823
FXUS62 KCAE 171946
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
246 PM EST TUE DEC 17 2024
SYNOPSIS
WARM AND DRY CONDITIONS CONTINUE THIS AFTERNOON, COURTESY OF
DEPARTING UPPER RIDGING. A COLD FRONT APPROACHES THE REGION ON
WEDNESDAY WITH 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 /THROUGH TONIGHT/
KEY MESSAGE(S):
- PATCHY DENSE FOG POSSIBLE LATE TONIGHT.
UPPER RIDGE HAS SHIFTED OFF THE COAST. UPPER TROUGH OVER THE
MIDWEST WITH SOUTHWEST FLOW ALOFT ACROSS THE AREA. AS THE UPPER
TROUGH TO THE WEST AMPLIFIES, A FRONTAL BOUNDARY IN EASTERN
TENNESSEE THIS AFTERNOON WILL SLIDE A LITTLE EAST BUT LIKELY
REMAIN NORTH AND WEST OF THE REGION. MOISTURE/CLOUDS WILL
SPREAD EAST FROM THE UPSTATE AS SEVERAL WEAK SHORT WAVE TROUGHS
MOVE TO THE NORTHEAST ACROSS NORTH CAROLINA. AT THE SURFACE,
RIDGE OFFSHORE WITH WEAK SOUTHWEST FLOW. WARM ADVECTION APPEARS
TO BE FOCUSED IN THE SOUTHEAST MIDLANDS, WHERE CLOUDINESS IS A
LITTLE MORE AGITATED. CAN'T RULE OUT A BRIEF LIGHT SHOWERS
MAINLY EAST OF I-95 THIS AFTERNOON. SO GENERALLY CLEAR EARLY
THIS EVENING ALTHOUGH AN INCREASE IN MID LEVEL CLOUDS POSSIBLE
OVERNIGHT ESPECIALLY IN THE PIEDMONT AND NORTH MIDLANDS.
GUIDANCE IS SUGGESTING AT LEAST PATCHY FOG OVERNIGHT, ESPECIALLY
IN THE CENTRAL AND SOUTHEAST MIDLANDS/CSRA WHERE UPPER LEVELS
REMAIN MAINLY CLEAR. OVERNIGHT LOWS A LITTLE WARMER THAN
PREVIOUS NIGHT, LOW TO MID 50S.
SHORT TERM /WEDNESDAY 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 MONDAY/
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 /19Z TUESDAY THROUGH SUNDAY/
VFR CONDITIONS EXPECTED THROUGH THE EARLY EVENING. RESTRICTIONS
POSSIBLE LATE TONIGHT DUE TO POSSIBLE FOG DEVELOPMENT.
HIGH PRESSURE OFFSHORE WITH LIGHT SOUTHWEST FLOW ACROSS THE
AREA. STRATO-CUMULUS DECK MAINLY IN THE COASTAL PLAIN THIS
AFTERNOON WELL EAST OF THE TERMINALS. CLOUDS IN THE UPSTATE
SHOULD STAY MAINLY NORTHWEST OF THE AREA. SO A FEW CUMULUS
POSSIBLE THIS AFTERNOON THEN MAYBE SOME MID AND HIGH CLOUDS
OVERNIGHT. MODELS ARE SUGGESTING AT LEAST SOME PATCHY, POSSIBLY
DENSE FOG DEVELOPING LATE TONIGHT. WENT WITH IFR VISIBILITY
RESTRICTIONS AT THIS TIME DEVELOPING AFTER 09Z AT ALL TERMINALS.
VISIBILITY SHOULD IMPROVE AROUND 14Z-15Z WEDNESDAY WITH
SCATTERED TO BROKEN STRATO-CU.
EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AHEAD OF A COLD
FRONT WEDNESDAY AFTERNOON AND EVENING WITH BRIEF RESTRICTIONS
POSSIBLE. PATCHY FOG POSSIBLE THURSDAY MORNING.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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