Area Forecast Discussion
Issued by NWS Charleston, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KCHS 300526
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1226 AM EST FRI JAN 30 2015

.SYNOPSIS...
A COLD FRONT WILL CROSS THE REGION LATE TONIGHT...THEN HIGH
PRESSURE WILL BUILD IN THROUGH SATURDAY. A WEAK COASTAL TROUGH
WILL DEVELOP SUNDAY AND LIFT NORTH AHEAD OF ANOTHER COLD FRONT
PASSING OVER THE AREA MONDAY. HIGH PRESSURE WILL THEN RETURN TO
THE REGION TUESDAY BEFORE SHIFTING OFFSHORE AHEAD OF ANOTHER STORM
SYSTEM.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
30/05Z SURFACE ANALYSIS PLACED THE COLD FRONT IN THE NORTH
CAROLINA FOOTHILLS AND EXTENDING SOUTHWEST INTO WEST-CENTRAL
GEORGIA. THE FRONT IS MOVING STEADILY EAST AND WILL BE
APPROACHING THE COAST AT SUNRISE. SHOWER ACTIVITY HAS BEEN MEAGER
SO FAR AHEAD OF THE FRONT. THIS TREND WILL PERSIST THROUGH THE
OVERNIGHT PERIOD WITH THE CHANCES FOR MEASURABLE RAINFALL LIKELY
REMAINING QUITE LOW. THERE WILL LIKELY BE SOME UPTICK IN ACTIVITY
IN THE 3-6AM TIME FRAME AS THE FRONT DRAWS CLOSER AND SHORTWAVE
ENERGY COMES MORE INTO PLAY...BUT HIGH RESOLUTION MODELS REALLY
ONLY SUPPORT MEASURABLE RAINFALL IN THE CHARLESTON TRI-COUNTY
AREA. HAVE ADJUSTED POPS TO MATCH THIS THINKING. OTHERWISE...NO
SIGNIFICANT CHANGES WERE MADE TO THE GOING FORECAST.

LAKE WINDS...THE COLD FRONT WILL MOVE ACROSS LAKE MOULTRIE LATE
TONIGHT. WINDS WILL SHIFT TO THE NORTHWEST AND FREQUENT GUSTS TO
25 KT ARE EXPECTED. A LAKE WIND ADVISORY BEGINS AT 2 AM...ALTHOUGH
STRONGEST WINDS COULD ARRIVE A FEW HOURS LATER.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/...
FRIDAY...HIGH PRESSURE WILL BE MOVING IN BEHIND A DEPARTING COLD
FRONT WITH ANY LINGERING SHOWERS NEAR THE COAST ENDING QUICKLY NEAR
DAYBREAK. IT WILL BE A BIT BREEZY...ESPECIALLY IN THE MORNING. SOME
COLD AIR ADVECTION...ESPECIALLY OVER SC...WILL BE OFFSET SOMEWHAT BY
THE WARMING DOWNSLOPE NORTHWEST WINDS. EXPECT HIGHS IN THE MID TO
UPPER 50S WITH SOME AREAS POSSIBLY HITTING 60...ESPECIALLY SOUTH OF
BEAUFORT. HIGH PRESSURE WILL BE MOVING IN FROM THE NORTHWEST
FRIDAY NIGHT MAKING FOR LIGHT WINDS AND GOOD RADIATIONAL COOLING
OTHER THAN SOME HIGH CLOUDS. EXPECT A COLD NIGHT WITH LOWS LIKELY
DIPPING INTO THE UPPER 20S INLAND AND FREEZING MOST OTHER PLACES
AWAY FROM THE IMMEDIATE COAST.

SATURDAY...HIGH PRESSURE WILL SLIDE OVER THE AREA WITH A DRY AND
COOL DAY ON TAP ALTHOUGH THERE COULD BE SOME HIGH CLOUDS AROUND.
HIGHS SHOULD STRUGGLE A BIT GIVEN THE COLD START LIKELY ONLY
REACHING THE MID 50S MOST PLACES...WITH LOWER 50S CLOSER TO THE
SANTEE RIVER AND UPPER 50S POSSIBLE SOUTH OF I-16. A BIT MORE HIGH
CLOUDS EXPECTED SATURDAY NIGHT AS HIGH PRESSURE SLIDES OFFSHORE AND
RETURN FLOW BEGINS TO INCREASE AHEAD OF THE NEXT STORM SYSTEM WELL
TO THE WEST OVER TEXAS. COULD SEE SOME WEAK TROUGHING OFFSHORE BUT
STILL DRY. LOW TEMPS SHOULD BE IN THE MID/UPPER 30S INLAND BUT LOWER
TO MID 40S AT THE COAST.

SUNDAY...ANY COASTAL TROUGH EARLY WILL DISSIPATE DURING THE DAY AS
THE SOUTHERLY LOW-LEVEL JET STRENGTHENS AHEAD OF AN APPROACHING COLD
FRONT. BEST RAIN CHANCES LOOK TO COME LATER IN THE DAY...MAINLY WELL
INLAND AND POSSIBLY SKIRTING THE SC COAST. DESPITE INCREASING
CLOUDINESS TEMPS SHOULD PUSH TO NEAR NORMAL AROUND 60 IN THE
CHARLESTON AREA WITH MID 60S NEAR AND SOUTH OF SAVANNAH.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
SUNDAY NIGHT THROUGH MONDAY NIGHT...THERE REMAINS SOME DIFFERENCES
IN MEDIUM RANGE MODEL SOLUTIONS REGARDING THE STRENGTH OF THE LOW
PRESSURE SYSTEM TRACKING JUST TO THE NORTH OF THE FORECAST AREA
SUNDAY NIGHT...AS WELL AS THE AMPLIFICATION OF THE UPPER SHORTWAVE
HELPING TO DRIVE ITS DEVELOPMENT. A BLENDED SOLUTION WILL SHOW THE
LOW SYSTEM DEEPENING ALONG THE VIRGINIA/CAROLINA COASTLINE BY
MONDAY MORNING...WITH THE TRAILING COLD FRONT OFF THE SOUTHEAST
COAST BY EARLY MONDAY AFTERNOON. THE SHORTWAVE WILL FOLLOW THE
SURFACE FRONT QUICKLY OFFSHORE THROUGH THE AFTERNOON/EARLY EVENING
HOURS...WITH SURFACE HIGH PRESSURE BUILDING INTO THE REGION FROM
THE WEST/NORTHWEST MONDAY NIGHT. WILL CONTINUE TO ADVERTISE THE
HIGHEST RAIN CHANCES SUNDAY NIGHT INTO MONDAY MORNING...COINCIDENT
WITH TIMING OF THE COLD FRONTAL PASSAGE. HAVE REMAINED SOMEWHAT
CONSERVATIVE WITH ACTUAL POPS...CAPPING RAIN CHANCES AT 50 PERCENT
OR LESS...DUE TO SOME HINTS IN BOTH ECMWF AND GFS SOLUTIONS OF A
POSSIBLE PRECIPITATION MINIMUM OVER THE AREA. RAIN CHANCES WILL
DECREASE LATE MORNING/EARLY AFTERNOON MONDAY...FALLING BELOW 10
PERCENT BY MONDAY EVENING.

TUESDAY THROUGH THURSDAY...MODEL SOLUTIONS ARE IN TEMPORARY
AGREEMENT THAT THE MAJORITY OF THE DAYTIME HOURS ON TUESDAY WILL
BE DRY...AS SURFACE HIGH PRESSURE BUILDS IN THE WAKE OF THE FRONT
AND QUICKLY PROGRESSES TOWARD THE COASTLINE. MEDIUM RANGE MODELS
THEN SERIOUSLY DIVERGE REGARDING THE DEVELOPMENT OF LOW PRESSURE
IN THE GULF OF MEXICO LATE TUESDAY INTO MID WEEK. THE DIFFERENCES
ARE NOT SUBTLE...WITH THE MORE AGGRESSIVE ECMWF SOLUTIONS DEPICTING
A WAVE OF LOW PRESSURE MOVING UP THE SOUTHEAST COAST AND BRINGING
NOTABLE RAINFALL TO THE AREA FOR EARLY TO MID WEEK. THE WAVE OF
LOW PRESSURE IS CONSIDERABLY DELAYED AND MORE SUBTLE IN THE
GFS...LEAVING LITTLE OPPORTUNITY TO REASONABLY BLEND THE TWO
SOLUTIONS. PREFER TO MAINTAIN SOME PERSISTENCE...AND WILL JUST
INDICATE SLIGHT TO LOW RAIN CHANCES TUESDAY NIGHT THROUGH
WEDNESDAY...WITH DRY WEATHER POSSIBLE BY LATE WEEK. HIGH
TEMPERATURES EACH AFTERNOON WILL BE JUST A FEW DEGREES BELOW
SEASONAL NORMALS. LOW TEMPERATURES COULD ACTUALLY BE A FEW DEGREES
ABOVE NORMAL...ESPECIALLY CONSIDERING POTENTIAL CLOUD COVER
THROUGH THE PERIOD.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
VFR. LOW-LEVEL WIND SHEAR WILL REMAIN A CONCERN AT BOTH TERMINALS
THROUGH 13Z AFTER WHICH THE LOW-LEVEL JET WILL SHIFT OFFSHORE WITH
THE COLD FRONT.

EXTENDED AVIATION OUTLOOK...VFR TO PREVAIL UNTIL SUNDAY NIGHT INTO
MONDAY WHEN MVFR OR POSSIBLY LOWER CONDS ARE POSSIBLE DUE TO A
PASSING COLD FRONT. BREEZY CONDS ALSO LIKELY SUN NIGHT/MON.

&&

.MARINE...
MAINTAINED ONGOING SMALL CRAFT ADVISORIES FOR ALL MARINE ZONES
EXCEPT AMZ374 OVERNIGHT. PER RECENT TRENDS...DELAYED THE START OF
THE SCA FOR CHARLESTON HARBOR UNTIL 2 AM...AND SCA WINDS COULD
EVEN DEVELOP A FEW HOURS LATER.

OVERNIGHT...WINDS WILL INCREASE AND VEER THROUGH THE SW TOWARD THE
W AS THE PRESSURE GRADIENT TIGHTENS AND LOW-LEVEL WINDS
INTENSIFY...AND GUSTS 25-30 KT SHOULD BECOME COMMON LATER TONIGHT.
SEAS WILL BUILD TO AS HIGH AS 3-4 FT WITHIN NEARSHORE WATERS AND
4-6 FT BEYOND 20 NM LATE TONIGHT.

FRIDAY THROUGH TUESDAY...A COLD FRONT RAPIDLY PROGRESSING OFFSHORE
EARLY FRIDAY MORNING WILL MAINTAIN ENOUGH OF A PRESSURE GRADIENT TO
KEEP SMALL CRAFT ADVISORY CONDITIONS OVER THE SC AND OFFSHORE GA
WATERS THROUGH AT LEAST THE MORNING. HIGH PRESSURE WILL THEN
STEADILY BUILD INTO THE REGION AND EVENTUALLY SHIFT OFFSHORE INTO
THE WEEKEND. SLIGHT NORTH/NORTHEAST WIND SURGE EXPECTED SATURDAY
NIGHT BEFORE WINDS DIMINISH DURING THE DAY SATURDAY...WITH
CONDITIONS LIKELY REMAINING JUST BELOW ADVISORY LEVELS...ALTHOUGH A
MARGINAL ADVISORY COULD BE NEEDED OVER THE CHARLESTON NEARSHORE
WATERS AND OFFSHORE GA WATERS.

A STRENGTHENING LOW PRESSURE SYSTEM WILL TRACK NORTH OF THE AREA
MONDAY...WITH ITS TRAILING COLD FRONT SWEEPING THROUGH THE REGION
MONDAY MORNING. INCREASING SOUTHERLY FLOW AHEAD OF THE FRONT...AS
WELL AS NORTHWEST FLOW IN ITS WAKE WILL LIKELY CREATE SMALL CRAFT
ADVISORY CONDITIONS OVER PORTIONS OF THE LOCAL WATERS LATE SUNDAY
NIGHT INTO MONDAY NIGHT. HIGH PRESSURE BUILDING IN TUESDAY WILL
THEN LEAD TO IMPROVING CONDITIONS.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...LAKE WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ330.
     SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR AMZ350-
     352-374.

&&

$$

ST


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.