606
FXUS62 KGSP 121120
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
620 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 620 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
FOG HAS LIFTED ACROSS THE FAR EASTERN PORTIONS OF THE FORECAST AREA
BUT HAS DEVELOPED IN THE LITTLE TN VALLEY, DESPITE INCREASING
CIRRUS. CIRRUS WILL CONTINUE TO THICKEN THROUGH DAYBREAK BEFORE
THINNING OUT SHORTLY AFTER. THIS WILL ALLOW LOWS THIS MORNING TO END
UP ~10 DEGREES ABOVE CLIMO. NO MAJOR CHANGES WERE NEEDED THIS UPDATE
AS THE FORECAST REMAINS ON TRACK.
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 SUNNY/CLEAR SKIES LATER THIS MORNING 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 /12Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: DRIER CONDITIONS ARE NOW IN PLACE ACROSS ALL
TERMINALS. NO ADDITIONAL FOG DEVELOPMENT IS EXPECTED THROUGH
DAYBREAK OUTSIDE OF THE LITTLE TN VALLEY. VFR WILL PREVAIL THROUGH
THE 12Z TAF PERIOD THANKS TO DRY HIGH PRESSURE BUILDING INTO THE
AREA THROUGH WEDNESDAY. UPPER CIRRUS CONTINUE TO THICKEN THIS
MORNING AND WILL LINGER THROUGH AT LEAST SUNRISE BEFORE THINNING OUT
SHORTLY AFTER. WINDS AT KAVL WILL REMAIN N/NW'LY THROUGH MUCH OF
TODAY BEFORE GRADUALLY TURNING S'LY THIS EVENING. WINDS EAST OF THE
MOUNTAINS WILL GRADUALLY KEEP TURNING NE THROUGH MID-MORNING,
REMAINING AT THIS DIRECTION THROUGH WEDNESDAY. WIND SPEEDS WILL
RANGE FROM 4-9 KTS THROUGH THE TAF PERIOD, WITH LOW-END GUSTS
DEVELOPING ACROSS THE SC UPSTATE TERMINALS AFTER 05Z WEDNESDAY.
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
SHORT TERM...WIMBERLEY
LONG TERM...WIMBERLEY
AVIATION...AR
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page