Severe Thunderstorm Warning 31, NWS Columbia, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
134 PM EDT MON MAY 4 2009

.SYNOPSIS...
A NEARLY STATIONARY FRONTAL BOUNDARY WILL SHIFT SOUTHEASTWARD
INTO THE MIDLANDS BY TONIGHT...BEFORE STALLING OUT AND BECOMING A
FOCUS FOR SHOWER AND THUNDERSTORM DEVELOP OVER THE NEXT SEVERAL
DAYS. A SERIES OF UPPER DISTURBANCES WILL MOVE INTO THE REGION
THROUGH THE WEEK...KEEPING THE WEATHER UNSETTLED.

&&

.NEAR TERM /THROUGH TONIGHT/...
UPDATE 15Z...SHOWERS MOVING NORTHEAST ACROSS THE PIEDMONT AND WEST
MIDLANDS THIS MORNING. TEMPERATURES ARE LOWER THAN PREVIOUS
FORECAST DUE TO RAIN. WILL LOWER MAXIMUM TEMPERATURES MOST AREAS
THIS AFTERNOON. BEST AREA FOR POTENTIAL SEVERE THUNDERSTORMS THIS
AFTERNOON APPEARS TO BE ACROSS THE CSRA AND EAST MIDLANDS.

06Z ANALYSIS SHOWED A SURFACE LOW CENTERED OVER SOUTHWEST VIRGINIA
WITH A NEARLY STATIONARY FRONT EXTENDING FROM THE LOW
SOUTHWESTWARD THROUGH CENTRAL TENNESSEE. A STRONG SHORTWAVE WAS
EVIDENT ON WATER VAPOR IMAGERY OVER NORTHERN GEORGIA...WITH MORE
SUBTLE SHORTWAVE ENERGY EMBEDDED WITHIN THE ZONAL FLOW ACROSS THE
LOWER MISSISSIPPI VALLEY AND CENTRAL PLAINS.

LATEST REGIONAL RADAR SHOWING CONVECTIVE DEVELOPMENT ACROSS
SOUTHERN MISSISSIPPI AND ALABAMA EARLY THIS MORNING...AND THIS IS
EXPECTED TO CONTINUE TO EXPAND AND LIFT NORTHEASTWARD. A MODERATE
LOW LEVEL JET OFF THE GULF IS FUELING THE STORMS AND CONTINUING TO
DESTABILIZE THE ATMOSPHERE AS SOUTHERLY WINDS OVERRUN AN OLD
OUTFLOW BOUNDARY FROM PREVIOUS CONVECTION ON SUNDAY.

MANY FACTORS METEOROLOGICALLY WILL COME TOGETHER TO PROVIDE THE
MIDLANDS AND CSRA WITH A HIGH CHANCE FOR PRECIPITATION THIS
AFTERNOON AND TONIGHT. THE FRONTAL BOUNDARY TO THE WEST WILL SHIFT
EASTWARD...CLOSER TO THE FORECAST AREA BY THIS AFTERNOON AS THE
SURFACE LOW TO THE NORTH REDEVELOPS CLOSER TO THE COAST. IN
ADDITION...UPSTREAM CONVECTION WILL MOVE NORTHEASTWARD TOWARDS THE
AREA TODAY AND INTERACT WITH PRECIPITABLE WATER VALUES AROUND 1.75
INCHES AND THE FORECAST AREA WILL BE IN THE FAVORABLE RIGHT
ENTRANCE REGION OF THE UPPER JET AFTER 18Z. THESE FACTORS ALONG
WITH A DESTABILIZING ATMOSPHERE...LI VALUES REACH -4C...WILL ALSO
ALLOW FOR A LOW END SEVERE THREAT...ALTHOUGH FORECAST SOUNDINGS
SHOW A MOIST ADIABATIC CHARACTERISTIC TO THEM...AND THINK HEAVY
RAIN WILL BE THE MORE LIKELY THREAT. SPC DID INCLUDE THE CSRA IN A
SLIGHT RISK FOR SEVERE WEATHER AND THIS WILL BE INCLUDED IN THE
HWO.

WILL CONTINUE WITH LIKELY POPS TODAY AND INTO THIS
EVENING...THEN DECREASE POPS SLOWLY FROM THE WEST AS THE FRONTAL
BOUNDARY SLIDES INTO THE MIDLANDS AND BECOMES STALLED.
TEMPERATURES WILL BE SLIGHTLY COOLER TODAY WITH EXPECTED
PRECIPITATION MOVING IN AND CLOUD COVER...BUT REMAIN ABOVE NORMAL.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
THE BEST CHANCES FOR PRECIPITATION SHIFT TO THE EASTERN MIDLANDS
AND COASTAL AREAS OF THE STATE ON TUESDAY AS THE FRONTAL BOUNDARY
REMAINS NEARLY STATIONARY AND BECOMES THE FOCUS FOR CONVECTIVE
DEVELOPMENT WITH DAYTIME HEATING. WILL KEEP HIGH CHANCE POPS IN
THE EAST ON TUESDAY...LOWER CHANCE FOR THE WESTERN MIDLANDS...AND
DECREASE POPS TUESDAY NIGHT WITH THE LOSS OF DAYTIME HEATING.
THERE SHOULD BE CONSIDERABLE CLOUDINESS ON TUESDAY AND WITH THE
FRONTAL BOUNDARY NEARBY...TEMPERATURES SHOULD BE IN THE UPPER 70S
TO LOWER 80S.

YET ANOTHER SHORTWAVE WILL MOVE THROUGH THE NEARLY ZONAL MID LEVEL
FLOW AND AFFECT THE FORECAST AREA ON WEDNESDAY. AN INCREASINGLY
UNSTABLE AIRMASS ON WEDNESDAY WITH SHORTWAVE ENERGY MOVING TOWARDS
THE REGION SHOULD TRIGGER SCATTERED CONVECTION AGAIN AND WILL HOLD
ON TO HIGH CHANCE POPS ACROSS THE AREA...WITH THE BEST CHANCES IN
THE WESTERN COUNTIES. TEMPERATURES WILL REBOUND A BIT ON WEDNESDAY
WITH A STRONGER SOUTHWESTERLY FLOW AT THE SURFACE...BACK INTO THE
MID 80S.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
LITTLE CHANGES MADE TO THE EXTENDED. PATTERN WILL REMAIN ACTIVE
THROUGH FRIDAY/FRIDAY NIGHT WHEN THE UPPER LEVEL TROUGH WILL MOVE
OFF THE ATLANTIC COAST. LOW CONFIDENCE REMAINS AS MODELS INDICATE
AS SERIES OF DISTURBANCES CROSSING THE REGION UNTIL THE FRONT
MOVES OFFSHORE BY THE WEEKEND. WILL CONTINUE LOW POPS THROUGH
EXTENDED AND TEMPERATURES SLIGHTLY ABOVE NORMAL.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
A FRONTAL BOUNDARY NORTH OF THE MIDLANDS WILL MOVE SOUTHWARD INTO
THE MIDLANDS TONIGHT. A MOIST SOUTH TO SOUTHWEST LOW LEVEL FLOW WILL
CONTINUE TO BRING MOISTURE TO THE AREA. A SERIES OF UPPER LEVEL
DISTURBANCES WILL CROSS THE REGION BRINGING SCATTERED TO NUMEROUS
SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND OVERNIGHT. CEILINGS
AND VISIBILITY EXPECTED TO BE MVFR OR LOWER IN THUNDERSTORMS.
RADAR AT 17Z SHOWING CONVECTION DEVELOPING ACROSS SOUTH CENTRAL
GEORGIA...SHOULD MOVE NORTHEAST INTO EASTERN SOUTH CAROLINA THIS
AFTERNOON. SO EXPECT CONVECTION WILL BECOME MORE WIDESPREAD THIS
AFTERNOON AND EVENING ALTHOUGH WEAK INSTABILITY REMAINS LIMITING
FACTOR FOR STRONG THUNDERSTORMS AROUND CAE/CUB. STRONGER STORMS
POSSIBLE NEAR OGB WHERE INSTABILITY STRONGER. GUIDANCE INDICATING MVFR TO
IFR CONDITIONS TOWARD THE END OF THE TAF PERIOD WITH NUMEROUS
SHOWERS DEVELOPING AGAIN TUESDAY MORNING.

EXTENDED AVIATION OUTLOOK...THE SLOW MOVING COLD FRONT WILL DRIFT
SOUTHWARD INTO THE AREA TUESDAY. THIS FRONT WILL GRADUALLY WEAKEN
WEDNESDAY. SUFFICIENT MOISTURE AND DIURNAL INSTABILITY WILL PROVIDE
A CHANCE OF AFTERNOON/EVENING SHRA/TSRA THROUGH THE PERIOD.
LATE NIGHT/MORNING FOG OR STRATUS ALSO POSSIBLE.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE COLUMBIA SC
459 AM EDT MON MAY 4 2009

GAZ040-063>065-077-SCZ015-016-018-020>022-025>031-035>038-041-051000-
LINCOLN-MCDUFFIE-COLUMBIA-RICHMOND-BURKE-LANCASTER-CHESTERFIELD-
MCCORMICK-NEWBERRY-FAIRFIELD-KERSHAW-EDGEFIELD-SALUDA-LEXINGTON-
RICHLAND-LEE-AIKEN-SUMTER-BARNWELL-ORANGEBURG-CALHOUN-CLARENDON-
BAMBERG-
459 AM EDT MON MAY 4 2009

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

.DAY ONE...TODAY AND TONIGHT

SCATTERED TO NUMEROUS THUNDERSTORMS WILL AFFECT THE AREA
THIS AFTERNOON INTO THIS EVENING. A FEW OF THESE STORMS COULD
BECOME SEVERE...PRODUCING LARGE HAIL AND DAMAGING WINDS. THE
GREATEST CHANCE FOR SEVERE STORMS WILL BE ACROSS THE CENTRAL
SAVANNAH RIVER AREA.

LOCALLY HEAVY RAINFALL MAY PRODUCE MINOR FLOODING OF LOW LYING
AND POOR DRAINAGE AREAS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.