Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 301438
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1038 AM EDT TUE JUN 30 2015

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL RESIDE ACROSS THE AREA WHILE A TROUGH
OF LOW PRESSURE PERSISTS INLAND.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY...THE FORECAST AREA WILL RESIDE ON THE WESTERN PERIPHERY OF
ATLANTIC HIGH PRESSURE WHILE A PIEDMONT TROUGH BECOMES MORE PRONOUNCED
INLAND. MEANWHILE ALOFT...A MID LEVEL TROUGH WILL CONTINUE TO
ENCOMPASS THE EASTERN HALF OF THE COUNTRY WITH SHORTWAVE ENERGY
PROGGED TO APPROACH AND CROSS THE FORECAST AREA LATER THIS
EVENING. PINNING DOWN CONVECTION TODAY IS QUITE TRICKY SEEING
THAT MODELS ARE PRETTY INCONSISTENT IN BOTH TIMING AND COVERAGE. MODIFYING
THE KCHS 12Z RAOB...SEVERE PARAMETERS ARE NOT OVERLY IMPRESSIVE
WITH CAPE QUITE MARGINAL AROUND 1500 J/KG...LIFTED INDEX OF -4
C...AND MID LEVEL LAPSE RATES ONLY AROUND -5.8 C/KM. GIVEN
THIS...COVERAGE SHOULD BE FAIRLY ISOLATED THROUGH AT LEAST EARLY
THIS AFTERNOON. LATER IN THE AFTERNOON/EARLY THIS EVENING...SUBTLE
MID LEVEL COOLING ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE AND
INCREASING MOISTURE WILL RESULT IN HIGHER INSTABILITY. IN
ADDITION...O-6 KM SHEAR DOES INCREASE TO 20-25 KT ESPECIALLY
INLAND. COLLECTIVELY...THIS MAY ALLOW COVERAGE TO INCREASE WITH A
FEW STRONGER TO SEVERE STORMS POSSIBLE WITH DAMAGING WIND GUSTS
THE PRIMARY THREAT. AT THIS TIME...HAVE OPTED TO KEEP CURRENT POP
SCHEME IN TACT UNTIL CONVECTIVE TRENDS BECOME BETTER DEFINED. HIGH
TEMPERATURES TODAY WILL MAINLY BE IN THE LOW TO MID 90S AWAY FROM
THE COAST.

TONIGHT...CONVECTIVE ACTIVITY WILL LARGELY DIMINISH BY 06Z. A
MILDER OVERNIGHT IS EXPECTED WITH LOWS IN THE MID 70S.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
WEDNESDAY...FLOW WILL BE RELATIVELY ZONAL FOLLOWING THE DEPARTURE OF
A SERIES OF SHORTWAVE PERTURBATIONS AROUND DAYBREAK. THERE ARE SOME
INDICATIONS THAT THERE WILL BE WEAK NEGATIVE VORTICITY ADVECTION
PRODUCING BROAD SUBSIDENCE ACROSS THE AREA AND ALLOWING DEWPOINTS TO
MIX INTO THE 60S IN THE AFTERNOON. PWATS ARE ONLY PROGGED AROUND
1.5" IN THE AFTERNOON. WITH 15-20 KT WSW 850 MB WINDS... THE SEA
BREEZE WILL BE PINNED NEAR THE COAST UNTIL LATE IN THE DAY.
CONDITIONS ARE NOT TERRIBLY CONDUCIVE FOR CONVECTIVE INITIATION
THOUGH WE CANNOT RULE OUT ISOLATED ACTIVITY. HIGHS WILL BE IN THE
LOW TO MID 90S.

THURSDAY...A SERIES OF SHORTWAVES WILL PUSH INTO THE AREA LATE IN
THE DAY. LOW-LEVEL FLOW WILL BACK...BRINGING BETTER MOISTURE INTO
THE AREA. PWATS WILL INCREASE SUBSTANTIALLY WITH READINGS
APPROACHING 2 INCHES BY LATE IN THE DAY. GIVEN BETTER MID-LEVEL
LAPSE RATES...INCREASING SURFACE THETA-E AND SYNOPTIC ASCENT... WE
EXPECT BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS ESPECIALLY IN
THE AFTERNOON AND EVENING. HIGHS WILL BE IN THE LOWER 90S.

FRIDAY...A FAIRLY SIMILAR PATTERN WILL EXIST THOUGH THERE MAY BE
LESS SHORTWAVE ENERGY AS ON THURSDAY. NEVERTHELESS...BROAD TROUGH
PATTERN AND AMPLE DESTABILIZATION WILL SUPPORT SCATTERED SHOWERS AND
THUNDERSTORMS DURING THE DAYTIME HOURS. HIGHS WILL BE IN THE LOW TO
MID 90S.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
THE UPPER TROUGH WILL DEAMPLIFY ALLOWING THE RIDGE TO BUILD OVER THE
SOUTHEAST UNITED STATES. ATLANTIC HIGH PRESSURE WILL PREVAIL AT THE
SURFACE WHILE A TROUGH EXISTS WELL INLAND. WARMING MID LEVELS WILL
DECREASE THE COVERAGE OF SHOWERS AND TSTMS WHILE INCREASING
THICKNESSES YIELD HIGH TEMPS IN THE MIDDLE 90S MOST DAYS.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
VFR THROUGH 12Z WEDNESDAY WITH THE ONLY POTENTIAL PUNCTUATION
IN THE FORM OF ISOLATED TSTMS WHICH COULD IMPACT THE COASTAL
CORRIDOR BETWEEN 21Z AND 02Z. THERE IS A FAIR POSSIBILITY THAT
VCTS/CB MAY NEED TO BE INTRODUCED AT EITHER OF THE TERMINALS BY
THE 18Z TAF CYCLE.

EXTENDED AVIATION OUTLOOK...MAINLY VFR. BRIEF FLIGHT RESTRICTIONS
POSSIBLE IN AFTERNOON SHOWERS/THUNDERSTORMS.

&&

.MARINE...
ATLANTIC HIGH PRESSURE WILL GENERALLY DOMINATE THE WEATHER
PATTERN OVER THE COASTAL WATERS WITH A PIEDMONT TROUGH SITUATED
INLAND. TIGHTENED PRESSURE GRADIENT BETWEEN THE TWO FEATURES
WILL KEEP WINDS FAIRLY ELEVATED THROUGH THE PERIOD...HOWEVER NO
HEADLINES ARE ANTICIPATED AT THIS TIME. SEA BREEZE CIRCULATIONS
AND NOCTURNAL LOW LEVEL JETTING WILL ALLOW SOUTH/SOUTHWEST WINDS
TO PEAK 15-20 KT OR EVEN CLOSE TO 20 KT LOCALLY AT TIMES IN
FAVORED LOCATIONS. SEAS WILL BE 2-4 FEET ON AVERAGE...BUT MAY
REACH 5 FT IN THE OUTER PORTIONS OF THE WATERS DURING NOCTURNAL
SURGES.

&&

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

&&

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



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