Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 301505
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1105 AM EDT THU OCT 30 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER THE AREA THROUGH FRIDAY. A STRONG
COLD FRONT WILL SWEEP THROUGH THE REGION FRIDAY NIGHT...FOLLOWED
BY ANOTHER HIGH PRESSURE BUILDING FROM THE WEST OVER THE WEEKEND.
THE HIGH WILL SETTLE ALONG THE SOUTHEAST COAST EARLY NEXT
WEEK...BEFORE SHIFTING OFFSHORE DURING THE MIDDLE OF NEXT WEEK AS
ANOTHER COLD FRONT APPROACHES.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY...THE COLD FRONT IS CURRENTLY LOCATED OFFSHORE BY MID
MORNING...WITH SURFACE HIGH PRESSURE BUILDING IN FROM THE
WEST/NORTHWEST. DRIER AIR HAS FILTERED INTO THE REGION IN WAKE OF
THE FRONT...AND RAIN CHANCES OVER LAND AREAS ARE NEAR ZERO FOR THE
REMAINDER OF THE DAY. HAVE MADE SOME ADJUSTMENTS TO CLOUD FORECAST
TO INDICATE LESS OVERALL COVERAGE...HOWEVER A SWATH OF LINGERING
STRATUS CONTINUES TO IMPACT PORTIONS OF SOUTHEAST GEORGIA. AS
THESE CLOUDS DRIFT SOUTHWARD...WILL NEED TO MONITOR ANOTHER AREA
OF STRATUS CURRENTLY NORTH OF THE SANTEE RIVER IN SOUTH CAROLINA
THAT IS ALSO SHIFTING SOUTH. IN GENERAL...WILL ADVERTISE MOSTLY
CLEAR TO PARTLY CLOUDY SKIES FOR THE FORECAST AREA TODAY. EXPECT
HIGH TEMPERATURES TO BE RIGHT AROUND SEASONAL NORMALS IN THE LOW
TO MID 70S.

TONIGHT...WEAK HIGH PRESSURE WILL CONTINUE TO BUILD
EASTWARD...ALTHOUGH CONSIDERING THE PERSISTENT UPPER
TROUGH...EXPECT ENOUGH LOW LEVEL MOISTURE TO SUPPORT SCATTERED
CUMULUS OR STRATOCUMULUS OVER THE WATERS AND PORTIONS OF COASTAL
AREAS. FARTHER INLAND...MODEST RADIATIONAL COOLING WILL ALLOW FOR
LOWS IN THE MIDDLE 40S. ELSEWHERE...THE GREATER SKY COVER AND
SLIGHT BOUNDARY LAYER MIXING WILL KEEP TEMPS IN THE UPPER 40S TO
LOWER 50S.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
FRIDAY...A POTENT SHORT WAVE WILL DIVE OUT OF THE GREAT LAKES REGION
AND INTO THE OHIO VALLEY...RESULTING IN THE AMPLIFICATION OF A MID
AND UPPER LEVEL TROUGH OVER THE EASTERN UNITED STATES. AT THE
SURFACE...THE DEEPENING TROUGH WILL ALLOW FOR CYCLOGENESIS TO OCCUR
OFF THE SOUTHEAST COAST WITH THE DEVELOPING SURFACE LOW LIFTING
NORTHEAST ALONG THE NORTH CAROLINA COAST THROUGH THE DAY. WEAK HIGH
PRESSURE OVER THE REGION WILL RESULT IN RAIN-FREE CONDITIONS BUT IT
WILL BE UNSEASONABLY COOL WITH HIGHS AROUND 70 OR IN THE LOWER 70S
DESPITE MOSTLY SUNNY SKIES.

FRIDAY NIGHT...AN UPPER LEVEL LOW WILL CLOSE OFF AS IT RAPIDLY DROPS
SOUTHEAST ACROSS THE TENNESSEE VALLEY AND INTO THE CAROLINAS. WHILE
THE INITIAL SURFACE LOW CONTINUES TO LIFT NORTHEAST OFF THE
MID-ATLANTIC COAST...ANOTHER SURFACE LOW WILL DEVELOP NEAR THE
SOUTHEAST NORTH CAROLINA COAST AND CAUSE A POWERFUL COLD FRONT TO
SWEEP THROUGH THE AREA OVERNIGHT. THERE APPEARS JUST ENOUGH MOISTURE
WRAPPING AROUND THE NEWLY FORMING SURFACE LOW TO ALLOW ISOLATED
SHOWERS TO DEVELOP ACROSS MAINLY THE CHARLESTON TRI-COUNTY AREA
OVERNIGHT IN CLOSER PROXIMITY TO THE UPPER LOW. GIVEN THE MAGNITUDE
OF THE DEVELOPING COLD POOL ALOFT...THERE IS CERTAINLY THE POTENTIAL
FOR SOME GRAUPEL TO OCCUR BUT WILL NOT INCLUDE MENTION IN THE
FORECAST AT THIS TIME.  COLD AIR ADVECTION AND DEEPER MIXING WILL
DEVELOP BEHIND THE FRONT...WITH TEMPERATURES QUICKLY FALLING LATE
INTO THE LOWER AND MID 40S WITH WINDS BECOMING GUSTY.

SATURDAY...A 535 DECAMETER UPPER LEVEL LOW WILL SWING ACROSS
NORTHERN SOUTH CAROLINA IN THE MORNING...BEFORE SHIFTING OFFSHORE
DURING THE AFTERNOON. THIS HIGHLY ANOMALOUS LOW AND VERY STRONG COLD
AIR ADVECTION WILL RESULT IN 850 MB TEMPERATURES OF -5C...WHICH IS 4
STANDARD DEVIATIONS BELOW NORMAL! NEEDLESS TO SAY...IT WILL BE A
VERY COLD DAY FOR EARLY NOVEMBER WITH HIGHS STRUGGLING TO REACH INTO
THE MID AND UPPER 50S. THIS WILL LIKELY RESULT IN A RECORD LOW
MAXIMUM AT KCHS...BUT SEE BELOW FOR OTHER RECORD INFORMATION. WINDY
CONDITIONS WILL ALSO OCCUR...WITH VERY STRONG LOW LEVEL WINDS OF 30
TO 40 KT DEVELOPING ALONG THE SOUTHERN PERIPHERY OF THE UPPER LOW.
DEEP MIXING PROFILES WILL TAP INTO THE STRONGER WINDS
ALOFT...PRODUCING SUSTAINED WINDS OF 20 TO 30 MPH WITH GUSTS UPWARDS
OF 35 MPH AT TIMES. THERE COULD BE SUFFICIENT MOISTURE WRAPPING
AROUND SURFACE LOW PRESSURE TRACKING OFF THE NORTH CAROLINA COAST TO
PRODUCE ISOLATED SHOWERS ACROSS PARTS SOUTHEAST SOUTH CAROLINA. THE
POTENTIAL FOR GRAUPEL TO OCCUR WILL CONTINUE AS WELL WITH THE CORE
OF THE COLD POOL ALOFT SHIFTING OVER THE AREA. PRECIPITATION CHANCES
WILL DIMINISH IN THE AFTERNOON AS THE SURFACE AND UPPER LOWS BEGIN
TO PULL AWAY.

SATURDAY NIGHT...THE SURFACE PRESSURE GRADIENT WILL REMAIN FAIRLY
TIGHT OVER THE REGION BETWEEN LOW PRESSURE BOMBING OFF THE
MID-ATLANTIC COAST AND HIGH PRESSURE OVER THE MISSISSIPPI VALLEY.
THIS COMBINED WITH CONTINUED COLD AIR ADVECTION WILL KEEP WINDS
COUPLED THROUGH THE NIGHT. TEMPERATURES WILL DROP INTO THE MID AND
UPPER 30S FOR LOWS...WITH COOL TEMPERATURES LIKELY OCCURRING ALL THE
WAY TO THE COAST GIVEN THE ADVECTIVE REGIME.

SUNDAY...SURFACE HIGH PRESSURE WILL BEGIN TO BUILD INTO THE REGION
FROM THE WEST RESULTING IN MAINLY SUNNY SKIES. NORTHERLY FLOW WILL
KEEP TEMPERATURES WELL BELOW NORMAL...WITH HIGHS ONLY
MODERATING INTO THE UPPER 50S OR LOWER 60S ACROSS THE AREA.

LAKE WINDS...THE COMBINATION OF WARM LAKE WATER TEMPERATURES AND
VERY STRONG COLD AIR ADVECTION ALOFT IN WAKE OF A POWERFUL COLD
FRONT FRIDAY NIGHT WILL RESULT IN POTENTIALLY DANGEROUS CONDITIONS
ON LAKE MOULTRIE FOR MARINERS. STRONG WINDS AND ROUGH WAVES ARE
EXPECTED THROUGH SATURDAY NIGHT AND A LAKE WIND ADVISORY WILL
CERTAINLY BE NEEDED.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
MEDIUM RANGE GUIDANCE IS IN GOOD AGREEMENT WITH THE GENERAL SYNOPTIC
PATTERN THROUGH THE LONG TERM PERIOD. IN THE MID AND UPPER LEVELS OF
THE ATMOSPHERE...A STRONG RIDGE WILL SHIFT EASTWARD AND EXPAND OVER
THE REGION EARLY NEXT WEEK...BEFORE SHIFTING INTO THE ATLANTIC AS A
TROUGH APPROACHES FROM THE WEST DURING THE MIDDLE OF THE WEEK.
MEANWHILE AT THE SURFACE...STRONG HIGH PRESSURE WILL SETTLE ALONG
THE SOUTHEAST COAST EARLY NEXT WEEK THEN SHIFT INTO THE ATLANTIC BY
MID-WEEK...WITH A COASTAL TROUGH POSSIBLY DEVELOPING WEDNESDAY
BEFORE A COLD FRONT MOVES THROUGH THURSDAY.

OVERALL...THIS PATTERN WILL FAVOR RAIN-FREE CONDITIONS EARLY IN THE
WEEK...WITH A SLIGHT CHANCE FOR SHOWERS WEDNESDAY WITH THE COASTAL
TROUGH/ONSHORE FLOW AND THURSDAY WITH THE COLD FRONT. PATCHY FROST
COULD OCCUR INLAND FROM THE COAST SUNDAY NIGHT...WITH SOME FREEZING
TEMPERATURES POSSIBLE IN WELL SHELTERED LOCATIONS AS WELL.
THEN...TEMPERATURES WILL MODERATE THROUGH THE REMAINDER OF THE LONG
TERM PERIOD RETURNING TO NEAR OR SLIGHTLY ABOVE NORMAL BY THE MIDDLE
OF NEXT WEEK.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
A PERIOD OF MVFR OR LOWER CEILINGS IS POSSIBLE THROUGH 16Z AT
KSAV DUE TO A LINGERING SWATH OF LOW STRATUS. OTHERWISE...VFR
CONDITIONS WILL PREVAIL AT THE TERMINALS THROUGH 12Z FRIDAY.

EXTENDED AVIATION OUTLOOK...STRONG WINDS ARE LIKELY AT THE
TERMINALS LATE FRIDAY NIGHT AND SATURDAY AS A COLD FRONT PASSES
THROUGH THE REGION. OTHERWISE...VFR CONDITIONS ARE EXPECTED TO
PREVAIL.

&&

.MARINE...
NORTH WINDS PREVAIL ACROSS THE WATERS IN WAKE OF A COLD FRONT
PUSHING FARTHER OFFSHORE. HIGH PRESSURE WILL GRADUALLY BUILD
TOWARD INLAND AREAS THROUGH THE DAY. WIND SPEEDS WILL BE AROUND 10
TO 15 KT TODAY...POSSIBLY INCREASING ANOTHER 5 KT OR SO TONIGHT
WITH A TIGHTENING LOW-LEVEL GRADIENT AND COLD ADVECTION OVER
FAIRLY WARM ATLANTIC WATERS.

FRIDAY THROUGH TUESDAY...HIGH PRESSURE WILL BUILD OVER THE AREA ON
FRIDAY...THEN A POWERFUL COLD FRONT WILL SWEEP OFFSHORE LATE FRIDAY
NIGHT. THE COMBINATION OF WARM SEA SURFACE TEMPERATURES...VERY
STRONG COLD AIR ADVECTION ALOFT AND POTENT LOW LEVEL WIND FIELDS
WILL RESULT IN POTENTIALLY DANGEROUS CONDITIONS FOR MARINERS LATE
FRIDAY NIGHT THROUGH SATURDAY NIGHT WITH GALE CONDITIONS LIKELY.
CONDITIONS WILL IMPROVE EARLY NEXT WEEK...AS HIGH PRESSURE BUILDS
OVER THE REGION.

&&

.CLIMATE...
RECORD LOW MAX TEMPERATURES FOR SAT NOV 1...
KCHS 56 /1993/...
KSAV 52 /1925/...
KCXM 52 /1925/...

&&

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

&&

$$

NEAR TERM...WMS
SHORT TERM...JAQ
LONG TERM...JAQ
AVIATION...WMS/JAQ
MARINE...WMS/JAQ/JRL
CLIMATE...






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