Severe Thunderstorm Warning 145, NWS Columbia, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1246 PM EDT THU JUL 5 2012

.SYNOPSIS...
WEAK SURFACE HIGH PRESSURE WILL REMAIN OVER THE SOUTHEASTERN
STATES THROUGH THE WEEKEND AS A STRONG UPPER LEVEL RIDGE OVER THE
CENTRAL PART OF THE NATION BUILDS EAST INTO THE AREA.
TEMPERATURES WILL REMAIN ABOVE NORMAL WITH A CHANCE OF DIURNAL
THUNDERSTORMS.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...FORECAST REMAINS ON TRACK WITH SOME CLOUDINESS JUST SOUTH
OF THE FORECAST AREA AND A FEW CUMULUS BEGINNING TO FORM OUTSIDE.
EXPECT THE DEVELOPMENT TREND TO CONTINUE THROUGH THE AFTERNOON
WITH SOME SHOWERS AND THUNDERSTORMS BY LATE AFTERNOON. BEST CHANCE
OF CONVECTION REMAINS OVER THE NORTHWESTERN AND SOUTHEASTERN
PORTIONS OF THE FORECAST AREA. THIS ALSO CORRELATES WITH SPC
EXPANDED SLIGHT RISK AREA WHICH NOW ENCOMPASSES THE UPSTATE AND THE
WESTERN HALF OF THE FORECAST AREA. UPDATE OUT MOMENTARILY FOR
COSMETIC CHANGES.

PREVIOUS DISCUSSION...WEAK HIGH PRESSURE REMAINS OVER THE REGION
WITH THE UPPER LEVEL RIDGE AXIS CENTERED OVER THE MID MS VALLEY.
WITH TEMPERATURES CLIMBING TOWARD TRIPLE DIGITS THIS AFTERNOON
WILL SEE SCATTERED CONVECTIVE ACTIVITY DEVELOP. ALTHOUGH
INSTABILITY WILL AGAIN BE PLENTIFUL WITH THE LACK OF A STRONG
TRIGGER EXPECT ACTIVITY TO REMAIN SCATTERED LATE THIS AFTERNOON.
BEST CHANCE FOR ACTIVITY WILL BE LATE THIS AFTERNOON INTO THIS
EVENING IN THE EASTERN MIDLANDS AND SOUTHERN CSRA...AND FAR
NORTHWESTERN MIDLANDS AS A SHORTWAVE MOVES THROUGH THE UPSTATE.
UPDATE ALREADY OUT TO ADJUST POPS AND CLOUDS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
SPC HAS ELAVATED THE THREAT OF SEVERE THUNDERSTORMS TO SLIGHT RISK
FOR THE REMAINDER OF THIS AFTERTOON AND THIS EVENING. PW VALUES
INCREASING TO AROUND 1.8 AND LI'S AROUND -4 TO -6. CONVECTIVE TEMP
OF 97 ALREADY REACHED AND CU DEVELOPING OVER THE CWA. CAPES
RUNNING BETWEEN 2500 AND 35OO SO EXPECT ISOLATED TO WIDELY
SCATTERED SEVERE STORMS THIS EVENING AND EARLY TONIGHT.

FRIDAY THROUGH SATURDAY...NOT MUCH CHANGE AS MODELS CONTINUE
BUILDING THE RIDGE EASTWARD. WITH THE UPPER RIDGE INCREASING H500
HEIGHTS A BIT CURRENT TEMP FCST OF 100 AGAIN FRIDAY AND 99
SATURDAY STILL LOOK GOOD. WILL INCLUDE A 20 PERCENT CHANCE OF
DIURNAL AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS AREA AS
LOW AND MID LEVEL MOISTURE GRADUALLY INCREASES. AT THE
SURFACE...MODELS INDICATE A WEAK THERMAL TROUGH ACROSS THE
UPSTATE/MIDLANDS EACH DAY. THIS WILL BE A FOCUSING MECHANISM FOR
THE CONVECTION. OVERNIGHT LOWS IN THE MIDDLE 70S. NORMAL HIGHS
AREA IN THE LOWER 90S AND LOWS IN THE LOWER 70S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
LITTLE CHANGE TO THE MEDIUM AND LONG RANGE MODELS WHICH HAVE THE
HIGH PRESSURE RIDGE CONTINUING TO RETROGRADE TO THE WEST TO THE
ROCKIES AND AMPLIFYING. THIS WILL ALLOW A DEEP TROUGH OF LOW
PRESSURE TO SETTLE OVER THE EASTERN U.S BEGINNING ON SUNDAY AND
CONTINUING INTO THE MIDDLE OF NEXT WEEK. TEMPS WILL REMAIN ABOVE
NORMAL OVER THE WEEKEND BUT WILL BY MID WEEK.

PRECIPITABLE WATER VALUES DURING THIS PERIOD WILL BE INCREASING
FROM AROUND 1.75 INCHES TO AROUND OR EXCEEDING 2 INCHES BY
SUNDAY INTO WEDNESDAY. WITH INCREASED MOISTURE AND SOME UPPER SUPPORT
WILL CONTINUE A DIURNAL TREND OF POPS. WILL CONTINUE WITH SLIGHT
CHANCE/CHANCE POPS OVER THE WEEKEND INCREASING TO CHANCE POPS MONDAY
THROUGH WEDNESDAY AS A FRONTAL BOUNDARY APPROACHESWARD THE AREA
FROM THE AREA FROM THE NORTH.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. HIGH PRESSURE WILL
REMAIN IN CONTROL OF THE REGION WITH WEST-SOUTHWEST WINDS OF 7
KNOTS OR LESS. SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN BE
POSSIBLE DURING THE AFTERNOON AND EVENING HOURS...HOWEVER
CONFIDENCE IN TIMING AND COVERAGE REMAIN TOO LOW TO INCLUDE IN TAF
ATTM. ANY ACTIVITY WHICH DEVELOPS WILL DISSIPATE WITH SUNSET AND
THE LOSS OF HEATING.

EXTENDED AVIATION OUTLOOK...RESTRICTIONS POSSIBLE IN DIURNAL
CONVECTION AND PATCHY EARLY MORNING FOG...FRIDAY THROUGH MONDAY.

&&

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

SYNOPSIS...
NEAR TERM...
SHORT TERM...02
LONG TERM...02
AVIATION...

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE COLUMBIA SC
511 AM EDT THU JUL 5 2012

GAZ040-063>065-077-SCZ015-016-018-020>022-025>031-035>038-041-060915-
LINCOLN-MCDUFFIE-COLUMBIA-RICHMOND-BURKE-LANCASTER-CHESTERFIELD-
MCCORMICK-NEWBERRY-FAIRFIELD-KERSHAW-EDGEFIELD-SALUDA-LEXINGTON-
RICHLAND-LEE-AIKEN-SUMTER-BARNWELL-ORANGEBURG-CALHOUN-CLARENDON-
BAMBERG-
511 AM EDT THU JUL 5 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...FRIDAY THROUGH WEDNESDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.