Area Forecast Discussion Issued by NWS Charleston, SC
000
FXUS62 KCHS 141537
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1137 AM EDT FRI JUN 14 2013
.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE WEEKEND AND PERSIST INTO EARLY
NEXT WEEK. A COLD FRONT WILL APPROACH FROM THE NORTHWEST BY THE
MIDDLE OF NEXT WEEK AND POSSIBLY STALL OVER THE REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
DEW POINTS HAVE DROPPED A LITTLE FASTER THAN ORIGINALLY THOUGHT
WITH UPPER 50S IN MOST AREAS. AS WINDS CONTINUE TO SHIFT TO A MORE
NORTHERLY DIRECTION...THEY WILL CONTINUE TO DROP BRINGING A STARK
CONTRAST TO THE HEAT WE FELT YESTERDAY. DROPPED PRECIP ALTOGETHER
EXCEPT OVER THE OUTER GA WATERS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
TONIGHT...HIGH PRESSURE WILL BUILD STEADILY SOUTH INTO THE AREA
TONIGHT AS UPPER RIDGING TAKES HOLD ALOFT. CLEAR SKIES...LIGHT
WINDS AND FAIRLY LOW DEWPOINTS WILL PROMOTE MODEST RADIATIONAL
CONDITIONS YIELDING SOME FAIRLY COOL LOWS COMPARED TO WHAT HAS
BEEN OBSERVED OF LATE. LOWS WILL RANGE FROM THE LOWER 60S WELL
INLAND TO THE LOWER 70S AT THE BEACHES WHERE INFLUENCES FROM THE
WARMER ATLANTIC WATERS AND WEAK ONSHORE FLOW WILL HELP KEEP
TEMPERATURES SOMEWHAT ELEVATED.
SATURDAY AND SUNDAY...SURFACE HIGH PRESSURE WILL STEADILY DESCEND
INTO THE REGION FROM THE NORTHWEST AND SETTLE INTO THE ATLANTIC OVER
THE WEEKEND...WHILE UPPER LEVEL RIDGING BUILDS INTO THE SOUTHEAST
STATES. THIS PATTERN WILL SUPPORT LARGE SCALE SUBSIDENCE THAT WILL
EFFECTIVELY SUPPRESS CONVECTIVE DEVELOPMENT SATURDAY AND SUNDAY
ACROSS THE FORECAST AREA. HAVE THUS INDICATED ZERO RAIN CHANCES BOTH
DAYS UNDER MOSTLY CLEAR TO PARTLY CLOUDY SKIES. THICKNESS VALUES
AGREE FAIRLY WELL WITH MODEL GUIDANCE REGARDING HIGH
TEMPERATURES...AND EXPECT TEMPERATURES TO PEAK IN THE UPPER 80S TO
AROUND 90 DEGREES AWAY FROM THE LOCALLY COOLER COASTLINE.
MONDAY...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL BEGIN TO
RETREAT AS THE DAY PROGRESSES...AHEAD OF SHORTWAVE ENERGY AND AN
ASSOCIATED SURFACE TROUGH APPROACHING FROM THE WEST. WILL
REINTRODUCE A SLIGHT CHANCE OF THUNDERSTORMS MAINLY ACROSS INLAND
AREAS...DUE TO UPSTREAM ACTIVITY POTENTIALLY SLIPPING INTO THE
WESTERN ZONES. THE MAJORITY OF THE FORECAST AREA COULD REMAIN
UNDER RESIDUAL CAPPING DURING THE DAYTIME HOURS. HIGH TEMPERATURES
WILL REACH THE UPPER 80S TO LOWER 90S WITHIN INCREASING WARM
SOUTHERLY FLOW.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THE PATTERN WILL BECOME MORE UNSETTLED EARLY NEXT WEEK AND THROUGH
MUCH OF THE EXTENDED FORECAST PERIOD. MEDIUM RANGE FORECAST
MODELS SUGGEST THAT A BROAD UPPER TROUGH DEVELOPING OVER THE EAST
COAST STATES WILL ALLOW A SERIES OF SHORTWAVES TO MOVE THROUGH THE
REGION...SUPPORTING THE EVENTUAL PROGRESSION OF A BACKDOOR COLD
FRONT INTO THE AREA BY THE MIDDLE OF NEXT WEEK. THE FRONT COULD
STALL OVER THE FORECAST AREA AS IT BECOMES MORE PARALLEL TO FLOW
ALOFT WEDNESDAY AND THURSDAY. IF THIS SCENARIO OCCURS...THEN
THUNDERSTORM POTENTIAL WILL INCREASE FROM SLIGHT CHANCE MONDAY
NIGHT AND EARLY TUESDAY INTO PERSISTENT 30 TO 40 PERCENT CHANCES
FROM LATER TUESDAY THROUGH AT LEAST THURSDAY. PREFERRED TO REMAIN
SOMEWHAT GENERIC THIS FAR IN ADVANCE...AND WILL REFINE DETAILS AS
MODEL SOLUTIONS COME INTO BETTER AGREEMENT. HIGH TEMPERATURES WILL
RANGE FROM THE UPPER 80S TO THE LOWER 90S AWAY FROM THE LOCALLY
COOLER COASTLINE EACH AFTERNOON.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
VFR.
EXTENDED AVIATION...NO CONCERNS.
&&
.MARINE...
BOTH WINDS AND SEAS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT
ADVISORY CRITERIA.
TONIGHT...EAST TO NORTHEAST WINDS WILL DOMINATE THROUGH TONIGHT
WITH BOTH WINDS AND SEAS REMAINING WELL BELOW ADVISORY THRESHOLDS.
SATURDAY THROUGH TUESDAY...BENIGN CONDITIONS ARE EXPECTED OVER
ALL COASTAL WATERS THROUGH THE WEEKEND...AS ATLANTIC HIGH PRESSURE
BUILDS BEHIND A COLD FRONT SHIFTING FAR OUT TO SEA. WINDS WILL
QUICKLY VEER FROM EAST TO SOUTHEAST ON SATURDAY...BECOMING
PREVAILING SOUTH/SOUTHEAST THROUGH EARLY NEXT WEEK. WINDS AND SEAS
WILL THEN STEADILY INCREASE/BUILD OVER ALL WATERS BY LATE
MONDAY...AS THE PRESSURE GRADIENT TIGHTENS BETWEEN LOW PRESSURE
ADVANCING TO THE NORTHEASTERN UNITED STATES AND HIGH PRESSURE OVER
THE WESTERN ATLANTIC. CONDITIONS SHOULD STILL REMAIN BELOW SMALL
CRAFT ADVISORY LEVELS THROUGH THE PERIOD...WITH WINDS PEAKING
BETWEEN 15 TO 20 KT AND SEAS UP TO 4 TO 5 FT...HIGHEST BEYOND 10
NM FROM THE COAST.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...BDC/ST
SHORT TERM...ST/WMS
LONG TERM...WMS
AVIATION...BDC/ST
MARINE...BDC/ST/WMS