Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 302006
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
406 PM EDT MON MAR 30 2015

.SYNOPSIS...
WEAK HIGH PRESSURE WILL PREVAIL INTO TUESDAY NIGHT...BEFORE A COLD
FRONT PUSHES INTO THE REGION ON WEDNESDAY. HIGH PRESSURE WILL THEN
BUILD OVER THE AREA BEHIND THE FRONT...BEFORE SETTLING OVER THE
ATLANTIC THURSDAY THROUGH FRIDAY. A STRONGER COLD FRONT WILL CROSS
THE REGION SATURDAY...FOLLOWED BY HIGH PRESSURE THROUGH EARLY NEXT
WEEK.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
THE MAIN BAND OF SHOWERS HAS MOVED QUICKLY OFFSHORE THIS
AFTERNOON...LEAVING PARTLY CLOUDY SKIES IN ITS WAKE. SINCE THE
FRONT ITSELF IS STILL UPSTREAM OVER CENTRAL GEORGIA AND THE
MIDLANDS AS OF MID AFTERNOON...I CANNOT COMPLETELY RULE OUT A
SHOWER BEFORE SUNSET...BUT CHANCES LOOK LOW AT THIS TIME.

BY LATER TONIGHT...SKIES WILL BE CLEARING FROM NORTHWEST TO
SOUTHEAST BEHIND THE FRONT...AND TEMPERATURES WILL GRADUALLY FALL.
WITH THE AREA OF HIGH PRESSURE BEHIND THE FRONT OF MODIFIED
PACIFIC ORIGIN...OVERNIGHT TEMPS WILL ACTUALLY BE A BIT MILDER
THAN LAST NIGHT IN MANY PLACES DESPITE THE FRONTAL PASSAGE. MIN
TEMPS WILL BOTTOM OUT IN THE LOWER TO MID 40S INLAND TO THE LOW
50S AT THE BEACHES.

WINDS WILL STILL BE A BIT GUSTY AT TIMES LATE THIS AFTERNOON...BUT
WILL DROP STEADILY DURING THE EVENING HOURS...BECOMING VARIABLE AT
AROUND 5 MPH OR LESS AFTER MIDNIGHT AS THE SURFACE PRESSURE
GRADIENT WEAKENS BEHIND THE FRONT AND THE ATMOSPHERE AT LEAST
PARTIALLY DECOUPLES.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...

TUESDAY AND WEDNESDAY...WEAK HIGH PRESSURE WILL PREVAIL AHEAD OF A
COLD FRONT THAT APPROACHES FROM THE NORTHWEST TUESDAY NIGHT INTO
WEDNESDAY MORNING. EXPECT MAINLY DRY CONDITIONS DURING THE DAY ON
TUESDAY...WITH 1000-850 THICKNESS VALUES SUPPORTING AFTERNOON HIGHS
IN THE MID 70S OVER MOST AREAS. PRECIP CHANCES SHOULD THEN INCREASE
LATE TUESDAY AS A DEVELOPING SOUTHWEST SFC FLOW ADVECTS MOISTURE TO
THE AREA AHEAD OF THE APPROACHING COLD FRONT. GREATEST CHANCES OF
PRECIP SHOULD OCCUR TUESDAY NIGHT WHILE PWATS APPROACH 1 TO 1.25
INCHES AND ISENTROPIC LIFT BECOMES SLIGHTLY ENHANCED OVER THE AREA.
GREATEST PRECIP COVERAGE SHOULD OCCUR OVER SOUTHEAST GEORGIA WHERE
MOISTURE BECOMES DEEPEST. GIVEN THE EXPECTED ARRIVAL TIME OF THE
FRONT...THUNDERSTORMS ARE NOT ANTICIPATED...BUT A FEW CAN NOT BE
RULED OUT. DESPITE FROPA...AFTERNOON TEMPS WILL ONCE AGAIN WARM INTO
THE LOW/MID 70S WITHIN WEAK HIGH PRESSURE ON WEDNESDAY...MAINLY DUE
TO A WEST/NORTHWEST DOWNSLOPING WIND ALOFT. WE COULD EVEN SEE UPPER
70S WELL INLAND.

WEDNESDAY NIGHT INTO THURSDAY...PRECIP CHANCES SHOULD INCREASE ONCE
AGAIN LATE WEDNESDAY NIGHT AND INTO THURSDAY AS MOISTURE ADVECTS
NORTHWARD ALONG THE WESTERN EDGE OF HIGH PRESSURE CENTERED OVER THE
ATLANTIC. CHANCES OF PRECIP SHOULD BE GREATEST OVER INLAND AREAS
THURSDAY AFTERNOON/EVENING AS ISENTROPIC ASCENT INCREASES AND A
DAMPENED H5 SHORTWAVE PASSES OVER THE AREA. GIVEN AFTERNOON TEMPS IN
THE UPPER 70S...A FEW THUNDERSTORMS WILL BE POSSIBLE...BUT SHOULD BE
PULSE TYPE IN NATURE DUE TO WEAK WIND FIELDS.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
AHEAD OF A COLD FRONT APPROACHING FROM THE NORTHWEST...EXPECT A WARM
AND RAIN-FREE DAY FRIDAY WITH HIGH TEMPS IN THE LOWER TO MID 80S.
THE COLD FRONT WILL PUSH INTO THE REGION EITHER LATE FRIDAY NIGHT OR
DURING THE DAY SATURDAY. MODELS HAVE TRENDED TOWARD A MORE
PROGRESSIVE COLD FRONT...ALTHOUGH PERSISTENT TIMING DIFFERENCES
OFFERED BY OPERATIONAL MODELS TRANSLATE TO UNCERTAINTY REGARDING
POPS...THE CHANCE FOR THUNDERSTORMS AND HIGH TEMPS SATURDAY. A
FASTER FROPA WILL SUPPORT LOWER POPS...A GREATLY REDUCED CHANCE FOR
THUNDERSTORMS AND A COOLING TREND STARTING SATURDAY. MAINTAINED
CHANCE POPS FOR SHOWERS/THUNDERSTORMS SATURDAY...BUT ADJUSTMENTS
COULD BE NEEDED WITHIN SUBSEQUENT FORECASTS. IN ANY CASE...POST
FROPA HIGH PRESSURE WILL PROVIDE SLIGHTLY COOLER THAN NORMAL
TEMPERATURES BY SUNDAY...PERHAPS EXTENDING INTO EARLY NEXT WEEK.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...

THERE CONTINUES TO BE SOME MVFR CIGS OVER UPSTATE SC AND GA
ASSOCIATED WITH THE FRONT...BUT THE CONTINUE TO DRY THINGS OUT AS
IT MOVES INTO THE AREA...SO I WILL LEAVE IT OUT OF THE TAFS. THE
OCCASIONALLY GUSTY WINDS THIS AFTERNOON SHOULD COME DOWN QUICKLY
BY SUNSET. CONDITIONS WILL CONTINUE TO IMPROVE TONIGHT AT BOTH
TERMINALS WITH CLEARING SKIES AND LIGHTER WINDS AS WEAK HIGH
PRESSURE MOVES IN BEHIND THE FRONT.

EXTENDED AVIATION OUTLOOK...BRIEF PERIODS OF MVFR CIGS ARE POSSIBLE
WITH SHOWERS AND/OR THUNDERSTORMS THURSDAY. OTHERWISE VFR.

&&

.MARINE...
WINDS ARE STILL 20 KT SUSTAINED GUST TO 25 KT AT BOTH FORT SUMTER
AND FOLLY BEACH...SO I WILL MAINTAIN THE SCA THROUGH 7 PM...WHEN
WINDS WILL LOWER ENOUGH TO BE BELOW CRITERIA. WINDS WILL CONTINUE
TO GRADUALLY DIMINISH OVERNIGHT AND BE GENERALLY 10 KT OR LESS BY
SUNRISE AS A WEAK HIGH PRESSURE RIDGE MOVES OVER THE WATERS.

THE MAIN BATCH OF SHOWERS HAS NOW MOVED EAST OF THE WATERS...BUT
WITH THE FRONT STILL LAGGING BEHIND...I CAN`T RULE OUT A FEW
ISOLATED SHOWERS THROUGH THE EVENING HOURS.

TUESDAY THROUGH SATURDAY...WE COULD SEE A PERIOD OF MARGINAL SMALL
CRAFT ADVISORY LEVEL CONDITIONS IN NORTHERN SC WATERS TUESDAY NIGHT
AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING COLD
FRONT. FREQUENT GUSTS UP TO 25 KTS ARE POSSIBLE...MAINLY BEYOND 10
NM FROM THE COAST. HOWEVER...MARINE LAYER STABILITY SHOULD HOLD
GUSTS AND ASSOCIATED SEAS BELOW SMALL CRAFT ADVISORY LEVELS AS HIGH
PRESSURE BEGINS TO BUILD BEHIND THE PASSING THE FRONT. AS HIGH
PRESSURE SHIFTS OFFSHORE...A WEAKER GRADIENT WILL SUPPORT CONDITIONS
REMAINING BELOW SMALL CRAFT ADVISORY THRESHOLDS AS EAST/NORTHEAST
WINDS VEER TO SOUTH/SOUTHWEST WEDNESDAY NIGHT THROUGH THURSDAY
NIGHT. A TIGHTENING GRADIENT AHEAD OF ANOTHER APPROACHING COLD FRONT
COULD SUPPORT MARGINAL SMALL CRAFT ADVISORY WINDS FRIDAY AND FRIDAY
NIGHT...ALTHOUGH MARINE LAYER STABILITY COULD AGAIN LIMIT THIS
POTENTIAL. AFTER COLD FROPA SATURDAY...EXPECT A STRONGER SURGE OF
NORTHEAST WINDS AS HIGH PRESSURE BUILDS DOWN THE COAST ESPECIALLY
SATURDAY NIGHT AND SUNDAY. THE PROBABILITY FOR SMALL CRAFT ADVISORY
WINDS/SEAS APPEARS RATHER HIGH THIS WEEKEND.

ALSO OF NOTE...HIGHER DEWPOINTS IN THE 60S ADVECTING OVER THE WATERS
COULD SUPPORT SOME SEA FOG THURSDAY AND FRIDAY. WILL CONTINUE TO
ASSESS.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR AMZ330-
     350.

&&

$$
SYNOPSIS...
NEAR TERM...FWA
SHORT TERM...DPB
LONG TERM...SPR
AVIATION...FWA
MARINE...DPB/FWA


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