Lake Wind Advisory 18, NWS Charleston, SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
345 PM EDT TUE APR 3 2007

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...HIGH PRES CENTERED N
OF THE BAHAMAS IS CONTINUING TO XTND NWWD OVR THE AREA TDA AND WILL
DO SO THROUGH TNGT. EVEN WITHIN THE WRN EXTENT OF THIS HIGH...
DEEPENING MOISTURE AND INCRG INSTABILITY AHEAD OF A STRONG CDFNT OVR
THE CENTRAL CONUS IS MAKING FOR SCATTERED CONVECTION OVR THE CWFA
TDA. SHWRS AND A FEW TSTMS HAVE POPPED UP ON KCLX RADAR...MEANING
THAT THEY WERE ABLE TO OVERCOME A NEARLY 6 DEGREE C CAP AND MAKE USE
OF NEARLY 2000 J/KG CAPE AND -6 LI. HOWEVER...RATHER ISOLD COVERAGE
SEEMS TO JUSTIFY THE SLIGHT/LOW CHC POPS THROUGH THE REST OF TDA AND
INTO TNGT. BOUNDARY INTERACTIONS AND THE SEABREEZE ARE ALSO HELPING
STORMS SUSTAIN THEMSELVES BUT STORM DURATIONS ARE RATHER LIMITED.

FOR TNGT...ALTHOUGH THE DAYTIME HEATING WILL BE LOST...DYNAMICS WILL
BE INCRG WITH A 50 KT LLVL JET AND 100 KT UPR LVL JET MOVG INTO THE
AREA TNGT AND LASTING THROUGH TMRW MRNG AS A PRE-FRONTAL SFC TROF
APCHS. EVEN SO...COVERAGE IS XPCTD TO BE QUITE LOW OVRNGT SO WILL
CONTINUE TO ADVERTISE ONLY SLGT CHC POPS.

WITH THE RETURN OF HEATING TO THE ALREADY IMPRESSIVE DYNAMICS
TMRW...STORMS WILL HAVE A BETTER CHANCE OF FORMING AND POSSIBLY
BECOMING STRONG TO SEVERE. OF NOTE IS A COLD POOL N OF THE CWFA...IN
NC AND JUST INCHING INTO SC...WHICH MAY MOVE S AND INTERACT WITH THE
CDFNT MOVG IN FROM THE W. IN ADDITION...CAPES WILL STILL BE IN THE
1500-2000 J/KG RANGE WITH DEWPTS IN THE LOW-MID 60S AND GOOD JETTING
PLUS XPCTD SEABREEZE DEVELOPMENT. COVERAGE IS STILL XPCTD TO BE
LACKING...SO ATTM WILL PUSH POPS INTO THE LOW CHC CATEGORY.

NO POPS XPCTD FOR TMRW NIGHT AS FRONT PUSHES OFFSHORE AND MUCH DRIER
AIR AND NWLY FLOW MOVES INTO THE AREA.

TEMPS WILL CONTINUE TO BE WARM THROUGH TMRW...PARTICULARLY WITH
DEWPTS HOLDING IN THE LOW-MID 60S THROUGH TMRW AHEAD OF THE FNT.
LOWS TNGT WILL FALL TO THE MID AND UPR 60S WHILE MAX TEMPS TMRW RISE
INTO THE LOW AND MID 80S. AS THE CDFNT PUSHES THROUGH THE CWFA
TMRW...WITH FROPA XPCTD ARND 00Z...CAA WILL BEGIN IN EARNEST TMRW
NIGHT AND FORCE LOW TEMPS THU MRNG IN THE MID 40S.
&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...A BIG PATTERN CHANGE IS IN
STORE FOR THE FORECAST AREA DURING THE EXTENDED PERIOD...WITH MEDIUM
RANGE OPERATIONAL AND ENSEMBLE GUIDANCE IN REMARKABLY GOOD AGREEMENT
THIS AFTERNOON. LARGE SCALE UPPER RIDGING WHICH HAS BEEN RESPONSIBLE
FOR THE UNSEASONABLY WARM WEATHER AS OF LATE...WILL BREAK DOWN BY
THE END OF THE WORK WEEK...WITH LONGWAVE UPPER TROUGHING THEN TAKING
HOLD OF THE EASTERN HALF OF THE CONUS THROUGH EARLY NEXT WEEK. AT
THE SURFACE...HIGH PRESSURE WILL CONTINUE TO BUILD IN BEHIND THE
DEPARTING COLD FRONT THURSDAY...AND WILL REMAIN IN FIRM CONTROL OF
THE AREAS WEATHER THROUGH EARLY NEXT WEEK. THEREFORE WILL KEEP THE
FORECAST RAIN FREE THROUGH THE EXTENDED PERIOD. TEMPERATURES ARE
EXPECTED TO RUN BELOW CLIMO THROUGH THE PERIOD...WITH HIGHS 10 TO 15
DEGREES BELOW NORMAL SAT AND SUN. FROST/FREEZE CONDITIONS APPEAR TO
BE A PRETTY GOOD BET BOTH SAT NIGHT AND SUN NIGHT...AND WILL
HIGHLIGHT THIS IN THE HWO.
&&

.AVIATION /18Z-18Z/...CONVECTIVE CAP WAS SUFFICIENTLY BROKEN THIS
AFTN WITH SCATTERED SHWRS/TSTMS BREAKING OUT ACROSS THE SC/GA
COASTAL PLAINS. A FEW SHWRS CAME OVER KCHS...INCLUDING A REPORT OF
TCU...BUT NO LIGHTNING STRIKES. MOST OF THE SHWRS WERE WITHIN THE
5-10NM DONUT AN HOUR BEFORE THE 18Z ISSUANCE TIME SO KEPT THE VC
IDEA GOING WITH VCSH THROUGH 19Z THEN SHIFTED TO VCTS AT 20Z TO
ACCOUNT FOR BETTER DAYTIME HEATING AND ANTICIPATED CONVECTION. DID
NOT FEEL COMFORTABLE ACTUALLY PINNING DOWN TS DUE TO SCATTERED TSTM
NATURE SO LEFT IT OUT AND WILL CONTINUE TO MONITOR RADAR TRENDS
THROUGH THE REST OF THE DAYLIGHT HOURS.

AFTER DARK...A RATHER POTENT CDFNT WILL APPROACH FROM THE NW WHICH
LOOKS TO PUSH THROUGH THE AREA LATE DAY WED. ALONG WITH THE
CONTINUED LOWER CLOUD DECKS LATE TNGT INTO TMRW...A SMALL CHC OF
SHWRS/TSTMS MAY OCCUR ALONG A PRE-FRONTAL TROUGH. CONFIDENCE REMAINS
LOW ON THIS SCENARIO SO HAVE NOT INCLUDED PRECIP MENTION BUT SHOULD
THE MODELS CONVERGE ON A BETTER SOLUTION...THEN LATER TAFS MAY HAVE
PRECIPITATION INCLUDED TMRW.

IN ADDITION TO PRECIP CONCERNS...LOW LEVEL JETTING AHEAD OF THE FNT
WILL PUT WINDS IN THE 25-35 KT RANGE AT ARND 2K FT AGL. WITH WINDS
XPCTD TO DECOUPLE LATE TNGT...LLWS CRITERIA IS EXPECTED TO BE MET
AROUND SUNRISE TMRW MRNG SO HAVE INCLUDED LLWS AT BOTH TERMINALS.
&&

.MARINE...WITH HIGH PRES REMAINING OVR THE WATERS THROUGH MIDDAY
TMRW AHEAD OF AN APCHG CDFNT...CONDS WILL REMAIN RATHER BENIGN.
WINDS MAY PICK UP A BIT TMRW...TO ARND 15 KT...AS THE GRADIENT
TIGHTENS BUT CONDS ARE XPCTD TO REMAIN BELOW SCA. SCA CONDS BECOME
POSSIBLE LATE WED NIGHT/EARLY THU MRNG...MAINLY OVR THE OUTER GA
WATERS...AS STRONG CAA OVR LAND PUSHES OUT OVR THE WATERS AND STRONG
SUBSIDENCE WILL FORCE QUITE EFFICIENT MIXING WITH THE WARM WATERS.
HOWEVER... AM HOLDING OFF RAISING THE 3RD PERIOD SCA DUE TO ONLY
MODERATE CONFIDENCE THAT SPEEDS WILL REACH SCA LEVELS. SEAS THROUGH
WED NIGHT WILL REMAIN AOB 3 FT IN ALL NEARSHORE WATERS AND AOB 5 FT
IN THE OUTER GA WATERS.

HIGH PRESSURE WILL BUILD IN BEHIND THE DEPARTING COLD FRONT ON
THURSDAY...AND WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH THE
WEEKEND. SCA HEADLINES MAY BE NECESSARY FOR PORTIONS OF THE WATERS
LATE WED NIGHT AND EARLY THU AM...FOR STRONG WINDS FOLLOWING FRONTAL
PASSAGE. OTHERWISE...CONDITIONS ACROSS THE COASTAL WATERS ARE
EXPECTED TO REMAIN BELOW SCA CRITERIA THU AFTERNOON THROUGH SUN.
&&

.FIRE WEATHER...DOWNSLOPE FLOW BEHIND A STRONG COLD FRONT WILL
RESULT IN CRITICAL RH VALUES ACROSS THE ENTIRE FORECAST AREA ON
THURSDAY. DRY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH EARLY NEXT
WEEK...WITH CRITICALLY LOW RH VALUES POSSIBLE EACH DAY THU THROUGH
MON.
&&

.LAKE WINDS...STRONG PRE-FRONTAL LOW LEVEL JETTING TMRW FOLLOWED BY
STRONG CAA BEHIND THE FNT TMRW NIGHT ARE EXPECTED TO INCRS WIND
SPEEDS RATHER SIGNIFICANTLY OVER LAKE MOULTRIE. LLVL JET OF 45-50 KT
OVR THE WARM LAKE WATERS LOOK TO MAKE FOR FAIRLY GOOD MIXING AND MAY
PUSH WIND SPEEDS IN EXCESS OF 20 KT. ATTM...AM NOT QUITE CONFIDENT
ENOUGH SPEEDS WILL REACH ENOUGH DURATION FOR A LWA BUT WILL MAINTAIN
STRONG WIND SPEEDS AND LET MIDNIGHT SHIFT MAKE FINAL DETERMINATION
ON NEED FOR A LWA.
&&

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

&&

JPC/JRJ

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE CHARLESTON SC
352 PM EDT TUE APR 3 2007

GAZ087-088-099>101-114>116-118-137-138-140-SCZ040-042>044-047>051-
040930-
JENKINS-SCREVEN-CANDLER-BULLOCH-EFFINGHAM-TATTNALL-EVANS-
INLAND BRYAN-INLAND CHATHAM-LONG-INLAND LIBERTY-INLAND MCINTOSH-
ALLENDALE-HAMPTON-INLAND COLLETON-DORCHESTER-INLAND JASPER-BEAUFORT-
COASTAL COLLETON-CHARLESTON-COASTAL JASPER-
352 PM EDT TUE APR 3 2007

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

.DAY ONE...TONIGHT. NO HAZARDOUS WEATHER IS EXPECTED AT THIS
TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
.FROST/FREEZE...WELL BELOW NORMAL TEMPERATURES WILL IMPACT MUCH
OF THE REGION THIS WEEKEND. THERE IS A CHANCE THAT FROST AND/OR
FREEZE CONDITIONS MAY OCCUR AWAY FROM THE IMMEDIATE COASTAL
AREAS...PARTICULARLY SATURDAY NIGHT AND AGAIN SUNDAY NIGHT.
FREEZE WATCHES MAY EVENTUALLY BE NEEDED.

.STRONG THUNDERSTORMS...A STRONG COLD FRONT WILL APPROACH THE
REGION FROM THE NORTHWEST ON WEDNESDAY...AND THIS MAY RESULT IN A
FEW STRONG THUNDERSTORMS CAPABLE OF PRODUCING STRONG GUSTY WINDS
AND LARGE HAIL.

.FIRE WEATHER...
CRITICAL RH VALUES ARE EXPECTED THURSDAY AFTERNOON. CRITICALLY LOW
RH VALUES WILL CONTINUE TO BE A POSSIBILITY FRI THROUGH MON. REFER TO
THE FIRE WEATHER FORECAST FOR ADDITIONAL DETAILS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

SCZ045-040930-
BERKELEY-
352 PM EDT TUE APR 3 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH CAROLINA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
.FROST/FREEZE...WELL BELOW NORMAL TEMPERATURES WILL IMPACT MUCH
OF THE REGION THIS WEEKEND. THERE IS A CHANCE THAT FROST AND/OR
FREEZE CONDITIONS MAY OCCUR BOTH SATURDAY NIGHT AND AGAIN SUNDAY
NIGHT. FREEZE WATCHES MAY EVENTUALLY BE NEEDED.

.STRONG THUNDERSTORMS...A STRONG COLD FRONT WILL APPROACH THE
REGION FROM THE NORTHWEST ON WEDNESDAY...AND THIS MAY RESULT IN A
FEW STRONG THUNDERSTORMS CAPABLE OF PRODUCING STRONG GUSTY WINDS
AND LARGE HAIL.

.FIRE WEATHER...
CRITICAL RH VALUES ARE EXPECTED THURSDAY AFTERNOON. CRITICALLY LOW
RH VALUES WILL CONTINUE TO BE A POSSIBILITY FRI THROUGH MON. REFER TO
THE FIRE WEATHER FORECAST FOR ADDITIONAL DETAILS.

.LAKE WINDS...A LAKE WIND ADVISORY FOR LAKE MOULTRIE MAY BE NEEDED
WEDNESDAY. REFER TO THE RECREATIONAL FORECAST FOR ADDITIONAL DETAILS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

AMZ330-350-352-354-370-374-040930-
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 SOUTH SANTEE RIVER SC TO SAVANNAH GA EXTENDING FROM
20 NM TO 40 NM-
WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA EXTENDING FROM 20 TO
60 NM-
352 PM EDT TUE APR 3 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
.STRONG THUNDERSTORMS...A STRONG COLD FRONT WILL APPROACH THE
REGION FROM THE NORTHWEST ON WEDNESDAY...AND THIS MAY RESULT IN A
FEW STRONG THUNDERSTORMS CAPABLE OF PRODUCING STRONG GUSTY WINDS
AND LARGE HAIL.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

GAZ117-119-139-141-040930-
COASTAL BRYAN-COASTAL CHATHAM-COASTAL LIBERTY-COASTAL MCINTOSH-
352 PM EDT TUE APR 3 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST GEORGIA.

.DAY ONE...THIS AFTERNOON AND TONIGHT.
NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.
.STRONG THUNDERSTORMS...A STRONG COLD FRONT WILL APPROACH THE
REGION FROM THE NORTHWEST ON WEDNESDAY...AND THIS MAY RESULT IN A
FEW STRONG THUNDERSTORMS CAPABLE OF PRODUCING STRONG GUSTY WINDS
AND LARGE HAIL.

.FIRE WEATHER...
CRITICAL RH VALUES ARE EXPECTED THURSDAY AFTERNOON. CRITICALLY LOW
RH VALUES WILL CONTINUE TO BE A POSSIBILITY FRI THROUGH MON. REFER TO
THE FIRE WEATHER FORECAST FOR ADDITIONAL DETAILS.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

JRJ