Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 011957
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
357 PM EDT WED JUL 1 2015

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL RESIDE ACROSS THE AREA WHILE A TROUGH
OF LOW PRESSURE PERSISTS INLAND.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
TONIGHT...LITTLE CHANGE EXPECTED IN THE OVERALL WEATHER PATTERN. THE
FORECAST AREA WILL REMAIN ON THE WESTERN PERIPHERY OF ATLANTIC
HIGH PRESSURE WITH A PIEDMONT TROUGH SITUATED INLAND. A WEAK
SHORTWAVE WILL ROUND THE BASE OF A MID LEVEL TROUGH SITTING OVER
THE EASTERN HALF OF THE COUNTRY...PUSHING ACROSS THE FORECAST AREA
LATE TONIGHT. THIS MAY ALLOW FOR SOME PRECIPITATION TO MOVE INTO
OUR INLAND ZONES THIS EVENING AND LINGER INTO TONIGHT AS SHOWN BY
A FEW MODELS...HOWEVER NOCTURNAL STABILIZATION SHOULD GENERALLY
HELP THIS ACTIVITY DECREASE IN COVERAGE...SO NO HIGHER THAN SLIGHT
CHANCE POPS ARE FEATURED IN THE FORECAST AT THIS TIME.

LATEST SATELLITE IMAGERY DEPICTS A THICK LAYER OF SMOKE BLANKETING
THE AREA WHICH HAS MOVED ALL THE WAY FROM WILDFIRES ACROSS WESTERN
CANADA. THE SMOKE IS LOCATED IN THE UPPER PARTS OF THE ATMOSPHERE
SO NO MAJOR IMPACTS ARE EXPECTED...HOWEVER THIS COULD SLIGHTLY
LIMIT RADIATIONAL COOLING TONIGHT. LOW TEMPERATURES ARE FORECAST
TO BE A COUPLE DEGREES ABOVE NORMAL...MAINLY IN THE LOW TO MID
70S.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
THURSDAY AND FRIDAY...A BROAD MID LVL TROUGH OF LOW PRESSURE WILL
EXPAND OVER MUCH OF THE EASTERN CONUS THROUGH LATE WEEK WITH A
SERIES OF H5 SHORTWAVES THAT ROUND ITS SOUTHERN PERIPHERY OVER THE
SOUTHEASTERN UNITED STATES. AT THE SFC...THE AREA WILL REMAIN
BETWEEN A PIEDMONT TROUGH INLAND AND HIGH PRESSURE OVER THE WESTERN
ATLANTIC. THE SETUP WILL FAVOR A SOUTHWEST FLOW THAT BUILDS DEEP
MOISTURE TO THE AREA WITH PWATS CHARACTERIZED AROUND 2.0 INCHES EACH
DAY. THESE MOISTURE LEVELS ALONG WITH FORCING ALONG THE BASE OF THE
LOW PRESSURE TROUGH CENTERED WELL TO OUR NORTH WILL FAVOR CHANCES OF
SHOWERS AND THUNDERSTORMS OVER THE AREA. A FEW THUNDERSTORMS COULD
ALSO BE STRONG OR SEVERE WHEN H5 SHORTWAVE ACTIVITY ALONG WITH THE
ARRIVAL OF A 20-30 KT LOW LVL JET SHIFTS OVER THE AREA ON THURSDAY.
WE COULD SEE A SIMILAR RISK OF STRONGER TO SEVERE THUNDERSTORMS ON
FRIDAY AS THE PIEDMONT TROUGH MAKES A SLIGHT SHIFT TOWARD THE COAST
IN RESPONSE TO LOW PRESSURE DEVELOPING OVER THE MID ATLANTIC REGION.
THE MAIN THREAT ASSOCIATED WITH STRONGER THUNDERSTORMS WILL BE
DAMAGING WIND GUSTS.

OVERALL HIGH TEMPS WILL GENERALLY BE IN THE LOWER 90S EACH DAY.
HOWEVER...TEMPS COULD BE A FEW DEGREES COOLER THAN CURRENTLY
FORECAST ON THURSDAY DUE TO SMOKE FROM FIRES ORIGINATING IN CANADA.
OVERNIGHT LOWS WILL RANGE IN THE LOW TO MID 70S AWAY FROM THE COAST
EACH NIGHT.

SATURDAY...WEAK LOW PRESSURE SHOULD REMAIN OVER THE MID ATLANTIC
STATES INTO THE WEEKEND...RESULTING IN STRONGER LOW LEVEL
CONVERGENCE ALONG A SEABREEZE ACROSS THE CHARLESTON TRI-COUNTY.
CHANCES OF SHOWERS AND THUNDERSTORMS WILL REMAIN IN THE FORECAST
FOR MOST AREAS...BUT EXPECT MOST ACTIVITY IN NORTHERN AREAS ALONG AN
INLAND MOVING SEABREEZE. IN GENERAL...HIGH TEMPS WILL BE IN THE LOW
90S FOR MOST AREAS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THE END OF THE WEEKEND WILL CONTINUE TO FEATURE AN INLAND TROUGH AS
HIGH PRESSURE CONTINUES TO BUILD IN FROM THE ATLANTIC. COVERAGE OF
SHOWERS AND THUNDERSTORMS SHOULD BE RATHER MINIMAL ON SUNDAY WITH
LITTLE IN THE WAY OF STRONG FORCING FOR ASCENT. BY EARLY NEXT
WEEK...MODELS ARE TRENDING A BIT WETTER AS THEY INDICATE MORE IN THE
WAY OF TROUGHING ALOFT. THIS WILL NOT ONLY SUPPORT AT LEAST
SCATTERED SHOWERS AND THUNDERSTORMS EACH DAY...BUT COULD ALSO RESULT
IN SLIGHTLY COOLER TEMPERATURES THAN WHAT IS CURRENTLY FORECAST.

&&

.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
VFR CONDITIONS WILL PREVAIL AT KCHS AND KSAV THROUGH 18Z
THURSDAY. THE POTENTIAL FOR DIRECT IMPACT FROM ANY SHOWERS/TSTMS
IS RATHER LOW...SO HAVE OPTED TO LEAVE MENTION OUT IN THE TAF. WILL
AMEND IF NEEDED. SHOWERS AND THUNDERSTORMS POSSIBLE ON
THURSDAY...BUT COVERAGE SHOULD LARGELY OCCUR AFTER THE VALID TAF
PERIOD.

EXTENDED AVIATION OUTLOOK...BRIEF FLIGHT RESTRICTIONS ARE POSSIBLE
IN MAINLY AFTERNOON/EARLY EVENING ISOLATED TO SCATTERED SHOWERS AND
THUNDERSTORMS. OTHERWISE...VFR CONDITIONS ARE GENERALLY EXPECTED TO
PREVAIL.

&&

.MARINE...
THROUGH MONDAY...ATLANTIC HIGH PRESSURE WILL GENERALLY DOMINATE
THE WEATHER PATTERN OVER THE COASTAL WATERS WITH A PIEDMONT TROUGH
SITUATED INLAND. A TIGHTENED PRESSURE GRADIENT BETWEEN THE TWO
FEATURES WILL KEEP WINDS FAIRLY ELEVATED THROUGH THE PERIOD. IN
FACT...IT APPEARS THAT CONDITIONS COULD REACH MARGINAL SMALL CRAFT
ADVISORY CRITERIA OVER A PORTION OF THE WATERS FRIDAY AFTERNOON
INTO FRIDAY NIGHT. OTHERWISE...SEA BREEZE CIRCULATIONS AND
NOCTURNAL LOW LEVEL JETTING WILL ALLOW SOUTH/SOUTHWEST WINDS TO
PEAK NEAR 15-20 KTS...WITH 25 KTS LOCALLY AT TIMES IN FAVORED
LOCATIONS. SEAS WILL BE 2-4 FEET ON AVERAGE...BUT COULD REACH 5 FT
IN THE OUTER PORTIONS OF THE WATERS DURING NOCTURNAL SURGES.

RIP CURRENTS...ASTRONOMICAL INFLUENCES FROM A FULL MOON ALONG WITH
SWELL OF 2 FT WITH A PERIOD OF 8-9 SECONDS WILL LEAD TO AN ENHANCED
PERIOD OF RIP CURRENTS ON THURSDAY. A MODERATE RISK OF RIP CURRENTS
IS THEREFORE POSSIBLE ALONG THE CHARLESTON COUNTY COAST.

&&

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

&&

$$
SYNOPSIS...
NEAR TERM...ECT
SHORT TERM...DPB
LONG TERM...JAQ
AVIATION...ECT
MARINE...DPB/ECT


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