Special Weather Statement, NWS Charleston, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
350 PM EDT SAT JUL 9 2011

.SYNOPSIS...
A WEAK COLD FRONT WILL DROP INTO THE AREA TONIGHT AND
SUNDAY...STALLING OVER THE AREA BEFORE DISSIPATING ON MONDAY.
ANOTHER FRONT WILL APPROACH FROM THE NORTH LATE NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
A PRONOUNCED ALBEIT ELONGATED SHORTWAVE WAS SEEN ON WATER VAPOR
IMAGERY THIS AFTERNOON DROPPING INTO NORTH CENTRAL SC. THIS
FEATURE IS ENTERING A REGION OF ENHANCED MIXED-LAYER CAPE THAT HAS
DEVELOPED OVER INTERIOR SC. APPROXIMATELY 3000-3500 JOULES ARE
CURRENTLY SHOWING UP ON THE SPC MESOANALYSIS. MID-LEVELS REMAIN
VERY WARM WHICH WILL LIMIT HAIL GROWTH. HOWEVER WITH ROBUST CAPE
VALUES...FAIRLY BEEFY CORES WILL BE ABLE TO DEVELOP WHICH CAN
PRODUCE ISOLATED DAMAGING WIND GUSTS WHEN THEY COLLAPSE.

EARLIER TODAY WE SAW SCATTERED COVERAGE OF SHOWERS AND
THUNDERSTORMS...INCLUDING A STORM THAT MOVED OVER THE CHARLESTON
AIRPORT. VISIBLE SATELLITE HAS SHOWED MOST OF THE CUMULUS FIELD
DISSOLVED IN SOUTHEAST GA AS EARLIER OUTFLOWS STABILIZED THE
BOUNDARY LAYER. A DECENT CU FIELDS REMAINS ACROSS SOUTHERN SC
WHILE SEVERAL CLUSTERS OF STRONG THUNDERSTORMS MOVE IN FROM THE
NW. BEST PRECIP CHANCES WILL BE IN SOUTHERN SC THROUGH MID EVENING
AS THE INCREASINGLY ORGANIZED UPSTREAM CONVECTION CONGEALS AND
MOVES SOUTHEAST WITH THE SHORTWAVE. LATER THIS EVENING AND
OVERNIGHT WE MAINTAINED 20-30 POPS FOR SHOWERS OR STORMS THAT POP
AHEAD OF THE SHORTWAVE. HOWEVER WITH THE LOSS OF DAYTIME HEATING
THE COVERAGE SHOULD BE SUBSTANTIALLY LOWER.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SUNDAY...A REMNANT BOUNDARY WILL EXTEND EAST/WEST ACROSS SOUTHEAST
GEORGIA WHILE A WEAK MID LVL LOW LINGERS ALONG THE SC/GA COASTLINE. A
SLIGHT CHANCE TO CHANCE OF SHOWERS AND THUNDERSTORMS ARE FORECAST
SUNDAY AFTERNOON...MAINLY FOR AREAS SOUTH OF THE SAVANNAH RIVER...AS
WEAK AREAS OF LOW PRESSURE DEVELOP ALONG THE REMAINING BOUNDARY.
PWATS BETWEEN 2-2.5 INCHES...DEWPTS IN THE MID 70S...AND A WEAK
SHEAR ENVIRONMENT...SUGGEST SCATTERED PULSE TYPE CONVECTION WITH
HEAVY RAINFALL BEING THE PRIMARY THREAT. CAN NOT RULE OUT AN
ISOLATED STRONG WIND GUST FROM THUNDERSTORMS NEAR THE REMNANT
BOUNDARY AS SBCAPES APPROACH 2500 J/KG. SHOWER/THUNDERSTORM ACTIVITY
WILL LIKELY DIMINISH SUNDAY EVENING AS THE SFC BOUNDARY WASHES OUT
AND MID LVL RIDGING BUILDS OVER THE REGION FROM THE WEST.

1000-850MB THICKNESS VALUES SUPPORT LOW/MID 90S FOR HIGHS
SUNDAY...WITH HIGHEST TEMPS OVER INLAND PORTIONS OF SC AND GA. THERE
IS POTENTIAL FOR HEAT ADVISORY CONDITIONS WEST OF INTERSTATE 95
SHOULD DEWPTS REMAIN IN THE MID 70S DURING AFTERNOON HOURS.
OVERNIGHT LOWS WILL BE IN THE LOW 70S...WITH MID/UPPER 70S ALONG THE
IMMEDIATE COASTLINE.

MONDAY AND TUESDAY...THE MAIN CONCERN EARLY NEXT WEEK WILL BE THE
POTENTIAL FOR SOLID HEAT ADVISORY CONDITIONS. 1000-850MB THICKNESS
VALUES SUPPORT OVERALL HIGH TEMPS IN THE MID/UPPER 90S OVER INLAND
AREAS AS SFC HIGH PRESSURE BUILDS IN FROM THE NORTH WHILE A STRONG
MID LVL RIDGE BECOMES CENTERED OVER THE SOUTHEAST. WITH SFC DEWPTS
REMAINING IN THE LOW 70S DURING PEAK HEATING HOURS...HEAT INDEX
VALUES BETWEEN 105 TO 110 ARE POSSIBLE. SHOULD EXPECTED CONDITIONS
PERSIST A HEAT ADVISORY WILL LIKELY BE NEEDED FOR MONDAY AND TUESDAY
AFTERNOON. OVERNIGHT LOWS WILL BE IN THE MID 70S...WITH UPPER 70S
ALONG THE COAST.

A SLIGHT CHANCE TO CHANCE OF SHOWERS/THUNDERSTORMS ARE FORECAST
MONDAY AND TUESDAY WITH HIGHEST POPS OVER EXTREME SOUTHERN PORTIONS
OF THE CWA WHERE PWATS BETWEEN 1.5 TO 2 INCHES RESIDE. OVERALL
COVERAGE WILL BECOME LESS MONDAY THROUGH TUESDAY AS THE MID LVL
RIDGE REMAINS OVER THE SOUTHEAST.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
WEDNESDAY WILL BE ANOTHER VERY WARM DAY WITH HEAT INDICES IN EXCESS
OF 100...ALTHOUGH THERE LOOKS TO BE A SLIGHTLY BETTER CHANCE FOR
DIURNAL CONVECTION...GIVING A FEW PLACES SOME TEMPORARY COOLING...AS
MID LEVEL MOISTURE BEGINS TO RETURN AND THE UPPER LEVEL RIDGE SLOWLY
WEAKENS. THE GFS IS MOST AGGRESSIVE WITH THE CHANCES OF PRECIP...BUT
EVEN THE SLOWER ECMWF INDICATES SOME THUNDERSTORM ACTIVITY DURING
THE TIME OF AFTERNOON MAXIMUM HEATING.

TIMING DIFFERENCES BETWEEN THE MODELS MAKE THE END OF THE WEEK SOMEWHAT
DIFFICULT FOR DETAILS...BUT THE GENERAL CONCEPT OF A STRONGER FRONT
MOVING THROUGH IS SIMILAR. FOR NOW...I AM GOING WITH THE FRONT
PASSING THROUGH THE CWA DURING THE DAY ON THURSDAY FROM NORTH TO
SOUTH...BUT I COULD BE BRINGING IT THROUGH A BIT QUICK IF THE
ECMWF/GEM SOLUTION TURN OUT TO BE BETTER.

IN ANY CASE...THE CHANCE OF PRECIP INCREASES AGAIN WITH THE FRONT ON
THURSDAY INTO THURSDAY EVENING.

THE GFS INDICATES SOME DRYING AND SLIGHT COOLING FOR FRIDAY AND
SATURDAY BEHIND THE FRONT...AND I HAVE FOLLOWED THIS SOLUTION FOR
NOW. IF THE FRONT IS SLOWER...HOWEVER...I MAY BE COOLING OFF THE
OVERNIGHT MINS TOO QUICKLY IN THE CURRENT FORECAST.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
SHOWERS/STORMS SHOULD INCREASE IN COVERAGE THROUGH THE AFTERNOON
AND INTO EARLY THIS EVENING AS A SHORTWAVE TROUGH DROPS IN FROM
THE NORTH AND THE SEABREEZE INTERACTS WITH RESIDUAL BOUNDARIES.
LOOKS LIKE BETTER CHANCES AT KCHS SO WE ADDED A TEMPO LATER THIS
AFTERNOON FOR SOME TSRA. LATER TONIGHT WE COULD SEE A BIT OF FOG
DEVELOPMENT GIVEN THE WET SOIL. WILL HOLD OFF ON VSBY RESTRICTIONS
UNTIL WE CAN BETTER PIN DOWN TIMING.

EXTENDED AVIATION...MVFR/IFR CIGS/VSBYS POSSIBLE DURING
THUNDERSTORMS SUNDAY AFTERNOON...MAINLY FOR THE KSAV TERMINAL.
MVFR VSBY/CIGS THEN POSSIBLE AT KSAV DURING EARLY MORNING HOURS
DUE TO SMOKE FROM FIRES FROM THE WEST.

&&

.MARINE...
WINDS AND SEAS WILL REMAIN BELOW SCA CRITERIA LATE THIS WEEKEND
INTO EARLY NEXT WEEK. IN GENERAL S/SE WINDS WILL REMAIN AT OR
BELOW 15 KTS...WITH PEAK WINDS ALONG THE COAST DURING AFTERNOON
SEABREEZE CIRCULATIONS MONDAY AND TUESDAY. SEAS BETWEEN 3 TO 4 FT
WILL SUBSIDE TO 2 TO 3 FT BY SUNDAY NIGHT WITH LITTLE CHANGE
THROUGH EARLY NEXT WEEK. A CHANCE OF SHOWERS AND THUNDERSTORMS ARE
POSSIBLE SUNDAY ALONG A REMNANT BOUNDARY EXTENDING ACROSS THE
COASTAL WATERS. ACTIVITY WILL LESSEN MONDAY AND TUESDAY AS THE
BOUNDARY WEAKENS.

WINDS WILL PICK UP A BIT AGAIN ON WEDNESDAY AHEAD OF THE NEXT
FRONT. WINDS MAY BE BACK INTO THE 15 TO 20 KNOT RANGE FROM THE
NORTHEAST OR EAST BEHIND THE FRONT LATE IN THE WEEK...BUT THE
TIMING IS SOMEWHAT UNCERTAIN AT THIS POINT.

&&

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

&&

JRL/DPB

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SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
424 PM EDT SAT JUL 9 2011

SCZ044-045-050-052-092115-
CHARLESTON-DORCHESTER-INLAND BERKELEY-TIDAL BERKELEY-
424 PM EDT SAT JUL 9 2011

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF DORCHESTER...
CHARLESTON AND BERKELEY COUNTIES THROUGH 515 PM EDT...
...MARINERS ON LAKE MOULTRIE SHOULD SEEK SAFE HARBOR...

AT 420 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM...NEAR NORTHERN LAKE MOULTRIE...MOVING SOUTHEAST
AT 10 MPH.

SOME LOCATIONS THAT WILL BE AFFECTED INCLUDE...
BONNEAU...BONNEAU BEACH...COLLEGE PARK...CROSS...EADYTOWN...EASTERN
LAKE MARION...HUGER...JAMESTOWN...JEDBURG...MONCKS CORNER...NORTHERN
LAKE MOULTRIE...OLD SANTEE CANAL STATE PARK...PINOPOLIS...SAINT
STEPHEN...SANGAREE...SOUTHERN LAKE MOULTRIE AND SUMMERVILLE...

PREPARE NOW FOR THE FOLLOWING HAZARDS...
GUSTY WINDS OF 40 TO 50 MPH...
PENNY SIZE HAIL...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS THUNDERSTORM IS CAPABLE OF PRODUCING VERY HEAVY RAIN...WHICH MAY
FLOOD DITCHES AND LOW-LYING AREAS. REDUCE VEHICLE SPEED TO LOWER THE
RISK OF HYDROPLANING. DO NOT DRIVE INTO PLACES WHERE WATER COVERS THE
ROAD. SEEK AN ALTERNATE ROUTE.

BE ALERT FOR RAPIDLY CHANGING WEATHER CONDITIONS AS STORMS APPROACH.
BE READY TO TAKE IMMEDIATE ACTION IN CASE A SEVERE THUNDERSTORM
WARNING IS ISSUED FOR YOUR LOCATION.

&&

LAT...LON 3304 7992 3300 8022 3326 8039 3328 8035
      3327 8030 3330 8026 3345 8022 3346 8015
      3348 8016 3350 8013 3351 8005 3350 7996
      3344 7986 3341 7985 3338 7979 3332 7974
      3323 7946
TIME...MOT...LOC 2024Z 315DEG 6KT 3332 8007

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHARLESTON SC
524 PM EDT SAT JUL 09 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0518 PM     TSTM WND GST     GOOSE CREEK             32.98N  80.03W
07/09/2011  E50 MPH          BERKELEY           SC   TRAINED SPOTTER

            TRAINED SPOTTER ESTIMATED 50 MPH WIND GUST.

&&

EVENT NUMBER CHS1100648

BDC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHARLESTON SC
553 PM EDT SAT JUL 09 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0454 PM     TSTM WND DMG     1 W JAMESTOWN           33.29N  79.71W
07/09/2011                   BERKELEY           SC   911 CALL CENTER

            TREES DOWN ALONG HWY 45 IN JAMESTOWN.

&&

EVENT NUMBER CHS1100649

BDC

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