Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 022010
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
410 PM EDT SUN AUG 2 2015

.SYNOPSIS...
A WEAK AREA OF LOW PRESSURE WILL LIFT NORTHEASTWARD ALONG A
STATIONARY FRONT TONIGHT THROUGH MONDAY NIGHT. HIGH PRESSURE WILL
BUILD IN TUESDAY AND WEDNESDAY BEFORE AN INLAND TROUGH OF LOW
PRESSURE DEVELOPS THURSDAY. A COLD FRONT WILL DROP INTO THE AREA
NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
WEAK LOW PRESSURE AROUND THE FLORIDA BIG BEND AREA WILL MOVE
NORTHEAST INTO SOUTHEAST GEORGIA ALONG A STATIONARY FRONT
INTO SOUTHEAST SC. INCREASING SOUTHERLY WINDS AHEAD OF THE LOW
WILL CONTINUE TO BRING ABUNDANT MOISTURE INTO THE AREA...MAINLY
ALONG THE COAST. THUS...AFTER AFTERNOON SHOWERS AND THUNDERSTORMS
WANE...EXPECT INCREASING SHOWER CHANCES NEAR THE COAST OVERNIGHT.
SOME OF THE RAIN COULD BE HEAVY AT TIMES. FAR INLAND AREAS OF
GEORGIA SHOULD REMAIN DRY AND THIS IS WHERE WE THINK THERE IS THE
BEST CHANCE OF FOG. LOWS MAINLY LOWER TO MID 70S INLAND AND CLOSER
TO 80 AT THE COAST.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
MONDAY AND MONDAY NIGHT...SIGNIFICANT CHANGES WERE MADE TO THE
FORECAST AS MODELS HAVE TRENDED MUCH WETTER THROUGH MONDAY NIGHT.
THE MAIN CAUSE OF THIS TREND IS THE WEAK AREA OF LOW PRESSURE
CURRENTLY NEAR THE BIG BEND OF FLORIDA THAT IS FORECAST TO LIFT
NORTHEASTWARD ALONG A STALLED FRONT. AS THIS OCCURS...A DEEP SOUTH
TO SOUTHEAST MOISTURE FEED WILL BECOME ENHANCED AHEAD OF THE SURFACE
LOW AND INTO COASTAL SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA.
THE PERCENT OF NORMAL PRECIPITABLE WATER SATELLITE PRODUCT CURRENTLY
SHOWS VALUES IN THE 120-130 PERCENT RANGE NEAR THE LOW...AND THIS
AIRMASS WILL BECOME SOLIDLY ENTRENCHED ACROSS THE FORECAST AREA
BEGINNING MONDAY MORNING. SUCH PERCENT OF NORMAL VALUES POINT TO
PWATS ON THE ORDER OF 2.25 INCHES FOR MUCH OF THE DAY ON MONDAY AND
INTO MONDAY NIGHT. THE MODELS...ESPECIALLY THE 02/12Z ECMWF...PUT
THE QPF BULLSEYE RIGHT ON THE FORECAST AREA AND MAINLY ALONG THE
SOUTH CAROLINA COAST. THIS SEEMS QUITE REASONABLE GIVEN THE DEGREE
OF MOISTURE...PRESENCE OF A LOW LEVEL FEATURE...AND EVEN SOME UPPER
LEVEL DIVERGENCE IN THE ENTRANCE OF A 250-300 MB JET. POPS HAVE BEEN
INCREASED INTO THE 60 PERCENT RANGE FOR MAINLY THE TRI-COUNTY
REGION...AND THIS MAY NEED TO BE EXPANDED DEPENDING ON HOW
PRECIPITATION EVOLVES OVERNIGHT INTO MONDAY MORNING. OVERNIGHT...THE
LOW WILL BEGIN TO LIFT NORTHEASTWARD AND THE AXIS OF DEEPER MOISTURE
AND BEST COVERAGE WILL SHIFT UP TOWARD THE NC/SC BORDER. HAVE
MAINTAINED AT LEAST CHANCE POPS ACROSS THE EAST UNTIL A MORE
DEFINITIVE TREND CAN BE IDENTIFIED. TEMPERATURES FOR MONDAY WILL BE
TRICKY AS AREAS ALONG AND EAST OF I-95 WILL LIKELY SEE LITTLE TO NO
DIRECT SUNLIGHT. THIS COULD KEEP HIGHS DOWN SIGNIFICANTLY...WITH
STILL LOW 90S POSSIBLE ACROSS INTERIOR SOUTHEAST GEORGIA.

TUESDAY THROUGH WEDNESDAY...MUCH DRIER DEEP LAYER AIR WILL WORK INTO
THE AREA AND POPS ARE NO MORE THAN 20 PERCENT AS HIGH PRESSURE
BUILDS IN BEHIND THE DEPARTING SURFACE WAVE. WARM TEMPERATURES WILL
RETURN...WITH HIGHS REACHING THE MID TO UPPER 90S AWAY FROM THE
IMMEDIATE COAST.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A RELATIVELY WET PATTERN IS ANTICIPATED WEDNESDAY NIGHT THROUGH
SUNDAY AS A LONGWAVE TROUGH TAKES SHAPE IN THE UPPER LEVELS. A
PRONOUNCED LEE TROUGH WILL DEVELOP LATE WEEK...THEN A COLD FRONT
WILL DROP INTO THE AREA OVER THE WEEKEND. PWATS SURGE BACK ABOVE 2"
LATE WEEK WITH VALUES APPROACHING 2.3" SATURDAY AND SATURDAY NIGHT.
WE SHOW INCREASING POPS DURING MUCH OF THE PERIOD...ESPECIALLY
DURING DAYTIME HOURS. TEMPERATURES WILL BE MODERATED BY LOWER
HEIGHTS AND GREATER CLOUD COVER...THUS HIGHS WILL MAINLY REACH NO
HIGHER THAN THE LOWER 90S.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
VFR CONDITIONS TO PREVAIL THIS AFTERNOON OUTSIDE SHOWERS AND SOME TSTMS
WHICH ARE MOST LIKELY THROUGH ABOUT 20Z AT KCHS AND 22Z AT KSAV.

MAINLY VFR TONIGHT BUT ADDITIONAL LOW CLOUDS AND SHOWERS/POSSIBLE
TSTMS NEAR THE COAST ARE EXPECTED OVERNIGHT AS LOW PRESSURE
ACROSS THE FLORIDA PANHANDLE TRACKS NORTHEAST INTO SOUTHEAST
GEORGIA ALONG A STATIONARY FRONT. MVFR AND MAYBE EVEN IFR CIGS
POSSIBLE.

EXTENDED AVIATION OUTLOOK...ELEVATED CHANCES OF DIRECT IMPACTS
FROM SHOWERS AND THUNDERSTORMS MONDAY AFTERNOON/EVENING.
THEREAFTER...VFR CONDITIONS WILL PREVAIL.

&&

.MARINE...
TONIGHT...A WEAK AREA OF LOW PRESSURE NEAR THE FLORIDA BIG BEND
AREA WILL MOVE NORTHEAST INTO SOUTHEAST GEORGIA. THIS WILL PLACE
THE TIGHTEST PRESSURE GRADIENT/LOW-LEVEL JET MAINLY BEYOND 20 NM
AND THIS IS WHERE WE HAVE RAISED A SMALL CRAFT ADVISORY. ACROSS
THE NEAR SHORE WATERS SOUTHERLY WINDS WILL SURGE BUT REMAIN
MAINLY 20 KT OR LESS WITH SEAS BUILDING UP TO 4 FT.

MONDAY THROUGH FRIDAY...A WEAK AREA OF LOW PRESSURE WILL MOVE
NORTHEASTWARD ALONG THE COAST THROUGH TUESDAY. HIGH PRESSURE WILL
THEN RETURN WITH A TROUGH OF LOW PRESSURE INLAND...WITH ANOTHER
FRONT REACHING THE AREA LATE IN THE WEEK. THIS SETUP WILL RESULT IN
A PREVAILING SOUTHWEST FLOW ACROSS THE WATERS THROUGH THE
WEEK...WITH VARIOUS PERIODS OF ENHANCED FLOW AS THE PRESSURE
GRADIENT TIGHTENS. WINDS WILL GENERALLY TOP OUT IN THE 15-20 KT
RANGE WITH SOME POTENTIAL FOR GUSTS TO AROUND 25 KT AT
TIMES...MAINLY OVER THE OUTER GEORGIA WATERS. SEAS WILL BE ELEVATED
THROUGH MUCH OF THE WEEK...ESPECIALLY MONDAY THROUGH TUESDAY NIGHT.
A SMALL CRAFT ADVISORY WILL BE IN EFFECT FOR THE OUTER GEORGIA
WATERS THROUGH MIDDAY TUESDAY TO ACCOUNT FOR 6 FT SEAS.
OTHERWISE...SEAS WILL BE 2-4 FT OUT TO 20 NM...AND 5 FT BEYOND.

&&

.TIDES/COASTAL FLOODING...
TIDES WILL REMAIN HIGHER THAN NORMAL THROUGH EARLY WEEK...POSSIBLY
GETTING CLOSE TO ADVISORY LEVELS IN CHARLESTON HARBOR DURING THE
HIGH TIDE TONIGHT. THUS...SOME SHALLOW SALTWATER INUNDATION IS
POSSIBLE IN THE NORMAL PRONE AREAS AND A COASTAL FLOOD ADVISORY
MAY EVENTUALLY BE NEEDED...ALTHOUGH SEEMS UNLIKELY AT THIS TIME
THAT LEVELS WILL REACH 7.0 FT MLLW.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO NOON EDT
     TUESDAY FOR AMZ374.

&&

$$
SYNOPSIS...
NEAR TERM...RJB
SHORT TERM...BSH
LONG TERM...
AVIATION...BSH/RJB
MARINE...BSH/RJB
TIDES/COASTAL FLOODING...



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