535
FXUS62 KCAE 180823
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
323 AM EST WED DEC 18 2024
SYNOPSIS
DENSE FOG TO START THE DAY AS A COLD FRONT APPROACHES THE
REGION THIS AFTERNOON. THERE IS A CHANCE FOR SHOWERS AND
ISOLATED THUNDERSTORMS DURING THE LATE AFTERNOON AND EVENING
HOURS. COLD AND DRY CONDITIONS THEN DOMINATE FOR THE REMAINDER
OF THE WEEK AND INTO EARLY NEXT WEEK.
NEAR TERM /UNTIL 6 AM THIS MORNING/
KEY MESSAGE(S):
- PATCHY DENSE FOG EXPECTED THROUGH DAYBREAK.
A DEEP UPPER LEVEL TROUGH TO OUR WEST WILL PROMOTE SOUTHWEST
FLOW OVER THE SOUTHEAST. AS THE UPPER TROUGH AMPLIFIES,
MOISTURE AND CLOUD COVER WILL INCREASE. THERE WILL ALSO BE A
SHORT WAVE WHICH MOVES ACROSS THE AREA EARLY WEDNESDAY MORNING.
WE CAN'T RULE OUT ISOLATED LIGHT SHOWERS ESPECIALLY ALONG THE
I-95 CORRIDOR EARLY THIS MORNING. DENSE FOG HAS DEVELOPED ACROSS
MUCH OF THE AREA AND CONTINUES TO ADVECT TOWARD THE UPSTATE.
VISIBILITIES OF LESS THAN 1/4 TO 1/2 MILE ARE EXPECTED.
OVERNIGHT LOWS WILL BE A LITTLE WARMER THAN THE PREVIOUS NIGHT,
LOW TO MID 50S.
SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/
KEY MESSAGE(S):
- WEDNESDAY IS WARM WITH A CHANCE FOR LATE DAY SHOWERS AND
ISOLATED THUNDERSTORMS AHEAD OF AN APPROACHING COLD FRONT.
- THURSDAY IS COOLER AND CLOUDY BEHIND THE COLD FRONT.
WEDNESDAY AND WEDNESDAY NIGHT: THE UPPER FLOW WILL BE
SOUTHWESTERLY AHEAD OF AN APPROACHING TROUGH, WHICH IS SLATED
TO MOVE INTO THE FORECAST AREA AROUND DAYBREAK THURSDAY. AT THE
SURFACE, THE ATTENDANT COLD FRONT WILL APPROACH DURING THE DAY
ON WEDNESDAY, CROSSING THE FORECAST AREA AT NIGHT. THIS WILL
ALLOW FOR MOISTURE ADVECTION OUT OF THE GOMEX WITH PWATS
GENERALLY IN THE 1 TO 1.25 INCH RANGE. EARLY MORNING LOW CLOUDS
AND FOG SHOULD GIVE WAY TO SCATTERED CUMULUS OR STRATOCUMULUS BY
MIDDAY. IN TERMS OF CONVECTIVE POTENTIAL, MODEL GUIDANCE SHOWS
A VARIETY OF SOLUTIONS WITH THE 12Z HRRR PRODUCING ISOLATED
DEVELOPMENT DURING THE LATE AFTERNOON AND EARLY EVENING WHILE
THE 12Z NAMNEST SHOWS NOTHING AT ALL. MODELED SBCAPE IN THE 500
TO 1000 J/KG RANGE AND 30 TO 40 KNOTS OF 0-6KM SHEAR WOULD BE
SUFFICIENT FOR A FEW STRONGER THUNDERSTORMS, HOWEVER THE OVERALL
LACK OF A TRIGGER AND CLOUD COVER COULD LIMIT ANY DEVELOPMENT
UNTIL THE COLD FRONT MOVES THROUGH AT NIGHT. WILL CONTINUE TO
MONITOR THE POTENTIAL FOR STRONGER THUNDERSTORMS BUT FOR NOW
AGREE WITH THE GENERAL THUNDER OUTLOOKED ON THE LATEST SPC DAY 2
SWO. A WARM DAY IS EXPECTED DESPITE THE ABUNDANT CLOUDINESS
WITH FORECAST HIGHS IN THE UPPER 60S TO LOWER 70S. TEMPERATURES
FALL INTO THE MID-40S TO MID-50S AT NIGHT.
THURSDAY AND THURSDAY NIGHT: SHORTWAVE TROUGH MOVES THROUGH THE
FA AT THE START OF THE DAY WHILE A SECOND TROUGH APPROACHES
FROM THE NORTH AND WEST. PWATS DECREASE AS A COLD AND DRIER AIR
MASS BEGINS TO FILTER INTO THE REGION. HOWEVER, LATEST GUIDANCE
SHOWS CLOUDS LINGERING THROUGH THE DAY AS MOISTURE BECOMES
TRAPPED IN THE LOWER LEVELS OF THE ATMOSPHERE. TEMPERATURES WILL
BE ABOUT 5 TO 10 DEGREES COLDER THAN WEDNESDAY WITH HIGHS IN
THE UPPER 50S TO UPPER 60S AND OVERNIGHT LOWS IN THE MID-30S TO
LOWER 40S.
LONG TERM /FRIDAY THROUGH TUESDAY/
KEY MESSAGE(S):
- THE EXTENDED IS COLD AND DRY AS TEMPERATURES DECLINE THROUGH
THE PERIOD.
- SEVERAL NIGHTS OF SUBFREEZING TEMPERATURES ARE EXPECTED.
SECOND TROUGH MOVES INTO THE EASTERN CONUS ON FRIDAY AND REMAINS
IN PLACE THROUGH THE WEEKEND, BEFORE RIDGING BUILDS IN NEAR THE
END OF THE LONG TERM. AT THE SURFACE, A WEAK CLIPPER SYSTEM WILL
PASS TO OUR NORTH, BUT IT APPEARS IT WILL BE TOO DRY FOR ANY
PRECIPITATION FROM IT. SKIES FINALLY CLEAR OUT ON FRIDAY ONCE
THIS SYSTEM PASSES TO OUR EAST AND WE COME UNDER THE INFLUENCE
OF CANADIAN HIGH PRESSURE. THIS WILL KEEP THE REGION IN A COLD,
DRY AIR MASS BUT WITH THE ANTICYCLONE NEVER PASSING OVERHEAD,
CONDITIONS WILL NOT BE IDEAL FOR RADIATIONAL COOLING AT NIGHT.
REGARDLESS, WELL BELOW NORMAL TEMPERATURES ARE EXPECTED WITH
SUNDAY AND MONDAY BEING THE COLDEST DAYS. OVERNIGHT TEMPERATURES
ARE LIKELY TO BE BELOW FREEZING EACH NIGHT BUT THE LACK OF A
SURFACE HIGH PASSING OVERHEAD CALLS INTO QUESTION HOW COLD
TEMPERATURES GET. WILL NEED TO MONITOR FOR A POTENTIAL COLD
WEATHER ADVISORY, ESPECIALLY ON SUNDAY NIGHT. REGARDLESS, COLD
WEATHER PRECAUTIONS SHOULD BE TAKEN, ESPECIALLY IF YOU PLAN TO
BE AWAY FROM YOUR HOME THIS WEEKEND INTO EARLY NEXT WEEK.
AVIATION /08Z WEDNESDAY THROUGH SUNDAY/
IFR TO LIFR RESTRICTIONS EXPECTED THROUGH MID-MORNING.
LOW LEVEL MOISTURE HAS INCREASED WHICH HAS LED TO WIDESPREAD
IFR/LIFR CIG/VSBY RESTRICTIONS. IMPROVEMENT IS LIKELY BY MID TO
LATE MORNING WITH LIGHT SOUTHWESTERLY WINDS. MVFR CONDITIONS ARE
EXPECTED BY MIDDAY, RETURNING TO VFR THIS AFTERNOON. SOME LIGHT
SHOWERS ARE POSSIBLE THIS AFTERNOON AND EVENING, BUT UNCERTAINTY
AS TO THEIR COVERAGE SO HAVE LEFT THEM OUT OF THE TAF. ANOTHER
ROUND OF RESTRICTIONS IS POSSIBLE TONIGHT, BUT THEY MAY NOT BE
AS WIDESPREAD.
EXTENDED AVIATION OUTLOOK...LINGERING SHOWERS POSSIBLE INTO
WEDNESDAY EVENING. PATCHY FOG AND LOW CEILINGS POSSIBLE
THURSDAY AND FRIDAY MORNING.
CAE WATCHES/WARNINGS/ADVISORIES
SC...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ018-020-
021-025-026-115-116.
DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ016-022-
027>031-035-037-038-041-135>137.
GA...DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR GAZ040-063-
064.
DENSE FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR GAZ065-077.
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