Area Forecast Discussion
Issued by NWS Charleston, SC

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000
FXUS62 KCHS 291213
AFDCHS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
713 AM EST THU JAN 29 2015

.SYNOPSIS...
HIGH PRESSURE WILL PUSH OFFSHORE TODAY IN ADVANCE OF AN APPROACHING
COLD FRONT. THE COLD FRONT WILL CROSS THE AREA LATE TONIGHT AND WILL
BE FOLLOWED BY HIGH PRESSURE 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 AND GRADUALLY DRIFT INTO THE ATLANTIC BY THE MIDDLE
OF NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
TODAY...TEMPS WILL START OFF CHILLY THIS MORNING FROM FAVORABLE
RADIATIONAL COOLING CONDITIONS EARLIER...BUT SHOULD WARM UP
QUICKLY ONCE A VERY SHALLOW INVERSION IS BROKEN WITH DAYTIME
HEATING. SFC HIGH PRESSURE CURRENTLY CENTERED OVER THE AREA WILL
THEN SLOWLY SHIFT OFFSHORE THROUGH EARLY AFTERNOON AHEAD OF A LOW
PRESSURE SYSTEM ADVANCING THROUGH THE GREAT LAKES REGION. AS HIGH
PRESSURE SLIDES OFFSHORE...A SOUTHWEST WIND WILL DEVELOP OVER THE
AREA WITH ONLY A SLIGHT INCREASE IN MOISTURE ADVECTING TO THE
REGION. WITH LITTLE IN THE WAY OF LOW/MID LVL FORCING
EARLY...RAINFREE CONDITIONS ARE EXPECTED THROUGH THIS EVENING.
HOWEVER...THESE WINDS IN COMBINATION WITH MID LVL RIDGING
EXPANDING OVER THE SOUTHEASTERN UNITED STATES WILL ALLOW TEMPS TO
EVENTUALLY WARM INTO THE MID/UPPER 50S IN NORTHERN AREAS TO AROUND
60 IN SOUTHEAST GEORGIA. CIRRUS SHOULD LIMIT FURTHER HEATING
POTENTIAL LATE AFTERNOON INTO EARLY EVENING AS THE NOSE OF A H25
JET SHIFTS OVER THE AREA.

TONIGHT...EXPECT DRY CONDITIONS TO PERSIST THROUGH AT LEAST LATE
EVENING...BUT CLOUD COVER WILL EXPAND ACROSS THE REGION AHEAD OF THE
APPROACHING COLD FRONT AND H5 SHORTWAVE ALOFT. A SLIGHT CHANCE OF
SHOWERS WILL BE POSSIBLE AFTER MIDNIGHT AS THE COLD FRONT ADVANCES
THROUGH THE AREA LATE...WITH BEST CHANCES OF MEASURABLE PRECIP
EXPECTED IN NORTHERN AREAS. OVERNIGHT TEMPS WILL REMAIN MUCH MORE
MILD THAN THE PREVIOUS NIGHT AHEAD OF THE FRONT AND UNDER CLOUD
COVER. IN GENERAL...LOW TEMPS SHOULD RANGE IN THE LOW/MID 40S AWAY
FROM THE COAST.

LAKE WINDS...WINDS WILL TURN WEST...THEN NORTHWEST BEHIND A PASSING
COLD FRONT LATE TONIGHT. WIND SPEEDS WILL ALSO INCREASE BEHIND
THE FRONT...WITH GUSTS UP TO 25 KNOTS POSSIBLE. A LAKE WIND
ADVISORY MAY EVENTUALLY BE NEEDED AFTER MIDNIGHT TONIGHT INTO
EARLY MORNING HOURS.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
FRIDAY...THE COLD FRONT WILL BE RAPIDLY MOVING OFFSHORE BY
DAYBREAK...WITH THE UPPER SHORTWAVE TROUGH QUICKLY FOLLOWING IN
ITS WAKE. ANY RAIN LINGERING ALONG THE COASTLINE DURING THE EARLY
MORNING HOURS WILL RETREAT FARTHER INTO THE ATLANTIC AS THE
MORNING PROGRESSES. COLD AND DRY SURFACE HIGH PRESSURE WILL THEN
BUILD FROM THE NORTH/NORTHWEST THROUGH THE AFTERNOON...SUPPORTING
CLEARING SKIES AND RAIN CHANCES FALLING TO ZERO. HIGH TEMPERATURES
WILL ONLY BE A DEGREE OR TWO COOLER THAN THE PREVIOUS DAY...AS
COLD ADVECTION BEHIND THE FRONT IS MITIGATED BY THE WARMING
EFFECTS OF DOWNSLOPE FLOW AND INCREASING SUNSHINE. EXPECT HIGH
TEMPERATURES TO REACH THE UPPER 50S...SLIGHTLY BELOW SEASONAL
NORMALS. LOW TEMPERATURES WILL BETTER REFLECT THE COOLER AIR MASS
IN PLACE...ESPECIALLY AS WINDS DIMINISH AND SUPPORT DECENT
RADIATIONAL COOLING CONDITIONS OVERNIGHT. TEMPERATURES WILL FALL
BELOW FREEZING MOST LOCATIONS EXCEPT FOR THE COASTLINE AND CLOSER
TO THE ALTAMAHA RIVER IN SOUTHEAST GEORGIA.

SATURDAY...AS THE SURFACE HIGH STEADILY PROGRESSES TOWARD THE EAST
COAST...LOW LEVEL WINDS WILL VEER MORE NORTH/NORTHEAST. THE LOSS
OF THE MORE SOLID DOWNSLOPE FLOW COMPONENT WILL KEEP TEMPERATURES
A BIT COOLER THAN FRIDAY...RANGING FROM THE LOW 50S NORTH TO THE
UPPER 50S SOUTH. SOME MID TO HIGH LEVEL CLOUDS WILL GRADUALLY
INCREASE FROM WEST TO EAST DURING THE EVENING AND OVERNIGHT
HOURS...WHILE RAIN CHANCES REMAIN AT ZERO. THE INSULATING EFFECTS
OF THICKENING SKY COVER WILL SUPPORT TEMPERATURES SLIGHTLY WARMER
THAN THE PREVIOUS NIGHT...MID 30S FAR INLAND TO LOW 40S EAST AND
SOUTH.

SUNDAY...HIGH PRESSURE WILL HAVE SLIPPED OFF THE COASTLINE BY THE
MORNING TIME FRAME...WITH THE PATTERN RAPIDLY TRANSITIONING AND
BECOMING MORE UNSETTLED THROUGH THE DAY. NUMERICAL MODELS ARE
STILL INDICATING A WEAK COASTAL TROUGH BRIEFLY DEVELOPING ALONG
THE SOUTHEAST COASTLINE IN THE MORNING. THE SURFACE TROUGH THEN
QUICKLY MOVES INLAND AND TRANSITIONS INTO MORE OF A WARM FRONTAL
FEATURE...AS IT LIFTS NORTH AHEAD OF A RAPIDLY DEVELOPING LOW
PRESSURE SYSTEM ACROSS THE TENNESSEE VALLEY. DURING THE DAYTIME
HOURS...THE FORECAST AREA WILL LIKELY FALL WITHIN A PRECIPITATION
GAP BETWEEN THE LIFTING COASTAL TROUGH/WARM FRONT AND THE
APPROACHING COLD FRONT FROM THE WEST. WILL THUS CAP RAIN CHANCES
BELOW 30 PERCENT UNTIL THE EVENING HOURS. INCREASING SOUTHERLY
FLOW WILL SUPPORT WARMER TEMPERATURES SUNDAY AFTERNOON...PEAKING
IN THE UPPER 50S NORTH TO THE LOW/MID 60S SOUTH.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
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 /12Z THURSDAY THROUGH MONDAY/...
VFR CONDITIONS ARE EXPECTED AT BOTH CHS AND SAV TERMINALS THROUGH AT
LEAST 06Z FRIDAY. HOWEVER...EXPECT INCREASING CLOUDS AHEAD OF A COLD
FRONT APPROACHING FROM THE NORTHWEST OVERNIGHT. A PERIOD OF MVFR
CIGS WILL BE POSSIBLE AFER MIDNIGHT TONIGHT AS THE COLD FRONT SHIFTS
THROUGH THE AREA WITH A FEW SHOWERS. CHANCES OF MVFR CIGS APPEAR
BEST AT THE CHS TERMINAL THROUGH 12Z FRIDAY.

EXTENDED AVIATION OUTLOOK...A COLD FRONT WILL MOVE THROUGH THE
TERMINALS BY EARLY FRIDAY MORNING. THERE IS A LOW END CHANCE FOR
A PERIOD OF MVFR CEILINGS ASSOCIATED WITH THE FRONT. OTHERWISE...VFR
CONDITIONS WILL PREVAIL.

&&

.MARINE...
TODAY...HIGH PRESSURE WILL DOMINATE OVER THE WATERS AS IT SLOWLY
SHIFTS OFFSHORE OVER THE WESTERN ATLANTIC WELL IN ADVANCE OF A
COLD FRONT APPROACHING FROM THE NORTH/NORTHWEST. EXPECT WINDS/SEAS
TO REMAIN BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THE DAYTIME
PERIOD. IN GENERAL...NORTH/NORTHEAST WINDS WILL BECOME
SOUTH/SOUTHWEST THIS AFTERNOON AHEAD OF THE APPROACHING COLD
FRONT...BUT WILL LIKELY REMAIN AT OR BELOW 15 KTS.

TONIGHT...THE COLD FRONT WILL PUSH THROUGH AFTER MIDNIGHT WITH
HIGH PRESSURE BUILDING BEHIND IT. WINDS WILL QUICKLY BECOME
WEST/NORTHWEST POST FROPA AND INCREASE AS COOLER AIR ADVECTS OVER
THE WATERS. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED STARTING AT
MIDNIGHT TONIGHT FOR NORTHERN SC WATERS AND OFFSHORE GEORGIA
WATERS. AT THIS TIME...CONDITIONS SHOULD REMAIN BELOW SMALL CRAFT
ADVISORY LEVELS FOR REMAINING WATERS...BUT A LOW CHANCE OF WIND
GUSTS NEAR 25 KTS REMAINS FOR WATERS BEYOND 10 NM INTO FRIDAY
MORNING.

FRIDAY THROUGH MONDAY...A COLD FRONT RAPIDLY PROGRESSING OFFSHORE
EARLY FRIDAY MORNING WILL MAINTAIN ENOUGH OF A PRESSURE GRADIENT
TO KEEP SMALL CRAFT ADVISORY CONDITIONS WITHIN PORTIONS OF THE
WATERS SHORTLY AFTER DAYBREAK. HIGH PRESSURE WILL THEN STEADILY
BUILD INTO THE REGION AND EVENTUALLY SHIFT OFFSHORE INTO THE
WEEKEND. NORTH/NORTHEAST WINDS WILL BE ELEVATED THROUGH
SATURDAY...YET LIKELY REMAIN JUST BELOW ADVISORY THRESHOLDS
FRIDAY AFTERNOON THROUGH SUNDAY AFTERNOON. A STRENGTHENING LOW
PRESSURE SYSTEM WILL TRACK NORTH OF THE AREA MONDAY...WITH ITS
TRAILING COLD FRONT SWEEPING THROUGH THE SOUTHEASTERN UNITED
STATES MONDAY AFTERNOON. INCREASING SOUTHERLY FLOW AHEAD OF THE
FRONT...AS WELL AS NORTHWEST FLOW IN ITS WAKE...COULD SUPPORT
SMALL CRAFT ADVISORY CONDITIONS OVER PORTIONS OF THE MARINE ZONES
BY SUNDAY NIGHT INTO MONDAY.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EST FRIDAY
     FOR AMZ350-374.

&&

$$
SYNOPSIS...
NEAR TERM...DPB
SHORT TERM...DPB
LONG TERM...WMS
AVIATION...DPB/WMS
MARINE...DPB/WMS



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