Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 231117
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
717 AM EDT SAT MAY 23 2015

.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION THROUGH NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE 00Z MODELS PORTRAYAL OF A BUILDING MID/UPPER LEVEL RIDGE IS
EMPHATIC DURING THE NEXT 24 HOURS. THE CENTER OF STRONG SURFACE
HIGH PRES TO THE NORTH WILL BUILD FROM THE OHIO VALLEY TO THE MID
ATLC COAST MAINTAINING ONSHORE FLOW IN THE BOUNDARY LAYER.

MORNING SUNSHINE IS EXPECTED TO GIVE WAY TO SCATTERED TO LOCALLY
BROKEN CU/SC FIELDS ACROSS SE GEORGIA AND PERHAPS FAR SOUTHERN
SOUTH CAROLINA TO THE SOUTH OF CHARLESTON THIS AFTERNOON. A STRONG
SUBSIDENCE INVERSION IS IN PLACE AND ANY DIURNAL CLOUDS SHOULD
FLATTEN OUT UNDER THIS CAP. NO CHANGE TO HIGH TEMP SCHEMES TODAY
WITH MID 80S A GOOD BET ACROSS INLAND GEORGIA ZONES AND 80-83
ELSEWHERE EXCEPT A BIT COOLER BEACHES AND BARRIER ISLANDS. IT WILL
ALSO BE SOMEWHAT BREEZY AT TIMES IN COASTAL ZONES THIS AFTERNOON
AS THE SEA BREEZE ROLLS INLAND...WITH THE BEST GRADIENT IN PLACE
ACROSS COASTAL SE GEORGIA.

SCATTERED CLOUDS COULD LINGER OR MOVE ONSHORE LATE TONIGHT BUT DRY
WEATHER WILL PERSIST. LOWS MAY DIP INTO THE UPPER 50S IN COOLER
SPOTS INLAND ACROSS AREAS TO THE NORTH OF I-16...OTHERWISE 60-65
DEGREE MIN TEMPS ARE EXPECTED.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
A STRONG UPPER LEVEL RIDGE WILL REMAIN OVER THE SOUTHEAST UNITED
STATES...WITH THE AXIS SHIFTING INTO THE WESTERN ATLANTIC BY
TUESDAY. THE SURFACE HIGH WILL GRADUALLY SINK SOUTH...TURNING LOCAL
WINDS SOUTHEAST AND THEN SOUTH-SOUTHEAST. THIS WILL BRING INCREASING
LOW-LEVEL MOISTURE INTO SOUTHEAST GA WITH DEWPOINTS INCREASING INTO
THE UPPER 60S BY MONDAY. WITH THE UPPER RIDGE SQUARELY OVER EASTERN
SC...THE CAP WILL BE TOO STRONG TO ALLOW MUCH OF ANY CONVECTION TO
FIRE OVER OUR EASTERN ZONES. HOWEVER WE SHOW ISOLATED SHOWERS AND
TSTMS DEVELOPING MONDAY AND TUESDAY ACROSS INTERIOR SOUTHEAST GA AND
FAR INLAND SC. EVEN IN THESE AREAS THE MID-LEVEL CAP WILL BE FAIRLY
STRONG WHICH SHOULD LIMIT CONVECTIVE COVERAGE. LOW-LEVEL THICKNESSES
SUPPORT HIGH TEMPS IN THE UPPER 80S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
A WEAK UPPER RIDGE WILL PERSIST OVER THE SOUTHEAST STATES WHILE A
WEAK UPPER TROUGH SITS TO THE WEST AND A LARGE CLOSED UPPER LOW
EXISTS NEAR BERMUDA. A WEAK SURFACE HIGH WILL BUILD DOWN THE EASTERN
SEABOARD...KEEPING DEWPOINTS IN THE LOW TO MID 60S. A SLIGHTLY
WEAKER CAP OVER INLAND AREAS WILL SUPPORT ISOLATED SHOWERS AND TSTMS
DURING THE AFTERNOON WEDNESDAY THROUGH FRIDAY. THEREAFTER THE UPPER
RIDGE WILL REBUILD OVER THE AREA...SUPPRESSING CONVECTION AND LIKELY
YIELDING A DRY WEEKEND. TEMPS WILL WARM THROUGH THE UPPER 80S INTO
THE LOWER 90S LATE WEEK INTO THE WEEKEND.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL PREVAIL AT KSAV/KCHS THROUGH 12Z SUNDAY.
ONSHORE FLOW IN THE BOUNDARY LAYER SHOULD PROMOTE WIND GUSTS IN
THE 18-22 KT RANGE THIS AFTERNOON...ESPECIALLY AT KSAV.

EXTENDED AVIATION OUTLOOK...MVFR CEILINGS WILL BE POSSIBLE AT KSAV
SUNDAY THROUGH TUESDAY...MAINLY BETWEEN DAYBREAK AND NOON.

&&

.MARINE...
HIGH PRES TO THE THE NE OF THE WATERS WILL MAINTAIN AN ENHANCED
LOW LEVEL PRESSURE GRADIENT OVER THE WATERS THIS WEEKEND. WILL
MAINTAIN AN ENE FLOW OVER THE COASTAL WATERS TODAY AND TONIGHT.
ONSHORE FLOW 15-20 KT WILL KEEP THE SEA STATE RATHER CHOPPY WITH
SEAS 2-4 FT NEARSHORE WATERS AND 4-5 FT OFFSHORE. A SMALL CRAFT
ADVISORY MAY EVENTUALLY BE NEEDED TONIGHT...MAINLY FOR THE GEORGIA
OFFSHORE LEG WHERE SEAS MAY BUILD CLOSE TO 6 FT BEYOND 20 NM AND
ESPECIALLY BEYOND 40 NM.

ONSHORE FLOW WILL PREVAIL THROUGH THE PERIOD AS HIGH PRESSURE
REMAINS ANCHORED OVER THE WESTERN ATLANTIC. A SLIGHTLY STRONGER
GRADIENT SUNDAY AND MONDAY MAY ALLOW SOME 6 FT SEAS TO MOVE INTO
THE OFFSHORE GA WATERS. THERE IS ALSO A CHANCE THAT WIND GUSTS
ALONG THE COAST WILL APPROACH 25 KT WITH THE AFTERNOON SEA
BREEZE...PERHAPS NECESSITATING A SMALL CRAFT ADVISORY IN
CHARLESTON HARBOR. OTHERWISE THERE ARE NO MAJOR CONCERNS WITH
WINDS EXPECTED TO BE AT OR BELOW 15 KT.

RIP CURRENTS...ENHANCED ONSHORE FLOW CLOSE TO 20 KT THIS AFTERNOON
BUMPED OUR FORECAST PROGNOSTICATION CLOSER TO A MODERATE RISK
ALONG THE GEORGIA COAST TODAY. WITH THE TIDE GOING OUT ALL AFTERNOON
WE ERRED ON THE SIDE OF CAUTION AND BUMPED THE RISK TO MODERATE AT
TYBEE TODAY. SIMILAR CONDITIONS ARE POSSIBLE FOR THE REMAINDER OF
THE HOLIDAY WEEKEND.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...JRL
LONG TERM...JRL
AVIATION...
MARINE...JRL



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