000
FXUS62 KGSP 180013
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
813 PM EDT MON JUN 17 2013

.SYNOPSIS...
WEAK UPPER LEVEL DISTURBANCES WILL CROSS THE AREA FROM THE WEST
THROUGH MID WEEK AS A ZONE OF RELATIVELY ABUNDANT MOISTURE LAYS
DRAPED ACROSS THE AREA. SLIGHTLY DRIER HIGH PRESSURE WILL BUILD INTO
THE REGION THROUGH FRIDAY...WITH WARMER BERMUDA HIGH PRESSURE
DOMINATING THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH TUESDAY/...
7 PM UPDATE...TRAINING CELLS PRODUCING HIGH RAIN RATES ARE ALIGNED
JUST TO OUR SOUTH...BUT CLOSE ENOUGH TO THINK SOME CONTINUED TSTM
ACTIVITY WILL OCCUR ALONG OUR SE BORDER ZONES. ADDITIONAL ACTIVITY
OVER THE WRN MTNS AND FOOTHILLS WILL LIKELY PERSIST FOR AT LEAST
ANOTHER HOUR OR TWO BEFORE INSTABILITY DIMINISHES. ALSO THESE CELLS
MAY SUFFER DUE TO THEIR INFLOW MOISTURE BEING CONSUMED BY THE
AFOREMENTIONED ACTIVITY TO OUR SOUTH. WHILE THESE AREAS OF PRECIP
SHOULD AFFECT THE AREA LESS AND LESS TONIGHT...THERE REMAINS REASON
TO BELIEVE CHC POPS GIVEN THE MOIST PROFILES AND CYCLONIC FLOW
ALOFT...SO POPS STABILIZE IN CHC RANGE LATE.

PREV DISCUSSION...
THIS AFTERNOON THROUGH TONIGHT...THE OVERALL CONV COVERAGE IS
BEGINNING TO PICK UP ACROSS THE CWFA WITH A DEFINITE MINIMA SEEN
OVER THE UPSTATE AND FAR ERN ZONES. SOME CELLS HAVE BECOME FAIRLY
STRONG AND A COUPLE COULD REACH SEVERE CRITERIA...MAINLY FOR LARGE
HAIL...AS THE AFTERNOON PROGRESSES. THE UPPER LEVEL VORT ACTIVITY IS
RATHER WEAK AND ILL DEFINED OVER THE CWFA...BUT WILL COUNT ON
GENERAL EASTWARD DEVELOPMENT OF STORMS THROUGH THE EVENING. THINGS
WILL BEGIN TO WANE AFT SUNSET AND LOSS OF SBCAPE...HOWEVER UPPER
POCKETS OF PVA WILL TRAVERSE THE DEEPLY MOIST AIRMASS AND ISOL/SCT
-SHRA/TSTMS ARE NOT OUT OF THE QUESTION THROUGH DAYBREAK. MIN TEMPS
WILL BE HELD A COUPLE CATS OR SO ABOVE NORMAL IN THIS ENVIRONMENT.

A SHARPENING H5 S/W WILL MOVE INTO TN TOMORROW AND CREATE A GOOD
AMOUNT OF DYNAMIC OMEGA...ABOUT TWICE AS MUCH VV/S AS TODAY.
THUS...WILL ANTICIPATE GOOD COVERAGE OF SHOWERS AND STORMS EARLY
ON...ESP ACROSS THE NC MTNS WHERE CAT POPS ARE ADVERTISED AFT 15Z.
DEEP LAYERED SHEAR WILL BE ABOUT 10 KTS HIGHER TOMORROW...BUT SBCAPE
MAY ACTUALLY BE LOWER DUE TO ALL THE CLOUD COVER. YET...STILL THINK
A BETTER POTENTIAL EXISTS FOR SVR STORMS TOMORROW AFTERNOON AS THE
DEFINED S/W CROSSES OVERHEAD DURING MAX HEATING. MAX TEMPS WILL BE
SIMILAR TO TODAY/S...OR RIGHT AROUND NORMAL.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
AT 215 PM EDT MON...THERE IS GOOD MODEL CONSENSUS THAT A WEAK AREA
OF LOW PRESSURE AND ASSOCIATED WEAK COLD FRONT WILL CROSS THE AREA
FROM WEST TO EAST TUE NIGHT. HOWEVER...THERE ARE SOME MINOR TIMING
DIFFERENCES. THE 12Z GFS IS A LITTEL STRONGER WITH THE SURFACE LOW
AND FASTER WITH THE SYSTEMS MOVEMENT. THE 12Z NAM IS SIMILAR TO THE
SREF IN REGARD TO TIMING...SO HAVE LEANED MORE TOWARD A NAM
SOLUTION. HENCE...WE EXPECT NUMEROUS SHOWERS/THUNDERSTORMS TO AFFECT
THE WESTERN CAROLINAS AND NE GA TUE NIGHT. THE HIGHEST QPF AND POPS
SHOULD BE OVER NORTHERN SECTIONS CLOSER TO THE BEST UPPER FORCING.
WITH PWATS AROUND 2 INCHES...SOME LOCALLY HEAVY RAIN IS CERTAINLY A
POSSIBILITY. HOWEVER...DO NOT BELIEVE THAT THE FLOOD THREAT IS MORE
THAN ISOLATED AT THIS POINT.

ON WED...THE FRONT IS FORECAST TO MOVE EAST OF THE I-77 CORRIDOR
DURING THE MORNING. HENCE...WILL HAVE SCATTERED POPS IN THAT AREA
EARLY...BUT WILL TAKE THE MENTION OF PRECIP OUT OF THE FORECAST BY
MIDDAY. ON WED AFTERNOON...THE GFS AND THE CMC BRING WINDS
AROUND TO AN UPSLOPE COMPONENT OVER THE MOUNTAINS AND RESPOND WITH
SOME QPF THERE. THE NAM IS ESSENTIALLY DRY. WILL COMPROMISE AT THIS
POINT WITH JUST SOME VERY LOW END POPS OVER THE MOUNTAINS.

WITH CONTINUING LIGHT UPSLOPE FLOW ADVERTISED BY THE GLOBAL MODELS
WED NIGHT...CAN`T RULE OUT AT LEAST SOME WIDELY SCATTERED SHOWERS
CONTINUING OVER THE MOUNTAINS. ON THU...EXPECT THAT SCATTERED SHOWERS
AND THUNDERSTORMS WILL DEVELOP OVER THE MOUNTAINS DURING THE
AFTERNOON AS THE WEAK UPSLOPE FLOW CONTINUES ALONG WITH WEAKLY
DIVERGENT FLOW ALOFT. USED THE ALL-BLEND GUIDANCE WHICH KEEPS MAX
TEMPS A CATEGORY OR SO BELOW AVERAGE.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AS OF 110 PM EDT MONDAY...HEIGHTS WILL SLOWLY BUILD FROM THE WEST
FROM THURSDAY NIGHT INTO THE WEEKEND AS THE CENTER OF THE UPPER
RIDGE SHIFTS EAST FROM TEXAS TO SOMEWHERE OVER THE SE
STATES...DEPENDING ON WHICH MODEL YOU REFERENCE. A LIGHT EASTERLY
LOW LEVEL FLOW FRIDAY AND SATURDAY WILL SHIFT TO LIGHT SOUTHWEST BY
LATE SUNDAY INTO MONDAY. LIGHT WIND ALL THE WAY UP TO AROUND 500MB
WITH AROUND 10 KTS AT 500MB AND GENERALLY LESS DOWN TO THE SURFACE
FROM DAY 5 THROUGH NEW DAY 7. SURFACE HIGH PRESSURE CENTERED NEAR
NEW JERSEY THURSDAY NIGHT WILL RIDGE DOWN THROUGH THE CAROLINAS WITH
THE COOLER THAN NORMAL TEMPERATURES. THE CENTER OF THIS HIGH WILL
DRIFT TO NEAR BERMUDA LATE IN THE WEEKEND AND EARLY NEXT WEEK
PROVIDING A CHANGE IN AIRMASS COMBINED WITH INCREASING INFLUENCE OF
THE UPPER RIDGE BUILDING FROM THE WEST. CAPE VALUES ON FRIDAY AND
SATURDAY WILL BE A LITTLE HIGHER OVER THE MTNS...1000 TO 1600 ON THE
GFS FRIDAY. CAPE VALUES DROP OFF VERY LOW SUNDAY AND MONDAY. VARYING
LEVELS OF LOW LEVEL MOISTURE THROUGHOUT THE MEDIUM RANGE WILL SERVE
FOR THE PRODUCTION OF PM SHOWERS AND T-STORMS. TEMPERATURES A BIT
WARMER AT END OF THE WEEKEND AND START OF NEXT WEEK.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
AT KCLT...WHILE -RA MAY LINGER FOR A COUPLE OF HOURS TO START THE
PERIOD...IT APPEARS THUNDER ACTIVITY WILL REMAIN WEST AND SOUTH OF
THE FIELD THIS EVENING. FEW-SCT CLOUDS BELOW 040 WILL BE SEEN THIS
EVENING AS LEFTOVERS FROM ONGOING TS. LIGHT SWLY WINDS ALOFT WILL
BRING IN MORE MOISTURE OVERNIGHT AND SHOULD DEVELOP A LOWER CIG.
GUIDANCE WIDELY DIFFERS ON CATEGORY...BUT RAW NAM SEEMS MOST
PLAUSIBLE IN LIGHT OF MOISTURE PROFILES AND THIS MORNING/S UPSTREAM
CIGS. THIS KEEPS MVFR...BUT TOWARD LOW SIDE. PRECIP CHANCES RAMP
BACK UP EARLY WITH UNSTABLE ATMOSPHERE AHEAD OF INCOMING FRONT.
-SHRA AFTER 15Z WITH TS CERTAINLY POSSIBLE...THOUGH HIGHLIGHTED
AFTERNOON IN A PROB30 WITH MVFR EFFECTS. WOULD NOT BE SURPRISED IF
IFR RESULTED IN SOME OF THE HEAVIER SHOWERS GIVEN ALL THE MOISTURE.
WINDS ALOFT PICK UP AHEAD OF THE FRONT AND GUSTS TO 20 KT LIKELY TO
MIX DOWN BY AFTN.

ELSEWHERE...TS AND SHRA WILL MAINLY FOCUS TONIGHT ALONG AXIS JUST TO
THE SOUTH OF OUR FORECAST AREA...ACROSS CENTRAL GA AND SC. A FEW TS
ARE ALSO OCCURRING IN THE MTNS. THIS ACTIVITY WILL CONTINUE THIS
EVENING BUT GRADUALLY DIMINISH. TEMPO FOR TS AT KAVL THRU 02Z.
SUFFICIENT DEEP MOISTURE AND FORCING ALOFT TO EXPECT SOME SHOWERS TO
BE ABLE TO POP UP OVERNIGHT. TS LESS LIKELY SO HANDLED CHANCES WITH
VCSH FOR THE MOST PART. THE INCREASING MOISTURE WILL LIKELY LEAD TO
A DEVELOPING MVFR CIG OVER MUCH OF THE AREA...BUT ESPECIALLY IN THE
MTNS WHERE PATCHY IFR MAY ALSO RESULT. FRONTAL PASSAGE LOOKS TO
OCCUR TOMORROW DURING PEAK OF AFTERNOON INSTABILITY SO TS LIKELY TO
BREAK OUT. FOR NOW HAVE INCLUDED VCTS AS NEEDED. GUSTY WINDS OF 15
TO 20 KT WILL DEVELOP IN THE STRENGTHENING FLOW AHEAD OF THE FRONT.
FROPA WILL CAUSE A NW SHIFT AT KAVL BY AFTN...BUT TOO LATE TO BE
REFLECTED IN TAFS FURTHER SOUTH AND EAST. OTHERWISE GENERALLY S TO
SW.

OUTLOOK...CONDITIONS WILL IMPROVE SOMEWHAT TUE NIGHT AS DRIER AIR
FILLS IN BEHIND A COLD FRONT...BUT SOME RESTRICTIONS ARE STILL
POSSIBLE IN THE MTNS WED MORNING. A MODERATELY UNSTABLE ATMOSPHERE
COMBINED WITH EASTERLY FLOW MAY LEAD TO SHOWER AND THUNDERSTORM
DEVELOPMENT MIDWEEK...CAUSING SPOTTY RESTRICTIONS.

CONFIDENCE TABLE...

            00-06Z        06-12Z        12-18Z        18-24Z
KCLT       HIGH  98%     HIGH  91%     HIGH  80%     HIGH 100%
KGSP       HIGH  95%     HIGH  92%     HIGH  87%     HIGH  85%
KAVL       HIGH 100%     HIGH  85%     MED   74%     HIGH  88%
KHKY       HIGH  95%     HIGH  89%     HIGH  93%     HIGH  84%
KGMU       HIGH 100%     HIGH  95%     MED   70%     MED   76%
KAND       HIGH 100%     HIGH  87%     HIGH  84%     HIGH  96%

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: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...SBK/WIMBERLEY
SHORT TERM...LG
LONG TERM...DEO
AVIATION...SBK/WIMBERLEY