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000
FXUS62 KCHS 160610
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
210 AM EDT SUN MAR 16 2014

.SYNOPSIS...
A WARM FRONT WILL DEVELOP OVER THE AREA EARLY THIS MORNING...THEN
LIFT NORTHWARD AS THE DAY PROGRESSES. A LOW PRESSURE SYSTEM AND
ASSOCIATED COLD FRONT WILL THEN MOVE THROUGH THE AREA FROM THE
WEST LATE TODAY AND TONIGHT. SEVERAL WAVES OF LOW PRESSURE WILL
THEN PASS OFFSHORE...AS HIGH PRESSURE WEDGES SOUTH INTO THE REGION
THROUGH TUESDAY. HIGH PRESSURE WILL THEN BUILD OVER THE AREA MID
AND LATE WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
EARLY THIS MORNING...LITTLE CHANGE WAS NEEDED TO THE ONGOING
FORECAST THROUGH DAYBREAK. A ROBUST SHORTWAVE TROUGH ACROSS THE
SOUTHERN PLAINS STATES HAS STEADILY DEVELOPED A SURFACE LOW OVER
THE LOWER MISSISSIPPI VALLEY. A WEAK PRESSURE GRADIENT CURRENTLY
EXISTS OVER THE FORECAST AREA ON THE PERIPHERY OF ATLANTIC HIGH
PRESSURE...WHILE A WARM FRONT EXTENDING DOWNSTREAM FROM THE LOW
SYSTEM WILL EVENTUALLY TAKE SHAPE ACROSS THE AREA THROUGH THE PRE-
DAWN HOURS. THE BULK OF PRECIPITATION REMAINS WELL WEST BY 2 AM
EDT. LATEST MODEL SOLUTIONS SUGGEST THAT BEST ISENTROPIC ASCENT
ASSOCIATED WITH THE LIFTING WARM FRONT WILL BE DELAYED UNTIL AFTER
SUNRISE. CONSIDERING RELATIVELY DRY AIR CURRENTLY IN THE LOW TO
MID LEVELS...WILL WAIT TO INTRODUCE A SLIGHT CHANCE FOR SHOWERS
UNTIL AROUND 09Z/5AM ACROSS INLAND AREAS. LOW TEMPERATURES WILL BE
IN THE LOW 50S FOR MOST LOCATIONS AWAY FROM THE LOCALLY WARMER
COASTLINE.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
TODAY AND TONIGHT...A STABLE AIR MASS WILL BE IN PLACE TO START
THE DAY AS A WARM FRONT EXTENDS INTO THE AREA FROM ASSOCIATED LOW
PRESSURE SHIFTING EAST ACROSS NORTHERN MISSISSIPPI AND ALABAMA. IT
IS STILL UNCLEAR IF AND HOW MUCH OF A WARM SECTOR WILL DEVELOP AS
THE LOW APPROACHES AND THE WARM FRONT LIFTS NORTHWARD LATE THIS
AFTERNOON INTO THIS EVENING. THERE IS A CHANCE OF RAIN ACROSS
NORTH AND WEST PORTIONS OF THE FORECAST AREA IN THE MORNING
ASSOCIATED WITH THE DEVELOPING WARM FRONT. THEN...THERE IS THE
POTENTIAL FOR SOME PRE-FRONTAL SHOWERS TO MOVE IN THROUGH EARLY
AFTERNOON...BEFORE A CONVECTIVE BAND OF SHOWERS AND PERHAPS A FEW
THUNDERSTORMS SPREAD IN FROM THE WEST DURING THE LATE AFTERNOON
AND EVENING. THESE SHOWERS WILL BE SUPPORTED BE STRONG FORCING FOR
ASCENT ALOFT DUE TO THE PLACEMENT OF A 130 KT UPPER LEVEL JET TO
THE NORTHWEST. IN ADDITION...SIGNIFICANT THETA-E ADVECTION WILL
OCCUR DUE TO A STRONG SOUTHWEST FLOW ALOFT...WITH PRECIPITABLE
WATER VALUES SURGING OVER 1.5 INCHES. GIVEN THESE CONDITIONS...THE
SHOWERS WILL BE HEAVY AT TIMES THIS AFTERNOON INTO TONIGHT. HIGHS
WILL RANGE ANYWHERE FROM THE UPPER 60S WELL INLAND TO THE MID 70S
NEAR THE ALTAMAHA RIVER.

THE DEVELOPMENT OF A WARM SECTOR WILL SUPPORT INCREASED SURFACE
BASED INSTABILITY...BUT NOT MUCH AS SURFACE WINDS WILL LIKELY BE OFF
THE COOL ATLANTIC WATERS ACROSS MOST AREAS EXCEPT THOSE WELL INLAND.
FORTUNATELY MODELS ARE NOT FORECASTING MUCH INSTABILITY EITHER. THIS
IS GOOD...SINCE THERE WILL BE CONSIDERABLE SHEAR IN PLACE WITH A
HIGHLY BACKED FLOW AT THE SURFACE AND A 35-45 SOUTHWEST FLOW JUST
ALOFT. IN FACT...MODEL HELICITY VALUES ARE AS HIGH AS 500-700 M2/S2
INLAND WITH SOUNDINGS SHOWING IMPRESSIVE VEERING IN THE HODOGRAPHS.
THE 0-3 KM SHERB PARAMETER...WHICH IS A GOOD INDICATOR OF A
POTENTIAL HIGH SHEAR LOW CAPE EVENT...SHOWS A CRITICAL VALUE OF
AROUND 1.00 ACROSS SOME INLAND AREAS...ESPECIALLY ACROSS SOUTHEAST
GEORGIA. SO HAVING SAID THAT...AS LONG AS SURFACE BASED INSTABILITY
DOES NOT DEVELOP...THE LIMITED MIXING TO THE SURFACE WILL JUST KEEP
THIS A HEAVY RAIN EVENT. HOWEVER IF SOME INSTABILITY DOES DEVELOP
OVER PARTS OF THE AREA...MIXING WILL BE DEEPER RESULTING IN THE
POTENTIAL FOR ISOLATED TORNADOES AND PERHAPS SOME DAMAGING WINDS
WITH ANY STORMS ALONG OR AHEAD OF THE MAIN CONVECTIVE BAND THIS
AFTERNOON INTO TONIGHT.

MONDAY AND MONDAY NIGHT...IT APPEARS THAT A COOL WEDGE OF HIGH
PRESSURE WILL EXTEND SOUTHWARD ACROSS THE AREA...AS ANOTHER WAVE OF
LOW PRESSURE PASSES TO THE SOUTH THEN OFF THE SOUTHEAST COAST.
CONTINUED DEEP LAYERED MOISTURE AND THE PASSAGE OF A SHORT WAVE
TROUGH WILL RESULT IN LIKELY TO CATEGORICAL RAIN CHANCES ACROSS THE
AREA...WITH THE HIGHEST PROBABILITIES ALONG THE COAST AND IN
SOUTHEAST GEORGIA. DAYTIME HIGHS ARE EXPECTED TO RANGE FROM THE MID
50S NORTH TO THE UPPER 60S SOUTH...WITH THE LIKELIHOOD OF
TEMPERATURES FALLING THROUGH THE DAY ACROSS MOST OF SOUTHEAST SC IF
NOT PORTIONS OF SOUTHEAST GA NEAR THE SAVANNAH RIVER AS THE WEDGE
BECOMES ESTABLISHED.

TUESDAY...THE COASTAL LOW WILL DEPART TO THE NORTHEAST...BUT THE
COOL/STABLE WEDGE OF HIGH PRESSURE WILL CONTINUE TO EXTEND SOUTHWARD
ACROSS THE AREA. WILL KEEP A CHANCE OF RAIN IN THE FORECAST TO
ACCOUNT FOR POTENTIAL WRAP-AROUND MOISTURE...BUT THE RAIN POTENTIAL
SHOULD DIMINISH THROUGH THE DAY. HIGHS ARE EXPECTED TO BE IN THE
MID 50S NORTH TO THE MID 60S SOUTH.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
DRY WEATHER IS ANTICIPATED MID AND LATE WEEK AS A WEDGE OF HIGH
PRESSURE WEAKENS OVER THE SOUTHEAST ON WEDNESDAY AND IS REPLACED BY
BROADER HIGH PRESSURE TO OUR WEST. THE PATTERN WILL LIKELY SUPPORT A
GRADUAL WARMING TREND THROUGH LATE WEEK AS HIGH PRESSURE BECOMES
CENTERED OVER THE SOUTHEAST...THEN GRADUALLY SHIFTS OFFSHORE.
OVERALL HIGH TEMPS SHOULD RANGE IN THE LOW 70S MID WEEK...THEN LOW
TO MID 70S LATE WEEK. OVERNIGHT LOWS SHOULD RANGE IN THE MID/UPPER
40S AWAY FROM THE COAST.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
MOISTURE WILL REMAIN SOMEWHAT LIMITED IN THE LOW TO MID LAYERS
THROUGH DAYBREAK. THE VERTICAL PROFILE THEN STEADILY
SATURATES...AS A WARM FRONT LIFTS NORTHWARD AND A COMPLEX LOW
SYSTEM MOVES INTO THE REGION. RAIN IS EXPECTED TO IMPACT KCHS
LATER THIS MORNING...SINCE NORTHERN AND INLAND AREAS WILL BE
CLOSEST TO THE LIFTING WARM FRONT. SOUTHEAST GEORGIA COULD REMAIN
WITHIN A TEMPORARY DRY SLOT INTO THE AFTERNOON HOURS...AND HAVE
DELAYED MENTION OF VCSH AND -RA UNTIL 18Z ACCORDINGLY. RAIN WILL
THEN INCREASE IN COVERAGE AHEAD OF THE LOW PRESSURE SYSTEM LATE
TODAY THROUGH THE NIGHTTIME HOURS...WITH AT LEAST MVFR CEILINGS
AND VISIBILITIES POSSIBLE AT BOTH TERMINALS FROM LATE AFTERNOON
THROUGH THE REMAINDER OF THE TAF PERIOD. SOUTHERLY WINDS COULD
BECOME BREEZY/GUSTY AT TIMES LATER TODAY INTO THE EVENING
HOURS...AS A STRONG LOW LEVEL JET MOVES ACROSS THE SOUTHEAST
STATES.

EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIGS/VSBYS ARE LIKELY
INTO EARLY TUESDAY WITH SHOWERS AND LOW CLOUDS ASSOCIATED WITH A
WEDGE OF HIGH PRESSURE BUILDING FROM THE NORTH AND A LOW PRESSURE
SYSTEM SHIFTING OVER THE AREA. VFR CONDITIONS SHOULD THEN RETURN
AT BOTH TERMINALS BY TUESDAY AFTERNOON AND PERSIST INTO THE MIDDLE
OF NEXT WEEK.

&&

.MARINE...
WINDS/SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH
EARLY TODAY...AS HIGH PRESSURE LINGERS OVER THE WATERS.
WINDS/SEAS WILL THEN INCREASE/BUILD THIS AFTERNOON INTO EARLY
MONDAY...AS A DEEPENING LOW PRESSURE SYSTEM APPROACHES FROM THE
WEST AND SHIFTS OFF THE SOUTHEAST COAST. MARINE ZONES COULD SEE
A PERIOD OF MARGINAL SMALL CRAFT ADVISORY LEVEL CONDITIONS OVER
MOST WATERS BEYOND 10 NM FROM THE COAST LATE TODAY AND INTO
TONIGHT...AS A POTENT LOW LVL JET SHIFTS OFFSHORE AHEAD OF THE
SYSTEM. 6 FT SEAS COULD LINGER OVER NORTHERN SC WATERS AND OUTER
GEORGIA WATERS INTO MONDAY...AS A WEDGE OF HIGH PRESSURE BUILDS
FROM THE NORTH AND WINDS BECOME NORTHERLY ALONG THE BACK EDGE OF
THE DEPARTING LOW PRESSURE SYSTEM. SMALL CRAFT ADVISORIES HAVE
BEEN ISSUED FOR ALL COASTAL WATERS AS A RESULT. CONDITIONS SHOULD
THEN IMPROVE BY TUESDAY AS HIGH PRESSURE SETTLES OVER THE WATERS
THROUGH MID WEEK.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT MONDAY
     FOR AMZ352-354.
     SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 6 AM EDT
     TUESDAY FOR AMZ374.
     SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO NOON EDT MONDAY
     FOR AMZ350.

&&

$$

NEAR TERM...WMS
SHORT TERM...JAQ
LONG TERM...JAQ/DPB
AVIATION...WMS/
MARINE...WMS/JAQ