Severe Thunderstorm Warning 683, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1059 AM EDT SUN SEP 25 2011

.SYNOPSIS...
A WARM AND MOIST AIR MASS WILL LINGER ACROSS THE SOUTHERN
APPALACHIAN REGION TODAY. A DEEP UPPER LOW OVER THE OHIO VALLEY WILL
REMAIN THROUGH THE EARLY WEEK...A COLD FRONT WILL SLOWLY MOVE ACROSS
THE REGION LATE MONDAY INTO TUESDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
ADJUSTMENTS BEING MADE FOR CLOUDS AND POPS WITH SLOW EWD CLEARING
AND CONVECTION TRYING TO DEVELOP ON DIFFERENTIAL HEATING AND ALONG
ELONGATED S/W CROSSING THE FORECAST AREA. IN ADDITION OUR EASTERN
FORECAST AREA SITS UNDER THE RIGHT ENTRANCE REGION OF A SLIGHTLY
ANTICYCLONIC JET FOR LIFTING PURPOSES...HOWEVER BEST INSTABILITY MAY
REMAIN WEST WHERE CLEARING CAN DESTABILIZE A BIT MORE. BELOW IS THE
EARLIER FORECAST DISCUSSION.

THE LATEST UPDATE KEEPS MORE SOLID CHC POPS ALONG THE ERN ESCARPMENT
OF THE MTNS THROUGH THE MORNING HOURS AS S TO SE UPSLOPE FLOW
CONTINUES.

OTHERWISE...THE CLOSED UPPER LOW CENTER LINGERS OVER IL THIS
MORNING. AN UPPER LEVEL JETLET EAST OF THE ASSOCIATED TROUGH HAS
PERSISTED ALONG THE APPALACHIAN MTN CHAIN FOR DAYS...AND DIVERGENCE
NEAR THE ENTRANCE REGION WILL CONTINUE THROUGH TODAY. SLIGHTLY DRIER
AIR WILL ADVECT INTO THE REGION ON SW FLOW AT MID LEVELS TODAY. THIS
SHOULD KEEP ANY PRECIP COVERAGE DOWN SOMEWHAT...BUT MAY ALLOW ANY
CONVECTION THAT DEVELOPS TO GENERATE BETTER OUTFLOWS GIVEN THE
STRONG SFC TO MID LEVEL THETA E LAPSE. SEVERE POTENTIAL STILL
APPEARS QUITE LIMITED THOUGH. WILL ADVERTISE BETTER POPS ACROSS NRN
AND ERN SECTIONS...AND THE LOWEST POPS IN THE DRIER AIR S AND SW.
WILL LEAN STRONGLY TOWARD THE WARMER MOS GUIDANCE FOR MAX TEMPS.

SRLY 850 MB FLOW WILL INCREASE TONIGHT...ALONG WITH SE BL FLOW...TO
BRING ANOTHER ROUND OF NOCTURNAL UPSLOPE SHOWERS TO THE ERN SLOPES
OF THE MTNS. PRECIPITABLE WATER VALUES WILL ALSO INCREASE THROUGH
THE EARLY MORNING HOURS MONDAY AHEAD OF AN APPROACHING FRONT. WILL
FOCUS SLIGHT CHC TO LOW END CHC POPS MAINLY ALONG THE EAST SIDE OF
THE MTNS ONCE AGAIN. WILL ADVERTISE RELATIVELY WARM MINS...ABOUT 10
DEGREES ABOVE NORMAL.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY/...
AS OF 4 AM SUNDAY...ON MONDAY...A H5 CLOSED LOW WILL GRADUALLY LIFT
NORTHEAST ALONG THE SOUTHERN PORTION OF LAKE MICHIGAN AS RIDGING
CONTINUES OVER THE ROCKIES AND THE WESTERN ATLANTIC. SHORT RANGE
MODELS INDICATE THAT A COLD FRONT WILL APPROACH THE SOUTHERN
APPALACHIANS DURING THE DAY. BY MONDAY EVENING AND OVERNIGHT...THE
COLD FRONT IS EXPECTED TO MOVE ACROSS THE MTNS AND SLOW IF NOT
STALL. CAPE VALUES ALONG AND AHEAD OF THE FRONT APPEAR TO RANGE
BETWEEN 500 TO 1000 J/KG THROUGH THE PERIOD. I WILL INDICATE 30 TO
40 POPS ACROSS THE CWA ON MONDAY...HIGHER VALUES ACROSS THE MTNS.
MONDAY EVENING...IT APPEARS THAT ISO TO SCT SHRA AND TSRA WILL
REMAIN ACROSS THE REGION AS THE FRONT SLOWS. HIGHS ON MONDAY MAY
PEAK A COUPLE OF DEGREES ABOVE NORMAL. LOWS SHOULD REMAIN BETWEEN 4
TO 6 DEGREES ABOVE NORMAL GIVEN THE PLACEMENT OF THE BOUNDARY.

ON TUESDAY...THE COLD FRONT IS EXPECTED TO SLOWLY SLIDE EAST DURING
THE DAY. IT APPEARS THAT MID LEVEL SUPPORT WILL REMAIN WEAK...WITH
WIDESPREAD WEAK INSTABILITY ALONG AND AHEAD OF THE FRONT. I WILL TIE
POPS TO THE FORECAST LOCATION OF THE SFC BOUNDARY...RESULTING IN
SCHC POPS WEST TO 40 POPS ALONG AND EAST OF I-77 DURING THE HEART OF
THE AFTERNOON. HIGH TEMPERATURES SHOULD VERIFY CLOSE TO MONDAY/S
VALUES.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AT 410 AM SUNDAY...THE CLOSED UPPER LOW WILL OPEN AND MOVE OVER
EASTERN CANADA DURING THE MID WEEK AS A STRONG RIDGE REMAINS OVER
THE ROCKIES. THIS PATTERN WILL LIKELY PERSIST INTO LATE IN THE WORK
WEEK. BY THE WEEKEND...A L/W TROF WILL DIG ACROSS THE ATLANTIC
STATES AS HEIGHTS RISE OVER THE WEST. A COLD FRONT IS EXPECTED TO
PUSH ACROSS THE REGION ON FRIDAY...BUT MOISTURE REMAINS VERY
LIMITED. THIS PATTERN SHOULD FAVOR DRY CONDITIONS ACROSS THE FA
THROUGH THE EXTENDED PERIOD. TEMPERATURES WILL RANGE CLOSE TO
SEASONABLE VALUES THROUGH FRIDAY...THEN TURNING COOLER FOR THE
WEEKEND.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
AT KCLT...MOIST ESE SFC FLOW CONTINUES THIS MORNING...AND IFR CIGS
AND VSBYS...WILL ONLY SLOWLY IMPROVE THROUGH MIDDAY...GIVEN THE FACT
OF LACK OF OVERALL MECHANISM TO SCOUR THINGS OUT.

SCATTERED THUNDERSTORMS WILL BE POSSIBLE WITH HE MOIST BL AND
LINGERING BOUNDARIES...BUT WITH CONFIDENCE TOO LOW TO MENTION FOR
THIS AFTN AT PRESENT. ANOTHER ROUND OF LOW CLOUDS APPEARS IN STORE
FOR TONIGHT. FLOW WILL CONTINUE TO TOGGLE BETWEEN ESE AND ENE
THROUGH THE PERIOD.

ELSEWHERE...UPSLOPE PRECIPITATION HAS WANED BUT NEW CONVECTION
CONTINUES TO DEVELOP ON THE DIFFERENTIAL HEATING AXIS. EXPECT A SLOW
RECOVERY OF CIGS/VSBYS AT ALL SITES BUT WILL HAVE TO PAY CLOSE
ATTENTION TO AN INCREASE IN TSTM POSSIBILITIES.

OUTLOOK...A MOIST BOUNDARY LAYER WILL PERSIST THROUGH MONDAY. A COLD
FRONT WILL MOVE INTO THE REGION MON NIGHT AND SLIP EAST OF THE AREA
THROUGH TUE NIGHT. DRYING IS EXPECTED FROM WED ONWARD.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM

&&

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

&&

SYNOPSIS...NED
NEAR TERM...HG/TS
SHORT TERM...NED
LONG TERM...NED
AVIATION...HG/TS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
342 AM EDT SUN SEP 25 2011

NCZ033-049-050-053-065-501>510-260745-
AVERY-YANCEY-MITCHELL-BUNCOMBE-HENDERSON-CALDWELL MOUNTAINS-
GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-MCDOWELL MOUNTAINS-
EASTERN MCDOWELL-RUTHERFORD MOUNTAINS-GREATER RUTHERFORD-
POLK MOUNTAINS-EASTERN POLK-
342 AM EDT SUN SEP 25 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

HEAVY RAIN SHOWERS AND ISOLATED THUNDERSTORMS MOVING REPEATEDLY
ALONG THE BLUE RIDGE THIS MORNING COULD PRODUCE ISOLATED FLOODING.
OTHERWISE...SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
THROUGH THE AFTERNOON AND EVENING HOURS. CLOUD TO GROUND
LIGHTNING...GUSTY WINDS...AND BRIEF HEAVY RAINFALL WILL BE
POSSIBLE WITH ANY THUNDERSTORMS. THE SHOWER MAY FOCUS ALONG THE
BLUE RIDGE AGAIN TONIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

NCZ035>037-048-052-056-057-059-063-064-068>072-082-SCZ002-003-
005>014-019-260745-
ALEXANDER-IREDELL-DAVIE-MADISON-HAYWOOD-CATAWBA-ROWAN-
NORTHERN JACKSON-SOUTHERN JACKSON-TRANSYLVANIA-CLEVELAND-LINCOLN-
GASTON-MECKLENBURG-CABARRUS-UNION NC-PICKENS MOUNTAINS-
GREENVILLE MOUNTAINS-GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-
CHEROKEE-YORK-ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
342 AM EDT SUN SEP 25 2011

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

.DAY ONE...TODAY AND TONIGHT.

ISOLATED THUNDERSTORMS ARE EXPECTED ACROSS THE REGION THIS
AFTERNOON AND EVENING. ANY THUNDERSTORMS MAY PRODUCE CLOUD TO
GROUND LIGHTNING...GUSTY WINDS...AND BRIEFLY HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

GAZ010-017-018-026-028-029-NCZ051-058-062-SCZ001-004-260745-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-SWAIN-GRAHAM-MACON-
OCONEE MOUNTAINS-GREATER OCONEE-
342 AM EDT SUN SEP 25 2011

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

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.