Area Forecast Discussion
Issued by NWS Greer, SC

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933
FXUS62 KGSP 051757
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
157 PM EDT THU MAY 5 2016

.SYNOPSIS...
COOLER AIR WILL FILTER IN FROM THE NORTHWEST TODAY IN THE WAKE OF A
COLD FRONT. THE WEATHER WILL REMAIN UNSETTLED AS A DEEP UPPER LOW
CENTER MOVES DOWN ACROSS THE CAROLINAS TODAY AND TONIGHT...AND
THEN MOVES AWAY TO THE NORTHEAST ON FRIDAY. ANOTHER FRONT IS
EXPECTED TO STALL JUST TO OUR NORTH ON SATURDAY AND SUNDAY. THE
FRONT SHOULD LIFT BACK TO THE NORTH ON MONDAY...AS HIGH PRESSURE
OFF THE SOUTHEAST COAST EXPANDS.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 130 PM...CLOSED CIRCULATION WITHIN UPPER LEVEL LOW PRESSURE IS
NOW CENTERED INVOF THE SMOKY MTNS. THE LOW WILL SHIFT SOUTHEASTWARD
THRU THIS EVENING. A DEEP LAYER OF MODESTLY FAVORABLE LAPSE RATES
IS PRESENT OVER THE AREA...AND WITH DIURNAL HEATING COVERAGE OF
SHOWERS IS INCREASING. AS FAR BACK AS WED AFTN...MOST CONVECTION
ALLOWING MODELS /CAMS/ HAVE FOCUSED ON THE SW HALF OF THE AREA AS
HAVING THE BEST COVERAGE THIS AFTN...WITH A SECONDARY FOCUS OVER
THE I-77 CORRIDOR. THIS APPEARS TO BE WORKING OUT FAIRLY WELL...WITH
THE LULL IN THE NC FOOTHILLS AND VCNTY POSSIBLY DUE TO DOWNSLOPING
NW WINDS. LATEST POP TRENDS WERE BASED ON CONSENSUS OF THE LATEST
CAMS. THOUGH COOL TEMP PROFILES WOULD SUGGEST CLOUDS WILL PRODUCE
ICE EASILY...ONLY A COUPLE OF LIGHTNING STRIKES HAVE BEEN REPORTED
OVER THE PAST COUPLE HRS. AT LEAST ONE STORM HAS PRODUCED GRAUPEL
OR SMALL HAIL...AND IT IS LIKELY THAT THE MORE ROBUST CELLS THIS
AFTN WILL PRODUCE MORE OF THE SAME. WHILE WINDS WILL BE FAIRLY
GUSTY ANYWAY...SUCH STORMS COULD BRING DOWN SOME STILL STRONGER
GUSTS IN LIGHT OF DCAPE VALUES NEARING 600 J/KG OVER PARTS OF THE
AREA PER NAM.

TONIGHT...SHOWERS WILL REMAIN ACROSS THE MTNS AND NC FOOTHILLS AND
PIEDMONT OVERNIGHT. OMEGA BLOCK WILL LINGER ACROSS THE CONUS AS THE
EASTERN CLOSED LOW LIFTS NORTH OVER THE MID ATLANTIC STATES. LOW
TEMPERATURES WILL REMAIN COOL...WITH 30S TO LOW 40S ACROSS THE
MTNS AND UPPER 40S ACROSS THE FOOTHILLS AND PIEDMONT.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...THE MODEL GUIDANCE KEEPS THE UPPER LOW IN
CLOSE ENOUGH PROXIMITY ON FRIDAY THAT THE MID LEVEL COOL POOL WILL
REMAIN OVER THE EASTERN ZONES WHILE WEAK VORT CENTERS DROP DOWN FROM
THE NORTH. THE COLD AIR ALOFT WILL KEEP ENOUGH INSTABILITY ACROSS
THE EASTERN HALF OF THE FORECAST AREA TO ACCOUNT FOR ISOLATED TO
SCATTERED SHOWERS....WHILE UPSLOPE FLOW WILL FORCE SOME SHOWER
ACTIVITY MAINLY OVER THE NRN MOUNTAINS. AS THE UPPER LOW PULLS
OUT...THE PRECIP CHANCES SHOULD DIMINISH THROUGH FRIDAY NIGHT. TEMPS
ARE EXPECTED TO BEGIN A REBOUND AS THE LOW PULLS AWAY...AND THEN GET
BACK CLOSE TO NORMAL ON SATURDAY. SOME OF THE MODEL GUIDANCE SHOWS
PRECIP ENCROACHING ON THE NRN ZONES ON SATURDAY AND THIS WAS KEPT IN
THE FCST ON OUR NRN FRINGES BASED ON NEIGHBORING FCSTS. PRECIP
CHANCES WILL START CREEPING UP FROM THE NORTH AS A COLD FRONT SAGS
DOWN TOWARD THE AREA SATURDAY NIGHT.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 315 AM THURSDAY...THE MODELS INDICATE A CHANGE IN THE
MID/UPPER LEVEL PATTERN THAT FAVORS A RETURN TO SOMETHING MORE
TYPICAL OF MID/LATE SPRING. THE DEEP UPPER TROF OVER THE NORTHEAST
SHOULD LIFT OUT ON SUNDAY AND SUNDAY NIGHT ALLOWING A FLAT UPPER
RIDGE TO MOVE IN FROM THE LOWER MS VALLEY. THIS SHOULD HELP LIFT A
SURFACE BOUNDARY BACK TO THE NORTH EARLY IN THE PERIOD AND SET THE
STAGE FOR TEMPS TO RETURN TO SOMETHING ON THE ORDER OF FIVE DEGREES
ABOVE NORMAL. FROM THE EARLY PART OF THE WEEK ONWARD...THE SOUTHEAST
WILL BE UNDER A WSW OR NEARLY ZONAL UPPER FLOW WITH SURFACE HIGH
PRESSURE OFF THE COAST THAT WILL PROVIDE FOR RETURN MOISTURE FROM
THE GULF. WHAT REMAINS TO BE SEEN IS THE EXTENT OF ANY DIURNALLY-
DRIVEN CONVECTION FROM TUESDAY ONWARD. THE FCST CONTINUES TO REFLECT
A MORE ECMWF-LIKE SOLUTION WITH THE PRECIP CHANCE OVER THE MTNS...
WHILE THE GFS HAS A CHANCE ACROSS THE WHOLE AREA. TEMPS WILL REMAIN
ABOVE NORMAL.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AT KCLT...UPPER LEVEL LOW OVER THE REGION WILL MAINTAIN GOOD
MIDLEVEL LAPSE RATES OVER THE REGION...AND HIGH BASED SCT SHRA/TSRA
WILL DEVELOP VIA DIURNAL HEATING THIS AFTN. DEEPER MOISTURE ARRIVES
FROM THE N BY EARLY EVENING AND THIS IS EXPECTED TO LEAD TO MORE
ROBUST AND WIDESPREAD SHRA AND A BETTER CHANCE OF RESTRICTED
VSBY...HENCE TEMPO. SOME POTENTIAL FOR ENHANCED GUSTS WITH THE
SHRA EXISTS BUT HARD TO PIN DOWN FOR INCLUSION IN TEMPO. CHANCE OF
SHRA DIMINISHES OVERNIGHT. VIRTUALLY ALL CIG GUIDANCE INDICATES
BASES WILL REMAIN VFR. WINDS WILL STAY IN THE NW QUAD THRU THE
PERIOD...BACKING TOWARD W FOR A TIME TONIGHT AS SFC LOW MOVES
NWD ALONG THE OUTER BANKS. THOUGH THE EFFECTS OF THE LOW WILL BE
LESS FRIDAY...LAPSE RATES ARE STILL SUFFICIENT TO EXPECT GOOD CU
DEVELOPMENT. A TIGHT PRS GRADIENT WILL ALLOW GUSTY WINDS TO RETURN.

ELSEWHERE...GENERALLY AS AT KCLT...BUT WITH PRECIP CHANCES SOMEWHAT
LOWER ACRS KGSP/KGMU/KAND PER CONSENSUS OF HIGH-RES GUIDANCE. KAVL
WILL CONTINUE TO SEE BRISK NWLY GUSTS INTO THE EVENING...AND LO
LEV MOISTURE IS A BIT MORE SIGNIFICANT...SUGGESTING A SMALL CHANCE
OF AN MVFR CIG EXISTS OVERNIGHT.

OUTLOOK...A LOW CHANCE OF SHRA/TSRA WILL PERSIST FRI AFTN MAINLY
ACROSS THE NC SITES...BEFORE UPPER LOW DEPARTS TO THE EAST. DRY
HIGH PRES RETURNS SATURDAY...WHILE ANOTHER COLD FRONT APPROACHES
FROM THE NORTH THRU SUNDAY.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH  93%     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 SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET 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...PM/WIMBERLEY
NEAR TERM...NED/WIMBERLEY
SHORT TERM...PM
LONG TERM...PM
AVIATION...WIMBERLEY



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