Area Forecast Discussion
Issued by NWS Columbia, SC

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000
FXUS62 KCAE 221509
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1009 AM EST MON DEC 22 2014

.SYNOPSIS...
A FRONTAL ZONE WILL REMAIN NEAR THE SOUTHEAST COAST THROUGH
TUESDAY. A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEASTWARD
ALONG THE FRONT...KEEPING WEATHER UNSETTLED. A STRONG COLD FRONT
APPROACHING FROM THE WEST WILL MOVE THROUGH THE FORECAST AREA
WEDNESDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
ISENTROPIC LIFT OVER THE WEDGE RIDGE WILL SUPPORT RAIN OR DRIZZLE
THROUGH TONIGHT. REGIONAL RADAR COMPOSITE LATE THIS MORNING SHOWS
AN AREA OF SHOWERS MOVING NORTHEAST ACROSS THE EASTERN PART OF THE
FORECAST AREA. MESOSCALE BRIEFING INDICATES THE HIGHEST
PRECIPITABLE WATER AND BEST MOISTURE TRANSPORT ACROSS THE EAST SO
HAVE RAISED POPS ACROSS THIS AREA FOR THE NEXT SEVERAL HOURS. FOR
MOST OF THE FORECAST AREA...THE MAIN PRECIPITATION TYPE WILL BE
OCCASIONAL DRIZZLE. THE NAM AND GFS INDICATE JUST LIGHT AMOUNTS
WITH THE HIGHEST AMOUNTS EAST. THE SPC WRF DISPLAYS SCATTERED AREAS OF
RAIN MAINLY TONIGHT. THE TEMPERATURE GUIDANCE IS LIKELY A LITTLE
TOO WARM BECAUSE OF THE WEDGE PATTERN. EXPECT LITTLE TEMPERATURE
CHANGE TONIGHT WITH CLOUDINESS.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
THE CHANCE OF MEASURABLE RAIN SHOULD BE ON THE INCREASE TUESDAY.
THE MODELS ARE CONSISTENT INDICATING DEEPER MOISTURE WITH THE H5
HEIGHTS BACKING. THERE WILL BE ISENTROPIC UPGLIDE. LIFT
ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THE H25 JET MAY
ALSO AFFECT THE AREA. THE NAM AND GFS MOS HAVE LIKELY OR
CATEGORICAL POPS. USED THE COOLER NAM MOS HIGH TEMPERATURES
BECAUSE OF THE WEDGE PATTERN.

THE NAM SURFACE-BASED LI PATTERN SUGGESTS THE WEDGE WILL HOLD
THROUGH TUESDAY NIGHT. THE AREA SHOULD CONTINUE UNDER THE MOIST
CONVEYOR BELT WITH ISENTROPIC UPGLIDE AND LIFT ASSOCIATED WITH THE
RIGHT ENTRANCE REGION OF THE UPPER JET. THE NAM...GFS...AND ECMWF
MOS ARE IN GOOD AGREEMENT WITH CATEGORICAL POPS. THE NAM AND GFS
DISPLAY RAINFALL OF ONE-HALF TO ONE INCH. EXPECT LITTLE CHANGE IN
TEMPERATURE OVERNIGHT.

THE SHOWER CHANCE WILL REMAIN HIGH WEDNESDAY AND WEDNESDAY NIGHT.
THE MODELS DISPLAY CONTINUED DEEP MOISTURE. THE NAM SURFACE-BASED
LI PATTERN SUGGESTS THE WARM FRONT MAY LIFT INTO THE FORECAST AREA
WEDNESDAY AHEAD OF THE STRONG COLD FRONT BUT STILL ONLY LOWERS
LI/S TO AROUND 1 IN THE EXTREME SOUTH PART. THE COLDER UPPER-AIR
TEMPERATURES APPEAR TO REMAIN TO THE WEST AND WITH WIDESPREAD RAIN
THE LACK OF SIGNIFICANT INSTABILITY AS FORECAST BY THE MODELS
APPEARS REASONABLE. THE THUNDERSTORM CHANCE APPEARS LOW AT THIS
TIME. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST
WEDNESDAY BUT CONFIDENCE IS LOW BECAUSE OF UNCERTAINTY WITH THE
PLACEMENT OF THE WARM FRONT.

THE MODELS SHOW THE COLD FRONT MOVING THROUGH THE FORECAST AREA
WEDNESDAY NIGHT. THE NAM WAS A LITTLE SLOWER WITH THE FRONTAL
TIMING COMPARED TO THE GFS AND ECWMF BUT ALL OF THE MODELS
INDICATED THE FRONT THROUGH THE AREA WITH DRYING BEFORE ABOUT
400 AM CHRISTMAS MORNING. EXPECT BREEZY CONDITIONS BEHIND THE
FRONT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE MODELS CONTINUE TO SHOW A DRY AIR MASS FOR CHRISTMAS DAY.
IF MAY REMAIN BREEZY...BUT THE MODELS INDICATE A DIMINISHING
PRESSURE GRADIENT AS THE RIDGE GETS CLOSER TO THE AREA. THE
GFS...ECWMF...AND EKD MOS SUPPORTS HIGHS IN THE UPPER 50S TO
AROUND 60 BUT BREEZY CONDITIONS SHOULD MAKE IT FEELER COOLER.

THE RIDGE SHOULD BE OVER THE AREA THURSDAY NIGHT. STRONG NOCTURNAL
COOLING SHOULD OCCUR WITH MOSTLY CLEAR SKIES AND LIGHT WINDS. THE
GFS AND ECWMF MOS HAVE LOWS MAINLY IN THE LOWER 30S.

THE DRY RIDGE SHOULD CONTINUE TO DOMINATE FRIDAY. MOISTURE MAY
INCREASE ASSOCIATED WITH ANOTHER COLD FRONT MOVING INTO THE AREA
SATURDAY OR SUNDAY. THE GFS AND ECMWF MOS POPS WERE 20 TO 40
PERCENT WITH THE ECMWF INDICATING THE GREATER SHOWER CHANCE.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
IFR CONDITIONS EXPECTED THROUGH THE 24 HOUR TAF PERIOD.

PATCHY LIGHT RAIN/DRIZZLE STILL CONTINUING AT THE TAF SITES LATE THIS
MORNING. REGIONAL RADAR COMPOSITE SHOWS A BAND OF SHOWERS MOVING
NORTHEAST ACROSS THE EASTERN FORECAST AREA WHICH SHOULD REACH OGB
WITHIN THE NEXT COUPLE OF HOURS. CONDITIONS NOT EXPECTED TO
IMPROVE AS NORTHEASTERLY FLOW CONTINUES TO PROMOTE WEDGE
CONDITIONS. EXPECT LIGHT RAIN/DRIZZLE TO REDUCE VSBYS INTO THE
MVFR RANGE WITH CIGS MAINLY IFR THROUGH THE AFTERNOON...AND IFR
CIGS/VSBYS THIS EVENING. ALTHOUGH PRECIPITATION MAY TAPER OFF SOME
THIS AFTERNOON...EXPECT MORE LIGHT RAIN AND DRIZZLE TO DEVELOP
ACROSS THE AREA LATER THIS EVENING INTO TONIGHT. SOME LIFR CIGS
POSSIBLE LATE TONIGHT. WINDS THROUGH THE PERIOD WILL BE
NORTHEASTERLY AT 7 KNOTS OR LESS FOR MUCH OF THE PERIOD.

EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR TO IFR CONDITIONS
EXPECTED TUESDAY THROUGH WEDNESDAY EVENING AS A SERIES OF SYSTEMS
CROSS THE REGION. BREEZY CONDITIONS POSSIBLE WEDNESDAY AFTERNOON
INTO THURSDAY MORNING.

&&

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

$$





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