645
FXUS62 KGSP 031743
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
143 PM EDT THU JUL 3 2008
SYNOPSIS
THE FORECAST AREA WILL REMAIN UNDER THE INFLUENCE OF A BROAD AREA OF
HIGH PRESSURE THROUGH SATURDAY MORNING. THEN...A WEAK COLD FRONT IS
EXPECTED TO MOVE SLOWLY ACROSS THE REGION SATURDAY AFTERNOON AND
EVENING...BEFORE BECOMING STATIONARY SATURDAY NIGHT AND DISSIPATING
ON SUNDAY. THE WESTERN PERIPHERY OF SUBTROPICAL HIGH PRESSURE WILL
RETURN ACROSS THE SOUTHEAST ON MONDAY...AND REMAIN IN CONTROL
THROUGH THE MIDDLE OF NEXT WEEK.
NEAR TERM /THROUGH FRIDAY/
WEAK SHORTWAVES WILL CONTINUE MOVING THROUGH RELATIVELY ZONAL FLOW
IN BROAD UPPER TROF TONIGHT. WEAK SUBTROPICAL SFC RIDGE WILL REMAIN
OFF E COAST WITH S TO SW LOW LEVEL FLOW ACROSS THE REGION. DEW
POINTS HAVE MIXED OUT AS EXPECTED BUT SHOULD RECOVER OVERNIGHT IN
CONTINUED MOIST...S FLOW. LAPS AND BUFKIT SOUNDINGS SHOW GOOD MID
LEVEL CAP IN PLACE THIS AFTN SO DO NOT EXPECT SHOWERS MOVING INTO W
GA TO MAKE IT THIS FAR E... ESP GIVEN THE DRYER LOW LEVELS. MODELS
IN GOOD AGREEMENT DEEPENING UPPER TROF AND INCREASING MOISTURE FRI
IN CONTINUING S FLOW. MODEL SOUNDINGS SHOW CAP ERODING WITH CAPES
BETWEEN 500 AND 1000 J/KG DEVELOPING BY MID AFTN. HAVE BUMPED UP
POPS LATE FRI AFTN TO SOLID CHANCE OVER MTNS WITH SLIGHT CHANCE
ACROSS THE PIEDMONT. EXPECT MILD OVERNIGHT LOWS AS MOISTURE
INCREASES. EVEN WITH INCREASING CLOUD COVER FRI AFTN...TEMPS SHOULD
WARM INTO THE LOW 90S PIEDMONT...WITH UPPER 70S TO MID 80S MTNS.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/
AS OF 140 PM THURSDAY...THE MODEL DEPICT AN UPPER TROUGH AMPLIFYING
OVER THE GREAT LAKES AND OH VALLEY FRIDAY NIGHT AND SATURDAY..WITH
AN UPPER LOW CLOSING OFF OVER OH ON SATURDAY NIGHT. THIS LOW OPENS
UP AN LIFT OUT TO THE NORTHEAST BY SUNDAY NIGHT. A COLD FRONT WILL
MOVE SLOWLY SOUTHEAST TOWARD THE MOUNTAINS FRIDAY NIGHT...WITH
INCREASING MOISTURE SUGGESTING SLIGHT CHANCE POPS IN THE MOUNTAINS.
THE NAM IS A BIT FASTER THAN THE GFS BRINGING THIS FEATURE ACROSS
THE MOUNTAINS ...BUT BY SATURDAY AFTERNOON MOISTURE ASSOCIATED WITH
THE FRONT WILL HAVE REACHED THE PIEDMONT...SUPPORTING SCATTERED
CONVECTION. THE SLOWING FRONT WEAKENS WHILE CROSSING THE FOOTHILLS
AND PIEDMONT ON SATURDAY NIGHT AND SUNDAY...WHILE SLOWLY MOVING
SOUTHEAST...BUT WILL STILL REMAIN A FOCUS FOR CONVECTIVE ACTIVITY.
TEMPERATURES WILL EXHIBIT A REDUCED DIURNAL RANGE UNDER CLOUD COVER.
LONG TERM /MONDAY THROUGH THURSDAY/
AS OF 130 PM THURSDAY...I GENERALLY FOLLOWED HPC THINKING FOR THE
MEDIUM RANGE WHICH CLOSELY MIRRORS THE 00Z/3 ECMWF. OVERALL THE MON
THROUGH THURS PERIOD IS PRETTY MUNDANE AND FEATURES A VERY TYPICAL
SUMMERTIME PATTERN. THE DOMINANT FEATURE ALOFT WILL BE A 595 DM
SUBTROPICAL HIGH THAT GRADUALLY WEAKENS BY THE MIDDLE OF THE WEEK.
THIS SLIGHT WEAKNESS IN THE RIDGE MAY ALLOW MORE ENERGY TO MAKE A
CLOSER APPROACH TOWARDS THE LATTER PART OF THE WEEK...BUT THIS IS
LIKE SPLITTING HAIRS THIS FAR OUT. THE ECMWF FEATURES AMPLE LLVL
MOISTURE AND MODERATE INSTABILITY EACH DAY SO SOLID CHC POPS SEEM
REASONABLE THROUGHOUT THE PERIOD. NO SIGNIFICANT SURFACE FEATURES
ARE EXPECTED TO MAKE IT INTO THE REGION SO LLVL CONVERGENCE AND
DIFFERENTIAL HEATING WILL SERVE AS THE MAIN TRIGGERS FOR DIURNAL
CONVECTION. AS FAR AS TEMPS ARE CONCERNED...I HAVE GONE WITH
SEASONABLE MAX/MIN VALUES BY BLENDING IN THE 12Z HPC GUIDANCE.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
EXPECT SCT HIGH-BASED CU INTO THIS EVE. WINDS WILL CONTINUE 6 TO 10
KTS FROM THE SW WITH ISOLD GUSTS....TAPER OFF OVERNIGHT...THEN PICK
UP AT 6 TO 8 KTS FROM THE SW AFT 15Z. CU WILL DIMINISH WITH COOLING
OVERNIGHT...THEN INCREASE WITH HEATING AGAIN FRI. THERE IS A CHANCE
OF OF MAINLY MTN SHOWERS/TSTMS FRI AFTN...BUT AFTER 18Z SO NO
MENTION ATTM.
OUTLOOK...MOISTURE WILL CONTINUE TO INCREASE FRI NIGHT THROUGH SUN
WITH A SOLID CHANCE OF SHOWERS/TSTMS OVER THE WEEKEND...INCLUDING
CIG/VSBY RESTRICTIONS. A DIURNAL CHANCE OF CONVECTION WILL CONTINUE
INTO MID WEEK.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...BSH
NEAR TERM...RB
SHORT TERM...JAT
LONG TERM...BSH
AVIATION...RB
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