Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
510 PM EDT THU JUL 19 2012

.SYNOPSIS...
HIGH PRESSURE WILL WEAKEN AND MOVE SOUTH TODAY. THIS WILL ALLOW
A FRONTAL BOUNDARY OVER THE OHIO VALLEY TO DROP SOUTH...INTO THE
CAROLINAS EARLY SATURDAY. THE FRONT WILL REMAIN OVER OR JUST SOUTH
OF THE REGION THROUGH THE WEEKEND AND DISSIPATE ON MONDAY.

&&

.NEAR TERM /THROUGH FRIDAY/...
AS OF 445 PM...COVERAGE OF CONVECTION IS INCREASING ALONG OUTFLOW
BOUNDARY MOVING INTO THE NC PIEDMONT. WE WILL INCREASE POPS TO HIGH
CHANCE ACROSS THIS AREA THROUGH EARLY EVENING. MEANWHILE...
CONVECTION IS WANING ACROSS MUCH OF THE REMAINDER OF THE AREA...
WHERE THE CU FIELD IS UNIMPRESSIVE OR NON-EXISTENT. THIS IS NOT
ENTIRELY SURPRISING...AS THE LATEST SPC MESOANALYSIS DEPICTS A
COMPARATIVELY STABLE AIR MASS (I.E. CAPE ~ 2000 OR LESS) ACROSS THE
WESTERN HALF OF THE UPSTATE AND NORTHEAST GEORGIA. WITH MULTIPLE
OUTFLOW BOUNDARIES AROUND AND A MODERATELY UNSTABLE AIR MASS...WE
WILL CONTINUE TO FEATURE LOW TO MID-CHANCE POPS THROUGH THE EARLY
EVENING. THE HIGHEST SEVERE THREAT WILL REMAIN IN THE NC PIEDMONT...
WHERE MARGINALLY DAMAGING OUTFLOWS AND VERY BRIEF PERIODS OF LARGE
HAIL WILL BE POSSIBLE.

BY ABOUT MID-EVENING...THE MCS OVER EASTERN KENTUCKY/SOUTHWEST
VIRGINIA SHOULD BE MAKING A RUN AT THE NORTHERN NC MTNS... SO POPS
WILL INCREASE TO LIKELY THERE BY 00Z. HOW FAR SOUTHEAST THIS
ACTIVITY THEN MARCHES (AFTER ENCOUNTERING THE RUGGED TERRAIN) WILL
BE LARGELY DEPENDENT UPON HOW EFFICIENTLY THE AIR MASS RECOVERS IN
THE WAKE OF THE MESOSCALE OUTFLOW BOUNDARY. FOR NOW...POPS THE
LIKELY POPS WILL BE CONFINED TO THE NORTHERN MTNS. AS LONG AS THIS
ACTIVITY REMAINS SOMEWHAT ORGANIZED...THE THREAT FOR DAMAGING
DOWNBURSTS WILL EXIST.

A COLD FRONT WILL APPROACH FROM THE NORTH ON FRIDAY...WHILE A PAIR
OF SHORTWAVES MOVES INTO THE BASE OF THE TROUGH. POPS AND QPF WILL
BE SIGNIFICANTLY HIGHER ON FRIDAY IN ADVANCE OF THE FRONT.
INSTABILITY WILL BE SUFFICIENT FOR SEVERE THUNDERSTORMS AGAIN...AND
WITH UNIDIRECTIONAL SHEAR PRESENT...SOME ORGANIZATION IS POSSIBLE...
ESPECIALLY IN THE PIEDMONT. WITH BETTER STEERING FLOW AND MOVING
STORMS...ANY HEAVY PRECIPITATION AMOUNTS WOULD BE FROM TRAINING OR
REPEATING CELLS. MAXIMUM TEMPERATURES WILL BE NEAR NORMAL...AS
ENOUGH BREAK IN CLOUD COVER WILL PERMIT HEATING TO OCCUR.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
AS OF 235 PM THURSDAY...SHORT WAVE TROF WITH A SERIES OF ENERGY
MAXES REMAINS OVER THE AREA FRI NITE AND SAT. SFC COLD FRONT BECOMES
STALLED ACROSS THE AREA AS WELL. THE ENERGY MAXES AND RIGHT ENTRANCE
REGION OF THE UPPER JET WILL PROVIDE SOME SYNOPTIC SCALE FORCING AND
UPPER DIVERGENCE WHILE THE FRONT PROVIDES LOW LEVEL CONVERGENCE.
STILL EXPECT A DIURNAL TREND TO THE CONVECTION...BUT THE COPIOUS
MOISTURE AND LARGE SCALE FORCING SHUD KEEP AT LEAST SOME ACTIVITY
GOING MUCH OF THE NIGHT FRI NITE. NUMEROUS COVERAGE IS EXPECTED
AGAIN FOR SATURDAY FOR THE SAME REASONS...AS IS THE LINGERING
COVERAGE OVERNIGHT. HOWEVER...AREAS OUTSIDE OF THE WRN MOUNTAINS
COULD SEE BETTER COVERAGE. LOWS WILL BE NEAR NORMAL...BUT HIGHS WILL
BE BELOW NORMAL WITH MORE CLOUDS EARLIER PRECIP ONSET.

THE SHORT WAVE TROF MOVES EAST OF THE AREA SUNDAY...BUT A SHEAR AXIS
WILL REMAIN IN ITS PLACE. THE FRONT WILL BEGIN TO WASH OUT...BUT A
WEAK BOUNDARY WILL LIKELY LINGER. LOOKS LIKE COVERAGE COULD BE A
LITTLE LESS THAN SATURDAY WITH LESS UPPER SUPPORT...BUT SHUD BE AT
LEAST SCT. LOWS WILL BE A TAD COOLER...BUT HIGHS SHUD REBOUND TO
JUST BELOW NORMAL.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...A WEAK TROF WILL KEEP A SPLIT OVER THE AREA
BETWEEN THE WEST-CENTRAL CONUS RIDGE AND THE BERMUDA RIDGE. AT THE
SFC...A LEE TROF AND COPIOUS LOW LEVEL MOISTURE WILL BE OVER THE
AREA. THIS WILL LEAD TO SCT DIURNAL TSRA AND NEAR TO SLIGHTLY ABOVE
NORMAL TEMPS. ON TUE AND WED...SHORT WAVES MOVING THRU THE NRN
STREAM FLOW HELP CARVE OUT AN UPPER TROF OVER THE EAST COAST. AT THE
SFC...LOW LEVEL MOISTURE AND THE LEE TROF REMAIN IN PLACE FOR TUE
WHILE A BACK DOOR COLD FRONT APPROACHES ON WED. AGAIN...GIVEN THE
MOISTURE...INSTABILITY AND WEAK FORCING...GENERALLY SCT DIURNAL
CONVECTION IS EXPECTED BOTH DAYS. TEMPS WILL INCREASE TO ABOVE
NORMAL BY WED. THE TROF MOVES OFF THE COAST THU AND RIDGING BEGINS
TO REASSERT ITSELF OVER THE SERN US AS MORE SHORT WAVE ENERGY MOVES
ACROSS THE NRN TIER OF THE COUNTRY. THE BACK DOOR FRONT MOVES NORTH
AWAY FROM THE AREA AS WELL. STILL EXPECT ENUF MOISTURE AND
INSTABILITY TO LINGER FOR SCT DIURNAL CONVECTION ONCE AGAIN. TEMPS
WILL FALL A DEGREE OR TWO FOR THU.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
AT KCLT...CONVECTION SHOULD HAVE GREATER COVERAGE TODAY AS A WEAK
UPPER IMPULSE MOVES INTO THE AREA. A TEMPO FOR GUSTY WINDS...MVFR
VSBY AND LOW VFR CIG WILL BE CARRIED FOR SEVERAL HOURS THIS
AFTERNOON. GUIDANCE AND TRENDS FAVOR MVFR FOG AROUND DAYBREAK
FRIDAY. GUIDANCE SUPPORTS A VFR CIG...BUT SOME SCATTERED VERY LOW
CLOUDS WILL BE CARRIED IN THE TAF. PRECIPITATION ASSOCIATED WITH AN
APPROACHING COLD FRONT ON FRIDAY SHOULD NOT BE A FACTOR UNTIL AFTER
THIS FORECAST PERIOD.

ELSEWHERE...CONVECTION IS ALREADY FIRING IN THE MOUNTAINS...BUT IS
EXPECTED OT SPREAD INTO THE FOOTHILLS...AND ALL SITES WILL GET A
TEMPO FOR MVFR CONDITIONS IN THUNDERSTORMS THIS AFTERNOON. GUIDANCE
AND RECENT TRENDS FAVOR FOG RETRACTIONS AT DAYBREAK FRIDAY...IFR AT
KAVL...AND MVFR IN THE FOOTHILLS. GUIDANCE FAVORS VFR DAYBREAK CIGS
AT TAF SITES...BUT TRENDS WOULD FAVOR A RESTRICTION AT KAVL...AND AN
IFR CIG WILL BE CARRIED THERE. CONVECTION IS EXPECTED TO GET GOING
EARLIER ON FRIDAY AS A COLD FRONT ARRIVES...BUT ONLY KAVL WILL HAVE
ENOUGH COVERAGE BEFORE THE END OF THE FORECAST PERIOD TO CARRY
THUNDER.

OUTLOOK...PRECIPITATION AND ASSOCIATED RESTRICTIONS REMAIN POSSIBLE
THROUGH THE WEEKEND. FOG AND STRATUS CHANCE WILL BE GREATEST IN THE
MORNING...ESPECIALLY IN THE MTN VALLEYS.

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...PAT
NEAR TERM...JAT/JDL
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...JAT

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
524 PM EDT THU JUL 19 2012

GAZ010-017-018-026-028-029-NCZ033-035>037-048>053-056>059-062>065-
068>072-082-501>510-SCZ001>014-019-202130-
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-
524 PM EDT THU JUL 19 2012

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

.DAY ONE...TONIGHT.

SCATTERED TO NUMEROUS THUNDERSTORMS WILL CONTINUE ACROSS THE
WESTERN CAROLINAS AND NORTHEAST GEORGIA INTO THE EVENING.

SEVERAL OF THE STORMS WILL BECOME SEVERE...PRODUCING AREAS OF WIND
DAMAGE AND LARGE HAIL. THE EFFECTS OF HEAVY DOWNPOURS AND
SATURATED SOILS WILL ENHANCE THE THREAT OF FALLING TREES.
LOCALLY VERY HEAVY RAINFALL WILL ACCOMPANY THE STORMS AND FLOODING
OF POOR DRAINAGE AREAS AND A FEW STREAMS WILL DEVELOP. THE STORMS
WILL ALSO PRODUCE FREQUENT CLOUD TO GROUND LIGHTNING.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY.

ANOTHER ROUND OF NUMEROUS THUNDERSTORMS IS EXPECTED FRIDAY
AFTERNOON AND EVENING. CONDITIONS WILL BE SIMILAR TO THE PAST FEW
DAYS WITH SEVERAL OF THE STORMS BECOMING SEVERE...PRODUCING AREAS
OF WIND DAMAGE AND LARGE HAIL. IN ADDITION...SATURATED SOILS WILL
ENHANCE THE THREAT OF FALLING TREES. LOCALLY VERY HEAVY RAINFALL
WILL ACCOMPANY THE STORMS AND FLOODING OF POOR DRAINAGE AREAS AND
A FEW STREAMS WILL DEVELOP. THE STORMS WILL ALSO PRODUCE FREQUENT
CLOUD TO GROUND LIGHTNING.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
628 PM EDT THU JUL 19 2012

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0600 PM     TSTM WND DMG     4 ESE EARL              35.18N 81.47W
07/19/2012                   CLEVELAND          NC   911 CALL CENTER

            TREES AND POWERLINES DOWN...RELAYED BY AMATEUR RADIO.

&&

CSH

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