Area Forecast Discussion
Issued by NWS Charleston, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KCHS 020138
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
938 PM EDT SAT AUG 1 2015

.SYNOPSIS...
A STATIONARY FRONT WILL DISSIPATE OVER OR NEAR THE AREA THROUGH
SUNDAY AS HIGH PRESSURE BUILDS IN EARLY NEXT WEEK. AN INLAND LOW
PRESSURE TROUGH WILL THEN DEVELOP BY LATE NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
CONDITIONS WILL FAVOR THE FORMATION AND THEN A SLOW EXPANSION OF
LOW STRATUS AND FOG EARLY SUNDAY. THE RISK FOR FOG WILL BE
HIGHEST ACROSS FAR INTERIOR SOUTHEAST SOUTH CAROLINA AND SOUTHEAST
GEORGIA CLOSEST TO THE WEAK STATIONARY FRONT...WHILE STRATUS IS
MORE LIKELY CLOSER TO THE COAST WHERE INFLUENCES FROM THE
NOCTURNAL LOW-LEVEL JET CURRENTLY ORGANIZING OFF THE GEORGIA
BEACHES WILL BE GREATER. IT IS STILL SOMEWHAT UNCLEAR EXACTLY HOW
WIDESPREAD EITHER ELEMENT WILL BECOME THIS FAR OUT...BUT THE
02/18Z NAM 1000 MB CONDENSATION PRESSURE DEFICIT PROGS WITH
SUPPORT FROM THE LATEST RAP AND 21Z RUN OF THE NCEP TIME-LAGGED
NORTH AMERICAN RAPID REFRESH ENSEMBLE SYSTEM /NARRE-TL/ ARE
CERTAINLY TRENDING TOWARDS A FOGGIER SOLUTION ACROSS THE SOUTHERN
SOUTH CAROLINA MIDLANDS...EAST-CENTRAL GEORGIA AND OUR FAR INLAND
ZONES. WILL INCREASE THE FOG COVERAGE QUALIFIER FROM PATCHY TO
AREAS OF ACROSS THE FAR INLAND TIER OF ZONES WITH PATCHY FOG
ELSEWHERE...EXCEPT SOUTH AND EAST OF A SAVANNAH-LUDOWICI LINE
WHERE NO MENTION OF FOG WILL BE INCLUDED.

THERE CONTINUE TO BE SIGNALS IN THE VARIOUS HIGH RESOLUTION
GUIDANCE THAT ISOLATED TO PERHAPS SCATTERED SHOWERS/TSTMS COULD
REDEVELOP ALONG THE GEORGIA COAST AFTER 3-4 AM AS LOW-LEVEL
JETTING INTENSIFIES AND INTERACTS WILL A MODEST AMOUNT OF
INSTABILITY THAT LINGERS JUST OFFSHORE. THE RAP IS STILL MUCH MORE
EMPHATIC ON THE REDEVELOPMENT OF DEEP CONVECTION PRIOR TO
SUNRISE...WHILE THE H3R IS LESS SO. WILL MAINTAIN 20-40 PERCENT
POPS ROUGHLY ALONG AND SOUTH OF HILTON HEAD-LUDOWICI
LINE...HIGHEST ACROSS COASTAL MCINTOSH COUNTY...WITH DRY
CONDITIONS ELSEWHERE.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SUNDAY THROUGH TUESDAY...OVERALL THE PATTERN WILL NOT CHANGE
APPRECIABLY THROUGH EARLY NEXT WEEK. ALOFT...THE FORECAST AREA WILL
BE POSITIONED ON THE SOUTHERN EXTENT OF TROUGHING ACROSS THE GREAT
LAKES AND NORTHEAST. THIS WILL RESULT IN A RATHER WEAK AND NEBULOUS
NEARLY ZONAL FLOW THROUGH THE PERIOD. AT THE SURFACE...THE NEARLY
STATIONARY FRONT WILL DISSIPATE AND ITS REMNANTS WILL LINGER ALONG
THE COASTLINE SUNDAY AND MONDAY. THIS WILL RESULT IN A RATHER TIGHT
PWAT GRADIENT ACROSS THE FORECAST AREA...RANGING FROM AROUND 1.5
INCHES OR LESS AROUND ALLENDALE TO WELL OVER 2 INCHES OVER THE
ATLANTIC COASTAL WATERS. BY TUESDAY THE DEEP MOISTURE WILL PUSH EVEN
FURTHER OFFSHORE AND MUCH DRIER AIR WILL COVER ALL OF THE REGION.
POPS FOR SUNDAY AND MONDAY ARE FOCUSED ALONG THE COAST AND OVER THE
COASTAL WATERS...WITH FURTHER DECREASING COVERAGE BY TUESDAY. POPS
MAY BE A BIT OVERDONE FURTHER INLAND AT TIMES...BUT IT WOULDN/T
REQUIRE A SIGNIFICANT SHIFT IN THE DEEP MOISTURE AXIS TO WARRANT
RAISING POPS. TEMPERATURES ARE PRETTY SIMILAR TO WHAT THEY HAVE BEEN
FOR THE LAST FEW DAYS. LOW TO MID 90S SUNDAY AND MONDAY WITH A
SLIGHT WARMING TREND BY TUESDAY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
UPPER SHORTWAVE ENERGY WILL BEGIN MOVING INTO THE SOUTHEAST UNITED
STATES MID TO LATE WEEK WITH A PRONOUNCED SURFACE TROUGH DEVELOPING
INLAND. PWATS WILL RETURN TO A MORE TYPICAL 2" FOR EARLY AUGUST BY
THURSDAY. A COLD FRONT MAY AFFECT THE AREA FRIDAY INTO SATURDAY. WE
HAVE INCREASING POPS DURING THIS PERIOD AND SLIGHTLY MODERATED
TEMPERATURES DUE TO THICKER CLOUD COVER.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
TSTM IMPACTS AT BOTH TERMINALS HAS ENDED. PRIMARY CONCERN
OVERNIGHT IS THE POTENTIAL FOR FOG/STRATUS IMPACTING KCHS/KSAV.
THE RISK FOR LOW STRATUS LOOKS HIGHEST AT KSAV AS LOW-LEVEL
JETTING TAKES HOLD AN INTERACTS WITH RICH LOW-LEVEL MOISTURE WHILE
FOG IS MORE LIKELY AT KCHS. THE DEGREE OF JETTING WILL ULTIMATELY
DETERMINE HOW IMPACTFUL EITHER ELEMENT WILL BECOME AT THE
TERMINALS. WILL CONTINUE TO TAKE A TRENDED YET CONSERVATIVE
APPROACH WITH THE 00Z TAF CYCLE. WILL CALL FOR LOW-END MVFR CIGS
09-14Z WITH VERY LIGHT FOG AT KSAV...WHILE A TEMPO GROUP FOR MVFR
VSBYS FROM 09-12Z WILL BE SHOWN AT KCHS. ADJUSTMENTS WILL MOST
LIKELY BE NEEDED AS TRENDS BECOME MORE APPARENT LATER TONIGHT.
ONCE FOG/STRATUS DISSIPATES...EXPECT VFR CONDITIONS.

EXTENDED AVIATION OUTLOOK...LOW CHANCES FOR DIRECT IMPACTS FROM
AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS. ALSO LOW CHANCES FOR
PERIODS OF STRATUS/FOG AROUND SUNRISE.

&&

.MARINE...
TONIGHT...WINDS WILL INCREASE ACROSS THE WATERS TONIGHT AS LOW-
LEVEL JETTING TAKES HOLD. BOTH WINDS AND SEAS COULD GET VERY CLOSE
TO SMALL CRAFT ADVISORY THRESHOLDS OVER THE THE FAR EASTERN
PORTIONS OF THE GEORGIA OFFSHORE ZONE...BUT THE DURATION OF SUCH
CONDITIONS LOOK TO BE ABOUT 3-4 HOURS AT BEST. GIVEN THE
RELATIVELY SMALL AREA IMPACTED...WILL CAP BOTH WINDS AND SEAS AT
20 KT AND SEAS 5 FT...OR JUST BELOW SMALL CRAFT ADVISORY
THRESHOLDS...AND NOT HOIST AN ADVISORY WITH THIS FORECAST CYCLE.

SUNDAY THROUGH THURSDAY...THE LINGERING WEAK FRONT WILL DISSIPATE
ALONG THE COAST ON SUNDAY AND SOUTHWEST FLOW WILL GENERALLY PREVAIL
ACROSS THE LOCAL WATERS THROUGH THE MIDDLE OF NEXT WEEK. AS AN
INLAND TROUGH OF LOW PRESSURE DEVELOPS...THE PRESSURE GRADIENT WILL
TIGHTEN AT TIMES AND LEAD TO PERIODS OF SURGING IN THE SOUTHWEST
FLOW. WIND SPEEDS WILL GENERALLY TOP OUT IN THE 15-20 KT RANGE...BUT
COULD MARGINALLY APPROACH SMALL CRAFT ADVISORY CRITERIA AT TIMES.
SEAS WILL INCREASE IN THE IMPROVING SOUTHWEST FETCH AS
WELL...INCREASING TO 2-4 FT WITHIN 20 NM AND MAINLY 4-5 FT BEYOND. 6
FT SEAS COULD BEGIN ACROSS THE OUTER GEORGIA WATERS STARTING MONDAY
AND A SMALL CRAFT ADVISORY COULD BE NEEDED.

&&

.TIDES/COASTAL FLOODING...
TIDES WILL REMAIN ELEVATED THROUGH SUNDAY...BUT THEREAFTER WILL
BEGIN TO DECREASE AS WE MOVE FURTHER AWAY FROM THE FULL MOON AND
PERIGEE. SHALLOW COASTAL FLOODING APPEARS UNLIKELY AFTER SUNDAY.

&&

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

&&

$$

ST


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.