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000
FXUS62 KCHS 150746
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
346 AM EDT SAT JUN 15 2013

.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY AND SHIFT
OFFSHORE TONIGHT. A COLD FRONT WILL APPROACH FROM THE NORTHWEST
BY THE MIDDLE OF NEXT WEEK AND POSSIBLY STALL OVER THE REGION LATE
IN THE WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
DEEP LAYERED HIGH PRESSURE WILL EXTEND ACROSS THE REGION TODAY.
EXPECT A RATHER PLEASANT DAY FOR MID-JUNE WITH A NOTICEABLE
ABSENCE OF OPPRESSIVE LEVELS OF HUMIDITY...SIMILAR TO FRIDAY.
SUNNY SKIES AND A SLIGHT INCREASE IN LOW-LEVEL THICKNESSES WILL
SUPPORT HIGHS IN THE UPPER 80S TO LOWER 90S WITH WARMEST READINGS
OCCURRING WELL INLAND. THERE COULD BE A FEW PATCHES OF CUMULUS
HUMILIS THAT DEVELOP AHEAD OF THE PURE SEA BREEZE CIRCULATION OR
THE OCCASIONAL HIGH CIRRUS ELEMENT PASSING THROUGH ALOFT...BUT
SKIES WILL GENERALLY BE SUNNY THROUGH SUNSET.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
TONIGHT...THE SYNOPTIC PATTERN WILL CHANGE LITTLE TONIGHT EXCEPT
THE SURFACE HIGH WILL SHIFT OFFSHORE INTO THE WESTERN ATLANTIC.
ITS INFLUENCE WILL STILL BE FELT...HOWEVER DEWPOINTS WILL BEGIN TO
CREEP UP AS THE LOW-LEVEL FLOW BECOMES MORE SOUTHERLY. SKIES WILL
REMAIN CLEAR AND THE BOUNDARY LAYER LOOKS TO DECOUPLE EARLY ONCE
AGAIN SO DECENT RADIATIONAL CONDITIONS WILL OCCUR ONCE AGAIN...
ESPECIALLY INLAND. LOWS WILL RANGE FROM THE MID 60S WELL INLAND TO
THE LOWER 70S AT THE BEACHES.

SUNDAY...SURFACE HIGH PRESSURE WILL SLIP INTO THE NEARBY
ATLANTIC...WHILE UPPER RIDGING LINGERS TO THE SOUTH. AS A
RESULT...EXPECT RATHER QUIET WEATHER TO CONTINUE FOR AT LEAST ONE
MORE DAY. A DECENT CAPPING INVERSION IS APPARENT IN FORECAST MODEL
SOUNDINGS...SUGGESTING THAT LARGE SCALE SUBSIDENCE WILL EFFECTIVELY
SUPPRESS CONVECTIVE INITIATION AGAIN ON SUNDAY. WILL MAINTAIN
ZERO RAIN CHANCES DURING THE DAYTIME HOURS...ONLY INCREASING POPS
UP TO 10 PERCENT OVERNIGHT WITH A SURFACE TROUGH DEVELOPING
UPSTREAM. HIGH TEMPERATURES WILL REACH THE UPPER 80S TO AROUND 90
DEGREES AWAY FROM THE LOCALLY COOLER COASTLINE...RIGHT AROUND
SEASONAL NORMALS FOR MID JUNE.

MONDAY...THE LATEST RUNS OF THE GFS AND ECMWF MODELS ACTUALLY
HAVE RATHER SIGNIFICANT DISAGREEMENT IN REGARDS TO THE
TRANSITIONING PATTERN AT THE SURFACE AND ALOFT. BOTH MODELS
INDICATE THE DEEP LAYER RIDGE BREAKING DOWN AHEAD OF SHORTWAVE
ENERGY APPROACHING FROM THE WEST...WHILE THE GFS AGGRESSIVELY
DEVELOPS A RATHER INTENSE LOW SYSTEM TRACKING INTO THE OHIO VALLEY
MONDAY NIGHT. PREFER TO LEAN TOWARD THE MORE CONSERVATIVE ECMWF
SOLUTION...WHICH DEPICTS MORE MODEST SHORTWAVE ENERGY SUPPORTING
THE DEVELOPMENT OF A SURFACE TROUGH JUST UPSTREAM. DESPITE THE
DIFFERENCES...BOTH MODELS DO AGREE THAT CONVECTIVE DEVELOPMENT
WILL RESUME MONDAY WITH THE REDUCTION IN SUBSIDENCE AND CAPPING.
HAVE ADVERTISED THUNDERSTORM CHANCES INCREASING INTO THE 30
PERCENT RANGE BY THE AFTERNOON HOURS...MAINTAINING SLIGHT CHANCE
OVERNIGHT GIVEN SOME SYNOPTIC LEVEL SUPPORT BEYOND THE WANING
DIURNAL HEATING/INSTABILITY. HIGH TEMPERATURES WILL CHANGE LITTLE
FROM THE PREVIOUS DAY...PEAKING IN THE UPPER 80S TO AROUND 90
DEGREES INLAND.

TUESDAY...MODEL DISCREPANCIES CONTINUE REGARDING THE INTENSITY OF
LOW PRESSURE DEVELOPING ALONG A COLD FRONT SHIFTING INTO THE AREA
FROM THE WEST/NORTHWEST. LATEST GUIDANCE KEEPS THE COLD FRONT JUST
OUTSIDE OF THE FORECAST AREA THROUGH TUESDAY NIGHT...WITH BEST
THUNDERSTORM POTENTIAL JUST UPSTREAM DURING THE DAYTIME HOURS
AND TRANSITIONING EASTWARD LATE. HAVE INDICATED RAIN CHANCES
INCREASING FROM NORTHWEST TO SOUTHEAST AS THE DAY
PROGRESSES...PEAKING AT AROUND 40 PERCENT DUE TO DECENT MODEL
AGREEMENT IN COVERAGE. TEMPERATURES COULD TREND A DEGREE OR TWO
HIGHER...REACHING THE LOWER 90S AWAY FROM THE COAST WITHIN THE
SUBTLE WARMING EFFECTS OF PRE-FRONTAL COMPRESSION.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
ONCE THE MAIN WAVE OF LOW PRESSURE PULLS NORTHEAST OF THE REGION
TUESDAY NIGHT INTO WEDNESDAY...THE WEAK COLD FRONT WILL BECOME
PARALLEL TO THE FLOW ALOFT AND LIKELY STALL OVER THE FORECAST
AREA. WITH A BROAD UPPER TROUGH IN PLACE FOR MUCH OF THE REMAINING
EXTENDED PERIOD...THE FRONT COULD LINGER ALONG THE SOUTHEAST
COASTLINE INTO AT LEAST LATE WEEK. ALTHOUGH DETAILS ARE STILL
UNCERTAIN THIS FAR IN ADVANCE...HAVE MAINTAINED SOLID THUNDERSTORM
CHANCES DURING THE DAYLIGHT HOURS EACH AFTERNOON...WITH SOME
REDUCTION IN COVERAGE DURING THE CLIMATOLOGICALLY UNFAVORED
NOCTURNAL PERIODS. HIGH TEMPERATURES EACH DAY ARE EXPECTED TO
REMAIN WITHIN A DEGREE OR TWO OF SEASONAL NORMALS...REACHING THE
UPPER 80S TO AROUND 90 DEGREES AWAY FROM THE LOCALLY COOLER
COASTLINE.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
VFR.

EXTENDED AVIATION...NO CONCERNS.

&&

.MARINE...
TODAY...EAST TO NORTHEAST WINDS WILL GRADUALLY VEER SOUTHEAST
TODAY AS HIGH PRESSURE BEGINS TO SHIFT OFF THE COAST. THERE COULD
BE A SMALL ENHANCEMENT TO THE LOW-LEVEL WIND FIELD AS THE SEA
BREEZE CIRCULATION TAKES HOLD...BUT NO SIGNIFICANT WIND SURGE IS
EXPECTED. WINDS WILL GENERALLY REMAIN 10-15 KT WITH SEAS 2-4 FT.

TONIGHT...SOUTHERLY FLOW REGIME WILL DOMINATE THE LOCAL MARINE
AREA AS HIGH PRESSURE SHIFTS FARTHER OFFSHORE INTO THE WESTERN
ATLANTIC. WINDS WILL AVERAGE 10-15 KT WITH SEAS 2-4 FT.

SUNDAY THROUGH WEDNESDAY...SOUTHERLY WINDS WILL GENERALLY PREVAIL
THROUGH THE PERIOD...AS THE COASTAL WATERS BECOME LOCATED BETWEEN
ATLANTIC HIGH PRESSURE AND AN INLAND TROUGH OF LOW PRESSURE. WIND
SPEEDS WILL BE 15 KT OR LESS SUNDAY AND MONDAY...EXCEPT FOR A FEW
HIGHER GUSTS ALONG THE COAST AND IN CHARLESTON HARBOR WHEN THE
SEABREEZE PUSHES INLAND EACH AFTERNOON. THE PRESSURE GRADIENT
COULD TIGHTEN UP AS A WAVE OF LOW PRESSURE TRACKS ALONG AN
APPROACHING FRONT...POSSIBLY SUPPORTING 15 TO 20 KT WINDS ON
TUESDAY. SPEEDS WILL DIMINISH AGAIN BY WEDNESDAY AS THE FRONT
STALLS OVER THE SOUTHEAST COASTLINE. WINDS AND SEAS ARE EXPECTED
TO REMAIN BELOW SMALL CRAFT ADVISORY CONDITIONS.

&&

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

&&

$$

ST/WMS