Severe Thunderstorm Warning 411, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
742 PM EDT MON SEP 8 2008

.SYNOPSIS...
MOISTURE WILL BE ON THE INCREASE THROUGH TUESDAY OUT AHEAD OF AN
APPROACHING COLD FRONT WHICH WILL MOVE THROUGH THE REGION BY
WEDNESDAY. A COOLER WEDGE OF HIGH PRESSURE WILL BUILD DOWN THE EAST
COAST LATE WEDNESDAY THROUGH THURSDAY. TEMPERATURES RIGHT AROUND
NORMAL AND AN UNSTABLE ATMOSPHERE WILL RETURN TO THE REGION FRIDAY
THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH TUESDAY/...
A MID LEVEL RIDGE AXIS REMAINS IN PLACE LATE TODAY ACROSS THE
FORECAST AREA...BUT WITH NO CAPPING APPARENT IN THE SOUNDINGS.
HIGHER CAPE VALUES ARE POOLED QUITE STRONGLY ALONG AND SOUTHEAST OF
THE INTERSTATE 85 CORRIDOR THIS AFTERNOON ON THE LATEST LAPS
ANALYSIS...AND SREF PROBABILITIES OF CAPE ABOVE 1000 J/KG REMAIN AT
75 PERCENT OR BETTER THROUGH EARLY EVENING. CONVERGENCE SHOULD
CONTINUED TO BE FOCUSED IN THE SE PIEDMONT AND THE WESTERN MOUNTAINS
THROUGH THE EVENING...BUT DEVELOPING SE UPSLOPE FLOW ALONG WITH WEAK
JET DIVERGENCE ALOFT WILL MAKE AN ISOLATED THUNDERSTORM POSSIBLE
JUST ABOUT ANYWHERE. MID LEVEL DRY AIR WILL PROVIDE THE THREAT OF A
DAMAGING WIND GUST WITH ANY THUNDERSTORM EXHIBITING CORES TO 30
KFT...OR 65+ DBZ AROUND 15 KFT OR HIGHER.

LOW LEVEL FLOW WILL STEADILY VEER FROM SOUTHEAST TO SOUTHERLY
OVERNIGHT...WITH CONTINUED UPSLOPE FORCING NEAR THE BLUE RIDGE. LOW
CLOUDS STAND A BETTER CHANCE OF DEVELOPING GIVEN THE UPSLOPE
COMPONENT AND THE MOIST BOUNDARY LAYER. SOUTHERLY UPSLOPE CONTINUES
THROUGH TUESDAY...WITH CONVERGENCE MAXIMIZING ALONG THE BLUE RIDGE
BY TUESDAY AFTERNOON. FORCING WILL IMPROVE THROUGH TUESDAY AFTERNOON
AS THE COLD FRONT APPROACHES THE NRN TIER...SHEARED OR CHANNELED H5
SHORTWAVES EMBEDDED IN WSW FLOW ALOFT CROSS THE MOUNTAINS...AND
UPPER JET SUPPORT IMPROVES THROUGH THE DAY. INSTABILITY DOES APPEAR
TO BE MORE LIMITED ON TUESDAY GIVEN THE CLOUD COVER...BUT SHEAR WILL
IMPROVE SLIGHTLY WITH 500 MB FLOW AROUND 30 KT. LIKELY POPS WILL BE
ADVERTISED OVER NW SECTIONS...WITH SOLID CHANCES SOUTHEAST.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
AS OF 230 PM MONDAY...BEGINNING WEDNESDAY 00Z THE COLD FRONT SHOULD
HAVE JUST PASSED OVER US BRINGING A GOOD CHANCE OF SHOWERS AND
POSSIBLY SOME THUNDERSTORMS. IT APPEARS THAT THE BEST CHANCE FOR ANY
THUNDER WILL BE EARLY IN THE PERIOD AND MOSTLY CONFINED TO THE
SOUTHERN PORTION OF THE CWA. ONCE THE WEDGE BEGINS TO ESTABLISH
ITSELF LATE WED AND THURS...THE PREDOMINANT PRECIP TYPE SHOULD BE
RAIN SHOWERS.

ON THURSDAY...COOL AIR DAMMING SHOULD BE WELL ESTABLISHED OVER THE
REGION AS NORTH EASTERLY SURFACE FLOW AND LINGERING DEEP MOISTURE
KEEP A SOLID CHANCE FOR PCPN THRU THE FIRST HALF OF THURS. POP
VALUES WERE LOWERED LATER ON THURS AS LOW LEVEL FORCING DECREASES.
BY EARLY FRIDAY...THE WEDGE BEGINS TO DISSIPATE AND THE SURFACE FLOW
WEAKENS. THE 12Z GFS AND 00Z ECMWF MAINTAIN DECENT AGREEMENT FOR
THIS PERIOD AND POPS WERE LOWERED A BIT TO REFLECT DRIER LOW LEVEL
AIR. OVERALL...TEMPS WERE LOWERED A FEW DEGREES ON WED AND THURS TO
REFLECT A MORE PROMINENT COOL AIR DAMMING SITUATION.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 230 PM MONDAY...LARGE SCALE SYNOPTIC PATTER CONTINUES TO
REMAIN PROGRESSIVE WITH S/W TROFFING/RIDGING AND QUASI ZONAL FLOW IN
THE NORTHERN LATITUDES. PARENT SFC HIGH PRESSURE OVER THE NE SHOULD
HAVE NO PROBLEM SHIFTING OFFSHORE IN THIS PATTERN AND CAD RIDGING
DOWN THE EAST COAST INTO THE CWFA SHOULD WEAKEN AND BURN OFF THROUGH
MID DAY FRI. THE 00Z ECMWF IS KEEPING THE CAD IN PLACE LONGER THAN
THE 06Z/12Z GFS...HOWEVER THE OVERALL TREND IS LOOKING MORE AND MORE
LIKE A DISSIPATION IS STORE WITH H7/H5 FLOW BECOMING W/LY AND MID
LEVEL OMEGA HELPING TO INCREASE INSTABILITY BY AFTERNOON. SO WILL
EXPECT A TYPICAL WEDGE BREAK DOWN WITH LOW CHC POPS EXPECTED IN
ASSOCIATING WITH TMB FRONT. MAX TEMPS COULD BE A CHALLENGE WITH THE
MORNING OVC STRATUS...AND THE LOW END OF HPC AND GMOS GUIDANCE HAS
BEEN USED WHICH GIVES MAXES ABOUT A DEGREE OR TWO BELOW NORMAL.

THE UPPER LEVEL PATTERN OVER THE SE REGION WILL REMAIN FAIRLY STEADY
STATE THROUGH THE EXTENDED PERIOD WITH STRONG 590 DM HIGH
PERSISTING. THIS SHOULD HAVE NO PROBLEM KEEPING THE SEASONAL COLD
FRONTS HUNG UP ACROSS THE TN/OH VALLEYS AND THE REMNANTS OF
HURRICANE IKE TRACKING UP THE MS VALLEY THROUGH MON. THE ATMOS LOOKS
TO REMAIN VERY MOIST AND UNSTABLE HOWEVER...WITH GOOD CONTINUOUS
S/LY H92/H85 MOISTURE TRANSPORT AFFECTING THE REGION. THE
STRONGEST FORCINGS ARE EXPECTED TO REMAIN TO THE WEST AND NORTH OF
THE AREA THROUGH THE EXT...SO POPS HAVE BEEN GIVEN A MORE DIURNAL
TREND AND OVERALL AFTERNOON VALUES TWEAKED DOWN A BIT. STILL EXPECT
AFTERNOON POPS RIGHT AROUND NORMAL AND A BIT HIGHER IN THE MTNS. A
BACK DOOR COLD FRONT IS NOW ADVERTISED TO REACH THE AREA MON AS
OPPOSED TO AN EARLIER COLD FRONT SUN NIGHT...AND IF THE UPPER HIGH
REMAINS INTACT THERE SHOULD BE NO REASON TO GO AGAINST THIS IDEA.
TEMPS THROUGH THE REST OF THE EXT SHOULD HOVER RIGHT AROUND NORMAL
AND PERHAPS A COUPLE DEGREES ABOVE.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
THE PREVIOUS SET OF TAFS IS IN GREAT SHAPE IN TERMS OF WHAT IS
EXPECTED OVERNIGHT. DEVELOPING SE UPSLOPE FLOW MAY ACT TO PROLONG
SCATTERED SHOWERS AND STORMS INTO THE LATE EVENING. KCLT HAS THE
IMMEDIATE THREAT...BUT KAND/KAVL WILL ALSO HAVE NEARBY STORMS. THIS
WILL BE HANDLED MAINLY THROUGH AMENDMENTS IF STORMS MATERIALIZE. LOW
LEVEL MOISTURE IS A BIT MORE PLENTIFUL THIS EVENING AND THAT
SITUATION SHOULD NOT CHANGE. WHILE IT IS NOTED THAT MOS GUIDANCE HAS
BEEN OVERDOING THE FOG DEVELOPMENT FOR THE LAST SEVERAL DAYS...AM
THINKING IT COULD BE LIKE THE CASE OF THE STOPPED CLOCK...SO IT WILL
BE INCLUDED IN ALL TAFS. MOISTURE POOLING AHEAD OF AN APPROACHING
FRONT ON TUESDAY SHOULD KEEP THE LOW CLOUDS OVER ALL TAF SITES. A
PERIOD OF MVFR CEILINGS IS POSSIBLE IN THE MORNING...BUT FOR NOW THE
TAFS WILL BE OPTIMISTIC AND KEEP THAT LEVEL AT THE LOW END OF VFR.
FORCING FOR CONVECTION WILL MOVE IN DURING THE AFTERNOON. SCATTERED
THUNDERSTORMS LOOK LIKE A GOOD BET AND FOR NOW THIS IS INCLUDED WITH
A VCTS AFTER 20Z.

OUTLOOK...SIGNIFICANT CEILING AND VISIBILITY RESTRICTIONS WILL
LIKELY DEVELOP ACROSS THE TERMINAL FORECAST AREA FROM LATE TUESDAY
THROUGH THROUGH THURSDAY...AND POSSIBLY INTO FRIDAY...AS MOISTURE
RIDES NORTHWARD OVER A WEDGE OF COOLER AIR TO PRODUCE MORE
WIDESPREAD PRECIPITATION. CONDITIONS MAY NOT IMPROVE SIGNIFICANTLY
BEFORE THE WEEKEND...AND EVEN THEN SCATTERED SHOWERS AND
THUNDERSTORMS MAY CONTINUE.

&&

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

&&

SYNOPSIS...SBK
NEAR TERM...HG
SHORT TERM...JPT
LONG TERM...SBK
AVIATION...PM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1050 AM EDT MON SEP 8 2008

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-091500-
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-
1050 AM EDT MON SEP 8 2008

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

.DAY ONE...TODAY AND TONIGHT.

ISOLATED TO SCATTERED THUNDERSTORMS WILL BE POSSIBLE THIS
AFTERNOON AND EVENING. BRIEF HEAVY RAIN...GUSTY WIND...SMALL
HAIL AND LIGHTNING WILL BE THE PRIMARY THREATS ASSOCIATED WITH
STRONGER STORMS TODAY. A FEW OF THE STRONGEST THUNDERSTORMS COULD
PRODUCE DAMAGING WIND GUSTS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED ON TUESDAY AS A
COLD FRONT MOVES INTO THE AREA FROM THE NORTH. ISOLATED SEVERE
STORMS WILL BE POSSIBLE...PRODUCING DAMAGING WIND GUSTS AND/OR
LARGE HAIL.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

HG

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
423 PM EDT MON SEP 8 2008

SCZ010-082100-
ANDERSON-
423 PM EDT MON SEP 8 2008

...A STRONG THUNDERSTORM WILL AFFECT WESTERN ANDERSON COUNTY THROUGH
500 PM EDT...

AT 420 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 5 MILES SOUTHWEST OF SANDY SPRINGS...OR 9 MILES
WEST OF ANDERSON. THIS STORM WAS NEARLY STATIONARY.

PEOPLE IN WESTERN ANDERSON COUNTY...INCLUDING THE FOLLOWING
LOCATION...

SANDY SPRINGS...

SHOULD MONITOR THE WEATHER SITUATION CLOSELY. LISTEN FOR POSSIBLE
WARNINGS AND BE PREPARED TO TAKE APPROPRIATE ACTION SHOULD SEVERE
WEATHER THREATEN.

SMALL HAIL...TORRENTIAL RAINFALL...AND WIND GUSTS OF 40 TO 50 MPH
ARE EXPECTED WITH THIS STORM.

HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS. WATER
LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE.

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
513 PM EDT MON SEP 8 2008

NCZ071-082145-
MECKLENBURG-
513 PM EDT MON SEP 8 2008

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN MECKLENBURG COUNTY
THROUGH 545 PM EDT...

AT 511 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR HUNTERSVILLE...MOVING NORTHEAST AT 8 MPH.

PEOPLE IN NORTHERN MECKLENBURG COUNTY...INCLUDING THE FOLLOWING
LOCATIONS...

HUNTERSVILLE AND DAVIDSON...

SHOULD MONITOR THE WEATHER SITUATION CLOSELY. LISTEN FOR POSSIBLE
WARNINGS AND BE PREPARED TO TAKE APPROPRIATE ACTION SHOULD SEVERE
WEATHER THREATEN.

SMALL HAIL...AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS
STORM.

HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS. WATER
LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE.

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
711 PM EDT MON SEP 8 2008

NCZ071-072-082345-
CABARRUS-MECKLENBURG-
711 PM EDT MON SEP 8 2008

...A STRONG THUNDERSTORM WILL AFFECT NORTHERN MECKLENBURG AND
NORTHWESTERN CABARRUS COUNTIES THROUGH 745 PM EDT...

AT 706 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 3 MILES SOUTHEAST OF HUNTERSVILLE...OR 7 MILES
NORTHWEST OF UNC CHARLOTTE...MOVING NORTH AT 6 MPH.

THIS STORM WILL BE NEAR...
  HUNTERSVILLE BY 725 PM EDT.

SMALL HAIL...AND WIND GUSTS UP TO 40 MPH ARE EXPECTED WITH THIS
STORM.

HEAVY RAINS MAY FLOOD LOW LYING AREAS SUCH AS DITCHES AND
UNDERPASSES. AVOID THESE AREAS AND DO NOT CROSS FLOODED ROADS. WATER
LEVELS OF SMALL STREAMS AND RIVERS MAY ALSO RISE.

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
915 PM EDT MON SEP 8 2008

SCZ001-004-090145-
GREATER OCONEE-OCONEE MOUNTAINS-
915 PM EDT MON SEP 8 2008

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL OCONEE COUNTY THROUGH
945 PM EDT...

AT 910 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 5 MILES SOUTHWEST OF SENECA...OR 11 MILES SOUTH
OF WALHALLA...MOVING NORTH AT 22 MPH.

THIS STORM WILL BE NEAR...
  SENECA BY 920 PM EDT.
  WALHALLA BY 940 PM EDT.

SMALL HAIL...AND WIND GUSTS OF 30 TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LANE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
922 PM EDT MON SEP 8 2008

NCZ036-056-069-071-090145-
CATAWBA-IREDELL-LINCOLN-MECKLENBURG-
922 PM EDT MON SEP 8 2008

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN LINCOLN...NORTHERN
MECKLENBURG...SOUTHEASTERN CATAWBA AND SOUTHERN IREDELL COUNTIES
THROUGH 945 PM EDT...

AT 919 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES SOUTH OF LAKE NORMAN...OR 17 MILES EAST
OF LINCOLNTON...MOVING NORTHWEST AT 13 MPH.

THIS STORM WILL BE NEAR...
  LAKE NORMAN BY 935 PM EDT.
  DENVER BY 940 PM EDT.
  TERRELL BY 945 PM EDT.

SMALL HAIL...AND WIND GUSTS OF 30 TO 40 MPH ARE EXPECTED WITH THIS
STORM.

LANE