Area Forecast Discussion
Issued by NWS Columbia, SC

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000 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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