Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 290155
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
955 PM EDT SAT MAR 28 2015

.SYNOPSIS...
HIGH PRESSURE WILL PREVAIL THROUGH SUNDAY. WEAK COLD FRONTS WILL
PUSH INTO THE REGION MONDAY AND AGAIN WEDNESDAY...AND BOTH FRONTS
SHOULD DISSIPATE OVER OR CLOSE TO THE AREA. WARMER ATLANTIC HIGH
PRESSURE WILL THEN BUILD OVER THE REGION THROUGH LATE WEEK. A
STRONGER COLD FRONT WILL ARRIVE NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SKIES WERE CLEAR THIS EVENING ACROSS THE FORECAST AREA AS THE
LAST FEW POCKETS OF FAIR WEATHER CLOUDS DISSIPATED AFTER SUNSET.
NO SIGNIFICANT CHANGES ON THE EVENING FORECAST AS A SECONDARY DRY
COLD FRONT PASSES THROUGH THE REGION OVERNIGHT WITH COLD HIGH PRES
BUILDING SE FROM NORTH GEORGIA AND THE WESTERN CAROLINAS. IN THE
WAKE OF THE FRONT A REINFORCING ROUND OF COLD ADVECTION IS ON TAP
OVERNIGHT. TEMPERATURES SHOULD REACH THE LOW TO MID 30S DURING THE
NEAR-DAWN HOURS. THE ONGOING FREEZE WARNING FOR THE NORTHWEST
TIER OF COUNTIES LOOKS ON TRACK AND HAS NEEDED NO CHANGE AGAIN
WITH THIS PACKAGE. MODELS CONTINUE TO INDICATE FALLING SURFACE DEW
POINTS AND INCREASING TEMP/DEW POINT SPREADS OVERNIGHT...THUS
CONCERNS FOR WIDESPREAD FROST APPEARS LOW IN LOCATIONS BORDERING
THE FREEZE WARNINGS IN PLACE.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
SUNDAY...AFTER A COLD START...TEMPERATURES WILL WARM UP UNDER
PLENTIFUL SUNSHINE TO THE UPPER 50S NORTH TO LOWER 60S SOUTH BY LATE
AFTERNOON AS POLAR HIGH PRESSURE SETTLES OVER THE AREA. THOSE TEMPS
ARE 10 DEGREES OR MORE BELOW AVERAGE. RELATIVE HUMIDITIES WILL BE
UNSEASONABLY LOW AS WELL WITH VALUES INTO THE TEENS AWAY FROM THE
COAST BY AFTERNOON. FORTUNATELY...WINDS WILL BE LIGHT...SO FIRE
WEATHER CONCERNS WILL NOT BE LARGE.

SUNDAY NIGHT WILL START WITH MAINLY CLEAR SKIES/LIGHT
WINDS...SUPPORTING EXCELLENT RADIATIONAL COOLING CONDITIONS. I AM
CONCERNED THAT WE COULD GET CLOSE TO FREEZING NEAR THE SANTEE RIVER
DURING THE LATE EVENING HOURS IN THE USUAL COLD SPOTS AROUND THE
FRANCIS MARION. FOR NOW...I DID NOT DROP THE TEMPS BELOW 34...BUT
THIS WILL NEED TO BE WATCHED. FROST WOULD ALSO BE POSSIBLE IN THOSE
AREAS. LATER AT NIGHT...AS THE GRADIENT TIGHTENS BETWEEN HIGH
PRESSURE SHIFTING SOUTH OF THE REGION AND A COLD FRONT APPROACHING
FROM THE NORTHWEST...AND AS CLOUDS BEGIN TO INCREASE...OVERNIGHT
TEMPERATURES WILL BEGIN TO SLOWLY RISE. THUS...HOURLY TEMPERATURES
INDICATE LOWS WITHIN A COUPLE OF HOURS OF MIDNIGHT...FOLLOWED BY
SLIGHTLY HIGHER TEMPS AROUND DAYBREAK MONDAY.

MONDAY...A WEAK COLD FRONT WILL MOVE THROUGH THE AREA ON MONDAY FROM
NORTHWEST TO SOUTHEAST. MODELS ARE A LITTLE MORE AGGRESSIVE IN THE
CHANCES OF RAIN WITH THE FRONT...SO I HAVE INCREASED POPS AND CLOUD
COVER JUST A TOUCH. AREAS THAT HAVE TEMPS REACH 70 OR ABOVE MAY GET
ENOUGH SURFACE INSTABILITY TO GENERATE SOME ISOLATED
THUNDERSTORMS...SO I DID ADD A SLIGHT CHANCE OF THUNDER DURING THE
AFTERNOON HOURS...AS WELL AS THE EARLY EVENING PRIOR TO SUNSET OVER
THE SOUTH.

MONDAY NIGHT...THE COLD FRONT WILL WEAKEN AND PUSH SOUTHEAST OF THE
AREA...ENDING THE THREAT FOR RAIN MOST PLACES. WITH THE FRONT
SLOWING DOWN CONSIDERABLY...I CANT RULE OUT A LINGERING SHOWER IN
THE SOUTHERN AREAS...SO A SLIGHT CHANCE OF POPS REMAINS SOUTH OF
ROUGHLY INTERSTATE 16. IF ANY SHOWERS DO OCCUR...AMOUNTS WILL BE
GENERALLY LIGHT. TEMPS WILL BE DOWN TO THE 40S TO NEAR 50 BY MORNING
AS WEAK PRESSURE BRIEFLY VISITS THE AREA.

TUESDAY...HIGH PRESSURE WILL WORK ITS WAY INTO THE ATLANTIC DURING
THE DAY TUESDAY...ALLOWING FOR A MILDER SOUTHWESTERLY WIND TO
DEVELOP. TEMPERATURES SHOULD GET TO 70 OR ABOVE DURING THE
AFTERNOON...ALTHOUGH PROBABLY 10 DEGREES COOLER DURING THE AFTERNOON
ALONG THE COAST AS THE WINDS BACK TO SOUTHERLY IN SC AND SOUTH
SOUTHEASTERLY IN GEORGIA. MOISTURE WILL ALSO BE INCREASING...SO I
HAVE MAINTAINED THE LOW END POPS FOR SOUTH IF INTERSTATE 16 THAT I
INHERITED FROM THE PREVIOUS FORECAST...BUT THAT IS PROBABLY A
TOUCH AGGRESSIVE...AND CERTAINLY IT DOES NOT LOOK ANYTHING LIKE A
WASHOUT OF A DAY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
THROUGH LATE WEEK...ABOVE NORMAL TEMPERATURES WILL PREVAIL... EXCEPT
PERHAPS THURSDAY IF SHOWERS/THUNDERSTORMS BECOME MORE WIDESPREAD
THAN CURRENTLY FORECAST. THEN...NORMAL TO BELOW-NORMAL TEMPERATURES
SHOULD RETURN NEXT WEEKEND.

ANOTHER COLD FRONT IS EXPECTED TO SETTLE INTO THE REGION FROM THE
NORTH WEDNESDAY. DISCOUNTING THE 28/00 UTC CANADIAN SOLUTION
DEPICTING A PROGRESSIVE FRONT FOLLOWED BY STRONG HIGH PRESSURE
BUILDING FROM THE N/NE...THIS FRONT SHOULD REMAIN WEAK AND WILL
LIKELY STALL AND DISSIPATE OVER OR CLOSE TO THE REGION. MEANWHILE...
A SHORTWAVE TROUGH ALOFT WILL ADVANCE THROUGH THE LOWER MS RIVER
VALLEY TOWARD THE NORTHERN GULF COAST...AND TO VARYING DEGREES
GUIDANCE DEPICTS AN EXPANDING PLUME OF MOISTURE/PRECIPITATION AHEAD
OF THIS FEATURE. GIVE THE SHORTWAVE RIDGING ALOFT OVER THE
REGION...FEEL THAT GUIDANCE COULD BE PUSHING CONVECTIVE PRECIPITATION
TOO QUICKLY TOWARD THE EAST/INTO THE REGION. THUS...HELD POPS BELOW
15 PERCENT WITH NO MENTION OF PRECIPITATION WEDNESDAY...BUT FORECAST
CONFIDENCE IS LOW. A BETTER CHANCE FOR SHOWERS AND PERHAPS
THUNDERSTORMS SHOULD DEVELOP WEDNESDAY NIGHT THROUGH AT LEAST
THURSDAY NIGHT AS THE UPPER TROUGH PASSES OVER THE REGION. A
STRONGER COLD FRONT WILL ARRIVE LATER FRIDAY OR SATURDAY...
JUSTIFYING AT LEAST CHANCE POPS AND A MENTION THUNDERSTORMS.

&&

.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
VFR AT KCHS AND KSAV THROUGH 00Z MONDAY.

EXTENDED AVIATION OUTLOOK...FLIGHT RESTRICTIONS POSSIBLE IN SHOWERS
ON MONDAY. OTHERWISE...MAINLY VFR.

&&

.MARINE...
OVERNIGHT...COLD HIGH PRESSURE WILL STEADILY BUILD FROM THE OHIO
VALLEY AND EXPAND ACROSS THE LOCAL WATERS OVERNIGHT. THE ACCOMPANYING
COLD ADVECTION AND TIGHTENED PRESSURE GRADIENT WILL ALLOW NW WINDS
TO VEER NORTH AND SURGE AFTER MIDNIGHT NORTHERN WATERS AND CLOSER
TO DAYBREAK GEORGIA LEGS. NORTH WINDS COULD NEAR 20 KT WITH HIGHER
GUSTS LATE ACROSS THE CHARLESTON COUNTY WATERS AND OFFSHORE
GEORGIA ZONES FOR A SHORT WINDOW LATER TONIGHT AND EARLY SUNDAY
MORNING.

SUNDAY THROUGH THURSDAY...WINDS WILL BE QUITE CHANGEABLE DURING
THE SUNDAY THROUGH THURSDAY TIME FRAME...BUT EXCEPT FOR POSSIBLY A
PERIOD MONDAY AFTERNOON AHEAD OF A FRONT...HEADLINES SEEM
UNLIKELY.

HIGH PRESSURE ON SUNDAY WILL SETTLE RIGHT OVER THE COASTAL
WATERS...LEADING TO A WEAKENING IN THE WINDS...WHICH SHOULD
EVENTUALLY VEER TO AN ONSHORE DIRECTION DURING THE AFTERNOON. WINDS
WILL TURN SOUTHERLY...THEN SOUTHWESTERLY SUNDAY NIGHT AHEAD OF A
COLD FRONT...INCREASING IN SPEED MONDAY. THERE IS A CHANCE WE WILL
NEED SMALL CRAFT ADVISORIES MONDAY AFTERNOON IN THE CHARLESTON
COUNTY WATERS...ALONG WITH THE OUTER GEORGIA WATERS...BUT FOR NOW I
HAVE KEPT THE SUSTAINED WINDS JUST BELOW HEADLINE CRITERIA AT 20
KNOTS OR SO. WINDS WILL VEER TO THE NORTHWEST AND COME BACK DOWN IN
SPEED MONDAY NIGHT BEHIND THE FRONT...AND TUESDAY THE WINDS SLACKEN
AS THE NEXT AREA OF WEAK HIGH PRESSURE SETTLES OVER THE WATERS.
ANOTHER FRONT IS EXPECTED TO PASS THROUGH WEDNESDAY...WITH WINDS
TURNING NORTHEASTERLY BEHIND THE FRONT WEDNESDAY NIGHT...VEERING
AROUND TO SOUTHEASTERLY BY THURSDAY AFTERNOON. SPEEDS WILL BE
GENERALLY 15 KNOTS OR LESS DURING THE MIDDLE OF THE WEEK.

&&

.CLIMATE...
RECORD LOWS MARCH 29TH...
KCHS...32 SET IN 1969.
KSAV...33 SET IN 1955.
KCXM...37 SET IN 1982.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...FREEZE WARNING FROM 4 AM TO 9 AM EDT SUNDAY FOR GAZ087-088.
SC...FREEZE WARNING FROM 4 AM TO 9 AM EDT SUNDAY FOR SCZ040-042>045.
MARINE...NONE.

&&

$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...FWA
LONG TERM...SPR
AVIATION...
MARINE...
CLIMATE...



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