Area Forecast Discussion
Issued by NWS Columbia, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KCAE 230256
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
956 PM 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 /UNTIL 6 AM TUESDAY MORNING/...
DEEP UPPER TROUGH OVER THE CENTRAL CONUS WILL CONTINUE TO PROMOTE
SOUTHWESTERLY FLOW ALOFT FOR OUR REGION...WITH EMBEDDED
DISTURBANCES. SURFACE HIGH PRESSURE CENTERED OVER NEW ENGLAND
WILL CONTINUE RIDGING INTO THE FA...PROMOTING A STRONG COLD AIR
DAMMING SETUP. ISENTROPIC LIFT OVER THE WEDGE RIDGE WILL SUPPORT
AREAS OF LIGHT RAIN OR DRIZZLE INTO THE OVERNIGHT PERIOD.
TEMPERATURES WILL REMAIN STEADY IN THE 40S OVERNIGHT UNDER CLOUD
COVER.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
VERY ACTIVE WEATHER EXPECTED DURING THIS PERIOD AS 500MB FLOW
BECOMES HIGHLY AMPLIFIED WITH LOW PRESSURE DEVELOPING ALONG THE
WESTERN GULF COAST BY TUESDAY AFTERNOON AND LIFTING NORTHWARD INTO
THE OHIO VALLEY ON WEDNESDAY...WHICH WILL DRIVE A COLD FRONT
ACROSS OUR AREA WEDNESDAY EVENING.

THERE SHOULD BE A RELATIVE BREAK IN THE PRECIPITATION TUESDAY
MORNING AS THE AREA REMAINS IN BETWEEN WAVES OF ENERGY ROTATING
THROUGH THE LONGWAVE TROUGH. THE CAD WEDGE CONDITIONS WILL PERSIST
AND THINK MODELS ARE TOO AGGRESSIVE IN ERODING THE WEDGE BY
TUESDAY AFTERNOON SO HAVE GONE WELL BELOW MOS GUIDANCE FOR MAX
TEMPS...HEAVILY LEANING TOWARDS OUR LOCAL WEDGE EQUATION WHICH
GIVES MAX TEMPS SIMILAR TO TODAY IN THE MID TO UPPER 40S...EXCEPT
SOME LOWER 50S POSSIBLE IN THE EASTERN MIDLANDS LATE IN THE DAY.
EXPECT PATCHY DRIZZLE WITH SCATTERED RAIN SHOWERS THROUGH THE
MORNING HOURS THEN POPS RAMP UP TO CATEGORICAL BY AFTERNOON AS
ANOTHER SHORTWAVE TROUGH MOVES INTO THE REGION FROM THE SOUTH
COINCIDING WITH STRONG ISENTROPIC LIFTING OVER THE AREA.

AS THE STORM SYSTEM MATURES AND DEEPENS TUESDAY NIGHT...850MB
FLOW OVER THE FORECAST AREA INCREASES AND MOISTURE TRANSPORT OVER
BECOMES MAXIMIZED. PRECIPITABLE WATER VALUES INCREASE TO OVER 1.75
INCHES WHICH IS NEAR THE CLIMATOLOGICAL MAXIMUM FOR OUR AREA AND
EXPECT WIDESPREAD RAINFALL...MODERATE AT TIMES...AND CANNOT RULE
OUT SOME ISOLATED THUNDER. THE WEDGE WILL BREAK DOWN AS LOW LEVEL
FLOW BECOMES MORE SOUTHEASTERLY AND EVENTUALLY SOUTHERLY BY
WEDNESDAY MORNING ALLOWING TEMPERATURES TO WARM UP THROUGH THE
NIGHT. USED A NON-DIURNAL TEMPERATURE TREND TUESDAY AND TUESDAY
NIGHT. SIGNIFICANT RAINFALL IS EXPECTED DURING THE TUESDAY EVENING
THROUGH WEDNESDAY AFTERNOON PERIOD WITH QPF BETWEEN 1-2 INCHES
ACROSS THE AREA.

THE AREA IS FORECAST TO FALL WITHIN THE WARM SECTOR ON WEDNESDAY
WITH A WARM FRONT LIFTING NORTH OF THE REGION WITH STRONG
SOUTHERLY FLOW SUPPORTING ABOVE NORMAL TEMPERATURES. FORECAST
INSTABILITY IS WEAK WITH LI VALUES STRUGGLING TO RISE ABOVE ZERO.
STRONG SHEAR IS EXPECTED WITH LOW LEVEL JET AROUND 55-60 KNOTS AND
COULD SUPPORT AN ISOLATED DAMAGING WIND THREAT DESPITE THE WEAK
FORECAST INSTABILITY. FRONT WILL CROSS THE AREA SOMETIME WEDNESDAY
EVENING WITH HIGH PRESSURE BUILDING IN FROM THE SOUTHWEST LATE
WEDNESDAY NIGHT. STRONG WINDS ARE EXPECTED BEHIND THE FRONT WITH
SOME GUSTS TO 15 TO 25 MPH DUE TO INCREASED PRESSURE GRADIENT.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
AN ACTIVE AND GENERALLY MERIDIONAL UPPER LEVEL FLOW PATTERN
PERSISTS ACROSS THE COUNTRY DURING THE EXTENDED FORECAST PERIOD.

THE STRONG STORM SYSTEM THAT WILL BRING SIGNIFICANT RAINFALL TO
THE REGION MID WEEK WILL LIFT INTO SOUTHEASTERN CANADA ON
CHRISTMAS DAY THURSDAY AS MID LEVEL 500MB FLOW BECOMES ZONAL BY
THURSDAY EVENING ACROSS THE SOUTHEASTERN STATES. MUCH DRIER AIR
WILL BUILD OVER THE FORECAST AREA THURSDAY BEHIND A COLD FRONT
WITH COOLER TEMPERATURES AND BREEZY CONDITIONS EXPECTED. NEAR
NORMAL TO SLIGHTLY BELOW NORMAL TEMPERATURES ARE EXPECTED ON
THURSDAY WITH HIGHS IN THE 50S AND LOWS THURSDAY NIGHT IN THE
LOWER TO MID 30S.

TRANQUIL WEATHER UNDER MOSTLY CLEAR SKIES WITH MODERATING
TEMPERATURES ARE FORECAST FOR FRIDAY AND SATURDAY AS SURFACE HIGH
PRESSURE SETTLES OVER THE AREA ON FRIDAY AND SHIFTS OFF THE COAST
ON SATURDAY WITH A RETURN SOUTHERLY FLOW DEVELOPING. TEMPERATURES
DURING THIS PERIOD WILL BE SLIGHTLY ABOVE NORMAL WITH HIGHS IN THE
UPPER 50S TO LOWER 60S AND ABOVE NORMAL OVERNIGHT LOWS IN THE
UPPER 30S TO 40S.

MORE UNCERTAINTY EXISTS IN THE LATER PART OF THE EXTENDED FORECAST
PERIOD DUE TO DIFFERENCES AMONG THE MEDIUM RANGE MODELS LEADING TO
LOWER CONFIDENCE IN THE FORECAST. THE GFS DEPICTS AN UPPER TROUGH
CROSSING THE OHIO VALLEY AND MID ATLANTIC WHICH PUSHES A COLD
FRONT THROUGH THE FORECAST AREA SATURDAY NIGHT. HOWEVER...LITTLE
MOISTURE IS AVAILABLE WITH THE SYSTEM. THE ECMWF IS A BIT SLOWER
THAN THE GFS AND BRINGS A STRONGER SHORTWAVE TROUGH ACROSS THE
APPALACHIANS ON SUNDAY WITH BETTER MOISTURE RETURN AND INFLOW
INTO THE FRONT RESULTING IN A BETTER CHANCE OF PRECIPITATION LATE
SATURDAY NIGHT AND SUNDAY. WILL LEAN TOWARDS THE HPC GUIDANCE
REGARDING POPS AND SINCE THERE IS REASONABLE CONSENSUS ON
SATURDAY BEING DRY WILL REMOVE POPS SATURDAY AND INCLUDE POPS ON
SUNDAY. TEMPERATURES WILL BE DETERMINED BY WHEN THE COLD FRONT
ACTUALLY PASSES THROUGH WITH COOLER TEMPERATURES EXPECTED BEHIND
THE FRONTAL PASSAGE.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
IFR/LIFR CONDITIONS EXPECTED THROUGH THE 24 HOUR TAF PERIOD.

STRATUS BUILD DOWN DEVELOPING ACROSS THE REGION. EXPECT CEILINGS
MAINLY LIFR OVERNIGHT WITH VISIBILITIES 2 MILES OR LESS THROUGH
DAYBREAK. RAIN MAINLY TO THE NORTHWEST OF THE TERMINALS THROUGH THE
OVERNIGHT ALTHOUGH PATCHY DRIZZLE POSSIBLE...WITH POSSIBLE RESULTING
LOWER VISIBILIIES AT TIMES.

CONDITIONS NOT EXPECTED TO IMPROVE AS NORTHEASTERLY FLOW
CONTINUES TO PROMOTE COLD AIR DAMMING WEDGE. MODELS INDICATE LIFR
CEILINGS THROUGH MORNING WITH SOME IMPROVEMENT BY
AFTERNOON...ALTHOUGH WIDESPREAD RAIN MAY DEVELOP...SO IFR FORECAST
THROUGH PERIOD.

EXTENDED AVIATION OUTLOOK...WIDESPREAD MVFR TO IFR CONDITIONS
EXPECTED TUESDAY EVENING 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.
&&

$$







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.