National Weather Service Weather Forecast Office

Area Forecast Discussion

501
FXUS62 KCAE 231750
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
150 PM EDT THU MAY 23 2013

.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. THE DRY AIR MASS BEHIND THE FRONT WILL DOMINATE DURING
THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
THIS AFTERNOON...MODEL FORECAST SOUNDINGS SHOW A CONDITIONALLY
UNSTABLE AIRMASS WITH A WEAK MID LEVEL CAP. MODELS GIVE AFTERNOON
CAPES 1000-2000 J/KG...LIS -5/-6 AND TOTALS AROUND 45. PW VALUES
INITIALLY AROUND 1.4 INCHES BUT DRIER AIR WORKS IN FROM WEST TO
LOWER PW TO 1.20 INCHES. KIS LESS THAN 30 AS MOISTURE IS MAINLY
BELOW 10 KFT. HOWEVER...AFTERNOON HEATING MAY LIFT MOISTURE ENOUGH
FOR A FEW THUNDERSTORMS MAINLY IN THE EAST PART. SPC HAS AREA IN
GENERAL THUNDERSTORMS OUTLOOK BUT IF HIGH ELEVATED CORES DEVELOP
THE POTENTIAL EXISTS FOR PERHAPS ISOLATED STRONG TO SEVERE STORMS
BUT AGAIN MAINLY IN THE EAST. HAVE MAINLY 20-30 PERCENT CHANCE BUT
IN FAR EAST AND NORTHEAST WILL KEEP 40-60 PERCENT CHANCE. HIGH
TEMPERATURES IN THE MID TO UPPER 80S.

TONIGHT...A 20 PERCENT CHANCE IN THE EAST DURING THE EVENING.
PLAN ON NO POPS IN THE WEST AS DRIER AIR MOVES IN FROM THE WEST
WITH THE COLD FRONT. LOWS UPPER 50S TO LOWER 60S.



&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
DRYING BEHIND THE FRONT SHOULD DOMINATE FRIDAY THROUGH FRIDAY
NIGHT. MIXING ASSOCIATED WITH THE FRONT SUPPORTED THE WARMER
TEMPERATURE GUIDANCE TONIGHT. HIGH PRESSURE WILL BRING COOLER
DRIER CONDITIONS FRIDAY NIGHT AND SATURDAY. WILL GO WITH GFS MOS
GUIDANCE IN THE MID 40S FRIDAY NIGHT AND MODEL BLEND UPPER 70S
TO LOWER 80S SATURDAY. AIRMASS MODIFIES BY SATURDAY NIGHT WITH
LOWS IN THE LOWER 50S.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
MEDIUM RANGE MODELS IN GOOD AGREEMENT WITH UPPER RIDGE WORKING
IN FROM THE WEST. BOTH MODELS SHOW A WEAK SURFACE FRONTAL BOUNDARY
WHICH REMAINS MAINLY TO THE NORTH BUT ECMWF SHOWS THE FRONT A
LITTLE BIT STRONGER THAN THE GFS. THE ECMWF ALSO KEEPS THE FRONT
A LITTLE FARTHER TO THE SOUTH. DRY TO START SUNDAY AND MONDAY BUT
BY THE END OF THE EXTENDED PERIOD...THE AIRMASS MOISTURE INCREASES
AND THE INSTABILITY INCREASES. EXPECT MORE DIURNAL SHOWERS AND
THUNDERSTORMS TUESDAY THROUGH THURSDAY. HIGH TEMPERATURES INCREASE
FROM THE LOWER 80S SUNDAY TO THE MID 80S MONDAY AND TUESDAY TO
THE UPPER 80S BY THURSDAY. OVERNIGHT LOW TEMPERATURES ARE EXPECTED
TO BE IN THE UPPER 50S SUNDAY NIGHT BUT INCREASE TO THE LOWER 60S
FOR THE REST OF THE PERIOD.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...

SATELLITE SHOWS PLENTY OF SC/CU AROUND THIS EARLY AFTERNOON. MOST
TAF SITES HAVE RETURNED TO VFR CONDITIONS...EXCEPT BOTH AGS/DNL
REPORTING MVFR CONDITIONS. EXPECT WITH ADDITIONAL DAYTIME HEATING
THAT CLOUD BASIS WILL RISE BETWEEN 19Z TO 20Z AND VFR CONDITIONS
WILL RETURN. AT THIS TIME...CONVECTION APPEARS TO BE MAINLY
CONCENTRATED ACROSS THE NORTHERN MIDLANDS/PEE DEE AND ALONG THE
COAST. THIS IS IN GOOD AGREEMENT WITH LOCAL/SPC WRF MODEL RUNS. WILL
CONTINUE WITH VFR CONDITIONS THROUGH THE PERIOD. WITH PASSAGE OF
COLD FRONT LATE THIS EVENING/OVERNIGHT...MODELS INDICATE A 30 KT LOW
LEVEL JET. THIS WILL KEEP WINDS UP SLIGHTLY OVERNIGHT BEFORE
BECOMING MORE BREEZE ON FRIDAY. ON FRIDAY...WINDS WILL BE FROM THE
NORTHWEST BEHIND THE FRONT AND BREEZY WITH WINDS AVERAGE 10 TO 15
KTS WITH GUSTS UP TO 25 KTS AT TIMES.

EXTENDED AVIATION OUTLOOK...DRIER AIR MOVING IN BEHIND A FRONT WILL
PRECLUDE ANY IMPACTS TO AVIATION.

&&

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

$$