Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 261020
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
620 AM EDT TUE MAY 26 2015

.SYNOPSIS...
CONTINUED ONSHORE FLOW ASSOCIATED WITH HIGH PRESSURE OFF THE MID-
ATLANTIC COAST WILL RESULT IN MODERATE TO HIGH MOISTURE THROUGH
MIDWEEK. THIS WILL ALSO INCREASE THE CHANCE OF MAINLY AFTERNOON
AND EVENING THUNDERSTORMS ACROSS THE AREA THROUGH THURSDAY. AN
UPPER RIDGE WILL BECOME ENTRENCHED OVER THE AREA AGAIN DURING THE
WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE ONSHORE FLOW ASSOCIATED WITH THE SURFACE HIGH WELL OFF THE
MID-ATLANTIC COAST WILL CONTINUE THROUGH TONIGHT. MOISTURE WILL
BECOME A BIT DEEPER MAINLY IN THE WEST PART OF THE FORECAST AREA
ASSOCIATED WITH A SHORTWAVE TROUGH PUSHING INTO THE RIDGE. SOME
OF THE NAM AND GFS MOS POPS MAY BE A LITTLE TOO HIGH BASED ON THE
LINGERING EFFECTS OF THE UPPER RIDGE. FORECASTED CHANCE POPS WEST
AND SLIGHT CHANCE EAST WHICH WAS SUPPORTED BY THE ARW. THE GFS HAS
LESS MOISTURE AND INSTABILITY COMPARED TO THE NAM. BASED ON
CONDITIONS JUST UPSTREAM...THE 2.3 INCHES OF PRECIPITABLE WATER
INDICATED BY THE NAM AT CAE LATE THIS AFTERNOON APPEARS OVERDONE.
BELIEVE CLOUDINESS WILL LIMIT INSTABILITY. THE SEVERE THUNDERSTORM
RISK APPEARS LOW AT THIS TIME. MOISTURE AND INSTABILITY ASSOCIATED
WITH A SHORTWAVE TROUGH MAY HELP SUPPORT CONTINUED SHOWERS AND
THUNDERSTORMS TONIGHT...BUT GENERALLY EXPECT LITTLE COVERAGE
BECAUSE OF THE LOSS OF HEATING. USED THE GUIDANCE CONSENSUS FOR
THE TEMPERATURE FORECAST.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
THE MODELS DISPLAY THE AXIS OF DEEPER MOISTURE SHIFTING A BIT
FARTHER EAST AND INTO THE FORECAST AREA FOR WEDNESDAY AND
THURSDAY. EXPECT A GREATER CHANCE OF THUNDERSTORMS WITH POSSIBLY
MORE ORGANIZATION AS MID-LEVEL SHORTWAVE TROUGHING MOVES INTO THE
AREA. THE GFS AND NAM MOS POPS RANGE FROM 30 TO 60 PERCENT. USED
AN AVERAGE OF THE MOS FOR THE POP FORECAST. LEANED TOWARD THE
COOLER HIGH TEMPERATURE GUIDANCE WEDNESDAY AND THURSDAY BECAUSE
OF CLOUDINESS AND SHOWERS. USED THE GUIDANCE CONSENSUS FOR THE LOW
TEMPERATURE FORECAST.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
THE GFS AND ECMWF DISPLAY HIGH PRESSURE RIDGING INTO THE AREA
FROM THE ATLANTIC DURING THE MEDIUM-RANGE PERIOD. ALOFT...RIDGING
FRIDAY THROUGH SUNDAY APPEARS TO WEAKEN MONDAY. THE GFS...
ECMWF...AND EKD MOS HAVE POPS 10 TO 30 PERCENT FRIDAY THROUGH
SUNDAY...AND 30 TO 40 PERCENT MONDAY. THE MOS HAS TEMPERATURES
NEAR CLIMATOLOGY.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
LOW STRATUS AND PATCHY FOG AT ALL TAF SITES EARLY THIS MORNING. VFR
ACROSS THE AREA BY 15Z. SOME MVFR/IFR CONDITIONS POSSIBLE AT ALL TAF
SITES BY TONIGHT.

EASTERLY ONSHORE FLOW CONTINUES AND SHOULD PROMOTE LOW LEVEL CLOUDS
THROUGHOUT THE AREA. WDLY SCTD/SCTD STORMS POSSIBLE BY LATE
AFTERNOON/EARLY EVENING ACROSS THE AREA SO WILL MENTION VCTS/VCSH IN
THE TAFS.

SURFACE WINDS BECOMING SOUTHERLY 5 TO 10 KTS FOR MOST OF TODAY.

SOME LOW CLOUDS POSSIBLE MAINLY LATE TONIGHT...WHICH MAY LEAD TO
SOME MVFR/IFR RESTRICTIONS. CONFIDENCE IS LOW AS TO HOW LOW CIGS MAY
GET IN THE LATTER PORTIONS OF THE TAF PERIOD.

EXTENDED AVIATION OUTLOOK...EARLY MORNING RESTRICTIONS ARE
POSSIBLE THROUGH THE END OF THE WEEK. THERE WILL ALSO BE AN
INCREASED CHANCE OF AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS
WHICH COULD REDUCE CEILINGS/VISIBILITIES AT TIMES.&&

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

&&

$$
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