Red Flag Warning 9, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
522 AM EDT THU MAR 13 2008

.SYNOPSIS...
WARM AND DRY HIGH PRESSURE ALONG THE SOUTHEAST COAST TODAY WILL GIVE
WAY TO A SERIES OF LOW PRESSURE SYSTEMS MOVING ACROSS THE REGION
FROM THE WEST FRIDAY AND SATURDAY. THE STRONGER SYSTEM ON SATURDAY
WILL HAVE THE POTENTIAL TO BRING SEVERE THUNDERSTORMS TO PARTS OF
THE FORECAST AREA. CLEARING CAN BE EXPECTED BEHIND THE TRAILING COLD
FRONT SUNDAY...WITH HIGH PRESSURE DOMINATING THROUGH THE EARLY PART
OF NEXT WEEK. ANOTHER COLD FRONT WILL APPROACH FROM THE WEST BY MID
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
UPPER RIDGE OVERHEAD...WITH SFC HIGH PRESSURE ALONG THE EASTERN
SEABOARD WILL SET UP FOR A VERY WARM DAY TODAY. SATELLITE IMAGERY
AND METARS UPSTREAM SHOWS ONLY SOME CIRRUS THAT IS FCST TO STREAM BY
THIS AFTN. SO WITH ALMOST FULL SUN AND SOUTHWESTERLY SFC WINDS...MAX
TEMPS SHOULD REACH THE MID 70S ACROSS THE PIEDMONT (PARTS OF THE
UPSTATE MAY GET INTO THE UPPER 70S). THE MTNS/VALLEYS WILL BE IN THE
60S TO LOWER 70S.

TONIGHT...RETURN FLOW CONTINUES UNDER THICKENING HIGH CLOUDS...AS A
SHORTWAVE APPROACHES FROM THE WEST. INCREASING CLOUDS AND LIGHT
SOUTHERLY WINDS WILL SUPPORT MIN TEMPS IN THE MID TO UPPER 40S
ACROSS THE PIEDMONT (30S TO LOWER 40S MTNS).

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...THE SHORT RANGE MODELS FEATURE DECENT
AGREEMENT IN SENDING A SHORTWAVE FROM THE MID MS RIVER VALLEY EARLY
FRIDAY ACROSS THE APPALACHIANS LATE IN THE DAY. A SHOT OF DEEPER
MOISTURE WILL MOVE QUICKLY ACROSS THE REGION DURING THE AFTERNOON
AND EVENING HOURS FRIDAY...FOLLOWED BY BRIEF DRYING AHEAD OF THE
NEXT WAVE DEEPENING IN THE MIDWEST LATE FRIDAY NIGHT. POPS WILL BE
FEATURED MAINLY FRI AFTN THROUGH EARLY EVENING...WITH THE HIGHEST
CHANCES IN THE MTNS.

THE FASTER AND SLIGHTLY SHALLOWER LOW ON THE GFS WILL CONTINUE TO BE
FAVORED OVER THE NAM FOR SATURDAY. UPGLIDE AND UPSLOPE FORCING ON
RAPIDLY INCREASING SOUTHERLY FLOW AT 850 MB WILL LIKELY ALLOW
SHOWERS TO BREAK OUT SAT MORNING WELL IN ADVANCE OF THE MAIN
CONVECTION. THE MORE SOUTHERLY TRACK OF THE SFC LOW CENTER ON THE
GFS IS FAVORED AS WELL...WHICH WILL KEEP STRONG LOW LEVEL
CONVERGENCE ACROSS PIEDMONT SECTIONS WHILE KEEPING THE ENTIRE
FORECAST AREA IN THE WARM SECTOR DURING THE DIURNALLY FAVORED
AFTERNOON HOURS. THERMODYNAMIC PROFILES ARE QUITE INTERESTING...WITH
SOUNDINGS CAPPED BY A SUB 800 MB INVERSION LAYER THROUGH THE
MORNING...BUT WITH INSTABILITY EXPLOSIVELY RELEASED DURING THE
AFTERNOON AS MID LEVEL TEMPERATURES COOL. STRONGLY ORGANIZED
CONVECTION APPEARS LIKELY SATURDAY AFTERNOON IN THE HIGH
SHEAR...STEEP LAPSE RATE...LOW WET BULB ZERO ENVIRONMENT. LIKELY
POPS WILL BE ADVERTISED...WITH A DAMAGING WIND/LARGE HAIL THREAT
MENTIONED IN THE HWO.

BRIEF NORTHWEST FLOW SNOW SHOWERS REMAIN POSSIBLE AT THE HIGHEST
ELEVATIONS LATE SATURDAY NIGHT/EARLY SUNDAY MORNING...BUT LITTLE TO
NO ACCUMULATION IS EXPECTED GIVEN THE MARGINALLY COLD AIR AND
SHALLOW UPSLOPE MOISTURE.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 300 AM THURSDAY...STRONG AND DRY HIGH PRESSURE WILL BUILD OVER
THE EASTERN U.S. SUNDAY THROUGH MONDAY. AN INCREASING SOUTHERLY
FETCH WILL SET UP ON TUESDAY AS THE RIDGE MIGRATES OFFSHORE AND LOW
PRESSURE MOVES THROUGH THE CENTRAL CONUS. PRECIP CHANCES WILL THEN
RAMP UP TUESDAY NIGHT THROUGH WEDNESDAY AS A COLD FRONT SWEEPS
THROUGH THE REGION. MAX/MIN TEMPS WILL RISE FROM NEAR NORMAL TO
ABOUT 5 DEGREES ABOVE NORMAL THROUGH THE PERIOD.

&&

.AVIATION /10Z THURSDAY THROUGH MONDAY/...
VFR NEXT 24 HOURS. SFC HIGH PRESSURE BUILDS OFF THE EAST
COAST...RESULTING IN SOUTHWESTERLY RETURN FLOW TODAY. CIRRUS WILL
INCREASE IN COVERAGE AS THE DAY PROGRESSES. MODEL SOUNDINGS AND
T-SECTIONS SEEM TO BE TOO DRY FOR ANY LOW OR MID CLOUD DEVELOPMENT
THROUGH THIS EVENING.

OUTLOOK...A COLD FRONT WILL MOVE IN FROM THE WEST ON FRIDAY AND
SATURDAY WITH AN INCREASING CHANCE OF SHOWERS ALONG WITH CEILING AND
VISIBILITY RESTRICTIONS. THUNDERSTORMS ARE EXPECTED SATURDAY. VFR
CONDITIONS SHOULD RETURN EARLY NEXT WEEK.

&&

.FIRE WEATHER...
DEWPOINTS RUNNING BELOW CURRENTLY FORECAST VALUES WILL REQUIRE AN
UPDATE TOWARD DRIER DEWPOINT VALUES FOR THE REMAINDER OF THE DAY.
THIS WILL PUSH RH ACROSS NE GA TO 25 PERCENT OR LESS FOR ABOUT FOUR
HOURS THIS AFTERNOON. WILL THUS HOIST ANOTHER RED FLAG WARNING FOR
TODAY GIVEN THE DRY FUELS.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...RED FLAG WARNING FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
     GAZ010-017-018-026-028-029.
NC...NONE.
SC...NONE.

&&

SYNOPSIS...HG
NEAR TERM...ARK
SHORT TERM...HG
LONG TERM...HG
AVIATION...ARK
FIRE WEATHER...HG