Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 051142
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
742 AM EDT SUN JUL 5 2015

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL PREVAIL WITH AN INLAND TROUGH OF LOW
PRESSURE INTO THE MIDDLE OF THE WEEK. HIGH PRESSURE WILL THEN
STRENGTHEN OVER THE AREA LATER IN THE WEEK BEFORE POSSIBLY
WEAKENING NEXT WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY AND EARLY THIS EVENING...A CLOSED UPPER LEVEL LOW WILL
LINGER OVER THE TENNESSEE VALLEY WHILE THE ASSOCIATED LONG WAVE
TROUGH PERSISTS EAST OF THE MISSISSIPPI VALLEY. AN UPPER LEVEL
DISTURBANCE WILL ROTATE AROUND THE BASE OF THIS TROUGH AN ADVANCE
TOWARD THE AREA TODAY. MEANWHILE AT THE SURFACE...THE REGION WILL
REMAIN ALONG THE WESTERN FRINGES OF ATLANTIC HIGH PRESSURE
CENTERED WELL OFFSHORE WHILE A PIEDMONT TROUGH REMAINS NORTHWEST
OF THE AREA.

A SYNOPTIC SOUTHWEST FLOW WILL ALLOW FOR DEEP MOISTURE
ADVECTION...PUSHING PRECIPITABLE WATER VALUES UPWARDS OF AROUND 2
INCHES TODAY. THIS DEEP MOISTURE COMBINED WITH FORCING FOR ASCENT
PROVIDED BY THE APPROACHING UPPER LEVEL DISTURBANCE WILL BE
SUFFICIENT TO GENERATE SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS THIS AFTERNOON AND THIS EVENING...WITH THE GREATEST
COVERAGE FOCUSED ALONG THE I-95 CORRIDOR WHERE LOW LEVEL
CONVERGENCE WILL BE MAXIMIZED. ONCE AGAIN...AT LEAST A FEW OF
THESE THUNDERSTORMS SHOULD BECOME SEVERE...WITH THE POTENTIAL FOR
SOME MULTI-CELLULAR CLUSTERS TO BECOME BETTER ORGANIZED AND FORM
LINE SEGMENTS CAPABLE OF PRODUCING DAMAGING WINDS. GIVEN THIS
POTENTIAL...THE STORM PREDICTION CENTER HAS THE AREA IN A MARGINAL
RISK FOR SEVERE STORMS AND MENTION WILL BE ADDED TO THE HAZARDOUS
WEATHER OUTLOOK.

INCREASING CLOUD COVER AND MIDDAY/EARLY AFTERNOON ONSET OF
PRECIPITATION SHOULD LIMIT HIGHS TO AROUND 90 FOR MUCH OF THE AREA
THIS AFTERNOON.

LATE THIS EVENING AND OVERNIGHT...THE CHANCE FOR SHOWERS AND
THUNDERSTORMS WILL CONTINUE DURING THE LATE EVENING AND EARLY
OVERNIGHT HOURS AS ADDITIONAL UPPER LEVEL SHORT WAVE ENERGY PASSES
THROUGH. WHILE THE SEVERE THREAT SHOULD DIMINISH...THE POTENTIAL
EXISTS FOR AT LEAST SOME STRONGER STORMS CAPABLE OF PRODUCING
GUSTY WINDS TO PERSIST. THE FOCUS FOR CONVECTION SHOULD THEN
SHIFT OUT INTO THE NEARBY ATLANTIC LATE TONIGHT WHERE INSTABILITY
WILL BE GREATEST. LOWS SHOULD BE AROUND 70 OR IN THE LOWER 70S
ACROSS THE AREA.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
OVERVIEW...GENERALLY A CONTINUATION OF THE SAME PATTERN WITH HIGH
PRESSURE OVER THE ATLANTIC AND LOW PRESSURE INLAND THROUGH MONDAY.
HIGH PRESSURE WILL THEN STRENGTHEN OVER THE AREA TUESDAY AND
WEDNESDAY AS THE UPPER TROUGH WEAKENS AND LIFTS NORTHWARD.

MONDAY...DEEP MOISTURE AND LINGERING SHORTWAVE ENERGY SHOULD LEAD TO
SCATTERED CONVECTION...MAINLY DURING THE AFTERNOON INTO THE EARLY
EVENING. SEVERE RISK IS LOW GIVEN REDUCED INSTABILITY/SHEAR. HIGHS
LIKELY IN THE LOWER 90S AWAY FROM THE LOCALLY COOLER COASTAL AREAS.
CONVECTION SHOULD PUSH OFFSHORE FOR THE MOST PART MONDAY NIGHT WITH
LOWS IN THE LOWER TO MID 70S.

TUESDAY...SCATTERED CONVECTION AGAIN ALTHOUGH PROBABLY NOT QUITE AS
MUCH AS HIGH PRESSURE EXERTS MORE INFLUENCE. WITH REDUCED CONVECTION
HIGHS WILL BE A DEGREE OR TWO WARMER THAN MONDAY.

WEDNESDAY...HIGH PRESSURE CONTINUES TO STRENGTHEN OVER THE AREA
LEADING TO WARMER TEMPERATURES MORE INTO THE MID 90S. ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED THOUGH GIVEN THE
MODERATE INSTABILITY AND SEA BREEZE.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
MEDIUM RANGE GUIDANCE IS IN FAIRLY GOOD AGREEMENT INDICATING HIGH
PRESSURE DOMINATING THROUGH AT LEAST FRIDAY...THEN THERE IS MORE
DISCREPANCY/FORECAST UNCERTAINTY REGARDING HOW QUICKLY THE RIDGE
BREAKS DOWN LATE WEEK AND OVER THE WEEKEND. EXPECT LOW SHOWER AND
THUNDERSTORM COVERAGE THROUGH THE PERIOD...MAINLY EACH
AFTERNOON/EVENING. TEMPERATURES WILL LIKELY BE A BIT WARMER THAN
NORMAL WITH HIGHS IN THE MID 90S AWAY FROM THE COAST AND LOWS IN THE
MID 70S INLAND AND MID TO UPPER 70S AT THE COAST. THE COMBINATION OF
SUCH TEMPS AND THE HUMIDITY LEVELS SHOULD RESULT IN HEAT INDEX
VALUES AT OR ABOVE 100 DEGREES.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS ARE GENERALLY EXPECTED TO PREVAIL AT KCHS AND KSAV
THROUGH 12Z MONDAY. SCATTERED TO NUMEROUS SHOWERS AND
THUNDERSTORMS ARE EXPECTED IN THE AFTERNOON AND EARLY
EVENING. HAVE THEREFORE INCLUDED A TEMPO GROUP FROM 18-22Z AT
BOTH TERMINALS TO INCLUDE THUNDERSTORMS CAPABLE OF PRODUCING
FLIGHT RESTRICTIONS AND GUSTY/ERRATIC WINDS. THE TIMING OF THE
THUNDERSTORMS MAY NEED TO BE REFINED A BIT MORE AS RADAR TRENDS
BECOME ESTABLISHED LATER TODAY.

EXTENDED AVIATION OUTLOOK...BRIEF FLIGHT RESTRICTIONS ARE POSSIBLE IN
MAINLY AFTERNOON/EARLY EVENING SHOWERS AND THUNDERSTORMS...WITH THE
BEST CHANCES MONDAY.

&&

.MARINE...
TODAY AND TONIGHT...SOUTH TO SOUTHWEST WINDS WILL PREVAIL OVER THE
WATERS BETWEEN ATLANTIC HIGH PRESSURE CENTERED WELL OFFSHORE AND A
TROUGH OF LOW PRESSURE NORTHWEST OF THE AREA. WIND SPEEDS SHOULD
GENERALLY REMAIN 15 KT OR LESS...BUT SOME LOCAL ENHANCEMENT IS
POSSIBLE NEAR THE LAND/SEA INTERFACE WITH THE SEA BREEZE LATE THIS
AFTERNOON AND EARLY THIS EVENING...AND A BIT FARTHER FROM THE
COAST LATER THIS EVENING INTO THE OVERNIGHT DUE TO NOCTURNAL
SURGING. SEAS SHOULD REMAIN 2-3 FT ACROSS THE WATERS.

MONDAY THROUGH FRIDAY...ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH
THE PERIOD WHILE AN INLAND TROUGH OF LOW PRESSURE WEAKENS LATER IN
THE WEEK. THIS WILL RESULT IN MOSTLY SOUTH/SOUTHWEST WINDS MAINLY 15
KT OR LESS WITH SEAS 2-4 FEET ON AVERAGE.

RIP CURRENTS...THE COMBINATION OF LINGERING LUNAR INFLUENCES...AN
EASTERLY SWELL OF 2 FT EVERY 8-9 SECONDS AND GUSTY WINDS WILL
SUPPORT A MODERATE RISK FOR RIP CURRENTS FOR THE LOWER SOUTH
CAROLINA BEACHES.

&&

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

&&

$$

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



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