National Weather Service Weather Forecast Office

Area Forecast Discussion

404
FXUS62 KCAE 210437
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1237 AM EDT TUE MAY 21 2013

.SYNOPSIS...
HIGH PRESSURE OFF THE SOUTHEAST COAST WILL CIRCULATE A MOIST
SOUTHERLY FLOW INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD
FRONT THROUGH THURSDAY. THE COLD FRONT WILL MOVE THROUGH THE AREA
THURSDAY NIGHT. THE DRY AIR MASS BEHIND THE FRONT WILL DOMINATE
DURING THE WEEKEND.

&&

.NEAR TERM /THROUGH TODAY/...
HIGH PRESSURE RIDGING INTO THE FORECAST AREA FROM THE ATLANTIC
WILL DOMINATE TODAY. A MOIST SOUTH FLOW IS ASSOCIATED WITH THIS
FEATURE. HIGH LOW-LEVEL MOISTURE AND LIGHT WIND WILL SUPPORT
AT LEAST PATCHY FOG EARLY THIS MORNING. THE MOISTURE PLUS HEATING
SHOULD SUPPORT SCATTERED THUNDERSTORMS THIS AFTERNOON. EXPECT THE
GREATER THUNDERSTORM COVERAGE IN THE EAST PART CLOSER TO THE
TROPICAL PLUME OF MOISTURE SHOWN BY THE WATER VAPOR IMAGERY.
CONVERGENCE ASSOCIATED WITH THE SEA-BREEZE FRONT SHOULD ALSO AID
COVERAGE IN THE EAST PART. SOME CLOUDINESS SHOULD LIMIT
INSTABILITY. THE NAM GENERALLY INDICATES WEAK TO MODERATE
INSTABILITY AND WEAK SHEAR. THE THREAT OF SEVERE THUNDERSTORMS
APPEARS LOW AT THIS TIME. THE GUIDANCE CONSENSUS SUPPORTS HIGHS IN
THE MIDDLE 80S WHICH IS NEAR CLIMATOLOGY.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
THE HIGH OFF THE SOUTHEAST COAST WILL CONTINUE TO DOMINATE
THROUGH WEDNESDAY NIGHT. THE MODELS SHOW CONSIDERATE MOISTURE IN
THE SOUTHERLY FLOW ON THE BACKSIDE OF THE OFFSHORE HIGH. EXPECT
SCATTERED THUNDERSTORMS ESPECIALLY DURING THE TIME OF MAXIMUM
HEATING. THE GUIDANCE CONSENSUS SUPPORTS CHANCE POPS. ALSO USED
THE CONSENSUS FOR THE TEMPERATURE FORECAST.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
CONVERGENCE ASSOCIATED WITH THE SLOW MOVING COLD FRONT SUPPORTS
THUNDERSTORMS THURSDAY AND THURSDAY NIGHT BUT THE MODELS SHOW
DEEPER MOISTURE SHIFTING FARTHER EASTWARD AHEAD OF THE FRONT. THE
GFS ENSEMBLE MEAN PLUS OPERATIONAL GFS AND ECMWF MOS SUPPORT
CHANCE POPS. THE DRY AIR MASS BEHIND THE FRONT SHOULD DOMINATE
DURING THE REST OF THE MEDIUM-RANGE PERIOD.

&&

.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
SCTD SHOWERS/STORMS HAVE ENDED ACROSS THE AREA WITH MAINLY
CONVECTIVE DEBRIS CLOUDS REMAINING. THESE CLOUDS SHOULD THIN DURING
THE EARLY MORNING HOURS. LOW LEVEL JET IS NOT AS STRONG AND LOW
LEVEL MOISTURE REMAINS PLENTIFUL SO FOG FIGURES TO BE A MORE FAVORED
THREAT. LIGHT TO CALM WINDS OVERNIGHT WILL ALLOW SOME RADIATIONAL
COOLING AND EXPECT SOME FOG TO DEVELOP AFTER 07Z-09Z. WILL INCLUDE
SOME IFR VSBYS AT AGS/OGB AND POSSIBLE THEY COULD OCCUR AT CAE
09Z-12Z. CONFIDENCE IS A LITTLE HIGHER TONIGHT THAN PREVIOUS NIGHTS
BUT GUIDANCE HAS NOT BEEN GREAT AS OF LATE. ANY FOG SHOULD BURN OFF
BY 14Z WITH VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE PERIOD.
WINDS WILL PICK UP OUT OF THE SOUTH TO SOUTHEAST AROUND 5-7 KNOTS.
WIDELY SCTD CONVECTION POSSIBLE LATER THIS AFTERNOON BUT NOT ENOUGH
CONFIDENCE TO MENTION AT ANY OF THE TAF SITES AT THIS TIME. MODEL
DATA SEEMS TO INDICATE THAT BULK OF CONVECTION THAT MAY DEVELOP
LATER THIS AFTERNOON MAY BE EAST OF THE TAF SITES.

EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND
THUNDERSTORMS...MAINLY AFTERNOON AND EVENING...POSSIBLE THROUGH
FRIDAY. LATE NIGHT/EARLY MORNING FOG/STRATUS ALSO POSSIBLE.

&&

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

$$