Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 280456
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1256 AM EDT TUE JUL 28 2015

.SYNOPSIS...
THE REGION WILL REMAIN BETWEEN WEAK HIGH PRESSURE TO THE NORTH AND
LOW PRESSURE TO THE SOUTH UNTIL LATE THIS WEEK. THEN...BROAD LOW
PRESSURE WILL DEVELOP AND PERSIST OVER THE REGION LATE THIS WEEK
THROUGH NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
CAREFULLY MONITORING TRENDS FOR FOG EARLY THIS MORNING. CIRRUS IS
STEADILY THINNING WITH HIGH DEWPOINTS AND LIGHT WINDS IN PLACE.
CONDITIONS APPEAR SIMILAR TO LAST NIGHT. LATEST NAM12 1000 HPA
CONDENSATION PRESSURE DEFICIT PROGS FAVOR SOUTHEAST GEORGIA FOR
THE GREATEST POTENTIAL FOR DENSE FOG...MOST LIKELY AS SOME MID-
LEVEL CLOUDINESS MAY MOVE INTO PARTS OF SOUTHEAST SOUTH CAROLINA
JUST BEFORE SUNRISE. WILL MAINTAIN AREAS OF FOG FOR ALL AREAS
UNTIL TRENDS BECOME MORE APPARENT.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
A LARGE MID LVL RIDGE OF HIGH PRESSURE WILL PERSIST OVER THE CENTRAL
AND SOUTHERN PLAINS WHILE A RELATIVELY FLAT MID LVL TROUGH OF LOW
PRESSURE REMAINS OVER THE NORTHEASTERN UNITED STATES. AT THE SFC...A
SERIES OF LOW PRESSURE WAVES WILL DEVELOP ALONG/NEAR A BOUNDARY
POSITIONED OVER FLORIDA AND OFF THE SOUTHEAST COAST...THEN LIFT
NORTH/NORTHEAST OFFSHORE. THESE WEAK AREAS OF LOW PRESSURE WILL BE
THE PRIMARY DRIVER OF PRECIPITATION ALONG COASTAL AREAS IN SOUTHEAST
SOUTH CAROLINA AND SOUTHEAST GEORGIA TUESDAY AND WEDNESDAY. FURTHER
INLAND...SLIGHTLY MORE COVERAGE ALONG WITH SOME ENHANCEMENT TO
OVERALL CONVECTION WILL BE POSSIBLE AS A WEAK H5 SHORTWAVE ROUNDS
THE NORTHEAST PERIPHERY OF HIGH PRESSURE CENTERED TO OUR WEST AND
ENCOUNTERS AMPLE MOISTURE CHARACTERIZED BY PWATS NEAR 2.0 INCHES
OVER THE SOUTHEAST. A SLIGHT CHANCE OF SHOWERS WILL THEREFORE REMAIN
THE FORECAST FOR INLAND AREAS ON TUESDAY...BEFORE CHANCES OF PRECIP
OCCUR ON WEDNESDAY. A MORE SUMMERTIME PATTERN WILL THEN BEGIN TO SET
UP ON THURSDAY BETWEEN HIGH PRESSURE DEVELOPING OVER THE WESTERN
ATLANTIC AND A COLD FRONT CROSSING THE APPALACHIAN MOUNTAINS. ONCE
AGAIN...CHANCES OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE.

OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO LOWER 90S NEAR
THE COAST AND MID 90S OVER INLAND LOCATIONS. OVERNIGHT LOWS WILL
REMAIN IN THE MID 70S INLAND TO UPPER 70S ALONG THE COAST.&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A POCKET OF RELATIVELY DRY/CAPPED AIR COULD LINGER OVER THE REGION
FRIDAY...PERHAPS LIMITING CONVECTION COVERAGE SOMEWHAT EVEN AS A
TROUGH OF LOW PRESSURE SETTLES INTO THE SOUTHEAST AT THE SURFACE AND
ALOFT. THEN...A TRANSITION TO A WETTER REGIME WITH SLIGHTLY BELOW
NORMAL HIGH TEMPERATURES IS EXPECTED THIS WEEKEND...AND THIS
UNSETTLED PATTERN COULD PERSIST INTO EARLY NEXT WEEK. THE LATEST
FORECAST DEPICTS ABOVE-NORMAL POPS THIS WEEKEND AND INTO EARLY NEXT
WEEK. BECAUSE OF THE UNCERTAINTY COMMON TO MEDIUM RANGE FORECASTS OF
CONVECTION...CAPPED MAXIMUM POPS AT AROUND 50 PERCENT SATURDAY
THROUGH MONDAY. EVENTUALLY...PERIODS OF HIGHER POPS WILL LIKELY BE
REQUIRED FOR SOME OR ALL OF THE FORECAST AREA.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A POCKET OF RELATIVELY DRY/CAPPED AIR COULD LINGER OVER THE REGION
FRIDAY...PERHAPS LIMITING CONVECTION COVERAGE SOMEWHAT EVEN AS A
TROUGH OF LOW PRESSURE SETTLES INTO THE SOUTHEAST AT THE SURFACE AND
ALOFT. THEN...A TRANSITION TO A WETTER REGIME WITH SLIGHTLY BELOW
NORMAL HIGH TEMPERATURES IS EXPECTED THIS WEEKEND...AND THIS
UNSETTLED PATTERN COULD PERSIST INTO EARLY NEXT WEEK. THE LATEST
FORECAST DEPICTS ABOVE-NORMAL POPS THIS WEEKEND AND INTO EARLY NEXT
WEEK. BECAUSE OF THE UNCERTAINTY COMMON TO MEDIUM RANGE FORECASTS OF
CONVECTION...CAPPED MAXIMUM POPS AT AROUND 50 PERCENT SATURDAY
THROUGH MONDAY. EVENTUALLY...PERIODS OF HIGHER POPS WILL LIKELY BE
REQUIRED FOR SOME OR ALL OF THE FORECAST AREA.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
THE PRIMARY CONCERN IS FOG/STRATUS THROUGH SUNRISE. CONDITIONS
APPEAR SIMILAR TO YESTERDAY MORNING WHERE DENSE FOG WAS FAIRLY
WIDESPREAD. LATEST HIGH RESOLUTION GUIDANCE FAVORS KSAV FOR THE
HIGHER PROBABILITIES FOR IFR OR LOWER CONDITIONS PRIOR TO
SUNRISE...ASSUMING A BATCH OF MID-LEVEL CLOUDS MOVES INTO THE KCHS
AREA AS EXPECTED. WILL GO AHEAD AND SHOW PREVAILING LOW-END MVFR
VSBYS 09-1330Z WITH TEMPO IFR FROM 10-12Z...BUT WILL NOT ESTABLISH
CIGS ATTM. AT KCHS...WILL KEEP CONDITIONS LOW-END MVFR. AMENDMENTS
WILL MOST CERTAINLY BE NEEDED THROUGHOUT THE EARLY MORNING AS
TRENDS BECOME MORE APPARENT. VFR WILL PREVAIL ONCE ANY FOG/STRATUS
MIXES OUT BY 13-14Z.

ONLY ISOLATED SHOWERS AND TSTMS EXPECTED TUESDAY AFTERNOON.
COVERAGE TOO LOW TO JUSTIFY ANY MENTION IN THE 00Z TAFS.

EXTENDED AVIATION OUTLOOK...FLIGHT RESTRICTIONS WILL BE POSSIBLE
WITH AFTERNOON THUNDERSTORMS WEDNESDAY THROUGH SATURDAY.

&&

.MARINE...
TONIGHT...DIFFICULT WIND FORECAST IN TERMS OF DIRECTION FOR
TONIGHT...BUT THE IMPACTS WILL BE MINIMAL SINCE THE WINDS WILL BE
AOB 10 KNOTS FOR ALL WATERS. SEAS ARE CURRENTLY AROUND 2 FEET IN
MANY AREAS. GUIDANCE SHOWS SEAS INCREASING SOME OVERNIGHT UP INTO
THE 2 TO 3 FOOT RANGE...BUT EVEN IF THAT OCCURS THE WATERS WILL BE
QUITE TRANQUIL TONIGHT.

TUESDAY THROUGH SATURDAY...WINDS/SEAS ARE EXPECTED TO REMAIN BELOW
SMALL CRAFT ADVISORY THRESHOLDS DURING THE PERIOD. HOWEVER...ONSHORE
WINDS WILL PERSIST TUESDAY THROUGH THURSDAY...WITH SOME ENHANCEMENT
OCCURRING DURING AFTERNOON SEABREEZE CIRCULATIONS. IN
GENERAL...WINDS WILL REMAIN AT OR BELOW 15 KTS WITH SEAS NO HIGHER
THAN 3 FT. WINDS SHOULD THEN BECOME SOUTH/SOUTHWEST FRIDAY AND
SATURDAY...PERHAPS INCREASING TO 15-20 KT IN SOME AREAS WITH THE
AFTERNOON SEABREEZE AND WITH NOCTURNAL SURGES. SEAS SHOULD REMAIN
BETWEEN 2-4 FT THIS WEEKEND...HIGHEST BEYOND 20 NM FROM THE COAST.

&&

.TIDES/COASTAL FLOODING...
PERIGEE AND PERSISTENT ONSHORE WINDS COULD CONTRIBUTE TO SHALLOW
SALT WATER FLOODING AROUND THE TIMES OF EVENING HIGH TIDES
STARTING TUESDAY AND POTENTIALLY THROUGH EARLY NEXT WEEK. WHILE
THE PROBABILITY FOR A SERIES OF COASTAL FLOOD ADVISORY EVENTS
SHOULD INCREASE AS WE DRAW CLOSER TO THE JULY 31 FULL MOON/AUG 2
PERIGEE...DUE TO PERSISTENT EAST/NORTHEAST WINDS FORECAST BY THE
GFS THE EXTRATROPICAL SURGE MODEL CONTINUES TO DEPICT THE EVENING
HIGH TIDE EXCEEDING SHALLOW COASTAL FLOODING LEVELS ALONG THE SC
COAST AS EARLY AS TUESDAY-WEDNESDAY. WILL CONTINUE TO HIGHLIGHT
THE POTENTIAL FOR SHALLOW SALT WATER FLOODING WITHIN THE HAZARDOUS
WEATHER OUTLOOK.

&&

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

&&

$$

ST


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