000
FXUS62 KGSP 180156
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
956 PM EDT WED MAR 17 2010

.SYNOPSIS...
LOW PRESSURE WILL MOVE AWAY FROM THE SOUTHEAST COAST TONIGHT AND
THURSDAY. HIGH PRESSURE WILL BUILD OVER THE AREA FRIDAY AND
GRADUALLY MOVE OFF THE CAROLINA COAST BY SUNDAY MORNING. A COLD
FRONT WILL MOVE INTO THE MISSISSIPPI VALLEY SATURDAY AND THEN CROSS
THE WESTERN CAROLINAS AND NORTHEAST GEORGIA ON SUNDAY. COOL HIGH
PRESSURE WILL RETURN TO THE REGION MONDAY THROUGH TUESDAY.

.NEAR TERM /THROUGH THURSDAY/...
EVENING RADAR IMAGERY CONTINUES TO INDICATE LIGHT RETURNS WRAPPING
AROUND UPPER LOW CURRENTLY SITTING OVER THE MIDLANDS. SOME OF THESE
RETURNS ARE RESULTING IN TRACE AMOUNTS OF PRECIP AT THE SURFACE...
MAINLY ACROSS THE UPSTATE. AS NORTHERLY FLOW WILL CONTINUE TO ADVECT
DRIER LOW LEVEL AIR INTO THE PIEDMONT OVERNIGHT...DO NOT DEEM IT
NECESSARY TO RAISE POPS ATTM. MEANWHILE...MOISTURE WILL REMAIN MORE
PERSISTENT ACROSS THE MTNS. INCREASING BUT STILL WEAK NORTHERLY
UPSLOPE FLOW IS RESULTING IN DEVELOPMENT OF SOME VERY LIGHT QPF IN
THE NEAR TERM MODELS IN THE VICINITY OF THE SMOKIES...SO WILL RETAIN
CHANCE POPS THERE. IT STILL APPEARS THAT HIGH ELEVATION SNOW WILL BE
POSSIBLE...BUT NO ACCUMULATION IS ANTICIPATED.

OTHERWISE...EXTENSIVE MID/HIGH CLOUDS ASSOCIATED WITH THE UPPER LOW
WILL PERSIST OVER THE AREA THROUGH THE NIGHT. THIS MAY MAKE IT
DIFFICULT TO REACH CURRENT FORECAST MIN TEMPS. HOWEVER...DO NOT FEEL
STRONGLY ENOUGH ABOUT THIS TO MAKE SIGNIFICANT TEMP CHANGES ATTM.

POPS WILL DECREASE ON THURSDAY AS DRIER LOW LEVEL AIR REACHES THE
FOOTHILLS. MINIMUM TEMPERATURES WILL RUN NEAR NORMAL TONIGHT...AS
CLOUD COVER OFFSETS THE LOWER HEIGHTS ASSOCIATED WITH THE CLOSED
LOW. MAXIMUM TEMPERATURES WILL BE ABOVE NORMAL ON THURSDAY AS
HEIGHTS RISE IN THE WAKE OF THE LOW AND WINDS BACK FROM NORTHEAST TO
NORTH...SETTING A DOWNSLOPE FLOW IN THE LEE OF THE MOUNTAINS.

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 155 PM WEDNESDAY...ALL THE MODELS AGREE ON DRYING OUT THE
ATMOSPHERE THURSDAY NIGHT WITH NORTHERLY DOWNSLOPE WIND FOR
LOCATIONS ON THE DOWNSLOPE SIDE OF THE MOUNTAINS. THE NAM AND GFS
SHOW A BIT OF REMAINING MOISTURE ALONG THE TENNESSEE SIDE AT 00Z
FRIDAY BUT ALL THAT IS GONE BEFORE 06Z.  DECIDED TO LEAVE OUT ANY
POP FOR THURSDAY EVENING PERIOD AFTER 00Z.  UPPER TROUGH OR CUT OFF
WEAK LOW MOVES EAST AND OFF THE CAROLINA COAST FRIDAY MORNING AS
HEIGHTS BUILD IN FROM THE WEST.  STRONGER SOUTHERLY FLOW DOES NOT
ARRIVE UNTIL VERY LATE FRIDAY OR EVEN FRIDAY NIGHT.  STILL EXPECT
TEMPERATURES WELL INTO THE 60S FOR THE MOUNTAINS AND 70 TO 74 FOR
THE FOOTHILLS AND PIEDMONT.  NEARLY ALL MODELS HAVE US IN THE AXIS
OF THE UPPER RIDGE AROUND 00Z SATURDAY.  THE GFS...SREF...GEM AND
ECMWF ALL SHOW THE APPROACH OF THE FRONTAL PRECIP FROM THE WEST ON
SATURDAY WITH SOME VARIATIONS IN THE TIMING OF THE ONSET OF THE
RAIN.  CERTAINLY MOST OF THE PRECIP WILL BE WELL AFTER 00Z
SUNDAY...BUT CONSIDERING UPSLOPE FLOW INCREASING LATE SATURDAY AND
ONE OF THE SOUNDINGS SHOWING BRIEF RAIN AT ANDERSON EARLIER...FELT
IT BEST TO INCLUDE SLIGHT CHANCE FOR THE FAVORED UPSLOPE AREAS LATE
SATURDAY.  TEMPERATURES SHOULD BE ABOUT THE SAME FRIDAY AND SATURDAY
IN THE AFTERNOON.

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 205 PM WEDNESDAY...A BLEND OF THE SLOWER ECMWF AND FASTER GFS
IS THE FAVORED HPC SOLUTION FOR THE EXTENDED PERIOD. H5 SHORTWAVE
OVER PLAINS WILL TRACK E ACROSS THE MS VALLEY SAT NIGHT AND INTO THE
CWA SUN. ASSOC COLD FRONT WILL PUSH INTO CWA DURING THE DAY SUN. AS
THE SYSTEM APPROACHES...DEEP MOISTURE WILL SURGE N WITH GOOD
ISENTROPIC LIFT AND UPPER LEVEL DIVERGENCE SO EXPECT AN INCRSNG CHC
OF SHWRS SAT NIGHT...BECMG LIKELY ACROSS MOST OF THE CWA AFTER
DAYBREAK SUN. EXPECT DECENT LAPSE RATES WITH TEMPS IN THE 60S ACROSS
THE PIEDMONT SUN AFTN. WITH INCRSNG SHEAR AND WEAK CAPE EXPECT A
SLIGHT CHC OF TSTMS ACROSS THE CWA SUN AFTN-EARLY EVE. PRECIP SHOULD
SLOWLY TAPER OFF FROM THE W SUN NIGHT WITH LOWS COOLING INTO THE LOW
40S...30S MTNS AND THERE WILL BE A CHC OF SNOW AT THE HIGHER ELEVS
OVERNIGHT WITH NO SIG ACCUM EXPECTED. SHOWERS WILL LINGER MON AS A
WEAK REINFORCING SHORTWAVE MOVES ACROSS THE CWA FROM THE NW...MAINLY
OVER THE NC MTNS AND FOOTHILLS. TEMPS SHOULD BE A CAT OR TWO BELOW
AVG MON...WARMING TO NEAR AVG TUE AS RIDGE BUILDS OVER THE REGION.
RIDGE AXIS MOVES OFFHSORE TUE NIGHT-WED WITH WARM SW FLOW DEVELOPING
AHEAD OF NEXT SYSTEM AND TEMPS WED ARE EXPECTED TO WARM TO ABOVE AVG.

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
AT KCLT AND OTHER NC TERMINALS...MID/HIGH LEVEL CLOUDS WILL BE THE
DOMINANT FEATURE OVER THE AREA THROUGH THE NEXT 24 HOURS...AS
NORTHERLY FLOW NEAR THE SURFACE BRINGS DRIER LOW LEVEL AIR INTO THE
REGION. VERY LIGHT NORTH WINDS WILL INCREASE TO NEAR 10 KT ACROSS
THE AREA BY EARLY THURSDAY AFTERNOON...AS LOW PRESSURE STRENGTHENS
OFF THE EAST COAST. THERE IS A POTENTIAL FOR REDUCED VISBY AT KAVL
DURING THE PRE-DAWN HOURS...AS DRIER AIR WILL BE SOMEWHAT DELAYED
THERE. FOR NOW WILL JUST HINT AT THIS POSSIBILITY WITH A FORECAST OF
6SM BEGINNING AT 10Z.

FOR KGSP...KGMU...KAND...EXPECT CEILINGS TO GRADUALLY LIFT THROUGH
THE TAF PERIOD WITH SCT CLOUDS IN 7-9 KFT RANGE REMAINING AFTER 12Z
OR SO FOR GSP AND GMU AND 18Z FOR AND. NO VISBY RESTRICTIONS
ANTICIPATED WITH ALL 3 SITES AT 6SM OR GREATER. VRB WINDS SHOULD
GIVE WAY TO LIGHT NW WINDS BY EARLY MORNING WITH THE WINDS AT AND
LAGGING BY A FEW HOURS. EXPECT WINDS TO BECOME NORTHERLY BY MID
MORNING AND CONTINUE A VEERING TREND TO NE BY THE EARLY AFTERNOON
AND INCREASING TO AROUND 7KTS.

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

SYNOPSIS...DEO
NEAR TERM...JAT/JDL
SHORT TERM...DEO
LONG TERM...RB
AVIATION...JDL/JPT