Severe Thunderstorm Warning 55, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1125 AM EDT SAT MAY 15 2010

.SYNOPSIS...
A WEAK COLD FRONT WILL SLOWLY MOVE SOUTH OVER THE AREA TODAY...
BEFORE MOVING BACK TO THE NORTH SUNDAY NIGHT AND MONDAY. A COLD
FRONT WILL APPROACH FROM THE WEST MONDAY AND CROSS THE AREA MONDAY
NIGHT AND TUESDAY. HIGH PRESSURE WILL SLOWLY BUILD IN FROM THE NORTH
FOR MID TO LATE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
LOW AMPLITUDE RIDGING WILL ROTATE ACROSS THE WESTERN CAROLINAS
AROUND A H5 RIDGE CENTERED OFF THE COAST OF GA AND SC THIS
AFTERNOON. MORNING SOUNDINGS INDICATE SLIGHTLY WEAKER SUBSIDENCE
INVERSIONS AT KFFC AND KGSO FROM YESTERDAY. OBSERVED SOUNDINGS
INDICATE CAPE VALUES WILL RANGE FROM 2000-3000 J/KG THIS AFTERNOON
AND THIS EVENING. WITH A WEAKER LAYER OF CIN AND MODERATE
INSTABILITY...DEEP CONVECTION SHOULD DEVELOP EARLIER THAN YESTERDAY.
AT 1445Z...VIS SAT INDICATED CU FORMING OVER THE RIDGES AND A BAND
OF OF CU ACROSS THE CLT METRO AREA. RADAR VELOCITIES INDICATE A
BOUNDARY ACROSS ROWAN AND CATAWBA...JUST NORTH OF THE BAND OF CU. I
WILL ADJUST POPS TO INDICATE THE GREATEST COVERAGE OF SHRA AND TSRA
ACROSS THE MTNS AND ALONG AN OLD OUTFLOW BOUNDARY ACROSS THE NC
FOOTHILLS AND PIEDMONT. HIGH TEMPERATURES SHOULD VERIFY CLOSE TO
YESTERDAYS VALUES.

GIVEN THE AMOUNT OF CONDITIONAL INSTABILITY AND MARGINAL WIND
FIELDS...STORMS MAY ORGANIZE IN CLUSTERS OR BROKEN LINES THIS
AFTERNOON AND EVENING. SLOW WNW STORM MOTIONS SHOULD KEEP COVERAGE
LIMITED UNTIL OUTFLOWS BEGIN TO INITIATE ADDITIONAL CONVECTION.
FREEZING LEVELS WILL REMAIN A FEW HUNDRED FEET LOWER THAN YESTERDAY
ACROSS THE FORECAST AREAS...POSSIBLY RESULTING IN SEVERAL HAIL
EVENTS. STORM STRUCTURE AND DCAPE VALUES AROUND 800 J/KG MAY SUPPORT
STRONG TO SVR WINDS. WE WILL CONTINUE TO HIGHLIGHT THE SVR POTENTIAL
IN THE HWO.

TONIGHT...CONVECTION SHOULD DISSIPATE AROUND MIDNIGHT.
HOWEVER...DEBRIS CLOUDS AND HIGH CLOUDS WILL KEEP SIGNIFICANT CLOUD
COVER ACROSS THE CWA OVERNIGHT. SOUTH WINDS AND SKY COVER WILL
PROMOTE ANOTHER NIGHT OF ABOVE NORMAL TEMPERATURES.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
AS OF 245 AM SATURDAY...FRONT REMAINS STALLED ACROSS AREA SAT NIGHT
AND SUN BEFORE LIFTING N. POPS SHOULD TAPER OFF SAT NIGHT WITH
COOLING...THEN INCREASE TO SOLID CHC SUN WITH HEATING AND MOISTURE
POOLING ALONG SFC BOUNDARY...WHILE A WEAK UPPER SHORTWAVE MOVES OVER
THE MTNS. BEST UPPER FORCING LIES N OF CWA AND MTNS SHOULD HAVE THE
BEST CHC OF STRONG STORMS. HIGHS SUN WILL BE ABOUT A CAT COOLER BUT
STILL ABOVE AVG. SFC BOUNDARY LIFTS N OF AREA SUN NIGHT BUT HELD ON
TO CHC POPS OVERNIGHT WITH WEAK FORCING AND ABOVE AVG TEMPS. DEEP S
FLOW DEVELOPS MON AS COLD FRONT APPROACHES FROM THE W. UPPER FORCING
INCREASES AS ASSOC SHORT WAVES MOVE IN AND KEPT LIKELY SHWRS WITH
SCT TSTMS. BEST FORCING/MOISTURE SHIFTS N MON NIGHT AND POPS BEGIN
TO TAPER OFF FROM THE W BUT CHC POPS LINGER ACROSS THE CWA THRU
TUE...ESP E OF I-77. TEMPS REMAIN ABOVE AVG.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
AS OF 245 AM SATURDAY...MODELS IN FAIR AGREEMENT ON DRYING TREND TUE
NIGHT INTO WED AS COLD FRONT SLOWLY MOVES E OF THE AREA. EVEN THOUGH
HIGH PRES TRIES TO BUILD IN FROM THE N LATE WED-THU...LOW LEVEL
MOISTURE LINGERS OVER MAINLY THE N AND E CWA AS IT WRAPS AROUND THE
DEPARTING 850MB LOW...SO WE HELD ON TO SLIGHT CHC POPS THERE THRU
FRI. TEMPS SHOULD BE SLIGHTLY ABOVE AVG THRU THE PERIOD.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...LTL CHANGE NEEDED TO 12Z TAFS. AS A COLD FRONT MOVES SOUTH
TOWARD INTERSTATE 40 THIS AFTERNOON...A LOW VFR CEILING SHOULD
FORM....WITH ENOUGH CONVECTIVE ACTIVITY TO MENTION CUMULONIMBUS.

ELSEWHERE...VFR LVL CLOUDINESS ON TAP...AS FOG BURNS/LIFT AT KAVL
AND KHKY. SOUTH WINDS TO RMN 5-10 KTS AS AFTN CONVECTION AHEAD OF A
SOUTHWARD MOVING FRONT WILL BE SIGNIFICANT ENOUGH TO MENTION
CUMULONIMBUS AND LOW VFR CEILINGS AT ALL SITES. KAVL AND KHKY HAVE
THE HIGHEST CHC FOR TSRA MAINLY IN THE 20-02 UTC TIME FRAME.

OUTLOOK...A COLD FRONT WILL STALL OVER THE REGION INTO EARLY NEXT
WEEK...WITH CONVECTION ASSOCIATED RESTRICTIONS IN THE AREA DURING
THE AFTERNOONS AND EVENINGS...AND POSSIBLE FOG BASED MORNING
RESTRICTIONS WHERE IT RAINS.

&&

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

&&

SYNOPSIS...RB
NEAR TERM...NED
SHORT TERM...RB
LONG TERM...RB
AVIATION...ARK

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
417 AM EDT SAT MAY 15 2010

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-160830-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-AVERY-ALEXANDER-
IREDELL-DAVIE-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-CATAWBA-
ROWAN-GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-
MCDOWELL MOUNTAINS-EASTERN MCDOWELL-RUTHERFORD MOUNTAINS-
GREATER RUTHERFORD-POLK MOUNTAINS-EASTERN POLK-OCONEE MOUNTAINS-
PICKENS MOUNTAINS-GREENVILLE MOUNTAINS-GREATER OCONEE-
GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-
ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
417 AM EDT SAT MAY 15 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING AS A COLD
FRONT MOVES IN FROM THE NORTH. SOME STORMS MAY BECOME SEVERE WITH
DAMAGING WIND AND LARGE HAIL. IN ADDITION...SLOW MOVING STORMS
COULD PRODUCE AREAS OF EXCESSIVE RAINFALL.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

THUNDERSTORMS ARE EXPECTED AGAIN SUNDAY WITH THE FRONT STALLED
OVER THE AREA. SOME OF THESE STORMS COULD ALSO BECOME SEVERE WITH
DAMAGING WIND AND LARGE HAIL. AREAS OF EXCESSIVE RAINFALL WILL BE
POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

NONE.