ANY MOST UNSTABLE INSTABILITY
(LET ALONE ANY SURFACE BASED CAPE); HREF MEAN MU CAPE ONLY CLIMBS TO
AROUND 100 J/KG WITH NO MEMBERS SHOWING ANYTHING MORE APPRECIABLE.
HOWEVER, THE SYNOPTIC AND MESOSCALE FORCING WILL BE SIGNIFICANT
ALONG THIS LINE, SO AN ISOLATED TORNADO IS NOT OUT OF THE QUESTION.
SPC CONTINUED THEIR MARGINAL RISK OUTLOOK AS A RESULT. A WIND
ADVISORY IS IN EFFECT STARTING AT 5AM TO COVER THE PREFRONTAL
GRADIENT WINDS AND COLD ADVECTION BEHIND THE LINE; SHORT FUSED
WARNINGS WILL BE USED AS NEEDED FOR SEGMENTS OF THE CONVECTIVE LINE
THAT WARRANT ADDITIONAL ATTENTION. THE STRONGEST WINDS FROM THE
SYSTEM WILL LIKELY OCCUR WITH THE MIXING FROM CONVECTION SHOWERS-
STORMS OR DIRECTLY BEHIND THE LINE. HRRR CROSS SECTIONS SUGGEST SOME
VERY STRONG DESCENT BEHIND THE LINE, ADDING ANOTHER MECHANISM TO MIX
DOWN STRONGER WINDS. THE GENERAL TIMING LOOKS TO BE ROUGHLY 7AM-
NOON FOR THE CONVECTIVE LINE TO PUSH FROM THE CSRA THROUGH THE
COASTAL PLAIN AND EASTERN MIDLANDS.
BEHIND THE FRONT, WINDS WILL SHIFT OUT OF THE WEST AND REMAIN BREEZY
THROUGHOUT THE AFTERNOON. COLD ADVECTION, RELATIVELY DEEP MIXING,
AND UNIDIRECTIONAL SHEAR SHOULD EASILY BE ABLE TO MECHANICALLY MIX
DOWN 25-35 MPH WINDS UNTIL SUNDAY EVENING.
LONG TERM /MONDAY THROUGH SATURDAY/
KEY MESSAGE(S):
-DRY AND COOL EARLY IN THE WEEK.
-POTENTIAL FOR WINTRY WEATHER MIDWEEK.
-COLDER THAN NORMAL INTO NEXT WEEKEND.
MONDAY AND TUESDAY...UPPER TROUGH OVER EASTERN CANADA AND
TROUGH OUT IN THE INTERMOUNTAIN WEST WITH RESULTING FAST ZONAL
FLOW ALOFT ACROSS THE EASTERN CONUS EARLY IN THE WEEK. AT THE
SURFACE, A VERY STRONG PRESSURE RIDGE OVER SOUTH CENTRAL CANADA
WILL BE BUILDING SOUTHEAST AND EXPECT GENERALLY DRY AND COOL
CONDITIONS, SLIGHTLY WARMER TUESDAY AS WARM ADVECTION DEVELOPS
AS THE UPPER TROUGH OUT WEST MOVES INTO THE PLAINS.
COLD AIR DAMMING EXPECTED MID WEEK WITH RIDGE BUILDING IN FROM
THE NORTH INTO THE WESTERN CAROLINAS. WARM FRONT EXPECTED IN
THE SC COASTAL PLAIN. ENSEMBLES SUGGEST WEAK LOW PRESSURE
DEVELOPING ALONG THE GULF COAST, MOVING NORTHEAST TO THE
CAROLINA COAST WEDNESDAY NIGHT. NBM POPS ARE QUITE HIGH DURING
THIS PERIOD SO EXPECT WIDESPREAD RAIN, ALTHOUGH HEAVIER RAIN
FOCUSED IN THE COASTAL PLAIN CLOSER TO MAX MOISTURE FLUX AXIS
SUGGESTED IN THE NAEFS GUIDANCE. CUT MAX TEMPS WEDNESDAY DUE TO
POTENTIAL COLD AIR DAMMING ESPECIALLY NORTH MIDLANDS. SOUNDINGS
SUGGEST A PRECIP TYPE ISSUE WEDNESDAY NIGHT INTO THURSDAY
MORNING WITH WINTRY PRECIP POSSIBLE IN THE NORTHERN MIDLANDS.
FREEZING RAIN THE MAIN THREAT. NOTE THE ECMWF DETERMINISTIC IS
RATHER THREATENING. ENSEMBLES SHOW AN ANOMALOUSLY DEEP UPPER LOW
FROM THE OHIO VALLEY EAST ACROSS THE MID ATLANTIC TRANSITIONING
TO FAST ZONAL FLOW ALOFT ACROSS THE SOUTHEAST. HIGH PRESSURE
WILL BE BUILDING SOUTHEAST FROM THE PLAINS AND THIS SHOULD LEAD
TO TEMPERATURES BELOW NORMAL AND COOLER NORMAL TEMPERATURES INTO
NEXT WEEKEND.
AVIATION /19Z SATURDAY THROUGH THURSDAY/
- MVFR-IFR CIGS SUNDAY AFTERNOON, LIFR LIKELY OVERNIGHT. A
STRONG FRONT IS EXPECTED EARLY SUNDAY BRINGING WIDESPREAD
RESTRICTIONS.
INCREASING LOW LEVEL MOISTURE WILL CONTINUE TO DROP CIGS THROUGHOUT
THE AFTERNOON AND INTO THE EVENING. MVFR CIGS WILL DROP TO IFR BY
ROUGHLY 21Z FOR THE TAF SITES ALONG WITH LLWS BEGINNING THIS
EVENING; WINDS AROUND 2K FEET WILL STEADILY INCREASE FROM 35-40
KNOTS TO 45-50 KNOTS OVERNIGHT. AS MOISTURE INCREASING AFTER 00Z,
SOME SCATTERED SHOWERS ARE LIKELY ACROSS THE AREA, BUT CONFIDENCE IS
TOO LOW FOR A DIRECT TAF MENTION. BUT AS MOISTURE INCREASES, CIGS
WILL LIKELY FALL TO LIFR AT CAE/CUB/AGS/DNL; OGB WILL BE ON THE
BORDER OF THE LOWERING CIGS. LOW CIGS WILL LINGER OVERNIGHT UNTIL A
STRONG FRONT PUSHES THROUGH SUNDAY MORNING. SURFACE WINDS WILL
INCREASE OUT OF THE SOUTH OVER 20 KNOTS AHEAD OF THE APPROACHING
LINE OF STRONG SHOWERS. WINDS WITH THIS LINE WILL LIKELY GUST OVER
40 MPH AT TIMES, MAINLY BETWEEN 12Z AND 15Z, BEFORE SHIFTING OUT OF
THE WEST BEHIND THE FRONT ITSELF. INCLUDED A TEMPO GROUP FOR THE
TIME BEING TO HIGHLIGHT THAT TIME PERIOD FOR THE FRONTAL PASSAGE AND
ASSOCIATED HEAVY, GUSTY SHOWERS. BREEZY CONDITIONS WILL LINGER
THROUGHOUT THE AFTERNOON AND WINDS TURN WESTERLY.
EXTENDED AVIATION OUTLOOK...A APPROACHING SYSTEM ON WEDNESDAY
AND THURSDAY WILL BRING SOME PRECIP AND ASSOCIATED RESTRICTIONS.
HYDROLOGY
RECENT RAINFALL TOTALS IN THE HEADWATERS OF THE AREA RIVERS IN
THE UPSTATE OF SC AND WESTERN NC INDICATE THAT 3 TO 5 INCHES
FELL WITH AMOUNTS FROM ONE HALF INCH EASTERN MIDLANDS TO 2
INCHES ACROSS THE PIEDMONT. THIS HAS PRODUCED RISES ON THE AREA
RIVERS AND STREAMS THAT WILL CONTINUE OVER THE WEEKEND. THE
RIVERS ARE NEAR CREST AND FORECAST TO FALL OVER THE NEXT COUPLE
OF DAYS. HOWEVER, ADDITIONAL SYSTEMS ARE EXPECTED TO BRING MORE
RAINFALL TO THE REGION THROUGH THE PERIOD.
CAE WATCHES/WARNINGS/ADVISORIES
SC...WIND ADVISORY FROM 5 AM TO 6 PM EST SUNDAY FOR SCZ016-018-
020>022-025>031-035-037-038-041-115-116-135>137.
GA...WIND ADVISORY FROM 5 AM TO 6 PM EST SUNDAY FOR GAZ040-063>065-
077.
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