411
FXUS62 KGSP 062352
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
752 PM EDT SUN JUL 6 2008
SYNOPSIS
A WEAK STATIONARY FRONT WILL REMAIN IN THE VICINITY OF THE FORECAST
AREA THROUGH MONDAY...BEFORE STRONG HIGH PRESSURE BUILDS EAST OFF
THE ATLANTIC COAST THROUGH MID WEEK. A COLD FRONT WILL MOVE INTO
NORTH CAROLINA THURSDAY AND SLOWLY MOVE NORTH OF THE AREA AND WEAKEN
THROUGH SATURDAY.
NEAR TERM /THROUGH MONDAY/
SHWRS/TSTMS WILL CONTINUE TO DEVELOP AND ENE ACROSS THE AREA THROUGH
THE EVENING HOURS WITH BETTER UPPER FORCING MOVING OVER AREA. THREAT
OF SEVERE STORMS HIGHER THAN YESTERDAY...ESP WITH DRIER AIR WORKING
IN AT THE MID LEVELS FROM THE W. WILL NEED CORES OF 50-55DBZ UP
AROUND 28-30KFT WITH WIND DAMAGE AND LARGE HAIL THE MAIN CONCERN.
THERE IS ALSO ENOUGH SHEAR TO SUPPORT A SLIGHT TORNADO THREAT.
CONVECTION WILL BEGIN TO TAPER OFF LATE THIS EVE BUT CHANCE POPS
CONTINUE OVERNIGHT. EXPECT LOWS TONIGHT GENERALLY IN THE 60S WITH
SOME 50S IN THE MTNS.
BEST UPPER FORCING AND LL CONVERGENCE MOVES E OF CWA MON BUT AIRMASS
REMAINS MOIST AND RELATIVELY UNSTABLE. EXPECT SCT MAINLY AFTN
CONVECTION...ESP ACROSS SE CWA. HIGHS WILL RANGE FROM AROUND 90 S TO
M80S N...WITH UPPER 70S TO MID 80S MTNS.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/
AS OF 1 PM SUNDAY...THE SOUTHERN STREAM TROUGH OVER THE APPALACHIANS
ON MONDAY NIGHT MOVES TO THE COAST BY TUESDAY NIGHT. A BROAD UPPER
TROUGH SETS UP OVER THE GREAT LAKES BY WEDNESDAY. THE MAIN UPPER
FEATURES CROSSING OUR AREA WILL BE THE SOUTHERN STREAM TROUGH ON
TUESDAY...AND THEN SOME WEAK CHANNELED IMPULSES ON WEDNESDAY. A COLD
FRONT WILL CROSS THE AREA FROM THE NORTHWEST ON WEDNESDAY.
ALTHOUGH MOISTURE WILL BE MORE LIMITED HERE THAN AT THE COASTAL
PLAIN...A LIGHT SOUTHERLY FLOW WILL PROVIDE SOME UPSLOPE COMPONENT
ALONG THE SOUTH FACING BLUE RIDGE ESCARPMENT OF GA AND SC. THE BEST
INSTABILITY WILL BE IN THE PIEDMONT ON TUESDAY WHERE THE GFS HAS
CAPE OF 2500 J/KG. BY WEDNESDAY THIS BELT OF INSTABILITY IS WELL
EAST OF OUR PIEDMONT...AND THE MOUNTAINS BECOME THE MOST UNSTABLE
PART OF OUR AREA...THOUGH WITH ONLY HALF THE CAPE OF THE PIEDMONT
THE DAY BEFORE. THE BEST CHANCE POPS WILL BE SHIFTED FROM THE EAST
ON TUESDAY TO THE WEST ON WEDNESDAY...THEN TO THE SOUTH ON WEDNESDAY
NIGHT. TEMPERATURES SHOULD WARM AS HEIGHTS RISE OVER THE AREA AND
CLOUD COVER BECOMES LESS EXTENSIVE IN THE WAKE OF THE SOUTHERN
STREAM TROUGH.
LONG TERM /THURSDAY THROUGH SUNDAY/
AS OF 155 PM SUNDAY...MODELS AGREE FAIRLY WELL DURING THE FIRST
COUPLE PERIODS OF THE EXTENDED...HOWEVER A NOTICEABLE DIFFERENCE IN
UPPER HEIGHTS BEGINS FRI ACROSS THE EASTERN CONUS. THE 12 GFS
CONTINUES TO SHOW A STRONG SUBTROPICAL HIGH BUILDING EAST ACROSS THE
DEEP SOUTH AND A DISJOINTED WAVY PATTERN ACROSS THE NORTHERN
CONUS....THEREBY GIVING THE SE A ZONAL FLOW PATTERN WITH CHANNELED
VORT KEEPING THE AIRMASS UNSETTLED. THE 00Z ECMWF BUILDS THE UPPER
RIDGE EAST...HOWEVER IT COMBINES WITH NORTHERN RIDGE...THEREBY
PRODUCING L/W RIDGING OVER THE EASTERN CONUS AND A DRIER SCENARIO
FOR THE SE STATES. FOR NOW THE...GFS TYPE SOLN IS PREFERRED WITH ITS
BETTER RUN TO RUN CONSISTENCY AND THE FORECAST GRIDS WERE ADJUSTED
MINIMALLY IN REGARDS TO POPS AND TEMPS. STILL EXPECT WEAK FRONT TO
LINGER OVER THE AREA THU AND MOVE NORTH FRI WHILE GETTING TRAPPED
UNDER INCREASING UPPER RIDGING. WITH THE GFS SUGGESTING THE PRESENCE
OF UPPER LEVEL SUPPORT...THE SFC BOUNDARY SHOULD HAVE NO PROBLEM
FIRING UP THU AFTERNOON. IN FACT...WEAK LEFTOVER CONVECTIVE SFC
BOUNDARIES SHOULD REMAIN ACROSS THE CWFA THROUGH THE EXTENDED RANGE
AND WILL EXPECT 30 TO 40 CHANCE POPS IN GOOD AFTERNOON HEATING. MAX
TEMPS DURING THE PERIOD WILL BE A CAT OR TWO ABOVE NORMAL WITH
STRONG RIDGING DEVELOPING AND WILL EXPECT MIN TEMPS A COUPLE DEGREES
ABOVE NORMAL WITH NO AIRMASS CHANGE AND VERY MOIST ATMOS
EXPECTED.
AVIATION /00Z MONDAY THROUGH FRIDAY/
SCATTERED TSTMS WILL CONTINUE TO ACROSS THE AREA INTO THE OVERNIGHT
HOURS...SIMILAR TO LAST NIGHT. W/V IMAGERY SHOWS DRY AIR ENTERING
THE MTNS...SO CONVECTIVE CHCS SHUD DIMINISH W TO E DURING THE EARLY
MORNING HOURS. AXIS OF UPPER TROF WILL BE ORIENTED N-S RIGHT THRU
THE WRN CAROLINAS. ANY CONVECTION THAT DEVELOPS...SHUD BE GENERALLY
E OF THE AXIS (KHKY/KCLT PRIMARILY). SINCE COVERAGE SHUD BE LESS
THAN THIS AFTN...JUST A CB WILL BE KEPT AFTER 03Z. MOST SITES WILL
HAVE OR HAVE HAD SOME RAIN. SO MVFR FOG/STRATUS EARLY MONDAY MORN IS
POSSIBLE AT ALL SITES...WITH PATCHY IFR PSBL AT KAVL/KHKY AROUND
DAYBREAK.
SCATTERED TSTMS ARE EXPECTED AGAIN MONDAY AFTN...ESP E (KHKY/KCLT).
FOR NOW...COVERAGE IS EXPECTED TO BE LOW ENOUGH THAT NO CB MENTION
HAS BEEN ADDED. HOWEVER...WILL LIKELY BE ADDED AT LATER ISSUANCE.
OVERALL...DECENT CU DECK IS EXPECTED...WITH VFR CONDITIONS AND SWLY
WINDS THRU 00Z TUESDAY.
OUTLOOK...LITTLE OVERALL CHANGE THRU THURSDAY...AS SFC RIDGE REMAINS
OFFSHORE BRINGING MOISTURE UP OVER OUR REGION. EXPECT MAINLY DIURNAL
CONVECTION WITH ASSOC HAZARDS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...SBK
NEAR TERM...RB
SHORT TERM...JAT
LONG TERM...SBK
AVIATION...ARK
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