Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 031135
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
735 AM EDT WED JUN 3 2015

.SYNOPSIS...
A COLD FRONT WILL STALL OVER THE AREA INTO THURSDAY BEFORE SLOWLY
SHIFTING OFF THE COAST LATE WEEK. ANOTHER COLD FRONT WILL AFFECT
THE AREA OVER THE WEEKEND...WITH A TROUGH OF LOW PRESSURE THEN
BECOMING ESTABLISHED INLAND EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
THE BIGGEST ADJUSTMENTS TO THE FORECAST UPDATE THIS MORNING WAS TO
ADD MENTION OF HEAVY RAINFALL FOR THE CHARLESTON TRI-COUNTY THIS
MORNING AND MOST AREAS THIS AFTERNOON.

A SLOW MOVING COLD FRONT WILL PUSH CLOSER TO THE AREA TODAY WHILE
A CLOSED UPPER LOW REMAINS OVER THE SOUTHERN APPALACHIANS. AHEAD
OF THE LOW WILL BE DEEP MOISTURE AND UPPER JET FORCING WHICH WILL
LEAD TO WIDESPREAD SHOWERS AND THUNDERSTORMS...MAINLY LATER THIS
AFTERNOON INLAND AS THE SEA BREEZE KICKS IN. MAIN CONCERN IS
LOCALLY HEAVY RAINFALL GIVEN PWAT VALUES 1.5-1.75 INCHES AND WEAK
STORM MOTIONS AND THUS LOCALIZED FLOODING IS POSSIBLE. WATER VAPOR
SHOWS A RICH AND DEEP FEED OF TROPICAL MOISTURE FROM CUBA AND THE
CARIBBEAN INTO SC AND PARTS OF GA. THIS OCCURS IN ASSOCIATION WITH
UPPER DIFLUENCE TO THE EAST/SE OF THE DEEP LOW PRESSURE ALOFT.
FORTUNATELY HIGH TIDE IS MID-MORNING WHEN OUR PRECIP COVERAGE/INTENSITY
SHOULD BE IN A LULL FOR MOST OF THE COASTAL CORRIDOR. BUT FLOOD
ADVISORIES AND MAYBE A FLASH FLOOD WARNING MIGHT BE REQUIRED ONCE
THE ATMOSPHERE AGAIN DESTABILIZES THIS AFTERNOON.

INSTABILITY LOOKS TO BE PRETTY WEAK BUT CAN/T RULE OUT A FEW
SEVERE STORMS THOUGH WITH DAMAGING WINDS THE MAIN HAZARD SINCE
THERE SHOULD BE A BIT MORE CONVECTIVE ORGANIZATION COMPARED TO
YESTERDAY GIVEN SLIGHTLY MORE DEEP LAYER SHEAR. ABUNDANT
CLOUD/RAIN COVERAGE SHOULD KEEP TEMPS INTO THE LOWER TO MID 80S
INLAND...COOLEST NORTH.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
A DEEP STACKED GYRE OVER SC ON THURSDAY WILL PULL INTO COASTAL NC ON
FRIDAY...THEN OPENS INTO A WAVE AS IT PULLS INTO THE ATLANTIC BY
SATURDAY. MEANWHILE AT THE SURFACE A WEAK COLD FRONT WILL LIE ACROSS
THE FORECAST TERRITORY THURSDAY BEFORE IT BECOMES MORE DIFFUSE AS IT
SLIPS INTO THE NEARBY ATLANTIC FOR LATE IN THE WEEK. WHILE THERE IS
LESS MOISTURE THAN PREVIOUS DAYS...THERE IS STILL AN ADEQUATE SUPPLY
OF MOISTURE TO KEEP RAIN CHANCES IN THE CHANCE RANGE DURING THE
DAYLIGHT HOURS...WITH COVERAGE MAINLY DWINDLING TO THE ISOLATED RANGE
AT NIGHT.

IN REGARDS TO ANY STRONG OR SEVERE STORMS WE DO FIND MODEST SHEAR
THURSDAY...WITH 0-6 KM BULK SHEAR AS HIGH AS 25-30 KT. THAT ALONG
WITH SOME COLD MID LEVEL AIR WHERE 500 MB TEMPS ARE AS LOW AS -11 TO
-13C MAY ALLOW FOR A MARGINAL RISK OF SEVERE STORMS AS DELINEATED BY
THE STORM PREDICTION CENTER IN PROXIMITY TO THE VERTICALLY DEVELOPED
LOW. MID LEVEL DRY AIR AND DCAPES APPROACHING 1000 J/KG IN A FEW
LOCALES SUGGESTS THAT STRONG WINDS ARE POSSIBLE WHERE UPDRAFTS ARE
MAXIMIZED. AND WITH WET BULBS NEAR 10-11K FT THERE COULD BE A
SECONDARY RISK OF MARGINALLY SEVERE HAIL AS WELL. THE ABSENCE OF
MOISTURE ALOFT FRIDAY AND SATURDAY COULD AGAIN LEAD TO LOW END RISK
OF SOME STRONG TO MARGINALLY SEVERE STORMS WHERE BOUNDARY
INTERACTIONS OCCUR...WITH UPSTREAM BOUNDARIES WITHIN THE NW FLOW AND
THE SEA BREEZE THE PROMINENT FORCING FEATURES.

WEAK FLOW EACH DAY COULD SUPPORT LOCALLY HEAVY RAINS...BUT
WIDESPREAD HEAVY RAINFALL IS NOT ANTICIPATED.

TEMPS EXTREMES WILL BE HELD IN CHECK DUE TO 50-75 PERCENT CLOUD
COVER AND MOSTLY NE AND EAST ONSHORE WIND TRAJECTORIES. OVERALL WE
ARE FORECASTING MAX/MIN TEMPS VERY NEAR EARLY JUNE NORMS THROUGH THE
PERIOD.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
THE DEPARTING WAVE ALOFT WILL LEAVE BEHIND SOME TROUGHINESS OVER THE
SE INTO NEXT WEEK BEFORE THE OVERALL PATTERN ALOFT GRADUALLY
FLATTENS. THE SURFACE SCENARIO WILL DEPICT A WEAK INLAND WEDGE FOR
SUNDAY THAT GIVES WAY TO A DECENT LEE SIDE TROUGH MONDAY THROUGH
WEDNESDAY. MESO-SCALE BOUNDARIES ARE THE MAIN DRIVERS FOR ISOLATED
TO SCATTERED AND MAINLY DIURNAL CONVECTION THROUGH THE PERIOD. TEMPS
WILL START THE EXTENDED PERIOD NEAR CLIMATOLOGICAL LEVELS...THEN
CLIMB A FEW DEGREES HIGHER AS THERE IS SOME DOWNSLOPE WARMING THAT
OCCURS MONDAY AND TUESDAY.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
MOSTLY VFR OUTSIDE SHOWERS AND TSTMS...ALTHOUGH MVFR CIGS ARE
POSSIBLE. BEST CHANCE OF SHOWERS AND T-STORMS AT THE TERMINALS
WILL BE THIS AFTERNOON/EVENING...THE RESULT OF VARIOUS MESO-SCALE
BOUNDARIES...THE SEA BREEZE AND STRONG UPPER FORCING IN PLACE
AHEAD OF AN UPPER LOW AND ASSOCIATED JET. HEAVY RAINS...GUSTY
WINDS AND AT LEAST MVFR OF NOT IFR CONDITIONS WILL OCCUR IN
RESPONSE TO NUMEROUS TO WIDESPREAD CONVECTION. ACTIVITY WILL
GRADUALLY FADE TONIGHT AND NOCTURNAL STABILIZING INFLUENCES TAKE
OVER. BUT GIVEN LINGERING BOUNDARIES THERE COULD STILL BE A PERIOD
OF SUB-VFR WEATHER IN ISOLATED TO SCATTERED SHOWERS/T-STORMS.

EXTENDED AVIATION OUTLOOK...SCATTERED SHOWERS AND THUNDERSTORMS WILL
AFFECT THE AREA INTO SUNDAY....RESULTING IN OCCASIONAL CEILING AND
VISIBILITY RESTRICTIONS...ESPECIALLY IN THE AFTERNOON AND EVENING
WHEN STORMS ARE MOST PROBABLE.

&&

.MARINE...
TODAY AND TONIGHT...NO CONCERNS OTHER THAN SOME STRONG
STORMS...MAINLY THIS AFTERNOON AND TONIGHT. WINDS WILL BE SOUTH
TO SOUTHEAST 15 KT OR LESS...SHIFT TO EAST/NORTHEAST LATE TONIGHT.
SEAS 2-3 FT.

THURSDAY THROUGH MONDAY...THE SYNOPTIC PATTERN FEATURES WEAK AND
ELONGATED LOW PRESSURE DEVELOPING NEAR THE BAHAMAS LATE THURSDAY INTO
EARLY FRIDAY...THAT CONSOLIDATES INTO ONE MAIN LOW AROUND 1009 MB IN
DEPTH LATER FRIDAY INTO SATURDAY OFF THE MID-ATLANTIC REGION. THAT
LOW THEN SLACKENS AS IT PULLS FURTHER INTO THE ATLANTIC SUNDAY AND
MONDAY. MEANWHILE...THE REMNANTS OF A COOL FRONT WILL SLIDE INTO THE
WATERS THURSDAY AND FRIDAY...BEFORE FALLING APART. SUBTLE HIGH
PRESSURE WILL THEN PREVAIL THIS WEEKEND...BEFORE AN INLAND TROUGH
DEVELOPS ON MONDAY. WINDS AND SEAS WILL BE WELL BELOW ANY ADVISORY
THRESHOLDS...ALTHOUGH MARINERS ARE ADVISED THAT ISOLATED TO
OCCASIONAL SCATTERED SHOWERS/T-STORMS WILL OCCUR THROUGH THE
FORECAST CYCLE.

&&

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

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...


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