Area Forecast Discussion
Issued by NWS Columbia, SC

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000
FXUS62 KCAE 281134
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
634 AM EST SAT FEB 28 2015

.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL BUILD INTO THE AREA OVER THE WEEKEND
WITH TEMPERATURES REMAINING BELOW NORMAL. A WARMING TREND IS
EXPECTED NEXT WEEK WITH SOUTHERLY FLOW DEVELOPING. A SERIES OF
FRONTS AFFECTING THE REGION WILL BRING PERIODS OF SHOWERS AND
POSSIBLY SOME THUNDERSTORMS.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WATER VAPOR IMAGERY CONTINUES TO SHOW A VERY BROAD UPPER TROUGH
EXTENDING ACROSS THE ENTIRE COUNTRY WITH SHORTWAVE ENERGY DIGGING
SOUTHWARD ALONG THE WEST COAST WITH WEAK CYCLONIC SOUTHWESTERLY
FLOW ACROSS THE SOUTHEASTERN STATES. AT THE SURFACE A 1040MB HIGH
WAS CENTERED OVER THE OHIO VALLEY AND BUILDING EASTWARD AND
STARTING TO RIDGE DOWN THE EAST COAST ON THE EAST SIDE OF THE
APPALACHIANS.

PERSISTENT NORTHEASTERLY FLOW EXPECTED TODAY AS THE RIDGE BUILDS
DOWN OVER THE AREA...USHERING IN COOL AND DRY AIR WITH DEWPOINTS
CURRENTLY IN THE TEENS NEAR THE CHARLOTTE METRO AREA AND SOME
SINGLE DIGITS FURTHER NORTH NEAR GREENSBORO. SATELLITE IMAGERY
SHOWS A BLANKET OF HIGH CLOUDS STREAMING FROM SOUTHWEST TO
NORTHEAST ACROSS THE GULF OF MEXICO AND COVERING THE EASTERN
MIDLANDS AND LOWER CSRA AND THIS WILL LIKELY REMAIN IN PLACE
THROUGH THE DAY. CLOUDS ARE EXPECTED TO INCREASE LATER TODAY AS
ISENTROPIC LIFT OVER THE REGION INCREASES DUE TO NORTHEASTERLY
FLOW IN THE LOWEST 3000 FT WITH INCREASING SOUTHERLY FLOW ABOVE
THAT LAYER. DESPITE SOME EARLY SUNSHINE THE INCREASING CLOUDS AND
PERSISTENT NORTHERLY FLOW SHOULD KEEP TEMPERATURES DOWN A BIT
COOLER THAN ON FRIDAY WITH HIGHS GENERALLY IN THE MID/UPPER 40S TO
AROUND 50. AS THE ISENTROPIC LIFT BEGINS LATE AFTERNOON THERE IS A
SLIGHT CHANCE OF LIGHT RAIN ACROSS THE SOUTHERN MIDLANDS AND CSRA.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
A COLD AIR DAMMING WEDGE BECOMES ESTABLISHED OVER THE FORECAST
AREA TONIGHT WITH STRENGTHENING ISENTROPIC LIFT AS LOW LEVEL
SOUTHERLY FLOW INCREASES TO NEAR 40 KNOTS ATOP THE SHALLOW NEAR
SURFACE LAYER WITH NORTHEASTERLY WINDS. THE BEST ISENTROPIC LIFT
DEVELOPS OVER THE CSRA AND SHIFTS NORTHWARD OVER THE WESTERN
MIDLANDS LATE TONIGHT AND THEN NORTHEASTWARD OVER THE ENTIRE
FORECAST AREA SUNDAY MORNING INTO EARLY AFTERNOON BEFORE SHIFTING
AWAY FROM THE REGION LATE SUNDAY. HAVE BUMPED UP POPS TO LIKELY
LATE TONIGHT AND SUNDAY AS MOS TRENDS HAVE CONTINUED TO INCREASE
POPS OVER THE PAST 4-5 MODEL RUNS...THOUGH THIS LOOKS LIKE A VERY
LIGHT PRECIPITATION EVENT WITH MOST LOCATIONS RECEIVING AROUND A
TENTH OF AN INCH OR LESS.

MODEL FORECAST SOUNDINGS CONTINUE TO INDICATE A THREAT OF POSSIBLE
FREEZING RAIN LATE TONIGHT INTO SUNDAY MORNING AS THE DRIER AIR
ADVECTING IN FROM THE NORTH MAY BE ENOUGH TO SUPPORT SOME DIABATIC
EVAPORATIVE COOLING WHICH COULD KEEP SURFACE TEMPS AT OR SLIGHTLY
BELOW FREEZING FOR A PERIOD OF TIME. WHILE THE THREAT
EXISTS...THE LIGHT NATURE OF THE PRECIPITATION AND UNCERTAINTY
THAT THE TEMPS WILL ACTUALLY BE AT OR BELOW FREEZING LEAD TO LOW
CONFIDENCE FOR ANY HEADLINES AND PREVENT ANYTHING MORE THAN A
MENTION IN THE FORECAST AND WILL INCLUDE A BRIEF MENTION IN THE
HWO PRODUCT. PRECIP SHOULD TURN TO ALL RAIN AFTER 15Z AS THE
ATMOSPHERIC COLUMN SATURATES AND WARMS DUE TO WARM ADVECTION.

TEMPERATURES TONIGHT WILL BE LIMITED BY THICKENING AND LOWERING
CLOUDS BUT EXPECTED TO FALL INTO THE LOWER 30S NORTH TO MID 30S
SOUTH. TEMPERATURES NOT EXPECTED TO MOVE TOO MUCH ON SUNDAY WITH
STRONG WEDGE CONDITIONS IN PLACE AND PRECIPITATION ACROSS THE
REGION. WELL BELOW NORMAL TEMPS WITH HIGHS IN THE UPPER 30S
NORTHERN MIDLANDS TO LOWER/MID 40S CSRA. PRECIPITATION WILL SHIFT
OUT OF THE AREA LATE SUNDAY THE WEDGE WILL BEGIN TO BREAK DOWN
SUNDAY NIGHT AS A COLD FRONT PUSHES INTO THE AREA FROM THE
WEST...AND MAY ACTUALLY SEE TEMPERATURES RISE A BIT AS THE COLD
AIR RETREATS. LOW CHANCES OF LIGHT RAIN OR DRIZZLE CONTINUE SUNDAY
NIGHT WITH LOWS IN THE UPPER 30S TO LOWER 40S.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
MEDIUM RANGE MODELS CONTINUE TO POINT TO A CHANGE IN THE UPPER
PATTERN FROM THE PERSISTENT EAST COAST TROUGH TO A PROGRESSIVE
UPPER RIDGE SHIFTING OUT OF THE WEST ACROSS THE COUNTRY AND
BRINGING WARMER TEMPERATURES BUT UNSETTLED WEATHER TO THE FORECAST
AREA BY MID WEEK.

SHORTWAVE ENERGY MOVING OFF THE NEW ENGLAND COAST ON MONDAY WILL
PUSH A FRONT THROUGH THE FORECAST AREA ON MONDAY WHICH WILL STALL
TO THE SOUTH. TRANSIENT SURFACE HIGH PRESSURE WILL MOVE ACROSS THE
OHIO VALLEY TO THE MID ATLANTIC COAST MONDAY INTO TUESDAY WITH
GENERALLY LOW POPS. INCREASING SOUTHWESTERLY FLOW OVER THE STALLED
FRONT WILL RESULT IN CHANCE POPS ACROSS THE REGION MONDAY NIGHT
INTO TUESDAY DUE TO THE OVERRUNNING OF THE MOIST WARM AIR OVER THE
COOL SURFACE LAYER.  THE STALLED COLD FRONT TO THE SOUTH WILL
RETURN NORTHWARD AS A WARM FRONT TUESDAY NIGHT AND LIFT NORTH OF
THE AREA ON WEDNESDAY WITH INCREASING SOUTHERLY FLOW AND
TEMPERATURES BECOMING ABOVE NORMAL. A LONG WAVE TROUGH WILL MOVE
OUT OF THE INTER MOUNTAIN WEST AND PUSH EASTWARD WHILE A COLD FRONT
APPROACHES AND CROSSES THE REGION SOMETIME WEDNESDAY NIGHT INTO
THURSDAY. HAVE BUMPED UP POPS WITH THE FRONT TO LOW LIKELY AND
CONTINUED THE MENTION OF THUNDER AHEAD OF THE FRONT. COOL AND DRY
HIGH PRESSURE BUILDS OVER THE AREA ON FRIDAY BEHIND THE FRONT.

TEMPERATURES THROUGH THIS PERIOD WILL GENERAL BE ABOVE NORMAL
WITH THE WARMEST DAY ON WEDNESDAY AS HIGHS PUSH INTO THE MIDDLE
70S.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...

SURFACE HIGH PRESSURE IS RIDGING DOWN THE MID ATLANTIC
COAST...BRINGING NE WINDS AND AN INFLUX OF DRIER LOW LEVEL AIR INTO
THE REGION IN THE NEAR TERM. MEANWHILE...MID AND HIGH LEVEL
CLOUDINESS WILL STREAM EAST ACROSS THE REGION. ISENTROPIC LIFT IS
EXPECTED TO COMMENCE LATE TODAY AND TONIGHT...PROVIDING LIGHT RAIN
POTENTIAL AND ACCOMPANYING RESTRICTIONS AS LOW LEVELS GRADUALLY
MOISTEN. LIGHT RAIN FALLING INTO COOL DRY AIR WILL LEAD TO
EVAPORATIONAL COOLING THAT COULD BRING SURFACE TEMPS DOWN TO NEAR
FREEZING NORTH OF COLUMBIA. AT THIS TIME...IT APPEARS FREEZING RAIN
POTENTIAL WILL BE NORTH OF OUR TERMINALS. GENERALLY FOLLOWED
GUIDANCE TREND OF BRINGING RESTRICTIONS DOWN TO MVFR TONIGHT...BUT
IFR CIGS COULD BE POSSIBLE LATE TONIGHT.

EXTENDED AVIATION OUTLOOK...IFR CIG/VSBY RESTRICTIONS AND A CHANCE
OF PRECIPITATION EXPECTED SUNDAY INTO SUNDAY NIGHT. RESTRICTIONS AND
A CHANCE OF PRECIPITATION POSSIBLE AT TIMES LATE MONDAY THROUGH
THURSDAY.

&&

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

$$





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