798
FXUS62 KGSP 120758
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
258 AM 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 230 AM 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
ANY LINGERING FOG IN THE EASTERN SC UPSTATE AND NEAR THE CHARLOTTE
METRO SHOULD CONTINUE TO DISSIPATE OVER THE NEXT HOUR OR TWO AS
DRIER AIR FILTERS INTO THE REGION BEHIND THE DEPARTING COLD FRONT.
SOME CIRRUS IS TRACKING EASTWARD ACROSS THE FORECAST AREA THIS
MORNING. CIRRUS WILL GRADUALLY THICKEN THROUGH SUNRISE BEFORE
THINNING OUT SHORTLY AFTER. THIS WILL ALLOW LOWS TO END UP ~10
DEGREES ABOVE CLIMO.
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 SUNNY/CLEAR SKIES THE REST OF TODAY INTO TONIGHT.
HIGHS THIS AFTERNOON WILL BE ROUGHLY 3-5 DEGREES COOLER COMPARED TO
YESTERDAY ACROSS MOST LOCATIONS. HOWEVER, TEMPS THIS AFTERNOON WILL
STILL END UP ~4-8 DEGREES ABOVE CLIMO. WITH DRIER AIR FILTERING INTO
THE REGION AND LEADING TO LOWER DEWPOINTS TONIGHT, 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.
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 /08Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: PATCHY FOG LINGERS AT KCLT AND KAND THIS
MORNING. FOG SHOULD GRADUALLY DISSIPATE OVER THE NEXT HOUR OR TWO
BASED ON THE LATEST SATELLITE TRENDS. ELSEWHERE, DRIER CONDITIONS
ARE IN PLACE SO FOG HAS NOT DEVELOPED (AND IS NOT EXPECTED TO
DEVELOP THROUGH DAYBREAK). VFR IS WILL PREVAIL THROUGH MOST OF THE
06Z TAF PERIOD OUTSIDE OF MORNING FOG THANKS TO DRY HIGH PRESSURE
BUILDING INTO THE AREA. UPPER CIRRUS ARE STARTING TO THICKEN AND
WILL LINGER THROUGH AT LEAST SUNRISE BEFORE THINNING OUT SHORTLY
AFTER. WINDS EAST OF THE MOUNTAINS WILL START OUT NW OR CALM EARLY
THIS MORNING, TURNING NE BY MID-MORNING. WINDS AT KAVL WILL REMAIN
N/NW'LY THROUGH MUCH OF TODAY BEFORE GRADUALLY TURNING S'LY THIS
EVENING.
OUTLOOK: DRY AND MOSTLY VFR WEATHER EXPECTED ON WEDNESDAY THANKS TO
HIGH PRESSURE. A COLD FRONT WILL BRING RAIN AND RESTRICTIONS BACK TO
THE TERMINALS WEDNESDAY NIGHT INTO THURSDAY. DRY HIGH PRESSURE
RETURNS FRIDAY INTO THE WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...WIMBERLEY
NEAR TERM...AR
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...AR
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