Area Forecast Discussion
Issued by NWS Charleston, SC

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FXUS62 KCHS 051741
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
141 PM 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/...
A CLOSED MID/UPPER LVL LOW OVER THE TENNESSEE VALLEY WILL GRADUALLY
LIFT NORTHEAST WITHIN A BROAD TROUGH OF LOW PRESSURE EXTENDING
ACROSS MUCH OF THE EASTERN CONUS. AT THE SFC...THE AREA WILL REMAIN
BETWEEN A WEAK TROUGH INLAND AND HIGH PRESSURE OVER THE WESTERN
ATLANTIC. THE PATTERN WILL SUPPORT DEEP MOISTURE ADVECTION TO THE
SOUTHEASTERN UNITED STATES THIS AFTERNOON WITHIN A SOUTHWEST
FLOW...SETTING UP FAVORABLE CONDITIONS FOR AFTERNOON/EVENING SHOWERS
AND THUNDERSTORMS.

THIS AFTERNOON AND EVENING...SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE FOR MOST AREAS STARTING EARLY TO MID AFTERNOON AS THE
LEADING EDGE OF A H5 SHORTWAVE ROUNDS THE SOUTHERN EDGE OF THE
MID/UPPER LOW CENTERED OVER TENNESSEE AND ENCOUNTERS DEEP MOISTURE
CHARACTERIZED BY PWATS NEAR 2.0 INCHES. THESE MOISTURE LEVELS ALONG
WITH STRONG SFC HEATING UNDER MOSTLY SUNNY SKIES...WILL SUPPORT A
HIGHLY UNSTABLE ENVIRONMENT DURING PEAK HEATING HOURS FOR MOST OF
THE AREA. LATEST MESOANALYSIS ALREADY INDICATES SBCAPES RANGING
BETWEEN 3500-4000 J/KG SOUTH OF THE TRI-COUNTY AREA WHERE
CONVECTIVE INITIATION IS STARTING TO TAKE PLACE. EXPECT PRECIP
COVERAGE TO GRADUALLY EXPAND TO THE SOUTHWEST AHEAD OF AN ONGOING
COMPLEX OF SHOWERS AND THUNDERSTORMS OVER SOUTH CENTRAL GEORGIA.
THE GENERAL CONSENSUS IS THAT MOST ENHANCED SHOWER AND
THUNDERSTORM WILL REMAIN FOCUSED ALONG THE I-95 CORRIDOR THIS
AFTERNOON AND EVENING WHERE LOW LEVEL CONVERGENCE IS MAXIMIZED
ALONG A SEABREEZE...BUT WE ALSO ANTICIPATE GREATER COVERAGE OF
SHOWERS/THUNDERSTORMS IN SOUTHEAST GEORGIA AS THE CONVECTIVE
COMPLEX TO OUR WEST SHIFTS TOWARD THE SOUTHEAST COAST. LIKE
PREVIOUS DAYS...A FEW THUNDERSTORMS COULD BECOME STRONG OR SEVERE
WITH DAMAGING WIND GUSTS BEING THE PRIMARY THREAT...ESPECIALLY AS
DCAPE VALUES APPROACH 800-1000 J/KG. GIVEN THIS POTENTIAL...THE
STORM PREDICTION CENTER HAS ALSO PLACED THE ENTIRE AREA IN A
MARGINAL RISK FOR SEVERE STORMS TODAY.

INCREASING CLOUD COVER AND THE ONSET OF PRECIP THIS AFTERNOON SHOULD
LIMIT MAX TEMPS A FEW DEGREES. IN GENERAL...HIGHS SHOULD PEAK IN THE
LOWER 90S AWAY FROM THE COAST.

LATE THIS EVENING AND OVERNIGHT...A 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 /18Z SUNDAY THROUGH FRIDAY/...
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED
DURING THE AFTERNOON AND EARLY EVENING AT BOTH CHS AND SAV
TERMINALS. HAVE MAINTAINED A TEMPO GROUP FROM 18-22Z AT CHS AND
19-21Z AT SAV FOR THUNDERSTORMS CAPABLE OF PRODUCING FLIGHT
RESTRICTIONS AND GUSTY/ERRATIC WINDS. CONDITIONS WILL LIKELY
IMPROVE NEAR SUNSET THIS EVENING. VFR CONDITIONS SHOULD PREVAIL
AT BOTH TERMINALS EARLY TONIGHT THROUGH 18Z MONDAY.

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

&&

.MARINE...
THIS AFTERNOON AND TONIGHT...CONDITIONS ARE EXPECTED TO REMAIN
BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THE PERIOD. 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 AT OR
BELOW 15 KTS...BUT SOME LOCAL ENHANCEMENT IS POSSIBLE NEAR THE
LAND/SEA INTERFACE WHERE A SEABREEZE OCCURS THIS AFTERNOON/EARLY
EVENING...AND A BIT FARTHER FROM THE COAST LATER THIS EVENING INTO
THE OVERNIGHT PERIOD 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.

&&

$$
SYNOPSIS...
NEAR TERM...DPB
SHORT TERM...RJB
LONG TERM...RJB
AVIATION...DPB/RJB
MARINE...DPB/RJB



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