Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 271658
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1258 PM EDT WED MAY 27 2015

.SYNOPSIS...
HIGH PRESSURE WILL EXTEND ACROSS THE REGION THROUGH EARLY NEXT
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
SURFACE HIGH PRESSURE WILL REMAIN ANCHORED OVER THE ATLANTIC
TODAY...WHILE A WEAK TROUGH DEVELOPS WEST OF THE FORECAST AREA.
MEANWHILE...THE UPPER RIDGE OFF THE SOUTHEAST COAST WILL WEAKEN A
BIT AS AN ELONGATED SHORTWAVE APPROACHES THIS AFTERNOON. GIVEN
SHORTWAVE ENERGY AND UPPER DIVERGENCE...SCATTERED SHOWERS AND
THUNDERSTORMS WILL CONTINUE TO DEVELOP MAINLY ACROSS INLAND
COUNTIES. SEVERE PARAMETERS ARE NOT OVERLY IMPRESSIVE. MID LEVEL
LAPSE RATES ARE RATHER POOR...CAPE TOPS OUT AT 1500 J/KG...AND
SHEAR IS LESS THAN 15 KT. HOWEVER VARIOUS BOUNDARY COLLISIONS
COULD ENHANCE UPDRAFTS AT TIMES. GUSTY WINDS WILL BE POSSIBLE
WITHIN STRONGER STORMS AS DCAPE VALUES ARE FORECAST TO BE NEAR
800-900 J/KG. HIGH TEMPERATURES WILL BE IN THE UPPER 80S AWAY FROM
THE LOCALLY COOLER COASTLINE.

FORECAST WAS IN PRETTY GOOD SHAPE SO ONLY MINOR CHANGES WERE MADE
WITH THE EARLY AFTERNOON UPDATE.

ANY DIURNAL CONVECTION WILL DIE OFF AFTER SUNSET. LOW CHANCES FOR
SHALLOW GROUND FOG IN AREAS WHERE PRECIPITATION OCCURS...
ESPECIALLY FARTHER INLAND WHERE THE BOUNDARY LAYER WILL DECOUPLE
LATE TONIGHT. LOWS WILL RANGE FROM THE LOWER 70S NEAR THE COAST
WHERE WINDS STAY UP...TO MIDDLE 60S INLAND.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
THURSDAY AND THURSDAY NIGHT...THE REGION WILL REMAIN ALONG THE
WESTERN PERIPHERY OF DEEP RIDGING CENTERED OVER THE WESTERN
ATLANTIC. THE COMBINATION OF WEAK CHANNELED VORTICITY AND THE
INLAND PROGRESSING SEA BREEZE SHOULD SUPPORT ISOLATED TO SCATTERED
SHOWERS AND THUNDERSTORMS IN THE AFTERNOON GENERALLY ALONG AND WEST
OF A MONCKS CORNER...WALTERBORO...CLYO TO REIDSVILLE LINE.
CONVECTION WILL THEN QUICKLY DISSIPATE BY EARLY EVENING WITH THE
LOSS OF DIURNAL HEATING AND AS THE SEA BREEZE PUSHES WEST OF THE
AREA. HIGHS WILL BE IN THE MID AND UPPER 80S INLAND OF THE IMMEDIATE
COAST...WITH NIGHTTIME LOWS IN THE MID 60S.

FRIDAY AND FRIDAY NIGHT...THE UPPER LEVEL RIDGE WILL EXTEND FARTHER
WEST OVER THE REGION...WITH STRONG SUBSIDENCE RESULTING IN RAIN-FREE
CONDITIONS FOR THE AREA DURING THE DAY. THE DEVELOPMENT OF A WEAK
COASTAL TROUGH FRIDAY NIGHT COULD RESULT IN ISOLATED SHOWERS AND
THUNDERSTORMS OVER THE COASTAL WATERS...BUT WILL NOT INDICATE ANY
ADVECTING ONSHORE AT THIS TIME ALTHOUGH IT IS POSSIBLE GIVEN ONSHORE
WIND TRAJECTORIES. HIGHS WILL ONCE AGAIN BE IN THE MID AND UPPER 80S
INLAND OF THE IMMEDIATE COAST. LOWS SHOULD BE IN THE MID TO UPPER
60S.

SATURDAY...DESPITE CONTINUED RIDGING ALOFT...MODELS INDICATE THE SEA
BREEZE BECOMING A BIT MORE ACTIVE WITH RESPECT TO CONVECTION AND THE
FORECAST SHOWS ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE AREA AS A RESULT. NO SIGNIFICANT CHANGES IN TEMPERATURES
ARE EXPECTED FROM PREVIOUS DAYS.

&&

.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
UPPER LEVEL RIDGING WILL EXTEND OVER THE REGION THROUGH MOST OF THE
LONG TERM PERIOD...ALTHOUGH AN UPPER LEVEL TROUGH WILL BEGIN TO
ENCROACH ON THE SOUTHEAST U.S. TOWARD THE MIDDLE OF NEXT WEEK. AT
THE SURFACE...ATLANTIC HIGH PRESSURE WILL GENERALLY PREVAIL INTO
EARLY NEXT WEEK. THERE IS THEN SOME INDICATION THAT HIGH PRESSURE
WILL TRY TO BUILD FROM THE NORTH TOWARD THE MIDDLE OF NEXT
WEEK...CAUSING A WEAK COASTAL TROUGH TO DEVELOP JUST OFFSHORE.
OVERALL...MOISTURE ADVECTION FROM A SYNOPTIC ONSHORE FLOW AND LOW
LEVEL CONVERGENCE WITH THE SEA BREEZE SHOULD SUPPORT ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS EACH DAY...WITH THE GREATEST
COVERAGE TUESDAY AND WEDNESDAY WITH THE NEARING UPPER TROUGH AND
DEVELOPMENT OF THE WEAK COASTAL TROUGH JUST OFFSHORE. TEMPERATURES
WILL BE NEAR TO SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
VFR IS EXPECTED TO PREVAIL THROUGH 18Z THURSDAY. AFTERNOON
SHOWERS/THUNDERSTORMS ARE EXPECTED TO REMAIN INLAND FROM THE
TERMINALS SO HAVE KEPT MENTION OUT OF THE TAF. WILL AMEND IF
NEEDED.

EXTENDED AVIATION OUTLOOK...MAINLY VFR THROUGH THE PERIOD.

&&

.MARINE...
WINDS TODAY AND TONIGHT WILL BE AT OR BELOW 15 KT WITH SEAS NO
HIGHER THAN 3 FT AS HIGH PRESSURE PERSISTS.

HIGH PRESSURE WILL CONTINUE OVER THE WATERS THROUGH EARLY NEXT
WEEK...GENERALLY MAINTAINING AN ONSHORE FLOW WITH SPEEDS OF AROUND
15 KT OR LESS. DESPITE THE WEAK WIND SPEEDS...FAVORABLE
TRAJECTORIES WILL RESULT IN SEAS OF 2-4 FT ACROSS THE WATERS.

&&

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

&&

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


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