Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 260630
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
230 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 /06Z TUESDAY THROUGH SATURDAY/...
LOW STRATUS AND PATCHY FOG POSSIBLE AT ALL TAF SITES EARLY THIS
MORNING. MVFR CEILINGS LIKELY AT ALL TAF SITES IN THE 07Z-15Z TIME
FRAME. MODELS ALSO INDICATE A LOWER CHANCE FOR IFR CIGS 09Z-14Z.

EASTERLY ONSHORE FLOW CONTINUES AND SHOULD PROMOTE LOW-LEVEL
CLOUDS THROUGHOUT THE FA. ISENTROPIC LIFT APPEARS TO BE STRONGEST
ALONG THE MIDLANDS INTO THE UPSTATE EARLY THIS MORNING ALLOWING
FOR LOW-LEVEL MOISTURE AND STRATUS TO FORM. THE NAM AND GFS ARE
IN BETTER AGREEMENT THAN LAST NIGHT WITH BRINGING IN LOW CLOUDS.
HIGHER DEWPOINTS SUPPORT MODEL GUIDANCE. PATCHY FOG MAY ALSO FORM
DURING THE PRE-DAWN HOURS AS WINDS BECOME LIGHT. THE GREATEST
CHANCE OF FOG FORMATION IS AT OGB AND ALONG THE COASTAL PLAIN
WHERE MID-LEVEL DRY AIR WILL BE A FAVORABLE SETUP FOR FOG.
SCATTERED STORMS ARE POSSIBLE BY LATE AFTERNOON/EARLY EVENING
ACROSS THE AREA BUT CONFIDENCE IS TOO LOW TO MENTION IN THE TAFS
AT THIS TIME.

MVFR/IFR CIGS SHOULD LIFT AFTER SUNRISE ALLOWING VFR CONDITIONS
TO RETURN AROUND 15Z WITH SURFACE WINDS BECOMING SOUTHERLY 5 TO 10
KTS.

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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