214
FXUS62 KGSP 121733
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1233 PM EST TUE NOV 12 2024
SYNOPSIS
DRY HIGH PRESSURE WILL LAST THROUGH WEDNESDAY. CLOUDS AND
PRECIPITATION ARRIVING LATE WEDNESDAY NIGHT WILL MAKE FOR A VERY
DAMP AND CHILLY THURSDAY. DRY WEATHER AND MILDER, MORE SEASONABLE
TEMPERATURES RETURN FRIDAY THROUGH THE WEEKEND.
NEAR TERM /THROUGH TONIGHT/
AS OF 1220 PM EST TUESDAY...
KEY MESSAGES:
1) TEMPERATURES REMAIN ABOVE NORMAL THROUGH THE NEAR TERM
2) DRY CONDITIONS EXPECTED AS HIGH PRESSURE BUILDS INTO THE AREA
3) LOWS TONIGHT WILL BE NOTICEABLY COOLER
LOTS OF BRIGHT SUNSHINE WITH ONLY A FEW CIRRUS STREAKS MOVING
OVERHEAD, AS DEPICTED BY THE SATELLITE IMAGERY EARLY THIS
AFTERNOON. THE FORECAST APPEARS TO BE ON TRACK, SO NO CHANGES.
OTHERWISE, THE SOUTHERN PERIPHERY OF DRY HIGH PRESSURE WILL BUILD
INTO THE SOUTHEAST THROUGH THE NEAR TERM AS THE CENTER OF THE
HIGH TRACKS EASTWARD ACROSS THE GREAT LAKES REGION AND EASTERN
CANADA. THIS WILL LEAD TO MOSTLY CLEAR SKIES INTO TONIGHT. TEMPS
THIS AFTERNOON WILL BE ROUGHLY 3-5 DEGREES COOLER COMPARED TO
YESTERDAY ACROSS MOST LOCATIONS. HOWEVER, HIGHS WILL STILL END
UP ~4-8 DEGREES ABOVE CLIMO. WITH DRIER AIR FILTERING INTO THE
REGION TONIGHT, LOWER DEWPOINTS ARE EXPECTED. THUS, FOG FORMATION
IS NOT EXPECTED. LOWS TONIGHT WILL DROP INTO THE LOWER TO UPPER
30S ACROSS THE MOUNTAINS AND THE UPPER 30S TO MID 40S EAST OF THE
MOUNTAINS. ALTHOUGH TEMPS TONIGHT WILL BE MUCH COOLER, THEY WILL
STILL REMAIN ABOVE NORMAL ACROSS MUCH OF THE AREA.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
AS OF 100 AM TUE: 1035+ MB SFC HIGH WILL BE CENTERED OVER QUEBEC ON
WEDNESDAY, EXTENDING DOWN THE EAST COAST UNDER A SHARP UPPER RIDGE.
THE HIGH IS MARGINALLY TOO WEAK FOR A CLASSICAL CAD EVENT, BUT
THICKNESSES ARE LOW ENOUGH THAT DESPITE SUNSHINE, WE EXPECT HIGHS IN
THE MID TO UPPER 50S IN THE PIEDMONT AREAS NORTH OF I-85, AND NEAR 60
IN THE LOWER PIEDMONT AND MOUNTAIN VALLEYS. MEANWHILE, A WEAK, MATURE
LOW PRESSURE SYSTEM WILL CROSS THE PLAINS WED AND THEN INTO THE OHIO
VALLEY WED NIGHT. THE WARM CONVEYOR BELT OF THIS SYSTEM WILL RIDE
OVER THE SOUTHERN APPALACHIANS EARLY THU MORNING, WITH MOIST UPGLIDE
RESULTING IN PRECIP OVER THE WESTERN HALF OF THE AREA, THEN SPREADING
EAST ACROSS THE REMAINDER OF THE CWA THROUGH THURSDAY.
THE COLUMN IS SHOWN TO BE EXCEPTIONALLY DRY THROUGH PRETTY MUCH THE
WHOLE TROPOSPHERE WED AFTERNOON. DEWPOINTS WILL BE IN THE 10S AND 20S
IN THE MOUNTAINS THU EVENING WHERE TEMPS START OUT COOLEST, SO
EVAPORATIVE COOLING AT THE ONSET OF PRECIP COULD BE A FACTOR FOR
P-TYPE. MOISTENING OCCURS FROM THE TOP DOWN AND A ROBUST WARM NOSE
(AT LEAST +5C OVER MOST OF THE LAYER FROM 850-700MB) SUGGESTS ICE
NUCLEI ARE NOT LIKELY TO BE PRESENT. SURFACE WET-BULB TEMPS ARE
EXPECTED TO BE JUST ABOVE FREEZING ONCE PRECIP BEGINS IN THE
MOUNTAINS, AND TREND WARMER FROM THERE WITH STRONG WAA ONGOING ABOVE
THE WEDGE. IT LOOKS TO BE A NEAR-MISS IN THE COOLER VALLEYS. THE
PRECIP SHOULD EASILY LOCK IN CAD AND RESULT IN QUITE CHILLY TEMPS FOR
THE CWA THU, WITH TEMPS PROBABLY REMAINING IN THE 40S IN MOST
LOCATIONS THROUGH THE AFTERNOON.
THE COLD FRONT WILL SWEEP ACROSS THURSDAY NIGHT, WITH SLIGHTLY BETTER
WIND SPEEDS THAN WE SAW WITH THE EARLY-WEEK CAD EVENT. UPSLOPE
CLOUDS/PRECIP WILL DEVELOP NEAR THE TN BORDER IN THE LATE AFTERNOON
AND CONTINUE MUCH OF THE NIGHT. HOWEVER, AS USUAL, NOCTURNAL WEDGE
EROSION IS A TALL ORDER AND THAT LIMITS CONFIDENCE IN THU NIGHT'S
FORECAST EAST OF THE MOUNTAINS. CLOUD COVER WILL LINGER FOR A TIME
AFTER SUNSET AND APPEARS LIKELY TO AT LEAST ERODE FROM THE FOOTHILLS,
BUT SOME GUIDANCE DOES SUGGEST STRATUS WILL REMAIN OVER THE LOWER
PIEDMONT AT DAYBREAK FRI. IN ADDITION TO PARTIAL CLOUD COVER, WINDS
ARE LIKELY TO BE ENOUGH TO MAINTAIN MIXING; EAST OF THE MTNS, FRI
MORNING MINS WILL BE LESS THAN 10 DEGREES BELOW THE THU MAXES. VIA
CAA, TEMPS MAY TREND COOLER NEAR THE TN BORDER, BUT STILL SHOULD
REMAIN ABOVE FREEZING THRU FRI MORNING.
LONG TERM /FRIDAY THROUGH MONDAY/
AS OF 200 AM TUE: CLOUD COVER WILL CONTINUE TO DIMINISH FRIDAY; THE
OHIO VALLEY SYSTEM WILL EXIT TO THE ATLANTIC, ITS SHORTWAVE BEING
CAPTURED BY AN EXISTING OFFSHORE CLOSED LOW AND REMAINING OFF THE NEW
NORTHEAST COAST THRU EARLY NEXT WEEK. SFC/UPPER RIDGING WILL BUILD
ACROSS THE WHOLE OF THE MISSISSIPPI VALLEY. TEMPS WILL REBOUND BACK
TO AROUND NORMAL FRIDAY, WITH MAXES TRENDING WARMER OVER THE WEEKEND
AS RIDGE MOVES TO THE EASTERN SEABOARD; SUNDAY'S MAXES WILL BE 7-10
ABOVE NORMAL. MINS WILL BE NEAR NORMAL FRI-SAT NIGHTS. FAIRLY HIGH
CONFIDENCE FOR A DRY FORECAST THROUGH SUNDAY.
WEST OF THE ROCKIES, A DEEP TROUGH WILL BE PRESENT AT THE START OF
THE PERIOD, BUT THE NORTHERN PORTION SHEARS OFF OVER THE WEEKEND AS
AN ACTIVE/PROGRESSIVE NORTHERN STREAM CONTINUES. THIS LEAVES A CUTOFF
LOW NEAR BAJA CALIFORNIA, AND SUBSEQUENTLY COULD LEAD TO A BROAD
OMEGA BLOCK ACROSS THE SPAN OF THE CONUS, GIVEN THE ATLANTIC LOW.
HOWEVER, THE NORTHERN STREAM TROUGH IS SHOWN TO ITSELF CUT OFF OVER
CENTRAL CANADA BY LATE SUNDAY. AS YOU MAY HAVE SURMISED BY NOW, THE
UPPER PATTERN BECOMES CHAOTIC BY THAT TIME, WITH MODELS DISAGREEING
ON WHERE THE CANADIAN AND SW CONUS UPPER LOWS END UP. CONFIDENCE THUS
DIMINISHES AFTER SUNDAY. THE RIDGE LOOKS LIKELY TO BE SUPPRESSED BY
THE ADVANCE OF THE LOWS, AND SOME FLAVOR OF A WEAKLY FORCED FRONT
PROBABLY WILL APPROACH OUR AREA FROM THE W OR NW SUNDAY NIGHT OR
MONDAY, WARRANTING SMALL POPS IN OUR WEST AT THE TAIL END OF THE
FORECAST PERIOD. TEMPS LOOK WARM ENOUGH THAT ONLY RAIN WOULD RESULT
IN SUCH A SCENARIO.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: VFR THROUGH THE PERIOD AT ALL TERMINALS,
WITH ONLY SOME PASSING THIN CIRRUS. DRY AIR SHOULD PRECLUDE FOG
FORMATION IN MOST PLACES ACROSS THE MTNS TONIGHT. WIND SHOULD BE
LIGHT N TO NE THIS AFTERNOON AND INTO THE OVERNIGHT HOURS, BUT
MAY PICK UP FROM THE NE IN THE PRE-DAWN HOURS WEDNESDAY AS HIGH
PRESSURE BUILDS DOWN FROM THE NORTH. MIGHT SEE OCCASIONAL GUSTS AT
SOME LOCATIONS AS WE MIX DEEPER AFTER MID-MORNING AS THE PRESSURE
GRADIENT IMPROVES. HIGH CLOUDS WILL BEGIN TO THICKEN WEDNESDAY
AFTERNOON AHEAD OF THE NEXT SYSTEM.
OUTLOOK: A COLD FRONT WILL BRING RAIN AND RESTRICTIONS TO THE
TERMINALS WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE BRINGS DRY
AND VFR CONDITIONS BACK FRIDAY INTO THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...AR/PM
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...PM
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