Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 182116 AAA
AFDCAE

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE COLUMBIA SC
516 PM EDT THU SEP 18 2014

.SYNOPSIS...
HIGH PRESSURE CENTERED OVER THE GREAT LAKES REGION WILL EXTEND
SOUTHWARD THROUGH THE CAROLINAS TO GEORGIA OVER THE WEEKEND. LOW
PRESSURE WILL DEVELOP OFF THE GEORGIA COAST AND LIFT NORTHEAST.
A COLD FRONT WILL BRING A CHANCE FOR SHOWERS AND THUNDERSTORMS
FOR MONDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
RELATIVELY QUIET ACROSS THE FORECAST AREA THIS AFTERNOON COMPARED
TO THE STRONG STORMS THAT WE HAD YESTERDAY. MORNING FOG AND
STRATUS WAS SLOW TO BURN OFF AND REALLY LIMITED DESTABILIZATION
THIS AFTERNOON BUT BREAKS IN THE CLOUDS HAVE ALLOWED THE
ATMOSPHERE TO BECOME MORE UNSTABLE AND SUPPORT A FEW SHOWERS AND
THUNDERSTORMS IN THE SOUTHERN MIDLANDS AND CSRA. VERTICAL
DEVELOPMENT OF THE STORMS HAS BEEN SLOW BUT IS INCREASING A BIT SO
WILL MONITOR FOR POSSIBLE WARNINGS IF NEEDED AS THE STORMS ARE
DRIFTING SOUTHEASTWARD INTO A MORE UNSTABLE ENVIRONMENT. UPDATED
POPS TO ACCOUNT FOR STORMS IN THE SOUTH BUT OTHERWISE EXPECT DRY
WEATHER ELSEWHERE AS DEWPOINTS ARE MIXING OUT INTO THE LOWER 60S
UNDER PARTLY CLOUDY SKIES.

OVERNIGHT LOWS TONIGHT AGAIN MAY BE IMPACTED BY LOW CLOUDS AND FOG
DEVELOPMENT LATE DUE TO LINGERING LOW LEVEL MOISTURE AND DRY AIR
ALOFT.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
A STRONG SHORT WAVE ROUNDING THE BASE OF THE UPPER TROUGH WILL
DEVELOP A CUT OFF LOW OVER OVER GEORGIA ON FRIDAY. THE UPPER LOW
WILL BEGIN TO FILL AND LIFT NORTHEAST ON SATURDAY. AN AREA OF
SURFACE LOW PRESSURE WILL DEVELOP OVER COASTAL GEORGIA IN RESPONSE
TO THE UPPER LOW. HIGH PRESSURE WEDGING IN FROM THE NORTH COUPLED
WITH THE DEVELOPING SURFACE LOW MOVING UP THE COAST WILL BRING
INCREASING MOISTURE AND NORTHEAST WINDS TO THE FORECAST AREA. COLD
AIR ALOFT WILL INCREASE INSTABILITY...ESPECIALLY ACROSS THE CSRA.
THE NAM MODEL INDICATED STRONGER MOISTURE CONVERGENCE...THUS
HIGHER POPS THAN THE GFS. HAVE TRENDED WITH MOS GUIDANCE WITH
HIGHER POPS...MAINLY DIURNAL...FOR THE FRIDAY THROUGH SATURDAY
PERIOD.

HIGHS WILL BE SEVERAL DEGREES BELOW CLIMATOLOGY UNDER THE
WEDGE-LIKE SETUP WITH HIGHS IN THE UPPER 70S NORTH TO LOWER 80S
SOUTH. WENT WITH CONSENSUS FOR LOWS IN THE LOW TO MID 60S.

THE AIR MASS DRIES OUT SUNDAY AS THE H850 FLOW BECOME DOWNSLOPE.
PWAT DECEASES TO AROUND ONE INCH WITH WEAK INSTABILITY. KEPT DRY
WEATHER FOR SUNDAY WITH HIGHS IN THE LOW TO MID 80S AND LOWS STILL
IN THE LOW TO MID 60S.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
THE UPPER LEVEL TROUGH WILL LIFT NORTHEAST ACROSS THE EASTERN THIRD
OF THE NATION MONDAY THROUGH WEDNESDAY. SURFACE LOW PRESSURE WILL
MOVE EAST THROUGH SOUTHEASTERN CANADA ON MONDAY DRAGGING THE NEXT
COLD FRONT ACROSS THE FORECAST AREA. WARM AIR ADVECTION AND
INCREASING MOISTURE ARE EXPECTED AHEAD OF THE FRONT. WILL KEEP LOW
CHANCE POPS MONDAY AS THE FRONT CROSSES THE FORECAST AREA. MAX
TEMPERATURES ON MONDAY ARE EXPECTED TO REACH THE LOWER 80S NORTH TO
UPPER 80S SOUTH.

COOLER AND DRIER AIR WILL REACH THE FORECAST AREA BY TUESDAY MORNING
IN THE WAKE OF THE FRONT. MAX TEMPERATURES ON TUESDAY ARE EXPECTED
TO BE AROUND 5 TO 7 DEGREES COOLER THAN ON MONDAY. GFS PRECIPITABLE
WATER VALUES DROP DOWN TO BELOW THREE QUARTERS OF AN INCH. A LARGE
AREA OF HIGH PRESSURE WILL BUILD ACROSS THE EASTERN HALF OF THE
NATION TUESDAY INTO THURSDAY BRINGING DRY WEATHER. SHOULD SEE HIGHS
IN THE MID 70S TO LOWER 80 AND OVERNIGHT LOWS IN THE UPPER 50S TO
LOWER 60S.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
ISOLATED SHOWERS/STORMS ACROSS THE AREA AT THE TIME. GIVEN LATEST
RADAR RETURNS...NOT EXPECTING ANY CELLS TO AFFECT ANY OF THE TAF
SITES...BUT WILL AMEND IF NECESSARY. ANY CONVECTION THAT DEVELOPS
SHOULD DIMINISH BY EARLY EVENING WITH LOSS OF DAYTIME HEATING. LOW
CLOUDS AND/OR FOG EXPECTED TO DEVELOP AGAIN LATE TONIGHT THROUGH
FRIDAY MORNING...WITH A SLOW RETURN TO VFR EXPECTED BY FRIDAY
AFTERNOON.

EXTENDED AVIATION OUTLOOK...LATE NIGHT AND MORNING FOG/STRATUS POSSIBLE
THROUGH SATURDAY.

&&

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

$$

NEAR TERM...HC
AVIATION...BC




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