Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 032201
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
601 PM EDT MON AUG 3 2015

.SYNOPSIS...
A WEAK AREA OF LOW PRESSURE WILL MOVE NORTHEAST UP THE COAST
OVERNIGHT BEFORE MOVING AWAY FROM THE FORECAST AREA ON TUESDAY. HIGH
PRESSURE WILL BRIEFLY BUILD IN FROM THE NORTHWEST INTO WEDNESDAY.
AN INLAND TROUGH OF LOW PRESSURE WILL DEVELOP BY THURSDAY AND A
COLD FRONT WILL APPROACH THE AREA FRIDAY INTO SATURDAY.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
03/21Z ANALYSIS BASED ON SATELLITE...RADAR AND SURFACE
OBSERVATIONS SHOWED 1009 HPA LOW PRESSURE VERY NEAR DARIEN...
GEORGIA. THE LOW REMAINS EMBEDDED WITHIN A BROAD SURFACE TROUGH
WHICH CURVES NORTHWEST THROUGH INTERIOR SOUTHEAST GEORGIA INTO THE
CSRA AND SOUTHWEST INTO NORTH-CENTRAL FLORDIA. THE LOW IS FORECAST
TO MEANDER NORTHEAST ALONG THE GEORGIA AND LOWER SOUTH CAROLINA
COAST TONIGHT...BECOMING SITUATED VERY NEAR OR JUST NORTHEAST OF
THE CHARLESTON AREA BY SUNRISE TUESDAY.

MOST OF THE CONVECTION HAS BEEN FOCUSED INLAND ALONG THE
AFOREMENTIONED SURFACE TROUGH SO FAR TODAY WITH POCKETS OF VERY
HEAVY RAIN BEING OBSERVED FROM ROUGHLY SOUTHERN BULLOCH COUNTY
NORTHEAST INTO HAMPTON AND WESTERN COLLETON COUNTIES. THIS
ACTIVITY WILL GRADUALLY DIMINISH AS INSOLATION WANES AND LOW-
LEVEL CONVERGENCE SHIFTS BACK TO THE COAST MAINLY ALONG AND
NORTHEAST OF THE TRACK OF THE SURFACE LOW. KCLX RADAR REFLECTIVITY
DATA SUGGEST THIS IS ALREADY TAKING PLACE WITH A DEFINITIVE
DOWNWARD TREND NOTED WITH THE INLAND CONVECTION AND EVIDENCE OF
LOW-LEVEL CONVECTIVE BANDS BEGINNING TO EVOLVE JUST OFF OFFSHORE.
MSAS ANALYSIS ALSO DEPICTS AN UPWARD TREND OF SURFACE MOISTURE
FLUX CONVERGENCE WITH A POCKET OF VALUES >50 G/KG/12HR CENTERED
JUST OFF EDISTO BEACH.

EXPECT A GRADUAL UPTICK IN CONVECTION ALONG THE COAST OVERNIGHT
WITH THE HIGHEST CONCENTRATION OF RAIN LIKELY BECOMING CENTERED
INTO THE HILTON HEAD TO MCCLELLANVILLE AREA...INCLUDING DOWNTOWN
CHARLESTON. WILL HAVE TO TO WATCH DOWNTOWN CHARLESTON VERY
CAREFULLY AS HEAVY RAINS COULD FALL DURING THE HIGH ASTRONOMICAL
TIDE LATE THIS EVENING. GIVEN TIDE LEVELS ARE PROJECTED TO BE IN
EXCESS OF 6.8 FT MLLW...ANY HEAVY RAIN THAT FALLS WITHIN AN HOUR
EITHER SIDE OF HIGH TIDE COULD CAUSE SOME PROBLEMS. HAVE
READJUSTED POPS TO MATCH EXPECTED TRENDS THROUGH THE OVERNIGHT
WITH POPS MAXING OUT AROUND 50 PERCENT. HIGHER POPS MAY EVENTUALLY
BE NEEDED.

LOWS WILL RANGE FROM THE LOWER-MID 70S INLAND WITH UPPER 70S/NEAR
80 AT THE BEACHES AND DOWNTOWN CHARLESTON.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
TUESDAY AND TUESDAY NIGHT...SHORTWAVE ENERGY ALOFT WILL PULL AWAY
FROM THE AREA TO THE NORTHEAST AS THE REGION REMAINS ON THE SOUTHERN
PERIPHERY OF THE LONGWAVE TROUGH THAT ENCOMPASSES MUCH OF EASTERN
CANADA AND THE NORTHEASTERN CONUS. AT THE SURFACE...THE SLOWLY
MEANDERING WEAK AREA OF LOW PRESSURE WILL MOVE ALONG THE FORECAST
AREA COASTLINE AND EVENTUALLY BECOME AN OPEN WAVE AND LIFT OUT TO
THE NORTHEAST. IN THE MORNING...IT APPEARS THE EASTERN REACHES OF
THE FORECAST AREA WILL STILL BE DEALING WITH THE DEEP ATLANTIC
MOISTURE FEED AND CORRESPONDING SHOWER ACTIVITY. HAVE INCREASED POPS
ACROSS EASTERN PORTIONS OF CHARLESTON AND BERKELEY COUNTIES TO 40-
50. THE REST OF THE DAY...DRIER AIR WILL WORK ITS WAY INTO THE AREA
AND RAIN CHANCES WILL BE QUITE MINIMAL. OVERNIGHT...THE FORECAST IS
DRY AS HIGH PRESSURE BRIEFLY BUILDS IN. HIGHS WILL BE IN THE LOW 90S
EAST...RANGING TO THE MID/UPPER 90S FOR INTERIOR SOUTHEAST GEORGIA.
LOWS WILL FALL INTO THE MID/UPPER 70S.

WEDNESDAY THROUGH THURSDAY...WEDNESDAY LOOKS LIKE THE MOST BENIGN
DAY WITH LIMITED CONVECTIVE POTENTIAL WITH JUST A WEAK LEE TROUGH.
DRIER LOW LEVELS WILL HELP RESULT IN VERY LITTLE SURFACE BASED
INSTABILITY. JUST A SLIGHT CHANCE POP IS IN PLACE FOR DIURNAL
CONVECTION. BY THURSDAY...MOISTURE IS A BIT BETTER AND THE INLAND
TROUGH BECOMES BETTER DEFINED AS A WELL DEFINED SHORTWAVE ALOFT
APPROACHES FROM THE WEST. DIURNAL CONVECTION CHANCES WILL BE
BETTER...WITH 30 POPS IN PLACE FOR LAND AREAS. THE WARMEST DAY WILL
BE WEDNESDAY WITH HIGHS IN THE MID/UPPER 90S...AND LOW/MID 90S ON
THURSDAY.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A PERSISTENT UPPER TROUGH THURSDAY NIGHT THROUGH SATURDAY WILL
MAINTAIN AN INLAND SURFACE TROUGH AND ABUNDANT LOW LEVEL MOISTURE
ACROSS THE FORECAST AREA. GREATER COVERAGE OF SHOWERS AND TSTMS
EXPECTED THROUGH SATURDAY. THE UPPER RIDGE MAY ATTEMPT TO REBUILD
SUNDAY INTO MONDAY WHICH COULD DECREASE CONVECTIVE COVERAGE SOMEWHAT.

&&

.AVIATION /22Z MONDAY THROUGH SATURDAY/...
KCHS...SHOWERS ARE BEGINNING TO WORK INTO THE TERMINAL AREA AT
20Z. THUNDERSTORMS REMAIN POSSIBLE AT THE TERMINAL MAINLY THIS
AFTERNOON...WITH THE HIGHEST POTENTIAL FOR STORMS TO PASS OVER THE
TERMINAL THROUGH ABOUT 22Z. DEEP MOISTURE WILL CONTINUE TO FUNNEL
INTO THE REGION THROUGH THIS EVENING AND OVERNIGHT...NECESSITATING
VCSH IN THE FORECAST THROUGH THIS PERIOD. CEILINGS COULD
TEMPORARILY DROP BELOW 3 KFT OVERNIGHT...BUT CONFIDENCE IS LOW AND
CEILING REDUCTIONS IF ANY SHOULD BE TEMPORARY..SO VFR CONDITIONS
HAVE REMAINED IN THE FORECAST FOR NOW. DRY CONDITIONS SHOULD
DOMINATE BY SUNRISE AND TOMORROW WILL SEE VFR CONDITIONS.

KSAV...AS THE AREA OF GREATEST CONVERGENCE MOVES NORTH OF
SAVANNAH...EXPECT SHOWER COVERAGE TO DECREASE THROUGH THE
AFTERNOON. SKIES WILL BEGIN TO CLEAR AS LOW PRESSURE MOVES NORTH
OF THE AREA OVERNIGHT AND VFR CONDITIONS SHOULD PERSIST OVERNIGHT
TONIGHT AND TOMORROW.

EXTENDED AVIATION OUTLOOK...MAIN CONCERNS ARE OCCASIONAL REDUCTIONS
IN VISIBILITY AND/OR CEILING DUE TO SHOWERS AND TSTMS. ALTHOUGH
IMPACTS CANNOT BE RULED OUT ANY DAY...GREATER COVERAGE IS EXPECTED
THURSDAY AND FRIDAY.

&&

.MARINE...
THROUGH TONIGHT...A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT
THROUGH TONIGHT FOR THE OFFSHORE GA WATERS AS LOW PRESSURE MOVES
UP THE SOUTHEAST COAST. SEAS IN THE 5 TO 7 FT RANGE AND GUSTS OVER
25 KTS...ESPECIALLY SEAWARD OF THE GREYS REEF BUOY WHERE THE
NOCTURNAL JET WILL BE THE HIGHEST...CAN BE EXPECTED IN THIS AREA.
SHOWERS AND THUNDERSTORMS WITH HEAVY DOWNPOURS ARE POSSIBLE
THROUGHOUT THE EVENING AND INTO THE LATE NIGHT HOURS...ESPECIALLY
FOR AMZ350.

TUESDAY THROUGH SATURDAY...SOUTHWEST WINDS WILL PREVAIL ACROSS THE
LOCAL WATERS INTO THE WEEKEND. THERE WILL BE PERIODS OF ENHANCED
FLOW...PRIMARILY WITH NOCTURNAL SURGES AND THE AFTERNOON SEA BREEZE
ALONG THE LAND/SEA INTERFACE. THE SMALL CRAFT ADVISORY FOR THE OUTER
GEORGIA WATERS WILL COME DOWN TUESDAY MORNING AS SEAS SUBSIDE TO
LESS THAN 6 FT. OTHERWISE...WINDS WILL GENERALLY TOP OUT IN THE 15-
20 KT RANGE DURING THE PERIODS OF SURGING. SEAS WILL BE HIGHEST
THROUGH TUESDAY NIGHT...UP TO 5 FT AROUND 20 NM AND BEYOND. FROM
WEDNESDAY ONWARD SEAS WILL BE IN THE 2-3 FT RANGE FOR THE NEARSHORE
WATERS AND THE 3-4 FT RANGE FOR THE OUTER WATERS.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 AM EDT TUESDAY FOR AMZ374.

&&

$$



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