Area Forecast Discussion
Issued by NWS Charleston, SC

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000 FXUS62 KCHS 230152 AFDCHS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 952 PM EDT FRI AUG 22 2014 .SYNOPSIS... THE REGION WILL REMAIN BETWEEN ATLANTIC HIGH PRESSURE AND AN INLAND TROUGH OF LOW PRESSURE THROUGH TONIGHT. A BACKDOOR COLD FRONT WILL PUSH SOUTH THROUGH THE AREA SATURDAY EVENING INTO SUNDAY FOLLOWED BY COOLER AND DRIER HIGH PRESSURE THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... OVERNIGHT...THE REGION WILL REMAIN UNDER THE EXPANSIVE UPPER RIDGE. AT THE SURFACE...THE INLAND TROUGH OF LOW PRESSURE WILL DRIFT A BIT CLOSER TO THE COAST AS THE OFFSHORE HIGH PRESSURE IS NUDGED BACK TO THE EAST. A DRY FORECAST REMAINS IN PLACE. A FEW OF THE MODELS TRY TO SQUEEZE OUT ISOLATED SHOWERS LATE...BUT THIS SEEMS UNLIKELY GIVEN THE LACK OF ANY FORCING AND MID LEVEL SUBSIDENCE SEEN ON 00Z SOUNDINGS. THEREFORE THE FORECAST REMAINS ON TRACK WITH MOSTLY CLEAR SKIES ONCE AGAIN FOR WHAT SHOULD BE ANOTHER WARM AND MUGGY NIGHT. LOOK FOR LOWS IN THE MID/UPPER 70S ACROSS MOST AREAS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY...HOT AND HUMID CONDITIONS WILL PERSIST AHEAD OF A BACKDOOR COLD FRONT APPROACHING THE REGION FROM THE NORTH THIS WEEKEND. 1000-850 MB THICKNESS VALUES SUGGEST ANOTHER DAY OF NEAR RECORD TEMPS SATURDAY AFTERNOON...WITH HIGHS PEAKING IN THE UPPER 90S AWAY FROM THE COAST. WE COULD SEE A FEW LOCATIONS HIT 100 DEGREES WEST OF INTERSTATE 95 IN SOUTHEAST GEORGIA AS COMPRESSIONAL HEATING AND A WEST/NORTHWEST WIND OCCURS AHEAD OF THE APPROACHING FRONT. DESPITE SOME MIXING OUT OF MID 70 DEW POINTS DURING AFTERNOON HOURS...HEAT INDEX VALUES SHOULD APPROACH 105-110 DEGREES OVER MOST LOCATIONS AND A HEAT ADVISORY SHOULD ONCE AGAIN BE NEEDED DURING AFTERNOON HOURS. LITTLE RELIEF WILL BE IN THE WAY OF THE HEAT AS LATEST MODEL SOUNDINGS INDICATE MOISTURE WILL REMAIN FAIRLY SHALLOW BEFORE FROPA. HAVE MAINTAINED NO MORE THAN 20 POPS OVER THE REGION SATURDAY AFTERNOON AND WITH THE TIMING OF THE FRONT OCCURRING MAINLY DURING EVENING AND OVERNIGHT HOURS SATURDAY NIGHT...SHOWER/THUNDERSTORM COVERAGE SHOULD REMAIN LIMITED. SATURDAY NIGHT LOWS WILL BE MILD AHEAD OF FROPA...IN THE MID TO UPPER 70S AWAY FROM THE COAST. SUNDAY...THE BACKDOOR COLD FRONT WILL CONTINUE PUSHING SOUTH THROUGH SOUTHEAST GEORGIA EARLY WITH COOLER HIGH PRESSURE BUILDING OVER THE AREA FROM THE NORTH. A SOMEWHAT BREEZY NORTHEAST FLOW SHOULD OCCUR...ESPECIALLY NEAR THE COAST. CHANCES OF SHOWERS/THUNDERSTORMS WILL REMAIN IN THE FORECAST THROUGHOUT THE DAY...WITH THE HIGHEST CHANCES IN SOUTHEAST GEORGIA EARLY AND NEAR THE VICINITY OF THE FRONT. WITH THE FRONT SHIFTING FURTHER SOUTH BY THE EVENING...WE SHOULD SEE A FAIRLY DECENT TEMPERATURE GRADIENT OVER THE FORECAST AREA...WITH AFTERNOON HIGH TEMPS IN THE UPPER 80S TO AROUND 90 IN SOUTHEAST SOUTH CAROLINA TO LOW/MID 90S IN SOUTHEAST GEORGIA. HEAT INDEX VALUES COULD STILL BE NEAR 105 DEGREES ACROSS SOUTHEAST GEORGIA BEFORE SUNSET. PRECIP CHANCES WILL LOWER CONSIDERABLY BY SUNDAY NIGHT AS DRYER AIR PUSHES INTO THE AREA FROM THE NORTH. OVERNIGHT LOWS SHOULD RANGE IN THE UPPER 60S WELL INLAND TO MID/UPPER 70S OVER SOUTHERN AREAS. MONDAY...QUIET AND NOTICEABLY COOLER CONDITIONS WILL OCCUR OVER THE SOUTHEAST AS DRY HIGH PRESSURE AND NORTHEAST FLOW PERSISTS BEHIND THE FRONT TO OUR SOUTH. HAVE KEPT MAINLY A DRY FORECAST IN PLACE...WITH THE EXCEPTION OF A POSSIBLE SHOWER OR TWO ALONG THE COAST IN SOUTHEAST GEORGIA. OVERALL HIGH TEMPS SHOULD RANGE IN THE MID TO UPPER 80S OVER MOST AREAS...WITH A FEW TEMPS AROUND 90 AWAY FROM THE COAST IN SOUTHEAST GEORGIA. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... HIGH PRESSURE LOOKS TO REMAIN IN CONTROL INLAND THROUGH MID WEEK. LOW PRESSURE...POSSIBLY A WEAK TROPICAL CYCLONE...SHOULD REMAIN WELL OFFSHORE. THE MAIN INFLUENCE ON OUR WEATHER WILL BE SLIGHTLY HIGHER WINDS...ESPECIALLY ALONG THE COAST. THERE COULD BE A FEW SHOWERS FROM TIME TO TIME...AGAIN MOSTLY NEAR THE COAST. ANOTHER COLD FRONT LOOKS TO APPROACH LATE IN THE WEEK ALTHOUGH THERE IS SOME UNCERTAINTY REGARDING MOISTURE LEVELS AND THUS RAIN CHANCES. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 00Z SUNDAY. ISOLATED TSTMS ARE POSSIBLE LATE IN THE TAF PERIOD AT KCHS...MAINLY 22Z TO 00Z SUNDAY. EXTENDED AVIATION OUTLOOK...EXTENDED AVIATION OUTLOOK...MVFR CIGS/VSBYS ARE THEN POSSIBLE SATURDAY EVENING INTO SUNDAY AT EITHER TERMINAL AS A BACKDOOR COLD FRONT ADVANCES THROUGH THE AREA. VFR CONDITIONS SHOULD THEN PREVAIL SUNDAY EVENING THROUGH TUESDAY...BUT IT COULD BE BREEZY EACH AFTERNOON AS NORTHEAST WINDS DEVELOP BEHIND THE PASSING COLD FRONT. && .MARINE... OVERNIGHT...THE LOCAL WATERS WILL REMAIN WITHIN A SOUTHWEST GRADIENT BETWEEN AN INLAND TROUGH OF LOW PRESSURE AND HIGH PRESSURE TO THE EAST. THE TROUGH WILL DRIFT A BIT CLOSER TO THE COAST AND THE TIGHTER PRESSURE GRADIENT WILL RESULT IN A MODEST NOCTURNAL WIND INCREASE INTO THE 10-15 KT RANGE. SEAS WILL BE 1-2 FT WITHIN 20 NM AND 2-3 FT CLOSER TO THE GULF STREAM. SATURDAY THROUGH WEDNESDAY...CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY THRESHOLDS THROUGH EARLY SUNDAY. WINDS/SEAS SHOULD THEN DETERIORATE LATER SUNDAY WHEN NORTHEAST WINDS INCREASE WITHIN HIGH PRESSURE BUILDING FROM THE NORTH BEHIND A COLD FRONT SHIFTING SOUTH. SMALL CRAFT ADVISORIES COULD BE NEEDED OVER WATERS NORTHERN SC WATERS AND OFFSHORE GEORGIA WATERS BY SUNDAY NIGHT AND THEN POSSIBLY IN REMAINING NEARSHORE WATERS BY DAYBREAK MONDAY. SEAS SHOULD ALSO BUILD AS HIGH AS 5-7 FT...LARGEST OVER OFFSHORE GEORGIA WATERS. CONDITIONS LOOK TO IMPROVE BELOW ADVISORY LEVELS WITHIN 20 NM TUESDAY NIGHT AND WEDNESDAY IN THE 20-60 NM GA ZONE. THE BRISK NORTHEAST WINDS WILL ALSO CAUSE AN INCREASE IN TIDE LEVELS ABOVE THE NORMAL ASTRONOMICAL TIDE...POSSIBLY REACHING CLOSE TO ADVISORY LEVELS DURING THE EVENING HIGH TIDE CYCLES THROUGH EARLY WEEK. LOW PRESSURE NEAR THE BAHAMAS COULD POSSIBLY BECOME A WEAK TROPICAL CYCLONE SUNDAY/MONDAY...BUT SHOULD REMAIN WELL EAST OF THE AREA. HOWEVER...MARINERS ARE URGED TO PAY CLOSE ATTENTION TO THE LATEST FORECASTS. && .CLIMATE... RECORD MAX TEMPS... KSAV HIT 100 DEGREES TODAY...THE FIRST TIME SINCE JULY 26 2012. SAT 8/23... KCHS...........98 SET IN 1983 KCXM...........97 SET IN 1987 KSAV...........99 SET IN 1987 LAST TIME 100 DEGREES OR HIGHER... KCHS..........JUNE 21 2011 KCXM..........JUNE 20 2011 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ NEAR TERM... SHORT TERM...DPB LONG TERM...RJB AVIATION... MARINE... CLIMATE...

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