Special Weather Statement, NWS Columbia, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
913 PM EDT WED AUG 8 2012

.SYNOPSIS...
WEAK HIGH PRESSURE AND SLIGHTLY DRIER AIR WILL PROVIDE DRY WEATHER
THROUGH THURSDAY...HOWEVER ANOTHER DISTURBANCE MOVING INTO THE
AREA THURSDAY NIGHT WILL BRING SHOWERS AND THUNDERSTORMS TO THE
AREA THROUGH THE WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
SCATTERED THUNDERSTORMS IN THE NORTHERN MIDLANDS AND PEE DEE THIS
EVENING. MAIN THREAT APPEARS TO BE HEAVY RAIN. EXPECT DIMINISHING
TRENDS BY MIDNIGHT AS INSTABILITY WEAKENS. OVERNIGHT MINIMUM
TEMPERATURES IN THE LOW 70S ON TRACK.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
UNSETTLED WEATHER IS EXPECTED DURING THIS PERIOD AS AN UPPER
TROUGH AMPLIFIES AND DEEPENS OVER THE GREAT LAKES REGION THURSDAY
AND EXTENDING INTO OHIO AND TENNESSEE VALLEYS BY FRIDAY...THEN
SLOWLY PUSHING THROUGH THE FORECAST AREA ON SATURDAY.

THURSDAY LOOKS TO BE A RELATIVELY DRY DAY WITH PRECIPITABLE WATER
VALUES AROUND 1.5 INCHES AND LITTLE IN THE WAY OF FORCING ACROSS
THE AREA THROUGH MID AFTERNOON. ISOLATED TO SCATTERED CONVECTION
MAY DEVELOP LATE THURSDAY AFTERNOON AND EVENING...MAINLY IN THE
CSRA WHERE MOISTURE WILL BE RECOVERING AS DEEP SOUTHWESTERLY FLOW
DEVELOPS AHEAD OF THE UPSTREAM DIGGING SHORTWAVE ENERGY. PVA
INCREASES THURSDAY NIGHT INTO FRIDAY ACROSS THE AREA AS MOISTURE
CONTINUES TO INCREASE AND WILL HOLD ON TO LOW CHANCE POPS THURSDAY
NIGHT BUT INCREASE TO HIGH CHANCE BY FRIDAY AFTERNOON COINCIDING
WITH THE UPPER SUPPORT AND MODERATE INSTABILITY. POPS MAY NEED TO
BE INCREASED FOR FRIDAY AND FRIDAY NIGHT BUT SOME MODEL
DIFFERENCES LEAD TO A LOW CONFIDENCE FORECAST IN TIMING.

THE MAIN TROUGH AXIS SHIFTS INTO THE MOUNTAINS AND THE UPSTATE BY
SATURDAY AFTERNOON WHICH SHOULD SUPPORT THE THREAT FOR RAIN AND
CONVECTION ALONG AND EAST OF THE MIDLANDS THROUGH SATURDAY AND
PUSHING TO THE COAST BY SATURDAY NIGHT. A COLD FRONT WILL TRY TO
PUSH INTO THE REGION AS WELL ON SATURDAY AND THIS ALONG WITH THE
RIGHT ENTRANCE REGION OF AN UPPER JET WILL PROVIDE PLENTY OF
OPPORTUNITY FOR CONVECTION ESPECIALLY ACROSS THE EASTERN PART OF
THE FORECAST AREA. HAVE BUMPED UP POPS TO HIGH CHANCE FOR THE
FRIDAY THROUGH SATURDAY TIME FRAME. HEAVY RAIN THREAT IS POSSIBLE
IN THE VICINITY OF THE FRONT AS THE UPPER SUPPORT AND MID LEVEL
FLOW BECOMES SOMEWHAT PARALLEL TO THE SURFACE BOUNDARY WHICH WOULD
SUPPORT TRAINING OF STORMS.

TEMPERATURES WILL BE IN THE LOWER 90S FOR DAYTIME HIGHS AND LOWER
70S THURSDAY NIGHT ALTHOUGH SATURDAY MAY BE THE COOLEST DAY WITH
MANY LOCATIONS IN THE 80S DUE TO CLOUD COVER AND PRECIPITATION.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
THE EXTENDED FORECAST FEATURES A DAY OF ZONAL WESTERLY UPPER LEVEL
FLOW WITH LOWER HUMIDITY ON SUNDAY FOLLOWED BY GENERAL TROUGHING
FROM THE GREAT LAKES THROUGH THE SOUTHEAST MONDAY THROUGH
WEDNESDAY.  MEDIUM RANGE GUIDANCE IS IN REASONABLE AGREEMENT WITH
THIS PATTERN AND YIELDS NORMAL CONFIDENCE IN THE FORECAST.

A LESS HUMID AIRMASS WILL BRIEFLY RESIDE OVER THE UPSTATE AND
WESTERN MIDLANDS ON SUNDAY WITH SOME WEAK DOWNSLOPING POSSIBLE AND
MOSTLY SUNNY SKIES.  PRECIPITABLE WATER VALUES DROP BELOW 1.5 INCHES
WHICH SHOULD LIMIT CONVECTION RESULTING FROM DAYTIME HEATING.
HOWEVER...SUNDAY NIGHT INTO MONDAY THE UPPER FLOW BACKS A BIT IN
RESPONSE TO A DIGGING UPPER TROUGH OVER THE GREAT LAKES REGION WHICH
SHIFTS INTO THE NORTHEASTERN STATES BY LATE TUESDAY.  SURFACE FLOW
AROUND THE BERMUDA HIGH WILL ALLOW MOISTURE TO ADVECT BACK OVER THE
AREA MON/TUE AND KEEP LOW CHANCES OF DIURNAL CONVECTION IN THE
FORECAST.  A FRONTAL BOUNDARY WILL ALSO PUSH INTO THE AREA BY
TUESDAY ALSO HELPING TO FOCUS PRECIPITATION AND WILL GO WITH HIGHEST
POPS ON THIS DAY.  THE FRONTAL BOUNDARY IS FORECAST TO SLIP JUST
SOUTH OF THE AREA BUT MAY STALL OUT OVER THE EASTERN MIDLANDS BY
MIDWEEK.  TEMPERATURES THROUGH THE PERIOD SHOULD REMAIN NEAR TO
SLIGHTLY ABOVE NORMAL.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
SHOWERS AND THUNDERSTORMS THAT WERE NW OF CAE/CUB HAVE DISSIPATED.
OTHER ACTIVITY CURRENTLY WELL TO THE NE OF THE TERMINALS. NOT ENOUGH
COVERAGE/CONFIDENCE TO INCLUDE PRECIP MENTION IN TAFS AT THIS TIME.

AFTER CONVECTION DISSIPATES...CONCERN WILL SHIFT TO POSSIBLE FOG
AND/OR STRATUS DEVELOPMENT LATE TONIGHT/THURSDAY MORNING. A BLEND OF
THE LATEST ARRAY OF GUIDANCE SUGGESTS MVFR CONDITIONS AT
CAE/CUB/DNL...WITH IFR POSSIBLE AT AGS/OGB. WILL NOT BE TOO
PESSIMISTIC ON THE 00Z TAFS. WILL EVALUATE TRENDS AND LATEST
GUIDANCE AND ADJUST IN LATER ISSUANCES IF NECESSARY.

SCATTERED AFTERNOON AND EVENING SHOWER AND THUNDERSTORM ACTIVITY
EXPECTED THURSDAY...BUT COVERAGE/CONFIDENCE NOT SUFFICIENT TO
WARRANT MENTION IN TAFS THIS FAR OUT.

EXTENDED AVIATION OUTLOOK...AN UNSETTLED WEATHER PATTERN WILL
PERSIST THROUGH SATURDAY. THE CHANCE FOR SHOWERS AND STORMS WILL
CONTINUE EACH DAY WITH THE DEVELOPMENT OF LATE NIGHT/EARLY MORNING
FOG/STRATUS POSSIBLE.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE COLUMBIA SC
442 AM EDT WED AUG 8 2012

GAZ040-063>065-077-SCZ015-016-018-020>022-025>031-035>038-041-090845-
LINCOLN-MCDUFFIE-COLUMBIA-RICHMOND-BURKE-LANCASTER-CHESTERFIELD-
MCCORMICK-NEWBERRY-FAIRFIELD-KERSHAW-EDGEFIELD-SALUDA-LEXINGTON-
RICHLAND-LEE-AIKEN-SUMTER-BARNWELL-ORANGEBURG-CALHOUN-CLARENDON-
BAMBERG-
442 AM EDT WED AUG 8 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR EAST CENTRAL GEORGIA AND
CENTRAL SOUTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE COLUMBIA SC
1120 PM EDT WED AUG 8 2012

SCZ028-031-036>038-090415-
CALHOUN-CLARENDON-ORANGEBURG-RICHLAND-SUMTER-
1120 PM EDT WED AUG 8 2012

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF RICHLAND...CALHOUN...
SUMTER...CLARENDON AND ORANGEBURG COUNTIES THROUGH 1215 AM EDT...

AT 1113 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS...ALONG A LINE EXTENDING FROM BISHOPVILLE
THROUGH OAKLAND TO 11 MILES WEST OF EASTOVER...MOVING SOUTH
AT 20 MPH.

SOME LOCATIONS THAT WILL BE AFFECTED INCLUDE...
OAKLAND...BOWMAN...BROOKDALE...EASTOVER...ELLOREE...MANNING...
MILLWOOD...MULBERRY...ORANGEBURG...SOUTH SUMTER...ST. MATTHEWS...
SUMMERTON AND SUMTER...

PREPARE NOW FOR THE FOLLOWING HAZARDS...
GUSTY WINDS OF 30 TO 40 MPH...
TORRENTIAL RAIN WHICH MAY PRODUCE LOCALIZED FLOODING...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REPORT LARGE HAIL...DAMAGING WINDS OR FLOODING TO YOUR COUNTY
SHERIFF...OR CALL THE NATIONAL WEATHER SERVICE TOLL FREE AT 1...8 7
7...6 3 3...6 7 7 2.

&&

LAT...LON 3369 7999 3356 8006 3331 8057 3328 8088
      3373 8099 3376 8092 3378 8100 3394 8102
      3409 8074 3407 8072 3412 8055 3377 7998
TIME...MOT...LOC 0318Z 002DEG 18KT 3402 8045 3389 8087