Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 131817
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
217 PM EDT SAT SEP 13 2014

.SYNOPSIS...
A FRONTAL SYSTEM WILL REMAIN IN THE FORECAST AREA THROUGH MONDAY.
VERY HIGH MOISTURE WILL BE ASSOCIATED WITH THE FRONT. THERE WILL
BE SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WITH HEAVY RAIN
AT TIMES...ESPECIALLY THIS AFTERNOON AND TONIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
REST OF THE AFTERNOON...REGIONAL RADAR IMAGERY SHOWS SCATTERED TO
NUMEROUS SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS THE
FORECAST AREA. CONVERGENCE ALONG A STALLED FRONTAL BOUNDARY AND
DIURNAL HEATING HAS HELPED TO IGNITE CONVECTION THIS AFTERNOON.
PRECIPITABLE WATER VALUES REMAIN ELEVATED RANGING FROM 2.0 TO 2.2
INCHES. LAPS SOUNDINGS SHOW LIFTED INDEX VALUES OF -5 TO -6. THE
MOST SIGNIFICANT THREAT AT THIS TIME APPEARS TO BE LOCALLY HEAVY
RAINFALL. WEAK STEERING FLOW IS PROMOTING SLOW STORM MOVEMENT.
RAINFALL RATES OF 1 TO 3 INCHES PER HOUR ARE POSSIBLE WITH THESE
STORMS. STRONG WINDS ARE ALSO POSSIBLE WITH PRECIPITATION LOADING
IN STORMS. CONSIDERABLE CLOUDINESS AND WEAK WARM ADVECTION WILL
PROMOTE MAX TEMPERATURES IN THE MIDDLE 80S NORTH TO AROUND 90
SOUTH.

TONIGHT...THE NAM AND GFS DISPLAY THE FRONT SINKING SOUTHWARD
TONIGHT. CONVERGENCE ASSOCIATED WITH THE FRONT SHOULD SUPPORT
NUMEROUS SHOWERS AND THUNDERSTORMS. THE HIGH-RESOLUTION MODELS
INDICATE CONSIDERABLE COVERAGE DURING THE EVENING. PRECIPITABLE
WATER OVER 2 INCHES WITH A SLOW STORM MOTION OR TRAINING ALONG THE
EAST-WEST ORIENTED FRONT WOULD LEAD TO FLOODING IN POOR-DRAINAGE
AREAS ALTHOUGH THIS THREAT MAY REMAIN ISOLATED BECAUSE OF
NOCTURNAL COOLING AND LITTLE UPPER-LEVEL LIFT. ALSO...THERE MAY BE
LITTLE REMAINING INSTABILITY BECAUSE OF PREVIOUS CONVECTION.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY/...
THE NAM AND GFS DISPLAY THE FRONT NEAR THE SOUTH PART OF THE
FORECAST AREA SUNDAY WITH THE FRONT MORE DIFFUSE MONDAY. THE
MODELS SHOW MOISTURE BECOMING A LITTLE MORE SHALLOW ESPECIALLY IN
THE NORTH PART OF THE FORECAST AREA. HOWEVER...EXPECT CONSIDERABLE
CLOUDINESS WILL CONTINUE WITH A CHANCE OF SHOWERS OR
THUNDERSTORMS. USED THE GUIDANCE CONSENSUS FOR THE POP FORECAST.
CLOUDINESS AND HIGH PRESSURE WEDGING INTO THE AREA FROM THE NORTH
SUPPORTED THE COOLER HIGH TEMPERATURE GUIDANCE ESPECIALLY IN THE
NORTH PART. FOLLOWED THE WARMER LOW TEMPERATURE GUIDANCE BECAUSE
OF CLOUDINESS.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE GFS AND ECMWF MAINTAIN HIGH MOISTURE THROUGH TUESDAY WITH A
FRONT NEAR THE FORECAST AREA. THE FRONT AND MUCH OF ITS
ASSOCIATED DEEPER MOISTURE APPEAR TO BE JUST SOUTH AND EAST OF
THE AREA DURING THE REST OF THE PERIOD BUT THE NEARNESS OF THE
FRONT ADDS UNCERTAINTY THROUGH THE PERIOD. THE GFS...ECMWF..AND
EKD MOS HAVE CHANCE POPS THROUGH THE MEDIUM-RANGE PERIOD WITH
THE HIGHER VALUES EARLY.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
VFR CONDITIONS FOR THE EARLY PART OF THE TAF PERIOD...WITH
MVFR...AND LOWER IN AFTERNOON/EVENING CONVECTION. MVFR CEILINGS
EXPECTED TO DEVELOP OVERNIGHT AND PERSIST THROUGH 14/18Z.

SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
THIS AFTERNOON IN THE VICINITY OF A FRONTAL BOUNDARY. EXPECT
COVERAGE TO INCREASE DURING THE AFTERNOON AND EVENING HOURS.
CONFIDENCE IN TIMING IS TOO LOW TO INCLUDE PREVAILING RESTRICTIONS
AT THIS TIME. HEAVY RAIN IS POSSIBLE OVER THE TAF SITES WHICH MAY
REDUCE VISIBILITIES TO LESS THAN A MILE. HAVE INCLUDED VCTS AND
WILL UPDATE AS CONFIDENCE IMPROVES. MODELS INDICATE MVFR CEILINGS
OR LOWER DEVELOPING DURING THE OVERNIGHT PERIOD AS HIGH PRESSURE
WEDGES INTO THE AREA BEHIND THE FRONT. HAVE INTRODUCED MVFR CIGS
FROM 14/09Z THROUGH THE END OF THE TAF PERIOD. LIGHT AND VARIABLE
WINDS THROUGH THE OVERNIGHT PERIOD WILL BECOME NORTHEASTERLY
SUNDAY MORNING.

EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR OR IFR CONDITIONS
WILL LIKELY BE ASSOCIATED WITH A STALLED FRONTAL BOUNDARY THROUGH
TUESDAY.

&&

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

$$






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