Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 050312
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1012 PM EST WED MAR 4 2015

.SYNOPSIS...
ATLANTIC HIGH PRESSURE WILL EXTEND ACROSS THE REGION OVERNIGHT. A
STRONG COLD FRONT WILL APPROACH FROM THE NORTHWEST THURSDAY AND
WILL PASS OFF THE COAST EARLY THURSDAY EVENING. COLDER HIGH
PRESSURE WILL BUILD OVER THE AREA THURSDAY NIGHT INTO SATURDAY. A
COASTAL TROUGH WILL DEVELOP OFFSHORE LATE IN THE WEEKEND. A STORM
SYSTEM COULD IMPACT THE AREA EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
ONGOING FORECASTS REMAINED ON TRACK AND REQUIRED FEW/MINOR TWEAKS
THROUGH THE OVERNIGHT. PERSISTENT SOUTH/SOUTHWEST WINDS WILL HOLD
TEMPERATURES IN THE 60S THROUGH MUCH OF THE NIGHT...AND EVEN BY
DAYBREAK ONLY A FEW LOCATIONS WILL BOTTOM OUT IN THE UPPER 50S.

LOW CLOUDS EXPANDING IN COVERAGE FROM THE NE GULF OF MEXICO INTO
SOUTHERN GA WILL SPREAD INTO THE FORECAST AREA FROM THE
SOUTH/SOUTHWEST OVERNIGHT. AREAS OF FOG COULD ACCOMPANY THESE LOW
CLOUDS...BUT ODDS ARE GREATER THAT ANY SIGNIFICANT FOG WILL REMAIN
CONFINED TO THE IMMEDIATE COAST AS CONDITIONS REMAIN FAVORABLE FOR
SEA FOG DEVELOPMENT.

NO RAIN IS EXPECTED OVERNIGHT.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/...
THURSDAY...SURFACE HIGH PRESSURE WILL BE CENTERED OVER THE ATLANTIC
WHILE A COLD FRONT APPROACHES FROM THE WEST...AND EVENTUALLY PASSES
THROUGH THE FORECAST AREA IN THE AFTERNOON INTO THE EVENING.
TIGHTENING PRESSURE GRADIENT WILL ALLOW FOR BREEZY CONDITIONS TO
DEVELOP WITH SOUTHWEST WINDS EXPECTED TO GUST UP TO AROUND 25 MPH.
COMPRESSIONAL HEATING AHEAD OF THE FRONT AND DEEP SOUTHWEST FLOW
WILL ALLOW TEMPERATURES TO SOAR WELL ABOVE NORMAL AGAIN. HIGHS WILL
WILL BE IN THE UPPER 70S/AROUND 80 WITH CURRENT RECORDS EXPECTED TO
STAY SAFE. GIVEN UPPER FORCING AND INCREASING
MOISTURE...PRECIPITATION WILL ACCOMPANY THE FRONT. WEAK INSTABILITY
AND UNIMPRESSIVE LAPSE RATES WILL KEEP THUNDER TO A
MINIMUM...HOWEVER COULD NOT RULE OUT A COUPLE RUMBLES IN THE
AFTERNOON. THURSDAY NIGHT...NORTH/NORTHEAST FLOW WILL HELP USHER
MUCH COLDER AIR INTO THE REGION. LOW TEMPERATURES WILL DROP TO THE
MID 30S/LOW 40S. FAVORABLE MIXING PROFILES WILL ALLOW FOR GUSTY
WINDS OVER LAKE MOULTRIE. A LAKE WIND ADVISORY MAY BE NEEDED LATE
THURSDAY NIGHT INTO FRIDAY.

FRIDAY...HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST WHILE THE
FRONT REMAINS NEARLY STATIONARY WELL OFF THE SOUTHEAST COAST. GIVEN
FORECAST AREA IS SITUATED IN THE FAVORABLE RIGHT ENTRANCE REGION OF
UPPER JET AND FORCING FROM WEAK MID LEVEL DISTURBANCE EMBEDDED
WITHIN SOUTHWEST FLOW ALOFT...PRECIPITATION WILL BE POSSIBLE. ONE
FORECAST CONCERN WILL BE PTYPE AS EARLY AS LATE THURSDAY NIGHT IN
INLAND BERKELEY COUNTY AND PERHAPS SPREADING INTO THE CHARLESTON
TRI-COUNTY REGION FRIDAY MORNING INTO EARLY AFTERNOON. SURFACE
WET BULB PROGS SHOW THE FREEZING LINE NUDGING DOWN INTO OUR
NORTHERN SC ZONES. MOISTURE WILL BE ONE OF THE BIGGER
QUESTIONS...BUT FORECAST SOUNDINGS DO HINT AT A WINDOW WHERE
FREEZING DRIZZLE/LIGHT FREEZING RAIN WILL BE POSSIBLE. WILL
CERTAINLY NEED TO CONTINUE TO MONITOR TRENDS. TEMPERATURES WILL BE
WELL BELOW NORMAL WITH HIGHS EXPECTED TO BE 30-40 DEGREES COLDER
THAN PREVIOUS DAYS. FRIDAY NIGHT...MOISTURE WILL QUICKLY START TO
DRY OUT WITH TEMPERATURES EXPECTED TO DROP AROUND FREEZING. A
FREEZE WATCH MAY EVENTUALLY BE NEEDED.

SATURDAY...HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE AT
THE SURFACE...WHILE NEARLY ZONAL FLOW REMAINS ALOFT. LACK OF
SIGNIFICANT FORCING AND MOISTURE WILL KEEP A DRY FORECAST IN TACT.
TEMPERATURES WILL BE MODERATE A BIT ALTHOUGH STILL BE BELOW NORMAL.
HIGHS WILL BE IN THE UPPER 50S.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
THERE REMAINS A GOOD BIT OF UNCERTAINTY IN THE LONG TERM PERIOD
AS AN ACTIVE BAROCLINIC ZONE IS EXPECTED TO WAVER FROM THE
NORTHERN GULF COAST REGION AND FLORIDA LATE IN THE WEEKEND TO
GEORGIA AND THE CAROLINAS DURING EARLY TO MID WEEK. GLOBAL MODELS
DIFFER ON TIMING AND STRENGTH OF THESE IMPULSES MOVING THROUGH THE
SE STATES DURING THIS TIME. WITH PERIODS OF CLOUDS AND SHOWERS
POSSIBLE FROM TIME TO TIME...TEMPS WILL PROBABLY BE NEAR OR
SLIGHTLY BELOW CLIMO.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
VFR UNTIL AFTER 06Z...THEN IFR/LIFR CEILINGS SHOULD DEVELOP
OVER THE TERMINALS AND/OR WILL ADVECT INTO THE REGION FROM THE
SOUTHWEST. VFR CEILINGS SHOULD THEN RETURN 15Z-18Z THURSDAY.
ALSO...LOW LEVEL WIND SHEAR REMAINS IN TAFS FOR TONIGHT...THEN
MIXING WILL PROMOTE SW GUSTS 20-25 KT AHEAD OF AN APPROACHING
COLD FRONT THURSDAY.

THE COLD FRONT WILL MOST LIKELY CROSS THE TERMINALS DURING THE
23Z-02Z TIME FRAME...ACCOMPANIED BY A SHARP WIND SHIFT AND SURGE
OF NE WINDS...AS WELL AS MVFR OR LOWER CEILINGS. SINCE THE
POTENTIAL COLD FROPA STRADDLES THE END OF THE 00Z TAF
PERIOD...THESE CONDITIONS ARE NOT YET ADDRESSED WITHIN THE TAFS.

EXTENDED AVIATION OUTLOOK...FLIGHT RESTRICTIONS LIKELY THURSDAY
NIGHT INTO FRIDAY ALONG WITH GUSTY N TO NE SURFACE WINDS. A LOW
PROBABILITY FOR LIGHT FREEZING RAIN/FREEZING DRIZZLE WILL EXIST
AT KCHS ESPECIALLY FRIDAY MORNING. CONDITIONS EXPECTED TO IMPROVE
OVER THE WEEKEND WITH HIGH PRES AND VFR.

&&

.MARINE...
AS S/SW WINDS AS HIGH AS 15-20 KT CONTINUE TO ADVECT DEWPOINTS IN
THE 60S OVER THE CHILLY ATLANTIC SHELF WATERS...CONDITIONS WILL
REMAIN VERY FAVORABLE FOR SEA FOG DEVELOPMENT OVER NEAR SHORE
WATERS OVERNIGHT. MAINTAINED THE ONGOING DENSE FOG ADVISORY FOR
ALL NEAR SHORE ZONES OUTSIDE CHARLESTON HARBOR. WHILE FOG COULD
OCCASIONALLY PUSH INTO CHARLESTON HARBOR...SW WINDS SHOULD HOLD
THE MOST PERSISTENT DENSE FOG OVER AMZ350...THUS NO DFA HAS BEEN
ISSUED FOR AMZ330. WILL CONTINUE TO ASSESS. SEAS OVERNIGHT WILL
RANGE FROM 2-4 FT WITHIN NEARSHORE WATERS TO 4-5 FT BEYOND 20 NM.

THURSDAY THROUGH MONDAY NIGHT...MARINE CONDITIONS ARE EXPECTED TO
DETERIORATE EARLY IN THE PERIOD AS A COLD FRONT APPROACHES AND
PASSES THROUGH THE WATER THURSDAY EVENING. WARM MOIST FLOW AHEAD OF
THE FRONT WILL BE FAVORABLE FOR SEA FOG DEVELOPMENT... THUS HAVE
MAINTAINED MENTION IN THE FORECAST. AS FRONT PASSES THROUGH THE
WATERS...STRONG COLD ADVECTION WILL ENSUE PROVIDING FAVORABLE MIXING
PROFILES. THIS WILL ALLOW FOR STRONGER WINDS ALOFT TO BE MIXED TO
THE SURFACE. HAVE ISSUED A GALE WATCH FOR NEARSHORE CHARLESTON
COUNTY WATERS AND OUTER GA WATERS LATE THURSDAY NIGHT INTO FRIDAY
MORNING...AND SMALL CRAFT ADVISORIES FOR THE REMAINING COASTAL
WATERS INCLUDING THE CHARLESTON HARBOR. CONDITIONS WILL SUBSIDE ON
FRIDAY AFTERNOON AS HIGH PRESSURE BUILDS IN AND THE PRESSURE
GRADIENT RELAXES. MARINE CONDITIONS WILL REMAIN FAIRLY BENIGN THE
REMAINDER OF THE WEEKEND INTO EARLY NEXT WEEK WITH WINDS/SEAS BELOW
SMALL CRAFT ADVISORY CRITERIA.

&&

.CLIMATE...
KSAV TIED THE RECORD HIGH OF 84 DEGREES FOR MARCH 4.

RECORD HIGHS FOR 5 MARCH...
KCHS... 85/1997
KCXM... 84/1923
KSAV... 86/1955

RECORD LOW MAXIMUMS FOR 6 MARCH...
KCHS... 43/1960
KCXM... 43/1960
KSAV... 42/1901

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THURSDAY TO 1 PM EST FRIDAY
     FOR AMZ330.
     DENSE FOG ADVISORY UNTIL 11 AM EST THURSDAY FOR AMZ350-352-354.
     SMALL CRAFT ADVISORY FROM 10 PM THURSDAY TO 4 PM EST FRIDAY
     FOR AMZ352.
     GALE WATCH FROM THURSDAY EVENING THROUGH FRIDAY MORNING FOR
     AMZ350.
     GALE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING FOR
     AMZ374.
     SMALL CRAFT ADVISORY FROM 1 AM TO 4 PM EST FRIDAY FOR AMZ354.

&&

$$
SYNOPSIS...
NEAR TERM...SPR
SHORT TERM...ECT
LONG TERM...
AVIATION...ECT/SPR
MARINE...ECT/SPR
CLIMATE...



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