Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 011127
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
627 AM EST SUN MAR 1 2015

.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL WEDGE INTO THE AREA FROM THE NORTH
THROUGH SUNDAY NIGHT. MOISTURE WILL INCREASE AHEAD OF AN
APPROACHING COLD FRONT WHICH WILL CROSS THE AREA MONDAY. A BRIEF
WARM UP IS EXPECTED FOR THE MIDDLE OF NEXT WEEK WITH SOUTHERLY
FLOW DEVELOPING. ANOTHER COLD FRONT WILL CROSS THE AREA WEDNESDAY
NIGHT INTO THURSDAY BRINGING A CHANCE OF SHOWERS AND POSSIBLY
THUNDERSTORMS.

&&

.NEAR TERM /THROUGH TONIGHT/...
CURRENT RADAR IMAGERY SHOWS WIDESPREAD LIGHT RAIN ACROSS THE
FORECAST AREA DUE TO ISENTROPIC LIFT WITH SOUTHERLY FLOW TOP THE
COOL SHALLOW CAD WEDGE IN PLACE. LATEST OBSERVATIONS SHOW
GENERALLY ABOVE FREEZING TEMPERATURES ACROSS MUCH OF THE AREA
EXCEPT FREEZING TEMPS ACROSS THE NORTHERN MIDLANDS. THE LAPS WET
BULB FREEZING LINE WAS ACROSS SOUTHERN LANCASTER AND CHESTERFIELD
COUNTY A FEW HOURS AGO BUT AS PRECIPITATION HAS MOVED NORTH INTO
THAT AREA WITH DRIER AIR IN PLACE...THAT LINE HAS SHIFTED SOUTH
OVER THE PAST COUPLE OF HOURS. WHILE DEWPOINT DEPRESSIONS ARE
DIMINISHING ACROSS THE NORTHERN MIDLANDS THERE STILL APPEARS TO BE
A PERIOD OF SEVERAL HOURS WHERE FREEZING RAIN IS POSSIBLE ACROSS
THE ADVISORY AREA. CONFIDENCE HAS DECREASED A BIT THAT MUCH IF ANY
ACCUMULATION WILL OCCUR IN SUMTER COUNTY AS TEMPERATURES ARE
SEVERAL DEGREES ABOVE FREEZING WITH A DEWPOINT JUST BELOW FREEZING
BUT WITH POSSIBLE DRIER AIR ADVECTING IN FROM THE NORTH HAVE OPTED
NOT TO DROP THEM FROM THE ADVISORY AT THIS TIME AND WILL RE-EVALUATE
LATER IN THE SHIFT. HAVE LOWERED THE ICE ACCUMULATIONS A BIT
ACROSS THE SOUTHERN PART OF THE ADVISORY AREA AS IT APPEARS
DIFFICULT TO ACCUMULATE MUCH WITH TEMPS AT 32 OR SLIGHTLY
ABOVE...WHILE KEEPING THE MOST ACCUMULATION IN LANCASTER AND
CHESTERFIELD COUNTIES LESS THAN A TENTH OF AN INCH. TEMPERATURES
EXPECTED TO WARM ABOVE FREEZING ALL LOCATIONS BY 15Z WITH A
CHANGEOVER TO ALL RAIN AFTER THAT TIME.

WILL CONTINUE CATEGORICAL POPS ACROSS THE REGION THROUGH MID
MORNING AND THEN GRADUALLY DECREASE POPS THROUGH THE AFTERNOON AS
ISENTROPIC LIFT WEAKENS AND SHIFTS AWAY FROM THE AREA. MODEL
SUGGEST THE WEDGE WEAKENING AND BREAKING LATE TONIGHT AS LOW
PRESSURE TRACKS ACROSS THE EASTERN OHIO VALLEY AND NORTHEAST AND
SOUTHERLY FLOW DEVELOPS. LOW CLOUDS AND PATCHY DRIZZLE POSSIBLE
THROUGH TONIGHT WITH OVERNIGHT LOWS IN THE UPPER 30S TO LOWER 40S.

&&

.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
A FAST MOVING SHORTWAVE PUSHING OFF THE NEW ENGLAND COAST ON
MONDAY WILL PUSH A WEAK COLD FRONT THROUGH THE AREA WHICH WILL
STALL JUST TO THE SOUTH BY MONDAY EVENING. WILL CARRY SLIGHT
CHANCE POPS WITH THE FRONT ALTHOUGH THERE IS LITTLE UPPER FORCING
ACCOMPANYING THE FRONT. A 1032MB SURFACE RIDGE WILL SETTLE OVER
NEW ENGLAND INTO THE MID ATLANTIC COAST AND RIDGE INTO THE
CAROLINAS...SETTING UP ANOTHER WEAK WEDGE. INCREASING SOUTHERLY
850MB FLOW AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM IN THE PLAINS
MONDAY NIGHT WILL RESULT IN ISENTROPIC LIFT ATOP THE COOL WEDGE
AND WARRANT INCREASED POPS MONDAY NIGHT. TEMPERATURES ON MONDAY
SHOULD WARM UP SIGNIFICANTLY COMPARED TO SUNDAY TEMPS WITH HIGHS
GENERALLY IN THE 60S. LOWS ON MONDAY NIGHT WILL RANGE FROM THE
LOWER 40S NORTHERN MIDLANDS WHERE SOME OF THE COOLER AIR BEHIND
THE FRONT PUSHES SOUTH...TO THE UPPER 40S TO NEAR 50 IN THE CSRA
CLOSER TO THE FRONTAL ZONE.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
LITTLE CHANGE TO THE EXTENDED FORECAST THINKING. OVERRUNNING WARM
ADVECTION IS EXPECTED ON TUESDAY AS SOUTHWESTERLY FLOW WILL
STRENGTHEN AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM OVER THE
PLAINS WHICH WILL RESULT IN CHANCE POPS ACROSS THE FORECAST AREA
WITH THE BEST CHANCES IN THE WESTERN MIDLANDS. THE STALLED FRONT
TO THE SOUTH WILL LIFT NORTH AS A WARM FRONT TUESDAY NIGHT AND THE
FORECAST AREA WILL FALL WITHIN THE WARM SECTOR ON WEDNESDAY. A
STRONGER COLD FRONT WILL BE SLOWLY PUSHING TOWARDS THE AREA FROM
THE NORTHWEST LATE WEDNESDAY BEFORE CROSSING THE FORECAST AREA
WEDNESDAY NIGHT INTO EARLY THURSDAY MORNING. GRADUALLY INCREASING
POPS LATE WEDNESDAY TO LIKELY POPS LATE WEDNESDAY NIGHT AND
THURSDAY. STILL A POSSIBILITY OF ISOLATED THUNDERSTORMS ALONG AND
AHEAD OF THE FRONT DESPITE MINIMAL INSTABILITY. COOL HIGH PRESSURE
WILL BUILD OVER THE AREA BEHIND THE FRONT THURSDAY NIGHT INTO THE
WEEKEND.

TEMPERATURES DURING THIS PERIOD SHOULD FEATURE A STRONG GRADIENT
ON TUESDAY WITH HIGHS RANGING FROM THE UPPER 40S NORTHERN MIDLANDS
TO LOWER 60S SOUTHEAST MIDLANDS AND CSRA WITH AN ERODING CAD
WEDGE. WEDNESDAY FIGURES TO BE THE WARMEST DAY WITH BREEZY
SOUTHWESTERLY WINDS AND HIGHS WELL INTO THE 70S IN THE WARM
SECTOR. COOLER ON THURSDAY WITH HIGHS IN THE 50S TO LOWER 60S
FOLLOWED BY EVEN COOLER TEMPERATURES ON FRIDAY IN THE 40S TO LOWER
50S.  A SLIGHT WARM UP ON SATURDAY IN THE 50S.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...

WIDESPREAD IFR CONDITIONS EXPECTED TO PERSIST TODAY.

IN SITU WEDGE OVER THE FORECAST AREA (FA)...AS ISENTROPIC LIFT
RESULTS IN LIGHT PRECIPITATION FALLING INTO A SURFACE RIDGE OF HIGH
PRESSURE. EVAPORATIONAL COOLING AND LOW LEVEL MOISTENING HAS
RESULTED IN RESTRICTIONS LOWERING TO IFR. LITTLE CHANGE EXPECTED
TODAY. IT APPEARS FREEZING RAIN POTENTIAL THIS MORNING WILL
REMAIN JUST N/NE OF CAE/CUB/OGB. LIGHT PRECIPITAION EXPECTED TO
DIMINISH AND MOVE OUT OF THE AREA LATE TODAY OR EARLY THIS EVENING
AS ISENTROPIC LIFT COMES TO AN END. AN INCREASING WESTERLY LOW
LEVEL FLOW LATE TONIGHT...DUE TO A COLD FRONT APPROACHING FROM THE
NORTH...MAY ALLOW THE LOW LEVEL IN SITU WEDGE TO GRADUALLY SCOUR
OUT LATE TONIGHT...THOUGH VERY UNCERTAIN...BUT WILL INDICATE SOME
IMPROVEMENT IN CIGS/VSBYS LATE IN THE TAF PERIOD.

EXTENDED AVIATION OUTLOOK...RESTRICTIONS AND A CHANCE OF
PRECIPITATION POSSIBLE AT TIMES LATE MONDAY THROUGH THURSDAY.


&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...FREEZING RAIN ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ015-
     016-020>022-029-031.
GA...NONE.
&&

$$






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