Special Weather Statement, NWS Charleston, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
147 PM EDT FRI JUL 1 2011

.SYNOPSIS...
THE REMNANTS OF A STATIONARY FRONT WILL LINGER NEARBY TODAY...AS
WEAK HIGH PRESSURE SETTLES INTO THE AREA THROUGH TONIGHT. ATLANTIC
HIGH PRESSURE WILL THEN PREVAIL THROUGH THE HOLIDAY WEEKEND INTO
EARLY NEXT WEEK. A COLD FRONT WILL APPROACH THE REGION AND STALL
JUST NORTH OF THE FORECAST AREA MIDWEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE FORECAST AREA REMAINS BETWEEN A PERSISTENT UPPER TROUGH ACROSS
THE EAST COAST AND A BUILDING UPPER RIDGE OVER THE CENTRAL UNITED
STATES. WATER VAPOR IMAGERY SHOWS A SERIES OF WEAK SHORTWAVES
SHIFTING SOUTHWARD BETWEEN THE TWO FEATURES ALOFT THROUGH THE DAY.
ALTHOUGH PWAT VALUES HAVE STEADILY DECLINED IN THE PAST TWO
DAYS...WITH THE MORNING CHARLESTON SOUNDING INDICATING ONLY 1.35
INCHES...THE PRESENCE OF UPPER LEVEL SUPPORT AND A LINGERING
SYNOPTIC BOUNDARY SUGGESTS HAS ALLOWED ISOLATED CONVECTION TO
INITIATE ONCE AGAIN THIS AFTERNOON.

PER EARLIER FORECAST MODEL SOLUTIONS...INITIAL DEVELOPMENT HAS
OCCURRED ALONG THE SEABREEZE IN NORTHERN CHARLESTON/EASTERN
BERKELEY COUNTIES...AS WELL AS FAR INTERIOR COUNTIES AHEAD OF THE
SEABREEZE. THE SEABREEZE COULD PUSH AWAY FROM THE SOUTHEAST
GEORGIA COASTLINE BEFORE CONVECTION CAN INITIATE...LOWERING
CONFIDENCE IN THUNDERSTORM COVERAGE EAST OF INTERSTATE 95 IN
SOUTHEAST GEORGIA. WHILE COVERAGE WILL BE SPARSE...GIVEN DCAPES
OF 1000-1200 J/KG AND THE DRY AIR ALOFT...A FEW OF THE LARGER
STORMS COULD PRODUCE STRONG OR PERHAPS DAMAGING DOWNBURST WINDS.

THE OTHER MAIN FORECAST CONCERN FOR TODAY IS THE PLUME OF SMOKE
CURRENTLY IMPACTING CHARLESTON COUNTY AND THE ADJACENT WATERS.
ALTHOUGH DIURNAL MIXING COULD REDUCE THE DENSITY OF THE SMOKE
PLUME OVER LAND AREAS...SEABREEZE PROGRESSION THIS AFTERNOON WILL
PUSH THE MORE STABLE MARINE LAYER AIR ONTO THE COAST...ADVECTING
PATCHY SMOKE FARTHER INLAND AND/OR FURTHER REDUCING VSBYS. AN
ONGOING SPECIAL WEATHER STATEMENT ADDRESSES REDUCED VISIBILITIES
IN SMOKE THROUGH THE AFTERNOON.

HIGH TEMPERATURES ARE EXPECTED TO PEAK IN THE LOW TO MID 90S
INLAND FROM US-17 THIS AFTERNOON...WHILE COASTAL AREAS WILL HOLD
IN THE MID OR UPPER 80S. THE DRY AIR ABOVE THE BOUNDARY LAYER WILL
MIX DOWN IN ADVANCE OF THE SEA BREEZE BOUNDARY...THUS PREVENTING
HEAT INDICES FROM GETTING ANY GREATER THAN 98-100 DEGREES.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/...
FOR TONIGHT...GEOSTROPHIC WINDS UNDER 10 KT AND DECREASING CLOUDS
GIVING WAY TO MOSTLY CLEAR OR PARTLY CLOUDY SKIES WILL ALLOW FOR
RADIATIONAL COOLING TO DROP MIN TEMPS INTO THE UPPER 60S AND LOWER
70S INLAND...INTO THE MID 70S AT THE COAST. PATCHY FOG IS AGAIN
POSSIBLE IN LOCATIONS THAT RECEIVE RAINFALL...BUT COVERAGE IS TOO
LIMITED TO ADD TO THE GRIDDED FORECASTS.

A MID AND UPPER LEVEL RIDGE WILL EXTEND FROM THE CENTRAL U.S. INTO
THE SE U.S. THROUGH THE PERIOD. LOOKS LIKE THE DRIEST DAY WILL BE
SATURDAY AS THE UPPER RIDGE WILL BE THE SHARPEST/STRONGEST AND DEEP
LAYER MOISTURE WILL BE MARGINAL. HAVE KEPT POPS NO HIGHER THAN
14%...WHICH ALSO MATCHES WELL WITH SURROUNDING OFFICES. BY
SUNDAY...SLIGHTLY BETTER DEEP LAYER MOISTURE MAY TRY TO WORK INTO
THE AREA FROM THE NW AROUND THE EAST SIDE OF THE UPPER RIDGE. HAVE
NUDGE POPS UP A TAD TO 15% TO SHOW SLIGHT CHANCE FOR AFTERNOON
CONVECTION SUNDAY AND UP TO 20-30 POPS MONDAY...MAINLY INLAND WITH THE
SEA BREEZE. ANY CONVECTION SHOULD BE DONE BY EARLY EVENING. TEMPS
WILL REMAIN SLIGHTLY ABOVE NORMAL IN THE LOWER TO MID 90S AND LOWS
IN THE LOWER TO MID 70S.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
THE UPPER LEVEL RIDGE MENTIONED ABOVE WILL WEAKEN AND SHIFT WESTWARD
DURING THIS PERIOD AS A BROAD UPPER TROUGH DEVELOPS OVER THE EASTERN
1/3 OF THE COUNTRY. GIVEN LOWER UPPER HEIGHTS...BETTER DEEP LAYER
MOISTURE AND THE POTENTIAL FOR UPPER LEVEL DISTURBANCES TO MOVE
ACROSS THE AREA...HAVE TRENDED POPS UP INTO THE CHANCE CATEGORY
DURING THE AFTERNOONS THROUGH THE PERIOD. A WEAK SURFACE FRONT MAY
STALL JUST NORTH OF THE REGION ON TUESDAY...WHICH COMBINED WITH A
LEE TROUGH AND SEA BREEZE BOUNDARY...SHOULD ALLOW FOR AT LEAST
SCATTERED AFTERNOON AND EVENING CONVECTION. THE SURFACE FLOW WILL BE
WEAK SOUTHERLY THROUGH THE PERIOD...WHICH SHOULD ALLOW DECENT INLAND
PENETRATION OF THE SEA BREEZE...ESPECIALLY NORTH OF THE SAVANNAH
RIVER.

TEMPERATURES ARE EXPECTED TO BE CLOSER TO NORMAL DURING THIS PERIOD.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
HAVE MAINTAIN MAINLY PREVAILING VFR CONDITIONS THROUGH THE 18Z TAF
PERIOD FOR KCHS AND KSAV...WITH THE EXCEPTION OF A FEW HOURS OF
INTERMITTENT MVFR VISIBILITIES DUE TO SMOKE AT KCHS THIS
AFTERNOON. AMENDMENTS MAY BE NEEDED AS THE SEA BREEZE PUSHES
INLAND AND ADVECTS MORE SMOKE ACROSS THE SOUTH CAROLINA AREA.
HOWEVER...LACK OF OBSERVATIONS OVER THE WATERS MAKES FORECASTING
THE TRACK OF THE SMOKE PLUME AND VISIBILITIES DIFFICULT.

REDUCED VISIBILITIES COULD EASILY LINGER THROUGH THE EVENING AND
OVERNIGHT AT KCHS DUE TO SMOKE...WHILE PATCHY FOG COULD ONCE AGAIN
DEVELOP ACROSS SOUTHEAST GEORGIA AND AFFECT KSAV EARLY SATURDAY
MORNING. HAVE KEPT BOTH SITES VFR OVERNIGHT FOR NOW...HOWEVER
DRASTICALLY REDUCED VISIBILITIES CANNOT BE RULED OUT...AS
LINGERING LOW LEVEL MOISTURE AND SMOKE BECOME TRAPPED UNDER THE
INVERSION. WILL REEVALUATE OVERNIGHT VISIBILITIES AT NEXT TAF
ISSUANCE.

EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE WEEKEND...WITH
PERHAPS AN INCREASED CHANCE OF OCCASIONAL MVFR CONDITIONS IN
DIURNAL CONVECTION MONDAY AND TUESDAY.

&&

.MARINE...
WEAK HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE ACROSS
THE COASTAL WATERS THROUGH THE NEAR TERM PERIOD. AS A
RESULT...EXPECT LIGHT SURFACE FLOW TO BECOME DRIVEN BY THE INLAND
SEABREEZE PROGRESSION THIS AFTERNOON. WINDS WILL STEADILY VEER AROUND
TO THE EAST AND SOUTHEAST AT 10 TO 12 KT THIS AFTERNOON/EVENING.
WINDS WILL THEN GRADUALLY DECREASE AGAIN THROUGH THE NIGHT...AS
LAND BREEZE CIRCULATIONS SET IN LATE. A SMALL EAST TO SE SWELL IS
BECOMING NOTICEABLE OVER THE ATLANTIC WATERS...BUT COMBINED SEAS
WILL BE HELD AT 3 FT OR LESS THROUGH TONIGHT.

SATELLITE PICTURES SHOW A LARGE AREA OF SMOKE FROM THE NORTH
CAROLINA WILDFIRE COVERING PORTIONS OF THE COASTAL WATERS THIS
AFTERNOON. VISIBILITIES IN THE SMOKE WILL BE DOWN NEAR 3 NM AT
TIMES...AND COULD PERSIST THROUGH THE AFTERNOON. SINKING AIR
ASSOCIATED WITH THE SEA BREEZE COULD PREVENT THE PARTICULATES FROM
DISPERSING. A MARINE WEATHER STATEMENT IS IN EFFECT FOR THE SMOKE
THROUGH THE AFTERNOON.

NO HIGHLIGHTS EXPECTED THROUGH THE PERIOD AS HIGH PRESSURE REMAINS
OVER AND JUST EAST OF THE REGION. SOUTHERLY WINDS OF 15 KT OR LESS
AND SEAS OF 3 TO 4 FEET OR LESS SHOULD PERSIST THROUGH TUESDAY.
WINDS NEAR THE COAST WILL LIKELY INCREASE TO NEAR 15 KT EACH
AFTERNOON WITH THE SEA BREEZE.

LATER MONDAY AND MONDAY NIGHT...WINDS MAY SURGE UP TO 15 TO 20 KT
AS A SURFACE TROUGH OF LOW PRESSURE BRIEFLY STRENGTHENS OVER THE MID
ATLANTIC AND CAROLINAS IN RESPONSE TO AN UPPER LEVEL TROUGH. THE
POTENTIAL FOR CONVECTION IS EXPECTED TO BE 20% OR LESS THROUGH THE
PERIOD...WITH THE BEST CHANCES MAINLY DURING THE LATE NIGHT AND
EARLY MORNING HOURS.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE CHARLESTON SC
402 AM EDT FRI JUL 1 2011

AMZ330-350-352-354-374-GAZ087-088-099>101-114>119-137>141-SCZ040-
042>045-047>052-020815-
CHARLESTON HARBOR-
WATERS FROM SOUTH SANTEE RIVER TO EDISTO BEACH SC OUT 20 NM-
WATERS FROM EDISTO BEACH SC TO SAVANNAH GA OUT 20 NM-
WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA OUT 20 NM...INCLUDING
GRAYS REEF NATIONAL MARINE SANCTUARY-
WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA EXTENDING FROM 20 TO
60 NM-JENKINS-SCREVEN-CANDLER-BULLOCH-EFFINGHAM-TATTNALL-EVANS-
INLAND BRYAN-COASTAL BRYAN-INLAND CHATHAM-COASTAL CHATHAM-LONG-
INLAND LIBERTY-COASTAL LIBERTY-INLAND MCINTOSH-COASTAL MCINTOSH-
ALLENDALE-HAMPTON-INLAND COLLETON-DORCHESTER-INLAND BERKELEY-
INLAND JASPER-BEAUFORT-COASTAL COLLETON-CHARLESTON-COASTAL JASPER-
TIDAL BERKELEY-
402 AM EDT FRI JUL 1 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL
WATERS...SOUTHEAST GEORGIA AND SOUTHEAST SOUTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

33

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
1149 AM EDT FRI JUL 1 2011

GAZ119-SCZ048>052-020000-
COASTAL CHATHAM-BEAUFORT-COASTAL COLLETON-CHARLESTON-
COASTAL JASPER-TIDAL BERKELEY-
1149 AM EDT FRI JUL 1 2011

...SMOKE FROM DISTANT WILDFIRES IN NORTH CAROLINA WILL IMPACT
PARTS OF THE COASTAL COUNTIES THROUGH THE AFTERNOON...

SMOKE BEING GENERATED FROM WILDFIRES ACROSS NORTH CAROLINA WILL
IMPACT PARTS OF THE SOUTH CAROLINA AND GEORGIA COASTAL COUNTIES
THROUGH THIS AFTERNOON. THIS INCLUDES THE COUNTIES OF
CHARLESTON...COLLETON...BEAUFORT...JASPER AND CHATHAM. THIS ALSO
INCLUDES SUCH COMMUNITIES AS MCCLELLANVILLE...ISLE OF
PALMS...KIAWAH ISLAND...EDISTO BEACH...HUNTING ISLAND...HILTON
HEAD ISLAND AND TYBEE ISLAND. VISIBILITIES WILL OCCASIONALLY BE
DOWN TO 3 TO 5 MILES.

IF YOU OBSERVE LOW VISIBILITIES...CONTACT THE NATIONAL WEATHER
SERVICE IN CHARLESTON AT 1-888-383-2724. YOU CAN ALSO EMAIL YOUR
REPORT TO CHS.SKYWARN@NOAA.GOV OR SEND A TWEET #WXREPORT.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
222 PM EDT FRI JUL 1 2011

SCZ045-050-011845-
CHARLESTON-INLAND BERKELEY-
222 PM EDT FRI JUL 1 2011

...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF CHARLESTON AND
BERKELEY COUNTIES THROUGH 245 PM EDT...

AT 220 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM...NEAR HAMPTON PLANTATION STATE PARK...MOVING
SOUTHWEST AT 10 MPH.

SOME LOCATIONS THAT WILL BE AFFECTED INCLUDE...
CAPE ISLAND...HAMPTON PLANTATION STATE PARK AND SANTEE COASTAL
RESERVE...

PREPARE NOW FOR THE FOLLOWING HAZARDS...
GUSTY WINDS OF 45 TO 55 MPH...
DIME SIZE HAIL...
FREQUENT CLOUD TO GROUND LIGHTNING...
TORRENTIAL RAIN WHICH MAY PRODUCE LOCALIZED FLOODING...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

HAVE AN ACTION PLAN READY IN THE EVENT THIS STORM STRENGTHENS OR A
WARNING IS ISSUED. CONTINUE TO MONITOR NOAA WEATHER RADIO ALL HAZARDS
FOR THE LATEST WEATHER INFORMATION.

&&

LAT...LON 3308 7933 3305 7933 3304 7934 3321 7971
      3328 7958 3328 7957 3325 7953 3324 7945
      3322 7945 3316 7935 3316 7933 3315 7928
      3311 7927
TIME...MOT...LOC 1822Z 024DEG 9KT 3322 7942