544
FXUS62 KGSP 192054
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
454 PM EDT SUN MAY 19 2019
SYNOPSIS
A FEW SHOWERS AND THUNDERSTORMS ARE EXPECTED ACROSS THE MOUNTAINS
THIS AFTERNOON AND EVENING. THUNDERSTORM COVERAGE MAY INCREASE
MONDAY AS A WEAK COLD FRONT CROSSES THE FORECAST AREA. FOLLOWING THE
FRONT, A STRONG AREA OF HIGH PRESSURE WILL BUILD ACROSS THE REGION
RESULTING IN WELL ABOVE NORMAL TEMPERATURES WITH LIMITED RAINFALL
INTO THE WEEKEND.
NEAR TERM /THROUGH MONDAY/
AS OF 450 PM EDT SUNDAY: THIS AFTERNOON IS EVOLVING SIMILAR TO THE
LAST COUPLE DAYS, THOUGH WITH TEMPERATURES A 2 OR 3 DEGREES COOLER
DUE TO WEAKENING OF RIDGE OVER THE AREA. UPPER TROUGH IS ADVANCING
WELL NORTH OF THE AREA AND WILL DRAG A WEAK TRAILING FRONT THROUGH
THE REGION FROM THE NORTHWEST LATE MONDAY MORNING THROUGH THE
AFTERNOON.
THE OTHER DIFFERENCE IS THE LACK OF CONVECTION ONGOING AT THE
MOMENT. MUCH LESS CONVECTION OVERALL AND LIMITED TO THE TN BORDER OF
THE NORTHERN MOUNTAINS SO FAR. HAVE UPDATED POP TRENDS TO SHOW THE
LOWER OVERALL TREND AND LIMITING LOCATION TO THE NC MOUNTAINS. WITH
FRONT ON MONDAY, COVERAGE OF SHOWERS IS EXPECTED TO INCREASE WITH
POPS REACHING 30% OVER THE MOUNTAINS AND SOME CHANCE FOR SHOWERS IN
THE FOOTHILLS AND PIEDMONT AREAS AS WELL. MOISTURE IS STILL LIMITED
OVER THE AREA, AND UPPER DYNAMICS ARE WELL TO THE NORTH, SO THE
CAPE/SHEAR COMBINATION SHOULD KEEP THINGS BELOW SEVERE LEVELS TODAY
AND ON MONDAY, AS CONFIRMED BY CAMS WHICH HAVE VERY WEAK UPDRAFTS IN
THEIR FORECAST.
DUE TO STILL SOMEWHAT WIDELY SCATTERED NATURE OF CONVECTION ON
MONDAY, TOTAL RAINFALL AMOUNTS ARE NOT EXPECTED TO BE HIGH, THOUGH
THOSE LOCATIONS DIRECTLY IMPACTED BY THUNDERSTORMS COULD RECEIVE
USEFUL RAIN AMOUNTS. PASSAGE OF THE MONDAY FRONT WILL BE FOLLOWED
FAIRLY QUICKLY BY RENEWED RIDGING AND THE BEGINNING OF A DRY AND
UNSEASONALLY WARM PERIOD.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
AS OF 125 PM SUNDAY: UPPER LEVEL HEIGHTS CONTINUE TO RISE OVER THE
SHORT RANGE BEFORE A PRONOUNCED H5 RIDGE AXIS FORMS AND BISECTS THE
FA EARLY WED. SOUNDINGS INDICATE A NEGLIGIBLE CHANCE FOR PRECIP TUE
AS DEEP LAYERED SUBS INCREASES AND PARCELS ONLY LIFT TO ARND 4-5 KFT
WITH NO IDENTIFIABLE LFC ABV A STG LLVL CAP. SO...WILL EXPECT A WARM
DRY DAY WITH MAX AND MIN TEMPS ARND 10 DEGREES ABV NORMAL. THE LLVL
PATTERN BEGINS TO CHANGE WED AS A NRN SFC HIGH SHIFTS OFFSHORE AND
BRINGS IN A GOOD AMT OF RETURN MOISTURE WITHIN A LOW BL. THE ATMOS
WILL BE BE TOO SUPPRESSED OUTSIDE THE MTNS FOR ANYTHING MORE THAN
SHALLOW CU. HOWEVER...ISOL MECH-LIFT SHOWERS AND PULSE MODE TSTMS
ARE POSSIBLE BY THE AFTERNOON AS RIDGE-TOP CONVG ENABLES THERMALS TO
REACH AN AREA OF ELEVATED WEAK INSTABILITY. ANOTHER ABV NORMAL TEMP
DAY IN STORE WED...BUT HIGHS SHUD BE CLOSER TO NORMAL ACROSS THE
NE/RN ZONES AS A ENE/LY FLOW VEERS WHILE A SFC WEDGE ERODES THRU THE
DAY.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
AS OF 220 PM SUNDAY: THE EXTENDED FCST PICKS UP AT 00Z ON THURSDAY
WITH PERSISTENT UPPER RIDGING STILL IN PLACE OVER THE REGION. OVER
THE NEXT COUPLE OF DAYS, THE UPPER RIDGE IS EXPECTED TO AMPLIFY AS
DEEP UPPER TROFING REMAINS OVER THE WESTERN CONUS. AS WE MOVE INTO
THE WEEKEND, THE LONG-RANGE GUIDANCE HAS THE RIDGE FLATTENING A BIT
BUT NOT BY VERY MUCH. AT THE SFC, BROAD AND TRANSIENT HIGH PRESSURE
WILL BE MOVING OFF THE ATLANTIC COAST AS THE PERIOD BEGINS. AS THE
HIGH MOVES FARTHER SE, WE REMAIN UNDER A WEAKLY FORCED AND STAGNANT
SYNOPTIC PATTERN THRU DAY 7. AS MENTIONED IN PREVIOUS DISCUSSIONS,
THIS PATTERN WILL MAINTAIN WELL-ABOVE NORMAL TEMPS THRU THE PERIOD,
WITH LOWER-TO-MID 90S LIKELY ACROSS THE LOWER ELEVATIONS AND MID-TO
UPPER 80S ACROSS THE HIGHER ELEVATIONS. AT THE SAME TIME, THE ATMOSPHERE
WILL REMAIN SUPPRESSED AND PROVIDE MINIMAL CHANCES FOR AFTERNOON/EVENING
SHOWERS AND THUNDERSTORMS. THE HIGH TERRAIN WILL SEE THE BEST CHANCES
FOR CONVECTION DURING THE PERIOD, HOWEVER EVEN OVER THAT AREA, POPS
ARE RESTRICTED TO JUST SLIGHT CHANCE.
AVIATION /21Z SUNDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: GENERALLY VFR EXPECTED FOR THE NEXT 24 HOURS,
EXCEPT FOR SOME ISOLATED SHOWERS OR THUNDER SHOWERS OVER THE
MOUNTAINS. SOMEWHAT WEAK FRONT IS EXPECTED TO REACH KCLT BY 21Z ON
MONDAY, AND WILL BRING THE WIND TO A MORE WESTERLY DIRECTION, AND
EVENTUALLY NORTHWESTERLY AFTER 00Z. WITH FRONT, CHANCES FOR
PRECIPITATION INCREASE, ESPECIALLY IN THE HIGHER TERRAIN AREAS, AND
KHKY AND KAVL HAVE A PROB30 FOR THIS. INCREASED CLOUD COVER IS ALSO
EXPECTED ON MONDAY AS THE FRONT ENTERS FROM THE NORTHWEST, BUT
SHOULD REMAIN ABOVE VFR LIMITS. WINDS ARE FAIRLY PERSISTENTLY
SOUTHERLY TO SOUTHWESTERLY THIS AFTERNOON WITH SOME GUSTS EXPECTED
WITH AFTERNOON MIXING, AND REMAIN SOUTHERLY THROUGH MONDAY MORNING,
WITH KAVL AND KHKY FIRST SEEING SOME VEERING LATE IN THE MORNING.
OUTLOOK: MOUNTAIN VALLEY FOG WILL BE POSSIBLE EACH MORNING THROUGH
MID-WEEK. DIURNAL SHOWERS AND THUNDERSTORMS POSSIBLE SUNDAY AND
MONDAY, WITH REDUCED CHANCES THEREAFTER.
CONFIDENCE TABLE...
21-03Z 03-09Z 09-15Z 15-18Z
KCLT HIGH 100% HIGH 100% LOW 59% HIGH 98%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:
WWW.WEATHER.GOV/GSP/AVIATION
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...SBK
NEAR TERM...RWH/WJM
SHORT TERM...SBK
LONG TERM...JPT
AVIATION...WJM
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