Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 270217
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
917 PM EST THU FEB 26 2015

.SYNOPSIS...
COLD HIGH PRESSURE WILL BUILD FROM THE NORTHWEST THROUGH SATURDAY. A
COASTAL TROUGH WILL DEVELOP SATURDAY AND PERSIST THROUGH SUNDAY. A
COLD FRONT WILL STALL OVER OR JUST NORTH OF THE REGION EARLY NEXT
WEEK...THEN WILL LIFT NORTH AS A WARM FRONT THROUGH THE MIDDLE OF
THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
HIGH PRESSURE OVER THE CENTRAL PLAINS WILL REMAIN ACROSS THE
REGION TONIGHT. LOW CLOUDS ARE STEADILY MIXING OUT PER AREA
OBSERVATIONS...BUT A THICK CIRRUS CANOPY ASSOCIATED WITH A
POWERFUL UPPER JET IS STEADILY EXPANDING ACROSS THE EASTERN
CAROLINAS AND GEORGIA. THE CIRRUS BAND WILL REMAIN IN TACT
THROUGH THE NIGHT YIELDING MAINLY CLOUDY SKIES AS IT THICKENS.
TEMPERATURES ARE BEING HELD UP DUE THE EXTENSIVE CLOUD
COVER...WHICH NECESSITATES ANOTHER SLIGHT INCREASE IN THE LOW
TEMPERATURE FORECAST FOR FRIDAY MORNING. LOWS WILL RANGE FROM THE
LOWER 30S INLAND TO THE MID-UPPER 30S ELSEWHERE...EXCEPT LOWER
40S ALONG THE GEORGIA COAST. THE RISK FOR FOG IS ESSENTIALLY NON-
EXISTENT THIS FAR SOUTH WITH EXTENSIVE CLOUD COVER REMAINING IN
PLACE...DESPITE WET GROUNDS.

FOR THE LATE EVENING UPDATE...
* ADJUSTED CLOUD COVER TO THE CLOUDY CATEGORY ALL AREAS.
* ADJUSTED HOURLY TEMPERATURES TO REFLECT WARMER OVERNIGHT LOWS.
* NUDGED LOW TEMPERATURES UP 1-3 DEGREES MOST AREAS.
* REMOVED MENTION OF PATCHY FOG/FREEZING FOG.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
A BROAD WSW 500 MB FLOW WILL PREVAIL FRIDAY THROUGH SUNDAY.
MEANWHILE EXPANSIVE CANADIAN HIGH PRESSURE TO THE NORTHWEST WILL
GRADUALLY SHIFT EAST INTO THE WESTERN ATLANTIC BY SUNDAY.

PARTIAL CLEARING ON FRIDAY ALONG WITH SOME DOWNSLOPE FLOW WILL PUSH
TEMPS INTO THE MID TO UPPER 50S. BY FRIDAY NIGHT A WEAK COASTAL
TROUGH WILL DEVELOP OFF THE GA COAST. LOW-LEVEL FLOW TURNS SOUTHERLY
WITH MOISTURE INCREASING ABOVE THE SURFACE HIGH...BRINGING LOW AND
MID CLOUDS BACK INTO THE AREA LATE FRIDAY NIGHT.

A PRONOUNCED HIGH PRESSURE WEDGE PATTERN WILL EXIST ON SATURDAY WITH
COOL NORTHEAST FLOW ACROSS THE AREA AND EXTENSIVE CLOUDS STREAMING
IN FROM THE SOUTHWEST. A FAIRLY DRY LAYER WILL BE IN PLACE OVER LAND
AREAS BUT THERE SHOULD BE ENOUGH MOISTURE AND FORCING FOR SOME
SHOWERS OVER THE COASTAL WATERS. HIGHS ON SATURDAY WILL BE IN THE
UPPER 40S TO LOWER 50S.

SATURDAY NIGHT AND SUNDAY AS THE SURFACE HIGH SHIFTS INTO THE
WESTERN ATLANTIC THE COASTAL TROUGH WILL SHIFT INLAND. THIS COULD
BRING SCATTERED RAIN SHOWERS TO INLAND AREAS...MAINLY SOUTHEAST GA
WHERE DEEPER MOISTURE EXISTS. TEMPS ON SUNDAY SHOULD REBOUND INTO
THE MID TO UPPER 50S.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE LONG TERM FORECAST PERIOD CONTINUES TO FEATURE A PATTERN SHIFT
THANKS TO A STRENGTHENING ANTICYCLONE OVER THE GULF OF MEXICO AND
BROAD RIDGING BUILDING ACROSS MUCH OF THE EASTERN CONUS THROUGH THE
MIDDLE OF NEXT WEEK. THE MID ATLANTIC HIGH WILL SHIFT EAST OUT OVER
THE ATLANTIC ON MONDAY AND A NEARLY STATIONARY FRONT WILL SET UP
JUST NORTH OF THE FORECAST AREA. THIS FRONT WILL SAG AND LIFT AT
TIMES AND MAY BRUSH THE NORTHERN TIER OF THE FORECAST AREA.
REGARDLESS THE OVERALL TREND IS FOR WARMING TEMPERATURES AND LOW END
POPS WITHIN THE WARM SECTOR. TEMPERATURES WILL FINALLY BE ABOVE
NORMAL THROUGH THE PERIOD THE BEST PERIODS OF RAIN CHANCES ARE
UNCERTAIN AT THIS POINT.

&&

.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
MVFR CIGS ARE EXPECTED TO LIFT BY 02-05Z WITH VFR CONDITIONS
PREVAILING THEREAFTER.

EXTENDED AVIATION OUTLOOK...FLIGHT RESTRICTIONS ARE BECOMING
INCREASINGLY LIKELY BEGINNING LATER SATURDAY OR SATURDAY
NIGHT...MAINLY IN LOW CEILINGS BUT FOG CANNOT BE RULED OUT
SATURDAY NIGHT AND SUNDAY MORNING.

&&

.MARINE...
TONIGHT...NORTH WINDS INCREASING UP TO NEAR 15 KT AS HIGH
PRESSURE BUILDS IN FROM THE NORTHWEST. SIGNIFICANT WAVE HEIGHTS
WILL DIMINISH SLOWLY TO NO HIGHER THAN 4 FT LATE TONIGHT.

HIGH PRESSURE WILL BUILD SOUTHEAST ON FRIDAY...STRENGTHENING TO THE
NORTH ON SATURDAY AS A COASTAL TROUGH DEVELOPS. A PINCHED NORTHEAST
GRADIENT WILL THUS SETUP OVER OUR COASTAL WATERS FRIDAY NIGHT AND
PERSIST INTO SATURDAY NIGHT BEFORE WEAKENING AS THE HIGH SHIFTS
EAST. SOLID SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TO DEVELOP
LATE FRIDAY NIGHT...WITH THE POTENTIAL FOR GALES ON SATURDAY OVER
OUTER PORTIONS. AT THIS POINT WE SHOW A FEW 34 KT GUSTS ACROSS THE
OFFSHORE GA WATERS ON SATURDAY...SO LATER SHIFTS MAY NEED TO
CONSIDER A GALE WATCH.

AS THE HIGH SHIFTS OVER THE ATLANTIC ON SUNDAY...WINDS/SEAS WILL
DECREASE CONSIDERABLY.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.

&&

$$

ST


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