503
FXUS62 KGSP 180605
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
105 AM EST WED DEC 18 2024
SYNOPSIS
TEMPERATURES WILL BE SEVERAL DEGREES ABOVE NORMAL TODAY, WITH A
STRONG COLD FRONT APPROACHING FROM THE WEST AND INCREASING RAIN
CHANCES AREA-WIDE THIS AFTERNOON AND EVENING. COOLER CONDITIONS
ARE EXPECTED BEHIND THE FRONT THROUGH THE WEEKEND WITH TEMPERATURES
SEVERAL DEGREES BELOW NORMAL SUNDAY AND MONDAY.
NEAR TERM /THROUGH TODAY/
AS OF 100 AM WED: FOG HAS REMAINED LARGELY VARIABLE ALTHOUGH THE
NUMBER OF SITES AT 1/4SM HAS RECENTLY INCREASED. EXPECTATION IS
THAT HIGHER CLOUD DECKS ASSOCIATED WITH VORT RIPPLES WILL EXIT OVER
THE NEXT COUPLE OF HOURS, ALLOWING BETTER RADIATION FROM THE TOP
OF THE FOG LAYER AND SOLIDIFYING IT INTO WIDESPREAD STRATUS. WILL
HOLD ONTO SPS FOR DENSE FOG FOR NOW, BUT BY 330 AM WE PROBABLY
WILL HAVE A CONTIGUOUS AREA OF FOG THAT WILL WARRANT A DENSE
FOG ADVISORY. MAIN CHANGES THIS UPDATE ARE TO VSBY/SKY/WIND FOR
AVIATION PACKAGE, WITH VSBY REFLECTING EVENTUAL NEED FOR DFA. NO
SIGNIFICANT CHANGES TO THE OVERALL THINKING FOR TODAY/TONIGHT.
FOG SHOULD DISSIPATE/LIFT BY MID TO LATE MORNING WITH DRY CONDITIONS
LINGERING THRU THE FIRST PART OF THE AFTERNOON. A COLD FRONT WILL
TRACK ACROSS THE CWA LATE WED AFTERNOON/EVENING INCREASING RAIN
CHANCES, MAINLY OVER THE NC MTNS. THE LATEST CAM RUNS CONTINUE TO
DEPICT MUCH OF THE PRECIP ACTIVITY ASSOCIATED WITH THE FRONT GRA-
DUALLY FALLING APART AS IT PUSHES EAST OF THE MTNS. AS SUCH, I LIMIT
ANY LIKELY POPS TO THE NC MTNS WITH POPS CAPPED AT SOLID CHANCE OUT-
SIDE THE MTNS. THE LATEST FCST SOUNDINGS CONTINUE TO DEPICT SOME
AMOUNT OF SFC-BASED INSTABILITY ACROSS MOST OF OUR FCST AREA WED
AFTERNOON/ EARLY EVENING, WITH AMOUNTS INCREASING THE FURTHER SE
YOU GO. HOWEVER, IT'S LOOKING LIKE THE FRONT AND ANY ASSOCIATED
SHOWER ACTIVITY WILL NOT MAKE IT EAST OF THE NC MTNS UNTIL PEAK
HEATING HAS PASSED AND CLOUDS REMAIN SCT TO BKN OVER THE AREA. THIS
SHOULD LIMIT ANY THUNDER POTENTIAL OUTSIDE THE MTNS. NONETHELESS,
I KEPT A MENTION OF THUNDER IN THE MTNS AS THE FRONT MOVES THRU AS
THIS WILL BE CLOSER TO PEAK HEATING AND THE CAMS CONTINUE TO DEPICT
A WELL-DEFINED LINE OF ACTI- VITY REACHING THE NC/TN BORDER AROUND
20Z. OVERALL QPF AMOUNTS SHOULD BE MINIMAL FOR MOST OF OUR CWA,
WITH THE HIGHEST AMOUNTS OF A QUARTER TO A HALF INCH ALONG THE NC/TN
BORDER. ANY LINGERING PRECIP SHOULD BE MOVING EAST OF OUR FCST AREA
BY LATE WED NIGHT WITH COOLER/DRIER AIR GRADUALLY WORKING ITS WAY
INTO OUR CWA. OTHERWISE, HIGHS ON WED WILL LIKELY BE A FEW DEGREES
WARMER THAN TUE, AND WELL-ABOVE CLIMO, ESPECIALLY OVER THE MTNS.
SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/
AS OF 150 PM EST TUESDAY: THE SHORT WAVE AND FRONTAL SYSTEM FROM THE
NEAR TERM MOVE OUT OF THE AREA WEDNESDAY NIGHT. SHOWERS WILL QUICKLY
END DURING THE EVENING AS DRY HIGH PRESSURE BUILDS IN OVERNIGHT.
WINDY TO BREEZY CONDITIONS EXPECTED OVERNIGHT INTO THURSDAY BEFORE
THE PRESSURE GRADIENT RELAXES. ANOTHER SHORT WAVE MOVES MOVES INTO
THE AREA FRIDAY WITH A WEAKENING CLIPPER TYPE SURFACE LOW. THERE
LOOKS TO BE ENOUGH MOISTURE FOR NW FLOW SNOW TO DEVELOP ACROSS THE
USUAL LOCATIONS ALONG THE TN BORDER FRIDAY AFTERNOON AND EVENING.
RIGHT NOW, THERE DOESN'T LOOK TO BE AN EXTENDED PERIOD OF MOISTURE
FLUX OR FORCING, SO SNOW AMOUNTS SHOULD BE RELATIVELY LIGHT AND
LIMITED TO THE HIGHER ELEVATIONS. EXPECT WINDY TO BREEZY CONDITIONS
TO REDEVELOP ON FRIDAY AND CONTINUE INTO FRIDAY NIGHT. LOWS
WEDNESDAY NIGHT WILL BE 5 TO 10 DEGREES ABOVE NORMAL, DROPPING TO
NEAR NORMAL THURSDAY NIGHT AND A FEW DEGREES BELOW NORMAL FRIDAY
NIGHT. HIGHS THURSDAY WILL BE A FEW DEGREES ABOVE NORMAL THEN
DROPPING A LITTLE BELOW NORMAL FOR THE MOUNTAINS ON FRIDAY BUT
REMAINING NEARLY STEADY ELSEWHERE.
LONG TERM /SATURDAY THROUGH TUESDAY/
AS OF 205 PM EST TUESDAY: ANY NW FLOW SNOW ENDS BY SATURDAY MORNING
BUT WINDY TO BREEZY CONDITIONS CONTINUE THROUGH THE DAY. A SHORT
WAVE CROSSES THE AREA SUNDAY KEEPING LOW H5 HEIGHTS ACROSS THE AREA.
A SHORT WAVE RIDGE THEN BUILDS IN FOR MONDAY AND TUESDAY AHEAD OF A
TROUGH MOVING INTO THE CENTRAL CONUS. COLD AND DRY HIGH PRESSURE
BUILDS INTO THE AREA IN A COLD AIR DAMMING CONFIGURATION SUNDAY AND
REMAIN IN PLACE THROUGH TUESDAY. EXPECT DRY BUT COLD CONDITIONS EACH
DAY. HIGHS 5 TO 10 DEGREES BELOW NORMAL SATURDAY DROP TO 10 TO 15
DEGREES BELOW NORMAL SUNDAY, REMAIN NEARLY STEADY MONDAY, THEN RISE
BACK TO 5 TO 10 DEGREES BELOW NORMAL FOR TUESDAY. LOWS DROP INTO THE
TEENS AND 20S THROUGH THE PERIOD.
AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: PATCHY/VARIABLE DENSE FOG AROUND THE TERMINAL
AREA TO START THE PERIOD. RAPID CHANGES IN FLIGHT CATEGORY GENERALLY
LOOK TO CONTINUE IN THE FIRST FEW HRS, ALTHOUGH AS HIGHER CLOUD
DECKS ADVECT EAST CLOSER TO DAWN, THE FOG PROBABLY WILL SOLIDIFY
AND MOST LIKELY LAST UNTIL 14-16Z. ALL SITES WILL BEAR SOME RISK
OF FALLING BELOW MINIMA UNTIL THE FOG LAYER DISSIPATES IN THE EARLY
DAYTIME. INVERSION CONTINUES SUCH THAT PATCHY MVFR CIGS WILL LINGER
MOST OF THE REMAINDER OF THE DAY. WINDS START OFF MOSTLY CALM/VRB
BUT ARE EXPECTED TO PICK UP FROM THE SW AFTER DAYBREAK. APPROACH
OF COLD FRONT THIS AFTN/EVENING WILL BRING A CHANCE OF -SHRA AND
MAYBE EVEN A FEW TSRA, BUT GIVEN SHALLOW MOIST LAYER AND INHIBITING
INVERSION, THIS IS MENTIONED ONLY AS VCSH FOR NOW; WILL CONSIDER
PROB30S FOR NEXT ISSUANCE. WINDS TURN TO NW BEHIND THE FRONT,
WITH SHIFT TIMED AROUND 00Z AT KAVL AND AFTER 06Z ELSEWHERE.
OUTLOOK: BEHIND THE COLD FRONT, HIGH PRESSURE AND DRY CONDITIONS
RETURN THURSDAY AND LAST THROUGH THE WEEKEND, WITH THE EXCEPTION
BEING A CHANCE FOR SNOW ALONG THE TN BORDER FRI NIGHT INTO SAT
(BUT NOT LIKELY AFFECTING ANY OF OUR TERMINALS). PERIODIC CIG
RESTRICTIONS CAN'T BE RULED OUT OVER THE WEEKEND BUT SHOULD BE
TOO DRY FOR FOG.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...AR/JPT/WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...WIMBERLEY
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