Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 062029
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
429 PM EDT FRI MAY 6 2016

.SYNOPSIS...
AN UPPER LEVEL LOW WILL BEGIN TO LIFT AWAY FROM THE AREA TONIGHT.
HIGH PRESSURE WILL PREVAIL SATURDAY THROUGH TUESDAY. A SERIES OF
WEAK FRONTAL SYSTEMS MAY AFFECT THE AREA MID TO LATE NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
THIS EVENING AND TONIGHT...A LARGE MID/UPPER LVL TROUGH OF LOW
PRESSURE WILL LINGER OVER THE EASTERN CONUS WITH ITS CENTER
POSITIONED OVER THE NORTHEASTERN UNITED STATES INTO THE OVERNIGHT
PERIOD. ALTHOUGH THE CORE OF THE LOW WILL GRADUALLY SHIFT NORTH AND
FURTHER AWAY FROM THE AREA...TEMPS NEAR -23C AT THE H5 LVL WILL
SUPPORT MID LVL LAPSE RATES NEAR 7.5 C/KM OVER THE SOUTHEASTERN
UNITED STATES. THESE RATES ALONG WITH MUCAPE BETWEEN 300-500 J/KG
AND PWATS NEAR 0.75 INCHES SHOULD SUPPORT A FEW SHOWERS AND PERHAPS
AN ISOLATED THUNDERSTORM CAPABLE OF PRODUCING SMALL HAIL AND/OR
GRAUPEL WITH FORCING THAT OCCURS ALONG THE SOUTHWEST EDGE OF THE
DEPARTING LOW ALOFT. CHANCES OF PRECIP WILL BE HIGHEST OVER
NORTHERN AREAS WHERE MARGINAL MOISTURE IS PRESENT THIS EVENING.
FURTHER SOUTH...ACTIVITY WILL BE LIMITED GIVEN CONSIDERABLE DRY
AIR ASSOCIATED WITH A DOWNSLOPING WEST/NORTHWEST WIND. EXPECT ALL
SHOWER ACTIVITY TO END AN HOUR OR TWO AFTER SUNSET THIS EVENING.

WEATHER CONDITIONS WILL BE QUIET TONIGHT AS THE UPPER LVL LOW
DEPARTS FURTHER TO OUR NORTH. RADIATIONAL COOLING UNDER CLEARING
SKIES WILL RESULT IN COOLER CONDITIONS AGAIN TONIGHT. LOWS SHOULD
DIP AROUND 50 DEGREES FOR MOST AREAS AWAY FROM THE COAST.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/...
SATURDAY...THE PERSISTENT UPPER LEVEL BLOCKING PATTERN AND THE
NEARLY STATIONARY UPPER LEVEL LOW OVER THE MID ATLANTIC WILL FINALLY
BEGIN LIFTING NORTHEASTWARD. AS THE UPPER LOW DEPARTS...IT WILL BE
REPLACED BY A BROAD/DEEP LAYER RIDGE FROM THE WEST. THERE MAY STILL
BE SOME WEAK UPPER IMPULSES MOVING AROUND THE BASE OF THE UPPER
TROUGH AS IT PULLS OUT...BUT DEEP LAYER MOISTURE NOT SUFFICIENT
ENOUGH TO WARRANT ANY MENTION OF POPS. HIGHS WILL MODERATE AS UPPER
HEIGHTS BEGIN TO RISE...LIKELY REACH THE LOWER 80S MOST AREAS. WITH
SURFACE DEWPOINTS IN THE MID TO UPPER 40S...IT WILL FEEL VERY
COMFORTABLE. BY SATURDAY NIGHT...THE SURFACE RIDGE WILL BE SOUTH AND
WEST OF THE AREA...WITH LIGHT WESTERLY WINDS ALL NIGHT. THIS WILL
KEEP TEMPERATURES FROM FALLING MUCH BELOW 60S MOST AREAS.

SUNDAY AND MONDAY...THE DEEP LAYER RIDGE WILL REMAIN CENTERED JUST
SOUTH OF THE AREA WITH LOW LEVEL SOUTHWEST FLOW. THIS WILL ALLOW
HIGH TEMPERATURES TO WARM DRAMATICALLY INTO THE UPPER 80S TO AROUND
90 MOST DAYS. WITH STILL RELATIVELY DRY LOW LEVELS IN PLACE...STILL
EXPECT LOWS TO GET BACK DOWN TO AROUND 60 SUNDAY NIGHT. NO
PRECIPITATION IS EXPECTED THROUGH THIS PERIOD.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
DEEP LAYERED RIDGING WILL PERSIST MONDAY NIGHT THROUGH TUESDAY
NIGHT...MAINTAINING DRY WEATHER AND ABOVE-NORMAL TEMPS. ON
WEDNESDAY SOME UPPER LEVEL VORTICITY ENERGY APPROACHES WESTERN
AREAS...PUSHING A WEAK COLD FRONT TOWARD THE FORECAST AREA. THIS
FRONT IS EXPECTED TO MEANDER OVER THE AREA THURSDAY AND THURSDAY
NIGHT...THEN POSSIBLY MOVING OFFSHORE FRIDAY MORNING. MODEL
INSTABILITY PARAMETERS ARE SUPPORTIVE OF ISOLATED TO SCATTERED
THUNDERSTORMS MID TO LATE WEEK IN ASSOCIATION WITH THE UPPER
SHORTWAVE ENERGY AND THE LINGERING SURFACE FRONT.

&&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDITIONS ARE EXPECTED AT BOTH CHS AND SAV TERMINALS THROUGH
18Z SATURDAY. HOWEVER...THERE WILL REMAIN A LOW CHANCE OF A SHOWER
CAUSING FLIGHT RESTRICTIONS AT THE CHS TERMINAL INTO EARLY
EVENING.

EXTENDED AVIATION OUTLOOK..VFR EXPECTED BOTH KCHS AND KSAV.
WEDNESDAY/MID WEEK...A WEAK FRONTAL SYSTEM POSSIBLY APPROACHES THE
AREA FROM THE WEST. LATEST FORECAST IS FOR SLIGHT CHANCE FOR
SHOWERS/TSTORMS WEDNESDAY AFTERNOON...WHICH COULD RESULT IN BRIEF
FLIGHT RESTRICTIONS.

&&

.MARINE...
THIS EVENING AND TONIGHT...WINDS/SEAS WILL SLOWLY IMPROVE AS A LARGE
MID/UPPER LVL LOW OVER THE NORTHEASTERN UNITED STATES SHIFTS FURTHER
NORTH AND AWAY FROM THE AREA. IN GENERAL...WEST/NORTHWEST WINDS WILL
PEAK BETWEEN 10-15 KT EARLY...WITH GREATEST SPEEDS IN NORTHERN SC
WATERS AND OFFSHORE GEORGIA WATERS. SEAS WILL BE NO HIGHER THAN
2-3 FT...HIGHEST IN OFFSHORE GEORGIA WATERS.

NO HIGHLIGHTS EXPECTED THROUGH THE PERIOD. AN EAST-WEST ORIENTED
RIDGE OF HIGH PRESSURE WILL BE CENTERED JUST SOUTH OF THE WATERS
THROUGH LATE SUNDAY...THEN BEGIN TO SHIFT EAST-NORTHEAST OF THE
WATERS MONDAY THROUGH WEDNESDAY. A WEAK FRONTAL SYSTEM MAY APPROACH
THE AREA FROM THE WEST WEDNESDAY. WESTERLY WINDS OF 15 KNOTS OR
LESS AND SEAS GENERALLY 4 FEET OR LESS SATURDAY AND SUNDAY...VEERING
TO SOUTHERLY MONDAY AND SOUTHEAST TUESDAY AND WEDNESDAY. WINDS MAY
SURGE UP TO 15 TO 20 KNOTS FOR SATURDAY NIGHT...BUT EXPECTED TO
REMAIN BELOW SMALL CRAFT ADVISORY LEVELS.

&&

.TIDES/COASTAL FLOODING...
DESPITE OFFSHORE WINDS THIS EVENING THROUGH SATURDAY...THE PERIGEAN
SPRING TIDES WILL RESULT IN A PERIOD OF ELEVATED TIDE LEVELS WITH
THE EVENING/EARLY NIGHT HIGH TIDE CYCLE. A COASTAL FLOOD ADVISORY
HAS BEEN ISSUED FOR THE ENTIRE COAST OF SOUTHEAST SOUTH CAROLINA
AND SOUTHEAST GEORGIA FROM 7 PM TO 11 PM THIS EVENING/TONIGHT.
HIGH TIDE IS EXPECTED AT 837 PM AT THE CHS HARBOR AND 843 PM AT
FORT PULASKI.

SATURDAY THROUGH MONDAY...ASTRONOMICAL TIDES WILL REMAIN ELEVATED
THROUGH MONDAY. LATEST EXTRA-TROPICAL SURGE GUIDANCE INDICATES
COASTAL FLOOD ADVISORY LEVEL TIDES WILL BE POSSIBLE DURING THE
EVENING HIGH TIDES EACH DAY. THUS...COASTAL FLOOD ADVISORIES MAY BE
NEEDED EACH EVENING.

&&

.CLIMATE...
RECORD LOWS FOR MAY 6...

CHARLESTON AIRPORT /CHS/...44/1973
SAVANNAH AIRPORT /SAV/...46/1957
DOWNTOWN CHARLESTON /CXM/...53/1921

&&

.EQUIPMENT...
THE CHARLESTON HARBOR NOS TIDE GAUGE AND GRAYS REEF BUOY 41008 REMAIN
OUT OF SERVICE.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...COASTAL FLOOD ADVISORY UNTIL 11 PM EDT THIS EVENING FOR GAZ117-
     119-139-141.
SC...COASTAL FLOOD ADVISORY UNTIL 11 PM EDT THIS EVENING FOR
     SCZ048>051.
MARINE...NONE.

&&

$$
SYNOPSIS...
NEAR TERM...DPB
SHORT TERM...RFM
LONG TERM...JRL
AVIATION...DPB/RFM
MARINE...DPB/RFM
TIDES/COASTAL FLOODING...
CLIMATE...
EQUIPMENT...



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