959
FXUS62 KCHS 060726
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
326 AM EDT SUN JUL 6 2008
SYNOPSIS
HIGH PRESSURE WILL REMAIN ANCHORED OVER THE ATLANTIC THROUGH THE END
OF THE WEEK. A LOW PRESSURE TROUGH WILL REMAIN OVER THE INLAND
CAROLINAS THROUGH WEDNESDAY...THEN GIVE WAY TO AN APPROACHING COLD
FRONT FOR THURSDAY. THE FRONT WILL STALL NORTH OF THE AREA FOR THE
END OF THE WEEK.
NEAR TERM /UNTIL 6 PM THIS EVENING/
THE UPPER LEVEL LOW OVER THE OH VALLEY WILL DIP FURTHER SE
TODAY...WHILE SHORTWAVE ACTIVITY CONTINUES TO STREAM INTO THE
FORECAST AREA ALONG THE BASE OF THE TROUGH. MODEL SOUNDINGS
INDICATE SOLID S/SW FLOW BRINGING DEEP LAYER MOISTURE INTO THE SE
STATES...WITH PWAT VALUES INCREASING TO 2 INCHES.
SLIGHTLY MORE FAVORABLE UPPER LEVEL DYNAMICS AND AN INCREASED
MOISTURE PROFILE...IN ADDITION TO TYPICAL SUMMERTIME SEABREEZE
FORCING AND INSTABILITY...SUGGEST THAT WIDESPREAD SHOWER AND
THUNDERSTORM DEVELOPMENT IS LIKELY. POPS IN THE LIKELY CATEGORY
DURING THE PEAK HEATING AND INSTABILITY TIMES OF THE AFTERNOON AND
EARLY EVENING LOOK GOOD.
THUNDERSTORMS THAT DEVELOP TODAY WILL HAVE THE POTENTIAL TO BECOME
SEVERE. THE STRONGEST STORMS WILL BE ABLE TO PRODUCE DAMAGING
WINDS AND PENNY HAIL...IN ADDITION TO FREQUENT CLOUD TO GROUND LIGHTNING
AND HEAVY DOWNPOURS WITH LOCALIZED FLOODING. WILL CONTINUE TO MENTION
THE SEVERE POTENTIAL IN THE HAZARDOUS WEATHER OUTLOOK.
HIGH TEMPS WILL LIKELY BE A DEGREE OR TWO COOLER THAN YESTERDAY
DUE TO THE INCREASED CLOUD COVER.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/
TONIGHT...SHOWERS AND THUNDERSTORMS WILL DIMINISH THIS
EVENING...ALTHOUGH CANNOT RULE OUT SOME ACTIVITY LINGERING AROUND
OVERNIGHT DUE TO CONTINUED RESIDUAL INSTABILITY AND SHORTWAVE
ENERGY ALOFT. THUS...WILL KEEP 30/40S POPS GOING. LOWS WILL BE IN
THE LOWER TO MID 70S.
MONDAY...THE UPPER LEVEL LOW WILL MOVE SLOWLY E MON WHILE SLOWLY
WEAKENING BUT WITH CONTINUED HIGH PWAT VALUES AND INSTABILITY
ALONG WITH FAVORABLE JET DYNAMICS/UPPER DIFFLUENCE OVER THE
FORECAST AREA...SHOULD SEE ANOTHER GOOD CHANCE FOR SHOWERS AND
THUNDERSTORMS. THE LACK OF SIGNIFICANT ENVIRONMENTAL FLOW POINTS TO
A HEAVY RAINFALL AND LOCALIZED FLOODING THREAT ALONG WITH DAMAGING
WINDS/HAIL. WILL CONTINUE TO HIGHLIGHT THESE HAZARDS IN THE
HAZARDOUS WEATHER OUTLOOK. HIGHS WILL LIKELY BE KEPT IN THE UPPER
80S DUE TO THE ABUNDANT CLOUD COVER.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
HIGH PRESSURE HOLDING FORT IN THE ATLANTIC WILL STEADILY BUILD
WESTWARD OVER THE SOUTHEAST STATES MONDAY NIGHT INTO TUESDAY WHILE A
SURFACE TROUGH BUILDS FURTHER SW OVER THE MID ATLANTIC STATES. THE
TROUGH WILL SETTLE OVER THE INLAND CAROLINAS TUESDAY AND REMAIN IN
PLACE THROUGH WEDNESDAY. RISING H5 HEIGHTS SUGGEST FEWER UPPER LEVEL
SHORTWAVES WILL BE AVAILABLE TO AID IN CONVECTIVE DEVELOPMENT...AND
THOSE THAT ARE WILL BE WEAKER. NEVERTHELESS...THE PERPETUAL PUMP OF
TROPICAL MOISTURE WILL KEEP PWATS BETWEEN THE 1.5-2.0 INCH RANGE
ALONG WITH CONTINUED HIGH INSTABILITY AND WEAK TO MODEST CAPS THAT
WILL LIKELY AGAIN BE BROKEN BY THE MID AFTERNOON HOURS. WITH
CONVECTIVE TEMPS EXPECTED TO BE REACHED BOTH TUE AND WED AND THE
SEABREEZE AT LEAST MODERATELY ACTIVE...WILL LOOK FOR SCATTERED
CONVECTION BUT COVERAGE SHOULD BE LESS THAN IN PREVIOUS DAYS. WILL
RUN WITH POPS IN THE MID-HIGH CHC CATEGORY TUE THEN DROP TO LOW-MID
CHC CATEGORY WED AS CONFIDENCE DROPS IN TRYING TO PIN DOWN EXACT
LOCATIONS OF BEST CONVECTION. IN ADDITION...HAVE LEFT POPS A BIT
LOWER ON WED THAN TUE AS SFC WINDS LOOK TO PIN THE SEABREEZE CLOSER
TO THE COAST ON WED. USING RECENT TRENDS AS A GUIDE...WILL GENERALLY
HIGHLIGHT SOUTHERN PORTIONS OF THE CWFA WITH THE HIGHER CHCS THEN
DROPPING POPS A BIT GOING NORTH. HAVE ALSO KEPT NIGHTLY POPS GOING
CONSIDERING RECENT TRENDS HAVE SEEN ISOLD SHOWERS/TSTMS DEVELOP.
BY THU...AN UPPER LEVEL TROUGH THAT LOOKS TO DIG THROUGH THE GREAT
LAKES WILL PUSH A COLD FRONT THROUGH THE OHIO VALLEY TOWARD THE
MASON DIXON LINE. HOWEVER...THE AFOREMENTIONED AREA OF SFC HIGH
PRESSURE WILL KEEP THE FRONT N OF THE AREA. WITH MOISTURE REMAINING
DEEP...INSTABILITY REMAINING HIGH AND AGAIN FACTORING IN THE
SEABREEZE...WILL KEEP CHC POPS IN PLACE.
FOR FRI-SAT...THE FRONTAL BOUNDARY WILL STALL N OF THE AREA WHILE
THE UPPER DOME OF HIGH PRES OVER THE FL BIG BEND AREA SHIFTS W. THIS
WILL ALLOW FOR LOWERING H5 HEIGHTS...WEAKER CAPPING AND THE
SEABREEZE TO WORK WITH THE RESIDUAL SFC TROUGH. MOISTURE WILL REMAIN
DEEP SO WILL CONTINUE WITH CHC POPS THROUGH THE END OF THE WEEK.
AS FOR TEMPS...WITH SLIGHTLY BUILDING H5 HEIGHTS THROUGH MIDWEEK AND
AN APPROACHING COLD FRONT THAT MAY MAKE FOR SOME COMPRESSIONAL
HEATING...MAX TEMPS WILL REMAIN IN THE LOWER 90S THROUGH THE END OF
THE WEEK. FACTORING IN DEWPOINTS IN THE LOWER 70S...HEAT INDEX
VALUES WILL LIKELY REACH THE 99-103 RANGE WED-SAT AND THE ISOLD 105
DEGREE READING CANNOT BE RULED OUT.
WE CONTINUE TO CAREFULLY MONITOR THE PROGRESSION OF TROPICAL STORM
BERTHA. THE DAY 7 NHC/HPC COORDINATED POSITION IS ROUGHLY 480 MILES
EAST OF DAYTONA BEACH FLORIDA.
AVIATION /07Z SUNDAY THROUGH THURSDAY/
THE WIND SENSOR AT THE KCHS ASOS REMAINS OUT OF SERVICE. AMENDMENTS
FOR WINDS WILL NOT BE ISSUED FOR THE KCHS TAF UNTIL FURTHER
NOTICE. KCHS TAFS WILL INCLUDE THE REMARK AMD LTD TO CLD AND VIS
UNTIL THE SENSOR IS REPAIRED.
MID CLOUD CEILINGS WILL PREVAIL THROUGH TONIGHT. CANNOT RULE OUT
BRIEF MVFR CEILINGS/VISIBILITIES OVERNIGHT DUE TO RAIN THAT FELL
AT BOTH SITES SATURDAY AFTERNOON. OTHERWISE...AFTER A VFR START...WITH
MID CLOUD CEILINGS POSSIBLE...THUNDERSTORM DEVELOPMENT IS LIKELY
THIS AFTERNOON...WITH IMPROVED DYNAMICS AND INCREASED MOISTURE ACROSS
THE AREA. CONFIDENCE IS SUFFICIENT TO INCLUDE TEMPO GROUPS FOR
THUNDERSTORMS AT BOTH SITES DURING THE 17Z-23Z TIME FRAME SUNDAY.
HOWEVER...LINGERING ACTIVITY IS POSSIBLE EVEN AFTER 23Z...ESPECIALLY
AT KSAV...SO AMENDMENTS TO ADJUST TIMING/IMPACTS OF THUNDERSTORMS
DURING THE AFTN/EVE ARE EXPECTED.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE POSSIBLE
WITHIN SHRA/TSRA...MAINLY EACH AFTERNOON/EVENING. OTHERWISE VFR
WEATHER WILL PREVAIL.
MARINE
THE COASTAL WATERS WILL REMAIN ON THE WESTERN PERIPHERY OF
ATLANTIC HIGH PRESSURE THROUGH MONDAY. BASICALLY A PERSISTENCE
FORECAST WITH NOT MUCH CHANGE TO THE OVERALL SYNOPTIC PATTERN.
EXPECT BRIEF INCREASES IN WINDS DURING THE AFTERNOON SEABREEZE
DEVELOPMENT ALONG THE COAST AND IN THE EVENING DUE TO NOCTURNAL
SURGING. SEAS WILL AVERAGE 2 TO 4 FT...PERHAPS AS HIGH AS 5 FT
TONIGHT BEYOND 20 NM.
MONDAY NIGHT THROUGH THURSDAY...GENERALLY SW-S FLOW WILL PREVAIL OVER
THE WATERS FROM THE MIDDLE OF THE WEEK THROUGH THE WEEKEND AS
ATLC HIGH PRESSURE REMAINS CENTERED OFFSHORE AND NO FRONTS ARE
EXPECTED TO MOVE THROUGH THE WATERS. ASIDE FROM TYPICAL DIURNAL
SURGES...ESP WITH THE SEABREEZE... CONDITIONS WILL REMAIN BELOW
SCA LEVELS WITH WIND SPEEDS CAPPED AT 15 KNOTS AND SEAS CAPPED AT
4 FT.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
RJB/JPC
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