Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 242326
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
726 PM EDT FRI APR 24 2015

.SYNOPSIS...
SURFACE HIGH PRESSURE WILL MOVE EAST OF THE REGION THIS EVENING.
MOISTURE WILL INCREASE LATE TONIGHT AHEAD OF A WARM FRONT. THIS
FRONT WILL BE A FOCUS FOR SHOWERS AND SOME THUNDERSTORMS SATURDAY.
DRIER WEATHER RETURNS FOR SUNDAY...LASTING INTO MUCH OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
CLOUD COVER SHOULD BE ON THE INCREASE LATE TONIGHT AHEAD OF AN
ADVANCING AREA OF LOW PRESSURE. MOISTURE IS ALSO FORECAST TO BE ON
THE INCREASE FROM TOP DOWN AFTER 06Z TONIGHT AS SOUTHWESTERLY
WINDS TRY BRINGING MOISTURE. BUFKIT SOUNDINGS INDICATING PW
VALUES INCREASING FROM AROUND AN INCH AT 06Z TO BETWEEN 1.25 AND
1.5 INCHES BY 12Z. EXPECT A DRY FORECAST THROUGH AT LEAST 06Z
TONIGHT...THEN POPS INCREASING TO CHANCE ACROSS THE WEST TOWARDS
MORNING...AND SLIGHT CHANCE ACROSS THE EAST. OVERNIGHT LOWS ARE
EXPECTED TO BE IN LOWER 50S IN MOST AREAS.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
PRECIPITABLE WATER VALUES RAPIDLY INCREASE FROM AROUND A HALF
INCH TO CLOSE TO 1.75 INCHES BY 18Z SATURDAY. FEEL CONFIDENT THERE
WILL BE MEASURABLE RAINFALL ON SATURDAY SO WILL CONTINUE THE
CATEGORICAL POPS AND EXPECT ON AVERAGE AROUND A HALF INCH OR SO
RAINFALL.

CONVECTION IS ANOTHER POTENTIAL ISSUE ON SATURDAY AS THE UPPER
TROUGH AND ATTENDANT SURFACE LOW TRACK EAST ACROSS THE PLAINS INTO
THE MISSISSIPPI VALLEY...STRONG KINEMATIC FIELDS SHIFT OVER THE
FORECAST AREA WITH SOUTHWESTERLY LOW LEVEL JET OF 50-60 KNOTS
COMBINED WITH SOME DIRECTIONAL WIND SHEAR WILL SUPPORT THE THREAT
FOR SEVERE WEATHER AS THE WARM FRONT LIFTS NORTHWARD ACROSS THE
REGION.  INSTABILITY REMAINS AN UNCERTAINTY BUT DEPENDING ON HOW
QUICKLY THE ISENTROPIC LIFT SHIFTS OUT OF THE AREA...LATE AFTERNOON
AND EVENING SATURDAY MAY ALLOW FOR SOME RECOVERY. POSSIBLE
ONGOING CONVECTION MOVING ACROSS THE TENNESSEE VALLEY SATURDAY
MORNING WHICH WILL THEN TRACK EAST- SOUTHEASTWARD INTO OUR REGION
SATURDAY AFTERNOON. SPC HAS EXPANDED THE SLIGHT RISK TO INCLUDE
THE MOST OF THE CWA WITH AN AREA OF ENHANCED RISK ACROSS TN/KY.

SOME LINGERING SHOWERS/STORMS POSSIBLE SATURDAY NIGHT INTO SUNDAY
WITH THE NORTHERN MIDLANDS LIKELY TO BE MORE FAVORED ON SUNDAY AS
THE SURFACE LOW SINKS SOUTHEASTWARD ACROSS VA/NC AND OFFSHORE BY
SUNDAY EVENING.  MODERATE TO STRONG INSTABILITY AND COLD 500MB TEMPS
NOTED ON SUNDAY BUT MOISTURE MAY BE LACKING TO SUPPORT MUCH
CONVECTION SO WILL CONTINUE WITH LOW CHANCE POPS ACROSS THE NORTHERN
MIDLANDS.

TEMPERATURES ON SATURDAY WILL BE LIMITED BY THE CLOUDS AND RAINFALL
FOR MUCH OF THE DAY BUT THERE IS SOME UNCERTAINTY ABOUT SOME
POSSIBLE RECOVERY LATE IN THE DAY AND ENSEMBLE DATA SUGGESTS SOME
UNCERTAINTY BUT WE SHOULD SEE A GRADIENT IN TEMPS FROM THE 60S NORTH
TO 70S SOUTH.  SUNDAY LOOKS TO BE A WARM DAY WITH SOME SUNSHINE AND
DOWNSLOPING NORTHWESTERLY FLOW WITH HIGHS BACK INTO THE 80S.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
MEDIUM RANGE MODELS APPEAR TO BE COMING INTO SOMEWHAT BETTER
AGREEMENT WITH THE OVERALL PATTERN NEXT WEEK. ON MON/TUE THE
FORECAST AREA WILL BE BETWEEN THE DEPARTING SYSTEM OFF THE EAST
COAST AND YET ANOTHER SLOW MOVING CLOSED UPPER LOW EJECTING
EASTWARD OUT OF THE SOUTHWESTERN STATES. EXPECT DRY WEATHER AND
BELOW NORMAL TEMPERATURES WITH A PERSISTENT NORTHERLY FLOW AND
SURFACE HIGH PRESSURE RIDGING INTO THE AREA FROM THE NORTH. THE
SOUTHERN STREAM CLOSED LOW WILL BEGIN TO OPEN AND DRIFT EASTWARD
EVENTUALLY PHASING WITH NORTHERN STREAM ENERGY BRINGING UNSETTLED
WEATHER TO OUR AREA TUESDAY INTO THURSDAY. LATEST GFS SHOWS DRY HIGH
PRESSURE BUILDING IN FROM THE WEST FRIDAY. TEMPERATURES GENERALLY
AT OR JUST BELOW NORMAL THROUGH THE EXTENDED PERIOD.

&&

.AVIATION /23Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL START THE TAF PERIOD WITH A DRY AIR MASS IN
PLACE. HIGH PRESSURE SHIFTING FARTHER OFF THE COAST AND AN
APPROACHING WARM FRONT WILL BRING INCREASING MOISTURE TONIGHT.
EXPECT CEILINGS LOWERING INTO THE MVFR CATEGORY AROUND 12Z AS RAIN
ENTERS THE REGION. CEILINGS WILL LIKELY DROP INTO THE LOWER MVFR
RANGE OR INTO THE IFR CATEGORY LATER SATURDAY MORNING AS THE WARM
FRONT MOVES NORTHWARD AND NEARS THE AREA. CEILINGS MAY BEGIN TO
BECOME MORE BROKEN TO SCATTERED DURING THE AFTERNOON AS THE WARM
FRONT LIFTS NORTH OF THE TAF SITES. LEANED TOWARD THE NAM MOS WITH
SLIGHT IMPROVEMENT LATER IN THE AFTERNOON ALTHOUGH THUNDERSTORMS
WILL STILL BE A THREAT DURING THAT TIME. LOW-LEVEL WIND SHEAR MAY
BE AN ISSUE BEFORE WARM FRONTAL PASSAGE. HIGH SHEAR AND INSTABILITY
NEAR THE WARM FRONT MAY HELP SUPPORT SEVERE THUNDERSTORMS WITH
DAMAGING WIND AND HAIL SATURDAY AFTERNOON.

EXTENDED AVIATION OUTLOOK...SHOWERS AND THUNDERSTORMS WITH
ASSOCIATED RESTRICTIONS WILL BE POSSIBLE INTO SATURDAY EVENING.
BREEZY CONDITIONS POSSIBLE SUNDAY. NO SIGNIFICANT IMPACTS EXPECTED
MONDAY AND TUESDAY. AN APPROACHING WARM FRONT MAY RESULT IN
WIDESPREAD RESTRICTIONS WEDNESDAY.

&&

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

$$





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