892
FXUS62 KCHS 181956
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
356 PM EDT WED SEP 18 2019
SYNOPSIS
HIGH PRESSURE WILL PROVIDE NOTICEABLY COOLER AND DRIER
CONDITIONS THROUGH LATE WEEK AND WILL PREVAIL THROUGH EARLY
NEXT WEEK. A COLD FRONT COULD PUSH INTO THE REGION AROUND THE
MIDDLE OF NEXT WEEK.
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
THIS EVENING AND TONIGHT: HIGH PRESSURE WILL BUILD ACROSS THE REGION
IN WAKE OF A COLD FRONT SHIFTING SOUTH OF THE AREA. HOWEVER, FEW TO
SCATTERED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM IS POSSIBLE,
MAINLY ACROSS PARTS OF SOUTHEAST GEORGIA WHERE MLCAPE AROUND
1500 J/KG AND PWATS BETWEEN 1.6-1.8 INCHES REMAIN. EXPECT THE
BULK OF PRECIP ACTIVITY TO WANE THIS EVENING, THEN DISSIPATE
AROUND SUNSET DUE TO THE LOSS OF DAYTIME HEATING. FEW TO SCATTERED
CLOUDS SHOULD THEN CLEAR ACROSS THE AREA FROM NORTH TO SOUTH
DURING THE FIRST HALF OF THE NIGHT. WEAK COLD AIR ADVECTION
ASSOCIATED WITH DRY HIGH PRESSURE BUILDING ACROSS THE AREA SHOULD
HELP MAINTAIN A 5-10 MPH NORTHEAST WIND OVERNIGHT. HOWEVER,
COLD AIR ADVECTION AND DRIER AIR WILL LIKELY SUPPORT COOLER
TEMPS, WITH LOWS EVENTUALLY DIPPING INTO THE UPPER 50S TO AROUND
60 WELL INLAND (COOLEST IN SOUTHEAST SOUTH CAROLINA) AND
MID/UPPER 60S NEAR THE COAST.
SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/
COOLER/DRIER HIGH PRESSURE WILL PREVAIL THROUGH THIS PERIOD. THE
ONLY WRINKLE WILL BE FOR ISOLATED/SCATTERED SHOWERS WHICH WILL CROSS
COASTAL WATERS AND DEVELOP ONSHORE WITHIN AN E/NE LOW-LEVEL FLOW
REGIME. SLIGHT CHANCE POPS ARE LIMITED TO FAR SOUTHERN/COASTAL
COUNTIES THROUGH THURSDAY, THEN COVERAGE OF SLIGHT CHANCE/CHANCE
POPS EXPANDS SOMEWHAT LATER THURSDAY NIGHT THROUGH FRIDAY AS A
COASTAL TROUGH BECOMES MORE PRONOUNCED, WITH HIGHEST POPS ACROSS
SOUTHERN/COASTAL COUNTIES. LIMITED INSTABILITY DOES NOT JUSTIFY ANY
MENTION OF THUNDERSTORMS THROUGH THIS PERIOD. FRIDAY NIGHT THROUGH
SATURDAY, GUIDANCE SUGGESTS THAT THE SURFACE HIGH WILL EXPAND AND
WILL PUSH THE CHANCE FOR SHOWERS SOUTH OF THE REGION.
OTHERWISE, HIGH TEMPERATURES IN THE UPPER 70S NORTH AND LOWER TO MID
80S SOUTH WILL WARM INTO THE MIDDLE/UPPER 80S SATURDAY AWAY FROM THE
BEACHES. THURSDAY NIGHT, LOW TEMPERATURES WILL AVERAGE 55-60F AWAY
FROM T HE COAST AND 65-70F ON THE BEACHES. LATE FRIDAY NIGHT,
TEMPERATURES WILL FALL INTO THE UPPER 50S TO MIDDLE 60S INLAND AND
WILL BOTTOM OUT IN THE UPPER 60S TO MIDDLE 70S ON THE COAST. THE
MOST NOTICEABLE CHANGE WILL BE THE DRIER AIR MASS FEATURING DAYTIME
DEWPOINTS IN THE 50S/60S THROUGH THIS PERIOD.
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
DEEP LAYERED RIDGING WILL PERSIST INTO MONDAY AND THEN TEND TO BREAK
DOWN THEREAFTER. MODELS HINT AT A WEAK FRONT AND STRONGER NORTHWEST
FLOW ALOFT BY MID-WEEK, HOWEVER THE DEPTH OF DRY-LAYERED AIR WAS
STILL ENOUGH TO KEEP MENTIONABLE POPS OUT OF THE FORECAST. TEMPS ARE
EXPECTED TO RUN ABOVE CLIMO EACH DAY WITH A RETURN TO SOME 90 DEGREE
HIGH TEMPS EARLY NEXT WEEK INLAND AND SOUTHERN ZONES.
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
A FEW SHOWERS COULD POTENTIALLY BRING BRIEF MVFR CONDITIONS AT THE
SAV TERMINAL LATE THIS AFTERNOON INTO EARLY EVENING. OTHERWISE,
VFR CONDITIONS ARE EXPECTED AT BOTH CHS AND SAV TERMINALS
THROUGH 18Z THURSDAY. NORTHEAST WINDS COULD GUST TO 15-20 KT
NEAR 18Z THURSDAY.
EXTENDED AVIATION OUTLOOK: VFR CONDITIONS WILL PREVAIL.
MARINE
THIS EVENING AND TONIGHT: HIGH PRESSURE WILL BUILD ACROSS COASTAL
WATERS THROUGH TONIGHT BEHIND A DEPARTING COLD FRONT TO THE SOUTH. A
FAIR AMOUNT OF COLD AIR ADVECTION ASSOCIATED WITH A NORTHEAST WIND
ALONG WITH LONG PERIOD SWELLS NEAR 11 SECONDS WILL RESULT IN ONGOING
SMALL CRAFT ADVISORIES FOR ALL WATERS OUTSIDE THE CHARLESTON HARBOR
THROUGH TONIGHT. SOME GUIDANCE SUGGESTS WINDS COULD INCREASE TOWARD
DAYBREAK THURSDAY, NECESSITATING A SMALL CRAFT ADVISORY IN THE
CHARLESTON HARBOR. IN GENERAL, NORTHEAST WINDS WILL GUST TO
20-25 KTS WHILE SEAS BUILD UP TO 5-7 FT IN NEARSHORE WATERS AND
7-10 FT IN OFFSHORE GEORGIA WATERS.
A TIGHT NORTHEAST GRADIENT ENHANCED BY HIGH PRESSURE CENTERED NORTH
OF THE WATERS WILL MAINTAIN HAZARDOUS WINDS/SEAS THROUGH FRIDAY.
NORTHEAST WINDS AVERAGING 20-25 KNOTS WITH GUSTS TO 30 KNOTS WILL
CONTRIBUTE TO COMBINED SEAS TOPPING OUT AT 5-8 FEET NEARSHORE WATERS
AND 8-12 FEET BEYOND 20 NM, WITH WORST CONDITIONS THURSDAY THROUGH
THURSDAY NIGHT. SMALL CRAFT ADVISORIES ARE IN EFFECT FOR ALL WATERS
OUTSIDE CHARLESTON HARBOR, AND WIND GUSTS COULD APPROACH SCA LEVELS
EVEN ON THE HARBOR THURSDAY.
FRIDAY AND ESPECIALLY FRIDAY NIGHT, THE PRESSURE GRADIENT/
ASSOCIATED WINDS WILL RELAX. WHILE SCA SEAS COULD PERSIST INTO THE
WEEKEND OVER THE OUTER GA WATERS, OVERALL WE CAN EXPECT A MUCH MORE
TRANQUIL REGIME THIS WEEKEND INTO EARLY NEXT WEEK. LONG PERIOD SWELL
CREATED BY OFFSHORE TC JERRY COULD REACH COASTAL WATERS BY EARLY
NEXT WEEK.
RIP CURRENTS: HIGH RISK OF RIP CURRENTS ON ALL BEACHES THROUGH
THURSDAY EVENING DUE TO STRONG NORTHEAST WINDS AND AT LEAST A
2-3 FT/11 SECOND PERIOD SWELL CREATED BY OFFSHORE HURRICANE
HUMBERTO. AN ELEVATED RISK FOR RIP CURRENTS WILL THEN CONTINUE
THROUGH AT LEAST THE END OF THIS WEEK.
TIDES/COASTAL FLOODING
LOW CHANCES FOR MINOR SALT WATER FLOODING AROUND THE TIMES OF HIGH
TIDE THROUGH LATE WEEK, ESPECIALLY ALONG THE SOUTH CAROLINA COAST.
CHS WATCHES/WARNINGS/ADVISORIES
GA...HIGH RIP CURRENT RISK THROUGH THURSDAY EVENING FOR GAZ117-119-
139-141.
SC...HIGH RIP CURRENT RISK THROUGH THURSDAY EVENING FOR SCZ048>051.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR AMZ350-352-354.
SMALL CRAFT ADVISORY UNTIL 4 AM EDT SUNDAY FOR AMZ374.
NEAR TERM...DPB
SHORT TERM...SPR
LONG TERM...
AVIATION...DPB/SPR
MARINE...DPB/SPR
TIDES/COASTAL FLOODING...
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page