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622
FXUS62 KCAE 180233
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1033 PM EDT THU APR 17 2014

.SYNOPSIS...
MOISTURE WILL INCREASE TONIGHT AND FRIDAY AHEAD OF LOW PRESSURE
DEVELOPING IN THE NORTHEAST GULF OF MEXICO. THE LOW WILL MOVE
SLOWLY ACROSS NORTH FLORIDA AND BE OFF THE SOUTHEAST COAST
SATURDAY AFTERNOON AND BE A LITTLE FARTHER OUT TO SEA EASTER
SUNDAY.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
SURFACE HIGH PRESSURE CONTINUES TO RIDGE DOWN THE EAST COAST FROM
NEW ENGLAND THIS EVENING...WHILE LOW PRESSURE BEGINS TO DEVELOP
INT HE WESTERN GULF OF MEXICO. WATER VAPOR IMAGERY SHOWS A DEEP
AND AMPLIFYING LONGWAVE TROUGH SLOWLY MOVING ACROSS THE CENTER OF
THE COUNTRY WITH DEEP CONVECTION OCCURRING IN THE NORTH CENTRAL
GULF OF MEXICO.

LATEST RUNS OF THE NAM/GFS AND HRRR HOLD BACK PRECIPITATION MOVING
INTO THE FORECAST AREA UNTIL AFTER 12Z. THIS SEEMS REASONABLE
GIVEN THAT BETTER ISENTROPIC LIFT ARRIVES AFTER 12Z AND SIGNIFICANT
DRY AIR IN PLACE WITH CURRENT PRECIPITABLE WATER VALUES LESS THAN
A HALF INCH WILL HAVE TO BE OVERCOME. ADJUSTED OVERNIGHT POPS TO
LOWER THEM THROUGH 12Z. ALSO LOWERED MIN TEMPERATURES OVERNIGHT A
BIT...ESPECIALLY IN THE NORTHERN MIDLANDS WHERE CLOUDS WILL BE
THIN FOR SEVERAL MORE HOURS BEFORE WIDESPREAD HIGH AND MID CLOUDS
OVERSPREAD THE AREA IN ADVANCE OF THE STORM SYSTEM.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
MODELS HAVE ONCE AGAIN BEEN INCONSISTENT BUT NOW SEEM TO BE
CONVERGING ON A SOLUTION. WHAT SEEMED LIKE A NICE EASTER WEEKEND
JUST TWO DAYS AGO NOW LOOKS TO BE WET FRIDAY AFTERNOON THROUGH
SATURDAY NIGHT WITH CONDITIONS POSSIBLY SLOWLY IMPROVING ON
SUNDAY. CONFIDENCE IN THE DETAILS OF THE FORECAST IS STILL LOW.

CONFIDENCE IS LOW BECAUSE OF MODEL INCONSISTENCY AND AN EXPECTED
TIGHT MOISTURE GRADIENT. THE NAM...GFS...AND ECMWF ALL AGREE
DEVELOPING A CUT-OFF H5 LOW AND ARE VERY CLOSE IN TIMING AND
LOCATION THROUGH SUNDAY. THE UPPER LOW IS FORECAST TO MOVE
ACROSS NORTH FL/SOUTH GA SATURDAY AND BE JUST OFF THE GA COAST ON
SATURDAY NIGHT AND THEN MOVE VERY SLOWLY NORTHEAST THROUGH SUNDAY.
THE MODELS ALSO HAVE THE SYSTEM VERTICALLY STACKED SO THAT THE
POSITION OF THE SURFACE LOW IS CLOSE TO THAT OF THE UPPER LOW.

EXPECT PRECIPITATION TO DEVELOP FRIDAY AFTERNOON ASSOCIATED WITH
ISENTROPIC LIFT AHEAD OF THE SURFACE LOW. THE ISENTROPIC LIFT
CONTINUES INTO SATURDAY. AS THE LOW MOVES OVER THE AREA THE
ISENTROPIC LIFT WILL DECREASE BUT THERE WILL STILL BE MOISTURE
FLUX OVER THE AREA WHICH MAY CONTINUE TO SUPPORT LIGHT RAIN OR
DRIZZLE. THE 500 MB FLOW HAS AN EASTERLY COMPONENT INTO SUNDAY
MORNING SO I WOULD NOT EXPECT THE PRECIPITATION THREAT TO DIMINISH
UNTIL THAT TIME. STORM TOTAL QPF RANGES FROM JUST OVER A HALF INCH
NORTH AND WEST PARTS OF THE CWA TO OVER 1.5 INCHES SOUTH AND EAST.
THE GRADIENT WITH THIS SYSTEM WILL BE TIGHT SO ANY VARIATION IN
THE TRACK WILL HAVE A BIG IMPACT ON AMOUNTS. AT THIS POINT IN TIME
EXPECT IT TO BE CLOUDY AT LEAST THROUGH SUNDAY MORNING WITH CLOUDS
POSSIBLY DECREASING FROM SOUTHWEST TO NORTHEAST SUNDAY AFTERNOON.
WILL KEEP THE DAYTIME HIGHS IN THE UPPER 50S TO AROUND 60 BOTH
FRIDAY AND SATURDAY THEN MODERATING TO THE UPPER 60S AND LOWER 70S
ON SUNDAY PROVIDED WE GET ENOUGH SUN. OVERNIGHT LOWS ARE EXPECTED
TO BE IN THE UPPER 40S TO LOWER 50S BOTH FRIDAY AND SATURDAY
NIGHTS.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
WARMER AND DRIER AIR WILL RETURN TO THE REGION ON MONDAY WITH AN
UPPER RIDGE BUILDING OVERHEAD AND HIGH PRESSURE AT THE SURFACE.
TEMPERATURES WILL RETURN TO NEAR NORMAL MONDAY WITH HIGHS
FORECAST MAINLY IN THE MID TO UPPER 70S. AN UPPER TROUGH WILL
APPROACH FROM THE WEST MONDAY NIGHT WITH INCREASING MOISTURE ON
TUESDAY. SURFACE LOW PRESSURE WILL SCOOT EAST ACROSS THE GREAT
LAKES LATE MONDAY AND TOWARD NEW ENGLAND ON TUESDAY...DRAGGING A
FRONTAL BOUNDARY ACROSS THE AREA TUESDAY AFTERNOON/NIGHT.
CONTINUED TO INDICATE A CHANCE OF SHOWERS TUESDAY ASSOCIATED WITH
THIS FEATURE. THE FORECAST LOOKS DRY FOR WEDNESDAY THROUGH THE END
OF THE WEEK AS AN UPPER RIDGE BUILDS OVER THE SOUTHEASTERN CONUS
WITH HIGH PRESSURE DOMINATING AT THE SURFACE. MAXIMUM TEMPERATURES
ARE FORECAST IN THE UPPER 70S AND LOWER 80S TUESDAY THROUGH FRIDAY
WITH OVERNIGHT LOWS IN THE 50S.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS THROUGH THE EARLY MORNING HOURS...WITH
DETERIORATING CONDITIONS FROM SUNRISE THROUGH THE END OF THE
PERIOD.

LOW PRESSURE CONTINUES TO DEVELOP OVER THE NORTHERN GULF WATERS
WITH HIGH CLOUDS ALREADY ENTERING THE TAF SITES. THE LOW WILL
CONTINUE TRACKING EASTWARD ACROSS THE NORTHERN GULF WITH EASTERLY
WINDS PUSHING ADDITIONAL MOISTURE INTO THE TAF SITES. THIS WILL
RESULT IN LOW CLOUDS DEVELOPING OVERNIGHT WITH MVFR CEILINGS
EXPECTED AT THE TAF SITES AROUND DAYBREAK. RAIN CHANCES WILL
ENTER THE TAF SITES DURING THE AFTERNOON HOURS WITH CONFIDENCE
HIGH ENOUGH TO INCLUDE SHOWERS BEGINNING AT THE TAF SITES NEAR THE
END OF THE PERIOD. WINDS THROUGH THE PERIOD WILL BE EASTERLY AT 10
KNOTS OR LESS...WITH GUSTS UP TO 15 KNOTS BETWEEN 16Z AND THE END
OF THE PERIOD.

EXTENDED AVIATION OUTLOOK...INCREASING CONFIDENCE IN MVFR TO IFR
CONDITIONS CONTINUING THROUGH SUNDAY AS LOW PRESSURE MOVES THROUGH
THE REGION.

&&

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

$$








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