Area Forecast Discussion
Issued by NWS Columbia, SC

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000
FXUS62 KCAE 211305
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
905 AM EDT THU AUG 21 2014

.SYNOPSIS...
RELATIVELY DRY AIR AND A BUILDING UPPER RIDGE JUST TO OUR WEST
WILL REDUCE THUNDERSTORM CHANCES THROUGH FRIDAY...AND LEAD TO
HOTTER HIGH TEMPERATURES. AN APPROACHING COLD FRONT AND INCREASING
MOISTURE WILL INCREASE THE THUNDERSTORM CHANCE OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
UPPER RIDGE CENTERED OVER THE LOWER MISSISSIPPI VALLEY/GULF COAST
WILL BE BUILDING INTO THE REGION. WARM START TO THE DAY ALONG WITH
850MB WARM ADVECTION/DOWNSLOPE FLOW WILL RESULT IN TEMPERATURES
APPROACHING 100 DEGREES THIS AFTERNOON. MAINLY SUNNY SKIES.
INSTABILITY APPEARS WEAKER THAN YESTERDAY GIVEN WARMER
TEMPERATURES ALOFT. LFC REMAINS HIGH...CONVECTIVE TEMPS HIGH AND
TRIGGER LACKING. ISOLATED AFTERNOON THUNDERSTORMS FROM LATE
AFTERNOON INTO EARLY EVENING EXPECTED. DEW POINTS MIXING OUT INTO
THE MID 60S TO LOW 70S THIS AFTERNOON SO HEAT INDEX LIKELY MAXING
OUT AROUND 105 DEGREES.

EXPECT DEBRIS CLOUDS TONIGHT FROM UPSTREAM CONVECTION. OVERNIGHT
LOWS IN THE LOW TO MID 70S ARE FORECAST.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
WARMING CONTINUES THROUGH FRIDAY AS UPPER RIDGE EXTENDS INTO THE
AREA. CONVECTION WILL LIKELY REMAIN ISOLATED WITH TRIGGER
LACKING/WEAK INSTABILITY. EXPECT TEMPERATURES SLIGHTLY WARMER THAN
THURSDAY MOST AREAS. HEAT INDEX EXPECTED TO REMAIN BELOW 110
DEGREES. BACK DOOR COLD FRONT APPEARS TO MOVE INTO THE REGION LATE
SATURDAY OR SATURDAY NIGHT FROM NORTH CAROLINA...HOWEVER LATEST
GFS SUGGESTS UPPER RIDGE WILL REMAIN STRONG WITH LONG WAVE TROUGH
OFF THE NORTH CAROLINA/VIRGINIA COAST. SO TEMPERATURES MAY REMAIN
QUITE HIGH THROUGH SATURDAY WITH COOLING DELAYED UNTIL SUNDAY AS
FRONT MOVES SOUTHWEST OF AREA. SCATTERED SHOWERS AND THUNDERSTORMS
AHEAD OF THE FRONT LATE SATURDAY OR SATURDAY NIGHT ALTHOUGH MODEL
POPS SUGGEST LARGE STANDARD DEVIATION/UNCERTAINTY.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
UPPER RIDGE TO OUR WEST WITH UPPER TROUGH AND CLOSED LOW TO OUR
NE...PROVIDING A NW FLOW ALOFT FOR OUR FA. SLIGHTLY COOLER
TEMPERATURES SUNDAY AS FRONT MOVES SLOWLY TO THE SOUTH OF AREA.
SCATTERED SHOWERS. LARGE POP UNCERTAINTY DUE TO TIMING ISSUE WITH
FRONTAL PASSAGE. FRONT MAY BE SLOW TO MOVE SOUTH OF THE AREA
SUNDAY...ESPECIALLY IN THE CSRA. FRONT TO PUSH TO OUR SOUTH EARLY
NEXT WEEK...WITH SURFACE AND UPPER RIDGE OVER THE EASTERN
SEABOARD. SO REDUCED POPS MONDAY THROUGH WEDNESDAY AS RIDGE BUILDS
IN FROM THE NORTHEAST.

&&

.AVIATION /13Z THURSDAY THROUGH MONDAY/...
VFR CONDITIONS EXPECTED TO DOMINATE THE PERIOD.

EXPECT SOME DIURNAL CUMULUS TO DEVELOP DURING THE LATE MORNING
AND AFTERNOON HOURS...POTENTIAL FOR CONVECTION REMAINS TOO LOW TO
INCLUDE IN TAFS. CUMULUS WILL DISSIPATE WITH SUNSET WITH
CONVECTIVE DEBRIS CROSSING THE AREA TONIGHT...WHICH WILL AGAIN
WORK TO PREVENT FOG DEVELOPMENT. WINDS THROUGH THE PERIOD WILL BE
NORTHERLY AROUND 5 KNOTS.

EXTENDED AVIATION OUTLOOK...MVFR OR IFR CONDITIONS POSSIBLE IN LATE
NIGHT AND EARLY MORNING FOG THROUGH THE PERIOD. ISOLATED AFTERNOON
AND EVENING THUNDERSTORMS MAY ALSO BRING RESTRICTIONS.

&&

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

$$





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