Special Weather Statement, NWS Greenville-Spartanburg, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
456 PM EDT FRI JUL 20 2012

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTHWEST TODAY AND ARRIVE ON
SATURDAY. THE FRONT IS EXPECTED TO STALL OVER THE AREA THROUGH THE
WEEKEND BEFORE DISSIPATING MONDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
AT 435 PM...NUMEROUS TO WIDESPREAD CONVECTION CONTINUES TO MOVE EAST
ACROSS THE SOUTHEAST QUADRANT OF THE FORECAST AREA. POPS HAVE BEEN
INCREASED TO HIGH LIKELY/CATEGORICAL FOR THE NEXT COUPLE OF HOURS.
MORNING RAOBS INDICATED SIGNIFICANT MOISTENING OF THE ENTIRE
TROPOSPHERE HAS OCCURRED OVER THE PAST 24 HOURS...AND DCAPE IS VERY
LOW AS A RESULT. IN ADDITION...FREEZING LEVELS ARE EXTREMELY HIGH...
ABOVE 15 KFT AGL. THEREFORE...THE SEVERE RISK DOESNT APPEAR TO BE AS
HIGH AS THE PAST FEW DAYS. IN FACT...WITH THE VERY MOIST AIR MASS...
HEAVY RAIN MAY BE THE MAIN CONCERN...ESPECIALLY IN URBAN AREAS
(INCLUDING CHARLOTTE METRO). HOWEVER...MEAN 0-6 KM FLOW OF 10-15 KT
IS ALLOWING CELLS TO MOVE ALONG STEADILY...SO TRAINING OF CELLS WILL
LIKELY BE NECESSARY TO PRODUCE FLASH FLOODING.

FURTHER WEST AND NORTH ACROSS THE FORECAST AREA...THE AIR MASS IS
COMPARATIVELY STABLE...OWING TO EXTENSIVE EARLY DAY CLOUD COVER. AS
SUCH...ONLY ISOLATED (AT BEST) CELLS WERE DEVELOPING IN THESE AREAS.
WE HAVE THEREFORE SCALED POPS BACK QUITE A BIT ACROSS FAR WESTERN NC
AND MUCH OF THE NORTHERN UPSTATE...WHILE HOLDING ON TO HEALTHY POPS
ACROSS THE SOUTHERN UPSTATE/NORTHEAST GEORGIA PIEDMONT...WHERE
INSTABILITY REMAINS HIGH. POPS WILL GRADUALLY RAMP UP OVER THE MTNS
TOWARD EARLY EVENING...TO ACCOUNT FOR CONVECTION CURRENTLY MOVING
ACROSS EAST TENN/EASTERN KENTUCKY.

OTHERWISE... MODELS IN PRETTY GOOD AGREEMENT REGARDING EVOLUTION OF
MID AND UPPER LEVEL FEATURES THROUGH DAYTIME SATURDAY. AT 500 MB...
LARGE RIDGE PERSISTS OVER WESTERN U.S. WITH BERMUDA HIGH OVER
ATLANTIC. 500 MB TROUGH EXTENDING DOWN EAST COAST INTO OUR CWA
PERSISTS THROUGH SATURDAY... BUT IT WITHDRAWS SLOWLY TO THE NORTH
LEAVING A SHEAR AXIS BEHIND. SHORT WAVE TROUGH CROSSING CWA THIS
AFTERNOON AND THIS EVENING WILL MAINTAIN SURFACE LOW ON FRONTAL
BOUNDARY ACROSS MID-ATLANTIC REGION. LOW WILL BE OFFSHORE SATURDAY
MORNING AND CONTINUE MOVING EAST THEREAFTER. BERMUDA HIGH BUILDS
SLOWLY WESTWARD AS 500 MB HEIGHTS INCREASE JUST A BIT. THIS WILL
MAKE SOUTHWARD MOVEMENT OF FRONTAL BOUNDARY VERY DIFFICULT TO
MAINTAIN. MOIST SOUTHWEST FLOW AHEAD OF THE FRONT ON WEST SIDE OF
BERMUDA HIGH WORKS IN COMBINATION WITH THE WEAK UPPER-LEVEL TROUGH/
SHEAR AXIS TO CONTINUE A MOIST SOUTHWEST FLOW INTO OUR AREA.
FORECASTS FOR OVERNIGHT AND SATURDAY ACCORDINGLY WILL CARRY POPS FOR
SHOWERS AND THUNDERSTORMS.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AT 230 PM EDT FRIDAY...AN UPPER TROUGH AXIS WILL REMAIN ALONG THE
EAST COAST FROM SATURDAY NIGHT THROUGH MONDAY...WHILE A RIDGE
REMAINS OVER THE PLAINS. A WEAKENING...STALLED SURFACE FRONT WILL
REMAIN OVER OUR AREA THROUGH MONDAY. ALTHOUGH THERE DOES NOT APPEAR
TO BE MUCH ISENTROPIC UPGLIDE OVER THE BOUNDARY...SHORTWAVES MOVING
INTO THE UPPER TROUGH AND OVER THE VICINITY OF THE FRONT WILL
SUPPORT PRECIPITATION THROUGH THE PERIOD...MAXIMIZED WITH GREATER
INSTABILITY DURING DAYLIGHT HOURS. WITHOUT A STRONG LIFTING
MECHANISM...PRECIPITATION AMOUNTS ARE EXPECTED TO BE MODERATE...BUT
SEVERAL DAYS OF RAIN COULD LEAD TO SOME LOCALIZED HYDROLOGICAL
PROBLEMS WITH TIME. MINIMUM TEMPERATURES WILL BE SLIGHTLY ABOVE
NORMAL...AND MAXIMUM TEMPERATURES NEAR NORMAL.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...THE CWFA WILL BE IN AN AREA BETWEEN RIDGING TO
THE SOUTH AND WEST AND NW TO SE ORIENTED NRN STREAM FLOW TO THE
NORTH. THE FLOW WILL BE CLOSE ENUF THAT WE SHUD SEE SOME EFFECT FROM
A SERIES OF WEAK SHORT WAVES MOVING THRU THE FLOW. AT THE SFC...A
BACK DOOR COLD FRONT WILL APPROACH THE AREA BUT STALL TO OUR NORTH.
A SERIES OF LOW PRESSURE WAVES WILL MOVE WEST ALONG THE FRONT. OVER
OUR CWFA...A LEE TROF AND COPIOUS LOW LEVEL MOISTURE WILL REMAIN IN
PLACE THRU THE PERIOD. THIS SHUD LEAD TO GENERALLY SCT DIURNAL
CONVECTION EACH DAY. LOWS WILL BE NEARLY STEADY AROUND 5 DEGREES
ABOVE NORMAL. HIGHS START OUT NEARLY 5 DEGREES ABOVE NORMAL THEN
FALL A COUPLE OF DEGREES BY THE END OF THE PERIOD.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT... SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE IN THE
VICINITY OF THE TERMINAL THROUGH 00Z. THUNDERSTORMS WILL BE CAPABLE
OF STRONG AND GUSTY WIND AND SMALL HAIL. AFTER 02Z... CEILING 4-6 KT
FT LOWERING TO NEAR 2K FT AROUND 12Z. POSSIBILITY EXISTS OF
VISIBILITY NEAR 5 MI IN FOG AROUND SUNRISE. CONSIDERABLE CLOUDINESS
WILL MAKE RADIATIONAL COOLING DIFFICULT... SO VISIBILITY RESTRICTION
NOT CURRENTLY IN TAF DUE TO UNCERTAINTY. EXCEPT NEAR
THUNDERSTORMS... SURFACE WIND WILL BE SOUTHWEST LESS THAN 10 KT.

REMAINDER TERMINALS... 4-6K FT BROKEN TO OVERCAST. VISIBILITY
UNRESTRICTED EXPECT VICINITY SCATTERED THUNDERSTORMS... MOST
NUMEROUS NEAR KAND... KGMU... AND KGSP. AFT 02Z... SHOWERS AND
THUNDERSTORMS BECOME MORE WIDELY SCATTERED. TOWARD SUNRISE... SOME
LOWER CEILING 2-4 KT FT AND POSSIBILITY OF VISIBILITY RESTRICTION IN
FOG... ESPECIALLY VICINITY KAVL.

OUTLOOK...AS A COLD FRONT STALLS OVER THE AREA...SCATTERED TO
NUMEROUS CONVECTIVE STORMS AND ASSOCIATED RESTRICTIONS WILL PERSIST
THROUGH THE WEEKEND. LATE NIGHT/MORNING FOG AND LOW STRATUS
PROBABILITIES WILL ALSO REMAIN FAIRLY HIGH...ESPECIALLY IN THE MTN
VALLEYS. THUNDERSTORMS WILL BECOME LESS NUMEROUS AS BERMUDA HIGH
BUILDS INTO THE REGION DURING THE FIRST PART OF THE WEEK.

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
421 PM EDT FRI JUL 20 2012

GAZ018-026-028-029-NCZ035>037-056-057-068>072-082-SCZ004>014-019-
212030-
STEPHENS-FRANKLIN-HART-ELBERT-ALEXANDER-IREDELL-DAVIE-CATAWBA-ROWAN-
CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-UNION NC-
GREATER OCONEE-GREATER PICKENS-GREATER GREENVILLE-SPARTANBURG-
CHEROKEE-YORK-ANDERSON-ABBEVILLE-LAURENS-UNION SC-CHESTER-GREENWOOD-
421 PM EDT FRI JUL 20 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
PIEDMONT OF THE WESTERN CAROLINAS AND NORTHEAST GEORGIA INTO THE
EVENING. A FEW OF THESE STORMS COULD BECOME SEVERE WITH LARGE HAIL
AND DAMAGING STRAIGHT-LINE WINDS THE MAIN THREATS. PERIODS OF
HEAVY RAIN WILL ALSO DEVELOP WITH AT LEAST MINOR FLOODING LIKELY
IN FLOOD PRONE AREAS. MORE SERIOUS FLOODING IS POSSIBLE...
ESPECIALLY IF SEVERAL STORMS TRAIN OVER THE SAME AREAS.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

GAZ010-017-NCZ033-048>053-058-059-062>065-501>510-SCZ001>003-212030-
RABUN-HABERSHAM-AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-
GRAHAM-NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
HENDERSON-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-
421 PM EDT FRI JUL 20 2012

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

.DAY ONE...TONIGHT.

ISOLATED THUNDERSTORMS ARE POSSIBLE ACROSS THE MOUNTAINS OF THE
CAROLINAS AND NORTHEAST GEORGIA EARLY THIS EVENING...WITH CLOUD
TO GROUND LIGHTNING AND GUSTY WINDS THE MAIN THREAT. A LINE OF
SCATTERED THUNDERSTORMS COULD DROP SOUTH INTO THE AREA LATER THIS
EVENING. IF THESE STORMS HOLD TOGETHER...AN ISOLATED SEVERE STORM
WITH DAMAGING WINDS IS POSSIBLE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
402 PM EDT FRI JUL 20 2012

NCZ070-071-SCZ009-202030-
GASTON-MECKLENBURG-YORK-
402 PM EDT FRI JUL 20 2012

...STRONG THUNDERSTORMS WILL AFFECT EASTERN YORK...SOUTHEASTERN
GASTON AND SOUTHWESTERN MECKLENBURG COUNTIES THROUGH 430 PM EDT...

AT 402 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 5 MILES SOUTHWEST OF
LAKE WYLIE TO 3 MILES WEST OF ROCK HILL TO 3 MILES NORTHEAST OF
LOWRYS...MOVING NORTHEAST AT 15 MPH.

THESE STORMS WILL IMPACT LOCATIONS NEAR...
  LAKE WYLIE...
  TEGA CAY...
  ROCK HILL...

PEA SIZE HAIL...FREQUENT LIGHTNING...WIND GUSTS UP TO 40 MPH...AND
TORRENTIAL RAIN ARE EXPECTED WITH THESE STORMS.

LAT...LON 3503 8077 3500 8084 3505 8089 3501 8090
      3495 8086 3491 8086 3482 8092 3482 8125
      3491 8116 3513 8120 3529 8088 3508 8072

HG

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
539 PM EDT FRI JUL 20 2012

NCZ057-202215-
ROWAN-
539 PM EDT FRI JUL 20 2012

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL ROWAN COUNTY THROUGH 615
PM EDT...

AT 539 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 4 MILES SOUTHWEST OF SALISBURY...MOVING NORTHEAST
AT 20 MPH.

THIS STORM WILL IMPACT LOCATIONS NEAR...
  SALISBURY...
  SPENCER...
  HIGH ROCK LAKE...

DIME SIZE HAIL...FREQUENT LIGHTNING...WIND GUSTS OF 40 TO 50
MPH...AND TORRENTIAL RAIN ARE EXPECTED WITH THIS STORM.

LAT...LON 3553 8056 3568 8068 3579 8050 3575 8045
      3574 8045 3572 8038 3573 8034 3571 8032
      3568 8033 3567 8030 3565 8029

HG

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