000
FXUS62 KCHS 250533
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
133 AM EDT SAT MAY 25 2013

.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE REGION THIS WEEKEND AND REMAIN
THE DOMINANT WEATHER FEATURE THROUGH LATE NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE SHARP UPPER TROUGH OVER THE MID-ATLANTIC WILL TRANSITION TO A
CLOSED LOW AS THE SURFACE HIGH CONTINUES TO BUILD IN FROM THE
NORTHWEST TONIGHT. UNDER CLEAR SKIES...NORTHERLY FLOW WILL
CONTINUE TO PUSH A VERY DRY AIRMASS FEATURING UNSEASONABLY COOL
TEMPS INTO THE REGION. DUE TO PERSISTENT N/NE WINDS AND ASSOCIATED
MIXING...TEMPERATURES WILL OCCASIONALLY EXHIBIT UNSTEADY HOURLY
TRENDS BUT IN GENERAL WILL BOTTOM OUT IN THE UPPER 40S/LOWER 50S
AT MANY LOCATIONS AWAY FROM THE BEACHES BY DAYBREAK. THESE MIN
TEMPS WILL BE 10-15 DEGREES BELOW CLIMO FOR LATE MAY.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/...
A DEEP UPPER TROUGH OVER NEW ENGLAND AND AN UPPER RIDGE OVER THE
CENTRAL PART OF THE COUNTRY WILL PREVAIL THROUGH THE SUNDAY...THEN
WEAK UPPER RIDGING BUILDS OVER THE SOUTHEAST BY MONDAY. AT THE
SURFACE...HIGH PRESSURE WILL BE CENTERED OVER AND NORTH OF THE
REGION ON SATURDAY...THEN SHIFT EAST AND SLIGHTLY SOUTHEAST OF THE
AREA BY SUNDAY AND MONDAY. LIGHT NORTHERLY FLOW BECOMING ONSHORE
NEAR THE COAST FOR SATURDAY WITH HIGHS IN THE UPPER 70S TO AROUND
80...ABOUT 3-5 DEGS BELOW NORMAL. A WEAK FRONT AND MOISTURE
BAND MOVES INTO THE NORTHERN AREA LATER SATURDAY NIGHT AND
SUNDAY...BUT NO PRECIP IS EXPECTED THROUGH SUNDAY. ANOTHER COOL
NIGHT IN THE LOWER TO MID 50S MOST AREAS...CLOSE TO 10 DEGS BELOW
NORMAL FOR SATURDAY NIGHT. HIGH TEMPERATURES BACK CLOSER TO NORMAL BY
SUNDAY IN THE LOWER TO MID 80S...EXCEPT MID TO UPPER 70S NEAR THE
COAST DUE TO AN AFTERNOON SEA BREEZE/ONSHORE FLOW. PARTLY CLOUDY
SUNDAY NIGHT WITH SLIGHTLY WARMER TEMPS...BUT SILL COOLER THAN
NORMAL IN THE MID TO UPPER 50S. BY MONDAY...PARTLY CLOUDY SKIES AS
SOME LOW LEVEL MOISTURE TRIES TO RETURN WITH SSE LOW LEVEL FLOW.
TEMPS BACK IN THE LOWER TO MID 80S. MODELS ARE INDICATING SOME VERY
ISOLATED SHOWERS/TSTMS BY AFTERNOON OVER THE INTERIOR TRI-COUNTY
REGION...BUT HAVE NOT ADDED ANY PRECIP MENTION AT THIS TIME.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
DECENT MODEL AGREEMENT THIS PERIOD WITH ABOVE AVERAGE FORECAST
CONFIDENCE. UPPER HIGH PRESSURE SHOULD BUILD ACROSS THE REGION
TOWARD THE MIDDLE OF NEXT WEEK LEADING TO WARMING TEMPERATURES AND
SLOWLY INCREASING LOW-LEVEL MOISTURE. RAIN CHANCES WILL REMAIN LOW
GIVEN THE LACK OF DEEP MOISTURE AND FORCING...MAINLY CONFINED TO
INLAND AREAS DURING AFTERNOON PEAK HEATING AS THE SEA BREEZE PUSHES
INLAND.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL THROUGH 06Z SUNDAY.

EXTENDED AVIATION...VFR.

&&

.MARINE...
MAINTAINED ONGOING SMALL CRAFT ADVISORIES FOR ALL WATERS OUTSIDE
CHARLESTON HARBOR.

OVERNIGHT...AS HIGH PRESSURE BUILDS IN FROM THE NORTHWEST...A
TIGHTENING PRESSURE GRADIENT AND COLD AIR ADVECTION/INCREASING
MARINE BOUNDARY LAYER INSTABILITY/MIXING ENHANCED BY WATER TEMPS
IN THE 70S WILL RESULT IN A SURGE OF N/NE WINDS 15-20 KT ALL
WATERS WITH GUSTS TO 25 KT ESPECIALLY OUTSIDE CHARLESTON HARBOR.
SEAS WILL BUILD TO AT LEAST 3-4 FT WITHIN 20 NM OF THE COAST AND
TO AT LEAST 5-6 FT BEYOND 20 NM. ELEVATED WINDS/SEAS WILL PERSIST
INTO SATURDAY MORNING.

NNE WINDS SATURDAY MORNING AT 15 TO 20 KTS WILL DECREASE BY
AFTERNOON AS HIGH PRESSURE SETTLES OVER THE REGION. WINDS EXPECTED
TO BE LIGHT ENOUGH BY AFTERNOON TO BECOME ONSHORE NEAR THE COAST.
LIGHT WINDS OF 10-15 KTS SHOULD BECOME ONSHORE NEAR THE COAST AGAIN
SUNDAY. HIGH PRESSURE WILL REMAIN GENERALLY OVER THE REGION THROUGH
MID WEEK WITH SSE PREVAILING WINDS AND NO HIGHLIGHTS EXPECTED.

RIP CURRENTS...EXPECT A MODERATE RISK TO CONTINUE SATURDAY DUE IN
LARGE PART TO 2-3 FOOT 8-9 SEC SWELLS AND THE FULL MOON AT
PERIGEE. WOULD NOT BE SURPRISED IF MODERATE RISK CONDITIONS
CONTINUE THROUGH THE REST OF THE HOLIDAY WEEKEND.

&&

.TIDES/COASTAL FLOODING...
HIGH ASTRONOMICAL TIDES DUE TO THE FULL MOON CYCLE AND FAVORABLE
NORTH/NORTHEAST WINDS COULD LEAD TO MINOR SALTWATER INUNDATION
NEAR THE COAST DURING THE HIGH TIDE CYCLES THROUGH THE WEEKEND. BY
THE TIME OF THE HIGH TIDE SUNDAY EVENING AND MONDAY
EVENING...WINDS WILL NOT BE AS CONDUCIVE...YET MINOR SALTWATER
FLOODING WILL STILL BE POSSIBLE AS ASTRONOMICAL FACTORS WILL CAUSE
HIGHER THAN TYPICAL TIDES. COASTAL FLOOD ADVISORIES MAY EVENTUALLY
BE NEEDED.

&&

.CLIMATE...
RECORD LOW TEMPERATURES FOR MAY 25TH /SAT/...
CHARLESTON INTERNATIONAL AIRPORT /KCHS/.....47 SET IN 1967
DOWNTOWN CHARLESTON /KCHL/..................54 SET IN 1979
SAVANNAH/HHI INTERNATIONAL AIRPORT /KSAV/...49 SET IN 1967

RECORD LOW TEMPERATURES FOR MAY 26TH /SUN/...
CHARLESTON INTERNATIONAL AIRPORT /KCHS/.....50 SET IN 1979
DOWNTOWN CHARLESTON /KCHL/..................50 SET IN 1979
SAVANNAH/HHI INTERNATIONAL AIRPORT /KSAV/...49 SET IN 1979

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR AMZ350-
     352-354-374.

&&

$$

SYNOPSIS...
NEAR TERM...SPR
SHORT TERM...RFM
LONG TERM...RJB
AVIATION...JAQ
MARINE...SPR/RFM
TIDES/COASTAL FLOODING...
CLIMATE...