Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 220819
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
419 AM EDT TUE JUL 22 2014

.SYNOPSIS...
A TROUGH OF LOW PRESSURE WILL LINGER OVER THE AREA TODAY BEFORE
DISSIPATING TONIGHT. ATLANTIC HIGH PRESSURE WILL THEN BUILD OVER
THE REGION THROUGH THE WEEKEND. A COLD FRONT WILL APPROACH FROM
THE NORTHWEST EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY...A TROUGH OF LOW PRESSURE STRETCHING FROM NEAR THE SOUTH
CAROLINA COAST SOUTHWEST INTO SOUTHERN GEORGIA THIS MORNING SHOULD
SHIFT INLAND THIS AFTERNOON AS THE UPPER LOW NEAR MOBILE ALABAMA
SHIFTS WEST. THIS BOUNDARY SHOULD BE THE MAIN FOCUS FOR SHOWERS
AND THUNDERSTORMS. THUS IT APPEARS THAT THE BEST RAIN CHANCES WILL
BE NEAR THE COAST THIS MORNING AND THEN INLAND THIS AFTERNOON AS
THE SEA BREEZE KICKS IN. PWATS ARE EXPECTED TO BE NEAR 2.25 INCHES
ACROSS MUCH OF THE AREA...ESPECIALLY SOUTH CAROLINA. IN
ADDITION...WEAK LOW- MID LEVEL FLOW WILL LEAD TO SLOW MOVING
STORMS AND THUS HEAVY RAINFALL WITH LOCALIZED FLOODING WILL BE
POSSIBLE. HIGHS SHOULD BE NEAR 90 AWAY FROM THE LOCALLY COOLER
COASTAL AREAS.

TONIGHT...THE UPPER LOW WILL CONTINUE TO SHIFT SLOWLY WEST TOWARD
NEW ORLEANS WITH THE TROUGH OVER THE AREA DISSIPATING. ANY EVENING
SHOWERS AND STORMS SHOULD DIMINISH PRETTY QUICKLY WITH CONVECTION
SHIFTING OFFSHORE WHERE THE GREATER INSTABILITY WILL BE FOUND.
LOWS IN THE LOWER TO MID 70S INLAND AND CLOSER TO THE UPPER 70S
AT THE COAST.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
WEDNESDAY AND WEDNESDAY NIGHT...A CLOSED MID AND UPPER LEVEL LOW
OVER THE DELTA OF THE MISSISSIPPI WILL OPEN AS IT SLOWLY
RETROGRADES...ALLOWING RIDGING OVER THE ATLANTIC TO EXPAND OVER THE
SOUTHEAST UNITED STATES. AT THE SURFACE...ATLANTIC HIGH PRESSURE
WILL PREVAIL WHILE A LEE SIDE TROUGH DEVELOPS INLAND. THIS IS A MORE
TYPICAL SUMMERTIME PATTERN FOR THE REGION...THUS EXPECT MAINLY
SCATTERED AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS ACROSS THE
AREA. A SOUTHERLY LOW LEVEL FLOW WITH SLIGHT VEERING OF THE FLOW
ALOFT SHOULD SUPPORT HIGHS IN THE LOWER TO MID 90S INLAND FROM THE
IMMEDIATE COAST. LOWS AT NIGHT SHOULD BE IN THE LOWER TO MID 70S.

THURSDAY AND THURSDAY NIGHT...AN UPPER LEVEL TROUGH WILL BEGIN TO
DIG INTO THE EASTERN UNITED STATES...CAUSING THE INLAND TROUGH TO
STRENGTHEN WHILE ATLANTIC HIGH PRESSURE CONTINUES ITS INFLUENCE OVER
THE REGION. A WESTERLY FLOW ALOFT WILL RESULT IN DRIER
CONDITIONS...AT LEAST ACROSS SOUTHEAST GEORGIA...BUT INCREASING LOW
LEVEL CONVERGENCE LATER IN THE DAY IN VICINITY OF THE INLAND TROUGH
AND CHANNELED VORTICITY ALOFT COULD RESULT IN A BETTER CHANCE OF
CONVECTION ACROSS PARTS OF SOUTHEAST SOUTH CAROLINA. THUS...THE
FORECAST INDICATES A LOW CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS
MUCH OF THE CHARLESTON QUAD-COUNTY AREA WITH A SLIGHT CHANCE
ELSEWHERE TO THE SOUTH. THE DOWNSLOPE FLOW WILL ALSO SUPPORT WARM
TEMPERATURES...WITH HIGHS SOLIDLY INTO THE MID 90S AWAY FROM THE
IMMEDIATE COAST WHERE THE SEA BREEZE SHOULD REMAIN PINNED. LOWS WILL
ONCE AGAIN BE IN THE LOWER TO MID 70S AT NIGHT.

FRIDAY...THE MID AND UPPER LEVEL TROUGH AXIS WILL SHIFT FARTHER EAST
WHILE AT THE SURFACE THE INLAND TROUGH WILL SHIFT CLOSER TO THE
COAST. PRECIPITABLE WATER VALUES WILL RISE AS WELL...AND THIS SHOULD
RESULT IN AN INCREASED POTENTIAL FOR CONVECTION WITH THE FORECAST
INDICATING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS...ESPECIALLY
IN THE AFTERNOON AND EVENING. LESS OF A DOWNSLOPE FLOW AND INCREASED
CLOUD COVER SHOULD RESULT IN HIGHS IN THE LOWER TO PERHAPS MID 90S
AWAY FROM THE COAST.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THE MID AND UPPER LEVEL TROUGH WILL WEAKEN OVER THE EASTERN UNITED
STATES OVER THE WEEKEND...AS RIDGING TRIES TO EXPAND SOUTH OF THE
REGION. THE UPPER TROUGH WILL THEN GET REINFORCED AND EXPAND
SOUTHWARD EARLY NEXT WEEK FROM ENERGY DROPPING ACROSS THE GREAT
LAKES REGION. AT THE SURFACE...ATLANTIC HIGH PRESSURE WITH A WEAK
TROUGH OF LOW PRESSURE INLAND WILL PREVAIL THROUGH THE
WEEKEND...BEFORE THE STRENGTHENING UPPER TROUGH DRIVES A COLD FRONT
TOWARD THE AREA FROM THE NORTHWEST EARLY NEXT WEEK. EXPECT MAINLY
DIURNAL SCATTERED SHOWERS AND THUNDERSTORMS OVER THE WEEKEND...BUT
COVERAGE COULD INCREASE EARLY NEXT WEEK AS THE FRONT NEARS AND
MOISTURE INCREASES. TEMPERATURES SHOULD BE NEAR NORMAL FOR MOST OF
THE LONG TERM PERIOD.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
MOSTLY VFR. SHOWERS AND MAYBE A THUNDERSTORM ARE POSSIBLE JUST
ABOUT ANYTIME THE REMAINDER OF THE NIGHT WITH A TROUGH OF LOW
PRESSURE OVER/NEAR THE AREA...WITH THE BEST CHANCES AT KCHS. WITH
ABUNDANT LOW-LEVEL MOISTURE IN PLACE THERE COULD ALSO BE SOME MVFR
CIGS/VSBYS TOWARD DAYBREAK...POSSIBLY IFR. ADDITIONAL SHRA/TSRA
WILL OCCUR AS THE SEA BREEZE BOUNDARY PUSHES INLAND DURING THE
LATE MORNING/AFTERNOON...ESPECIALLY AT KCHS...THEN MOSTLY DRY THROUGH
06Z/WED.

EXTENDED AVIATION OUTLOOK...VFR CONDITIONS EXPECTED TO PREVAIL.
BRIEF FLIGHT RESTRICTIONS POSSIBLE WITHIN SCATTERED MAINLY
AFTERNOON/EARLY EVENING SHOWERS AND THUNDERSTORMS. THE BEST COVERAGE
IS EXPECTED FRIDAY AND SATURDAY.

&&

.MARINE...
TODAY AND TONIGHT...A TROUGH OF LOW PRESSURE NEAR THE COAST THIS
MORNING WILL DISSIPATE THROUGH TONIGHT. THE WEAK PRESSURE GRADIENT
WILL LEAD TO WINDS MAINLY 15 KT OR LESS...GENERALLY PEAKING NEAR
THE COAST THIS AFTERNOON WITH THE SEA BREEZE...AND POSSIBLY ALONG
THE CHARLESTON COUNTY WATERS THIS EVENING. SEAS MOSTLY 3 FT OR
LESS BUT POSSIBLY REACHING 4 FT OFFSHORE TONIGHT.

WEDNESDAY THROUGH SUNDAY...ATLANTIC HIGH PRESSURE WILL BUILD OVER
THE WATERS THROUGH SUNDAY WHILE A TROUGH OF LOW PRESSURE LINGERS
INLAND. AS A RESULT...A GENERAL SOUTH/SOUTHWEST FLOW IS EXPECTED TO
PREVAIL. THE STRONGEST WINDS WILL OCCUR DURING THE AFTERNOON/EARLY
EVENING HOURS ALONG THE LAND/SEA INTERFACE DUE THE SEA BREEZE...AND
AS A NOCTURNAL SURGE DEVELOPS OVER THE COASTAL WATERS DURING THE
EVENING/LATE NIGHT HOURS...PUSHING WINDS AS HIGH AS 15-20 KT WITH
THE POTENTIAL FOR HIGHER GUSTS. SEAS WILL GENERALLY RANGE FROM 2-4
FT.

&&

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

&&

$$

NEAR TERM...RJB
SHORT TERM...JAQ
LONG TERM...JAQ
AVIATION...JAQ/RJB
MARINE...JAQ/RJB





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