Severe Thunderstorm Warning 175, NWS Columbia, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
236 PM EDT TUE AUG 11 2009

.SYNOPSIS...
AN UPPER TROUGH...A SURFACE FRONT..AND INCREASING ATMOSPHERIC
MOISTURE WILL LEAD TO INCREASED RAIN CHANCES THIS WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
WEAKENING UPPER LEVEL RIDGE AXIS TO OUR SOUTH WITH UPPER TROUGH
MOVING SE ACROSS THE MIDWEST. SURFACE TROUGH CURRENTLY STRETCHED
ACROSS THE CENTRAL PART OF OUR FORECAST AREA. RADAR INDICATING
CONVECTION DEVELOPING ALONG IT. OTHER SURFACE FRONT TO OUR NORTH
APPROACHING THE MOUNTAINS...WHERE CONVECTION DEVELOPING ALONG IT AS
WELL. WILL EXPECT CONVECTION TO CONTINUE DEVELOPING ALONG THESE
BOUNDARIES AS THEY SHIFT SLOWLY SE TODAY/THIS EVENING.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
SOME SUBTLE DIFFERENCES BETWEEN GFS/NAM...BUT GENERAL CONSENSUS
IS UPPER TROUGHINESS TO CONTINUE DEVELOPING OVER THE EASTERN
CONUS...WITH A SURFACE BOUNDARY OR TWO IN OUR VICINITY...AND
ABUNDANT ATMOPSHERIC MOISTURE TO WORK WITH. WILL MAINTAIN A MOS
BLEND...WHICH PROVIDES LIKELY POPS FOR WED/THU. PROJECTED MODERATE
TO STRONG INSTABILITIES ALSO PROVIDES A SEVERE THREAT ALONG AND
SOUTH OF BOUNDARY. PRECIPITABLE WATER VALUES WELL OVER 2
INCHES...PLUS POSSIBLE TRAINING EFFECT ECHO MOVEMENT ALONG
BOUNDARY WILL ALSO PROVIDE A LOCALLY HEAVY RAIN/FLOODING THREAT AS
WELL.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
MODELS MAINTAIN INDICATIONS OF SLOWLY INCREASING UPPER HEIGHTS OVER
OUR REGION AS UPPER HIGH SLOWLY TRIES TO BUILD BACK NW TOWARD THE
SE US COAST. MODELS MAINTAIN COPIOUS ATMOSPHERIC MOISTURE FOR OUR
REGION...AND WILL CONTINUE TO EXPECT A CHANCE OF SHOWERS AND
THUNDERSTORMS THROUGH THE FORECAST PERIOD.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
A LEE SIDE TROF OVER THE MIDLANDS OF SOUTH CAROLINA AND EXTENDING
INTO THE CSRA WILL BE THE FOCUS OF SCATTERED THUNDERSTORMS THIS
AFTERNOON. STORMS WILL BE SCATTERED WIDELY ENOUGH TO ONLY MENTION
IN THE CLOUD IDENTIFIER AT ALL TERMINAL LOCATIONS. ACTIVITY WILL
DECREASE AFTER SUNSET. EXPECT VFR CONDITIONS TO PREVAIL AT ALL
LOCATIONS THROUGH TO EARLY WEDNESDAY MORNING EXCEPT IN
THUNDERSTORMS...WHEN THERE WILL BE A CHANCE OF MVFR FOG AT AGS
AND OGB. A DECK OF MIDLEVEL CLOUDINESS WILL OVERSPREAD THE LATER
WEDNESDAY MORNING AHEAD OF AN APPROACHING COLD FRONT.

PERIODS OF MVFR VISIBILITIES MAY BE ENCOUNTERED IN SHOWERS AND
THUNDERSTORMS ON WEDNESDAY.  OTHERWISE...NO SIGNIFICANT IMPACTS
EXPECTED DURING THE EXTENDED PERIOD.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE COLUMBIA SC
ISSUED BY NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1053 AM EDT TUE AUG 11 2009

GAZ040-063>065-077-SCZ015-016-018-020>022-025>031-035>038-041-121500-
LINCOLN-MCDUFFIE-COLUMBIA-RICHMOND-BURKE-LANCASTER-CHESTERFIELD-
MCCORMICK-NEWBERRY-FAIRFIELD-KERSHAW-EDGEFIELD-SALUDA-LEXINGTON-
RICHLAND-LEE-AIKEN-SUMTER-BARNWELL-ORANGEBURG-CALHOUN-CLARENDON-
BAMBERG-
1053 AM EDT TUE AUG 11 2009

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

.DAY ONE...TODAY AND TONIGHT

ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS
THIS AFTERNOON AND TONIGHT. SOME OF THESE THUNDERSTORMS COULD BECOME SEVERE
AND PRODUCE DAMAGING WINDS...LARGE HAIL...HEAVY RAINFALL...AND
DANGEROUS CLOUD TO GROUND LIGHTNING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
DEVELOP IN A WARM AND UNSTABLE AIRMASS DURING THE AFTERNOON HOURS
ON WEDNESDAY AND THURSDAY. SOME STORMS MAY BE STRONG TO
SEVERE...WITH THE MAIN THREATS BEING DAMAGING WINDS AND HAIL.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY.