Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 260547
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
147 AM EDT SUN APR 26 2015

.SYNOPSIS...
A COLD FRONT WILL MOVE SOUTH THROUGH THE AREA SUNDAY EVENING INTO
SUNDAY NIGHT. DRY HIGH PRESSURE WILL PREVAIL MONDAY INTO TUESDAY.
A GULF OF MEXICO STORM SYSTEM WILL IMPACT THE REGION MID WEEK WITH
DRY HIGH PRESSURE THEN LIKELY RETURNING THROUGH THE END OF THE
WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
OTHERWISE RAIN-FREE CONDITIONS ARE EXPECTED THE REMAINDER OF THE
NIGHT AS SUBSIDENCE DEVELOPS IN WAKE OF A DEPARTING SHORT WAVE.
SKIES WILL CONTINUE TO CLEAR OVERNIGHT...EXCEPT SOME LOW STRATUS
COULD DEVELOP AROUND DAYBREAK DUE TO MOIST SOILS AND THE PRESENCE
OF A SUBSIDENCE INVERSION. LOWS HAVE ALREADY BEEN REACHED IN RAIN
COOLED AIR IN SOME LOCATIONS...SO NON-DIURNAL TEMPERATURE CURVES
ARE EXPECTED. OVERALL TEMPERATURES SHOULD BE IN THE MID TO UPPER
60S.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
SUNDAY...LOW PRESSURE WILL SHIFT OFF THE MID ATLANTIC COAST
EARLY...ALLOWING A BACKDOOR COLD FRONT TO APPROACH THE SOUTHEAST
DURING THE DAY. DEEP WESTERLY FLOW AHEAD OF THE FRONT WILL ALLOW
FAIRLY SIGNIFICANT HEATING OVER THE AREA...WITH AFTERNOON TEMPS
EXPECTED TO PEAK IN THE UPPER 80S TO AROUND 90 DEGREES. GIVEN THIS
AMOUNT OF HEATING...LOW LVL MIXING WILL BE ENHANCED AND WILL LIKELY
RESULT IN BREEZY CONDITIONS THROUGHOUT THE AFTERNOON AS A 30-40 KT
LOW LVL JET PASSES OVER THE SOUTHEASTERN UNITED STATES. AS THE FRONT
BEGINS TO ENTER NORTHERN AREAS DURING THE EVENING...IT WILL BE
SOMEWHAT MOISTURE STARVED. HOWEVER...WE COULD SEE A FEW SHOWERS
AND/OR THUNDERSTORM DURING LATE AFTERNOON INTO EARLY OVERNIGHT HOURS
AS THE FRONT CONTINUES A SOUTHWARD SHIFT OVER THE AREA. SFC WINDS
WILL QUICKLY BECOME NORTH BEHIND THE FRONT...WITH RAPIDLY COOLING
AND DRYING CONDITIONS FROM NORTH TO SOUTH SUNDAY NIGHT. IN
GENERAL...LOW TEMPS WILL RANGE IN THE MID 50S NORTH TO LOW 60S
SOUTH.

MONDAY AND TUESDAY...DRY HIGH PRESSURE WILL BUILD FROM THE
NORTH/NORTHWEST BEHIND A COLD FRONT WELL TO OUR SOUTH. AS A
RESULT...TEMPS WILL BE MUCH COOLER WITHIN NORTHERLY FLOW. IN
GENERAL...MONDAY AFTERNOON HIGHS WILL RANGE FROM THE LOW TO MID
70S...THEN COOL A FEW MORE DEGREES ON TUESDAY AS HIGH PRESSURE
BECOMES CENTERED OVER THE SOUTHEAST. BY TUESDAY EVENING...MOISTURE
RETURNS AS ONSHORE FLOW DEVELOPS WELL AHEAD OF LOW PRESSURE SHIFTING
OVER THE NORTHERN GULF OF MEXICO. A FEW SHOWERS WILL BE
POSSIBLE...MAINLY SOUTH OF INTERSTATE 16 BEFORE SUNSET.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
RAIN CHANCES WILL BE INCREASING FROM THE SOUTHWEST TUESDAY NIGHT AS
DEVELOPING LOW PRESSURE ALONG THE NORTHERN GULF COAST MOVES TOWARD
THE AREA ALONG WITH DEEPER MOISTURE. STILL SOME TIMING/STRENGTH
DIFFERENCES THOUGH WITH THIS SYSTEM WITH THE ECMWF CONTINUING TO BE
FASTER AND STRONGER WITH THE LOW AS IT MOVES THROUGH SOUTHEAST
GEORGIA WEDNESDAY/WEDNESDAY NIGHT. THE LOW SHOULD BE PULLING AWAY
FROM THE AREA THURSDAY WITH IMPROVING CONDITIONS...ALTHOUGH CANNOT
RULE OUT SOME LINGERING SHOWERS AS DUE TO THE SLOW PROGRESSION OF
THE UPPER TROUGH. FRIDAY AND SATURDAY LOOK DRIER WITH TEMPS GETTING
BACK TO AT OR JUST ABOVE NORMAL.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
LOW STRATUS COULD DEVELOP AROUND DAYBREAK AT THE TERMINALS DUE TO
LINGERING LOW LEVEL MOISTURE...WET GROUND CONDITIONS AND A
SUBSIDENCE INVERSION...POSSIBLY RESULTING IN MVFR OR LOWER
CONDITIONS FOR A FEW HOURS. OTHERWISE...VFR CONDITIONS ARE
EXPECTED TO PREVAIL. A POTENT 35-40 KT LOW LEVEL JET AT 2K FT WILL
RESULT IN SOME LOW WIND SHEAR AT THE TERMINALS THROUGH ABOUT
1330Z. ONCE THE INVERSION LIFTS AND MIXING COMMENCES IN THE
MORNING...THE STRONGER WINDS ALOFT WILL MIX DOWN IN THE FORM OF
HIGHER GUSTS...WHICH COULD PEAK UPWARDS OF 25-30 KT IN THE
AFTERNOON WHEN THE DEEPEST MIXING WILL OCCUR. A BACKDOOR COLD
FRONT WILL DROP IN FROM THE NORTH THIS EVENING...AND COULD PRODUCE
SOME ISOLATED SHOWERS AND THUNDERSTORMS AROUND KCHS IN THE 22-03Z
TIME FRAME...AND VICINITY THUNDERSTORMS HAVE BEEN ADDED TO THE TAF
ACCORDINGLY.

EXTENDED AVIATION OUTLOOK...VFR CONDITIONS SHOULD PREVAIL INTO
TUESDAY BEFORE SHOWERS AND TSTMS RETURN MAINLY TUESDAY NIGHT INTO
WEDNESDAY NIGHT.

&&

.MARINE...
TONIGHT...MODEST SOUTH/SOUTHWEST WINDS WILL PERSIST OVERNIGHT
WITH SPEEDS 15-20 KT NEARSHORE WATERS AND 20-25 KT OFFSHORE
WATERS. A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR THE GEORGIA
OFFSHORE LEG THROUGH THE NIGHT. SEAS WILL AVERAGE 2-4 FT NEARSHORE
WATERS AND 4-6 FT OFFSHORE WATERS.

SUNDAY THROUGH THURSDAY...WINDS WILL REMAIN ELEVATED FROM THE WEST
ON SUNDAY AHEAD OF A BACKDOOR COLD FRONT THAT PUSHES SOUTH THROUGH
THE WATERS EARLY SUNDAY NIGHT. WE COULD SEE A BRIEF PERIOD OF SMALL
CRAFT ADVISORY LEVEL CONDITIONS IN THE CHS HARBOR SUNDAY AFTERNOON
AS STRONG HEATING OVER LAND PROMOTES MIXING OF A 30-40 KT LOW LVL
JET TO SFC. BEHIND THE COLD FRONT...A NORTHERLY SURGE WILL ENSUE
WITH CONDITIONS NEAR ADVISORY LEVELS MAINLY BEYOND 20 NM SUNDAY
NIGHT. HIGH PRESSURE WILL THEN CONTINUE BUILDING FROM THE NORTH ON
MONDAY...THEN BECOME CENTERED OVER THE AREA ON TUESDAY...LEADING TO
A WEAKENING PRESSURE GRADIENT THROUGH THE PERIOD AND IMPROVED
WINDS/SEAS. CONDITIONS SHOULD THEN GO BACK DOWNHILL AS DEVELOPING
LOW PRESSURE APPROACHES FROM THE SOUTHWEST WEDNESDAY AND PASSES
THROUGH THE AREA WEDNESDAY NIGHT...WITH SMALL CRAFT ADVISORIES
POSSIBLY BEING NEEDED FOR AT LEAST THE WATERS BEYOND 20 NM FROM
SHORE. THERE IS STILL SOME UNCERTAINTY THOUGH REGARDING THE
STRENGTH/TRACK/TIMING OF THE LOW AND THUS FORECAST CONFIDENCE IS LOW
AT THIS TIME.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 AM EDT THIS MORNING FOR AMZ374.

&&

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


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