758
FXUS62 KCHS 232346
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
632 PM EST SAT FEB 23 2019
SYNOPSIS
A WARM FRONT WILL LIFT NORTH THROUGH THE FORECAST AREA TONIGHT.
THEN ON SUNDAY, A COLD FRONT WILL SWEEP THROUGH FROM THE WEST
AND MOVE OFFSHORE IN THE EVENING. HIGH PRESSURE IS EXPECTED TO
PREVAIL INTO THE MIDDLE OF NEXT WEEK AND AN AREA OF LOW
PRESSURE COULD PASS OFF THE COAST LATE IN THE WEEK.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
A COMPLEX SURFACE PATTERN IS IN PLACE THIS EVENING AS INSITU
COLD AIR DAMMING HOLDS ACROSS MUCH OF NORTH CAROLINA, SOUTH
CAROLINA AND INTO GEORGIA. 23/23Z SURFACE ANALYSIS PLACED
A STATIONARY WEDGE FRONT EXTENDING FROM JUST OFFSHORE OF THE
CHARLESTON COUNTY COAST TO NEAR HILTON HEAD, THEN ARCING BACK
INLAND ALONG THE I-16 CORRIDOR INTO CENTRAL GEORGIA. NORTH OF
THE WEDGE FRONT, FOG/STRATUS WITH AREAS OF DRIZZLE ARE COMMON,
WHILE SOUTH OF THE FRONT, MUCH WARMER CONDITIONS ARE FOUND WITH
LITTLE IN THE WAY OF FOG/DRIZZLE, EXCEPT ALONG THE IMMEDIATE
GEORGIA AND FAR SOUTHERN SOUTH CAROLINA COAST WHERE SEA FOG IS
PRESENT. FARTHER SOUTH, A SHARPENING WARM FRONT EXTENDED FROM
ROUGHLY JACKSONVILLE, FLORIDA, TO ALMA, GA, THEN EXTENDING
NORTHWEST THROUGH CENTRAL INTO WEST-CENTRAL GEORGIA NEAR
COLUMBUS, GA. THE INLAND AND NORTHWARD PROGRESSION OF THESE
FEATURES WILL MAKE FOR A RATHER DIFFICULT OVERNIGHT FORECAST
WITH A NUMBER OF FORECAST CHALLENGES TO ADDRESS.
RAIN: KCLX/KVAX RADARS SHOW ISOLATED SHOWERS DEVELOPING JUST
SOUTH OF THE ALTAMAHA RIVER. THIS ACTIVITY APPEARS TO CORRELATED
TO A SMALL AREA OF ENHANCED ISENTROPIC ASSENT ALONG THE 305K
ISOSURFACE FORMING JUST NORTH OF THE SYNOPTIC WARM FRONT. THE
23/22Z RAP INITIALIZED THIS ACTIVITY RATHER WELL AND ACTUALLY
SHOWS A SLIGHT AREAL EXPANSION OVER THE NEXT SEVERAL HOURS AS THE
REGION OF ISENTROPIC LIFT PROPAGATES NORTHEAST INTO PARTS OF
SOUTHEAST GEORGIA AND EVENTUALLY SOUTH COASTAL SOUTH CAROLINA
THROUGH 24/06Z. WILL LIKELY KEEP POPS IN THE ISOLATED CATEGORY
FOR NOW, BUT SOME AREAS COULD DEFINITELY SEE A FEW HUNDREDTHS
OF AN INCH OVER THE NEXT FEW HOURS, INCLUDING THE SAVANNAH METRO
AREA. ONCE THIS REGION OF LIFT EXITS OFF THE MIDDLE SOUTH
CAROLINA COAST AFTER 1-2 AM, EXPECT A MOSTLY DRY NIGHT.
TEMPERATURES: A LARGE THERMAL GRADIENT IS IN PLACE THIS EVENING
WITH THE WEDGE FRONT BISECTING THE REGION. NIGHTTIME LOWS (6PM-
7AM) WILL LIKELY OCCUR THIS EVENING FOR MANY LOCATIONS WITH
TEMPERATURES EXPECTED TO SLOWLY RISE OVERNIGHT AS THE WEDGE
FRONT IS EVENTUALLY OVERTAKEN FROM THE SOUTH BY THE SYNOPTIC
WARM FRONT. BY DAYBREAK, TEMPERATURES ARE EXPECTED TO BE IN THE
MID-UPPER 60S WITH BREEZY CONDITIONS. ADJUSTED NIGHTTIME LOWS
SLIGHTLY BASED ON CURRENT OBSERVATIONS AND SHORT TERM TRENDS.
UPDATED TEMPERATURES SHOW LOWS FROM THE LOWER 50S ACROSS FAR
INTERIOR SOUTHEAST SOUTH CAROLINA TO THE MID 60S ALONG THE
ALTAMAHA.
FOG: COASTAL WEBCAMS, PILOT BOAT REPORTS AND A FEW SHIP
OBSERVATIONS SHOW WIDESPREAD DENSE FOG HAS DEVELOPED ACROSS THE
NEARSHORE WATERS OF SOUTHEAST SOUTH CAROLINA AND FAR SOUTHERN
SOUTH CAROLINA. THIS FOG IS EXPECTED TO MOVE STEADILY
INLAND AND NORTH THROUGH THE EVENING HOURS, IMPACTING COASTAL
GEORGIA INTO THE BEAUFORT-HILTON HEAD AREAS EARLY, THEN
SPREADING WELL INLAND AND INTO THE CHARLESTON METRO AREA
OVERNIGHT. DENSE FOG IS LIKELY TO OCCUR WITH NARRE-TL
PROBABILITIES FOR DENSE FOG RUNNING WELL ABOVE 80% IN MANY
AREAS. DENSE FOG ADVISORIES ARE LIKELY TO BE ISSUED. THE FOG IS
EXPECTED TO STEADILY LIFT FROM SOUTH-NORTH DURING THE EARLY
MORNING HOURS SUNDAY AS THE WARM FRONT LIFTS NORTH AND LOW-LEVEL
WINDS INCREASE. EXPECT THE DENSE FOG TO MOSTLY CLEAR SOUTHEAST
GEORGIA BY 4-5AM AND THE CHARLESTON TRI-COUNTY AREA BY 6-7AM.
SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/
SUNDAY AND SUNDAY NIGHT: A FAST MOVING COLD FRONT WILL APPROACH THE
ARE FROM THE WEST IN THE MORNING AND THEN PUSH OFFSHORE BY THE LATE
AFTERNOON. GOOD FRONTAL FORCING WILL RESULT IN A BAND OF SHOWERS
THAT SHOULD MAINTAIN ACROSS THE FORECAST AREA. THE BEST RAIN CHANCES
WILL BE DURING THE LATE MORNING TO EARLY AFTERNOON WITH ABRUPT
DRYING TAKING PLACE BEHIND THE FRONT. THERE ARE SOME INDICATIONS OF
VERY WEAK INSTABILITY ALONG AND AHEAD OF THE FRONT, BUT NOT ENOUGH
TO INTRODUCE THUNDER TO THE FORECAST. TEMPERATURES WILL WARM QUICKLY
IN THE MORNING WITH UPPER 70S AND EVEN SOME LOW 80S POSSIBLE
DEPENDING ON HOW INSOLATION WORKS OUT. SOUTHWESTERLY WINDS WILL
BECOME GUSTY IN THE MORNING IN THE WARM MIXING AHEAD OF THE FRONT,
WITH GUSTS INTO THE 25-30 MPH RANGE EXPECTED. THEN BEHIND THE FRONT
WINDS WILL TURN WESTERLY AND REMAIN GUSTY AS COOLER AIR STARTS TO
FILTER IN. THROUGH THE OVERNIGHT, SKIES WILL CLEAR BEHIND THE FRONT
AND WINDS WILL GRADUALLY RELAX. LOWS ARE FORECAST TO RANGE FROM
AROUND 40 INLAND TO THE MID AND UPPER 40S ALONG THE COAST.
LAKE WINDS: WIND. AROUND LAKE MOULTRIE WILL BECOME GUSTY ON SUNDAY
OUT OF THE SOUTHWEST. GUSTS TO 25 KNOTS WILL BE POSSIBLE ON THE
LAKESHORE, ESPECIALLY ON THE SOUTH AND WESTERN SIDES OF THE LAKE.
THEN BEHIND A COLD FRONT IN THE AFTERNOON WINDS WILL TURN MORE
WESTERLY AND NORTHWESTERLY THROUGH THE OVERNIGHT. GUSTS TO 25 KNOTS
WILL STILL BE POSSIBLE AND A LAKE WIND ADVISORY COULD BE NEEDED.
MONDAY THROUGH TUESDAY: HIGH PRESSURE WILL PREVAIL THROUGH THE EARLY
PART OF THE WEEK WITH QUIET CONDITIONS. HIGHS ON MONDAY ARE FORECAST
TO RANGE FROM THE MID TO UPPER 60S, THEN INTO THE UPPER 60S AND LOW
70S ON TUESDAY. MONDAY NIGHT WILL BRING GOOD RADIATIONAL COOLING
CONDITIONS AND LOWS WILL FALL INTO THE UPPER 30S INLAND, AND MID TO
UPPER 40S ALONG THE COAST.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
ZONAL FLOW IN THE MID AND UPPER LEVELS WILL PREVAIL UNTIL LATE IN
THE WEEK, WHEN A SHORT WAVE TROUGH IS CURRENTLY FORECAST TO
APPROACH THE REGION. AT THE SURFACE THERE REMAIN MODEL DIFFERENCES,
AND AS SUCH OUR CONFIDENCE WEDNESDAY THROUGH FRIDAY IS LOW. DUE THE
UNCERTAINTY WE HAVE LEANED CONSIDERABLY TOWARD THE PREVIOUS FORECAST
WHICH SHOWS NO MORE THAN CHANCE POP'S THROUGH THE PERIOD, WHILE
TEMPS WILL AVERAGE ABOVE NORMAL AS THE CALENDAR CHANGES FROM
FEBRUARY TO MARCH.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
WIDESPREAD FOG/STRATUS IS EXPECTED TO IMPACT BOTH KCHS AND KSAV
OVERNIGHT. THE FOG COULD REACH KSAV VERY EARLY, THEN SPREAD INTO
THE KCHS TERMINAL IN THE 03-06Z TIMEFRAME. VSBYS/CIGS BELOW
AIRFIELD MINIMUMS ARE LIKELY, ESPECIALLY AT KSAV WHERE
WIDESPREAD DENSE FOG IS LIKELY. CONDITIONS WILL IMPROVE FROM
SOUTH-NORTH EARLY SUNDAY AS A WARM FRONT LIFTS NORTH, CLEARING
KSAV BY 09-10Z AND KCHS 11-13Z. A PERIOD OF VFR WILL OCCUR JUST
BEFORE A COLD FRONT PUSHES THROUGH THE TERMINAL AROUND 17Z. THE
FRONT WILL BE ACCOMPANIED BY AN AREA OF RAIN. INTRODUCED 5SM IN
-RA FOR NOW. WEST/NORTHWEST WINDS WILL PREVAIL AFTER FROPA.
GUSTY WINDS WILL IMPACT THE TERMINAL FROM 12-13Z ON.
EXTENDED AVIATION OUTLOOK: THE NEXT CHANCE OF ANY SUB-VFR WEATHER
WILL NOT BE UNTIL THE MIDDLE OF NEXT WEEK. ALSO, GUSTY SW AND W
WINDS WILL OCCUR AT TIMES SUNDAY, PEAKING AROUND 20-25 KT AT
BOTH TERMINALS.
MARINE
TONIGHT: ISSUED A MARINE DENSE FOG ADVISORY FOR THE GEORGIA AND
BEAUFORT NEARSHORE LEGS THROUGH NOON SUNDAY. WIDESPREAD DENSE
SEA FOG HAS DEVELOPED AND WILL MOVE SLOWLY NORTH THROUGH THE
NIGHT, LIKELY IMPACTING CHARLESTON HARBOR AND THE CHARLESTON
NEARSHORE WATERS. THE ADVISORY MAY NEED TO BE EXPANDED LATER
THIS EVENING. OTHERWISE, WINDS WILL TURN SOUTHERLY THROUGH THE
NIGHT WITH SPEEDS GENERALLY HOLDING LESS THAN 10 KT. SEAS WILL
AVERAGE 2-4 FT.
SUNDAY THROUGH THURSDAY: SOUTHWESTERLY WINDS WILL STRENGTHEN AND
SHOULD HELP TO DISPERSE LINGERING MORNING SEA FOG BY THE LATE
MORNING HOURS. WINDS WILL BECOME STRONG ENOUGH THAT SMALL CRAFT
ADVISORIES WILL LIKELY BE NEEDED, ESPECIALLY FOR CHARLESTON HARBOR,
THE CHARLESTON COUNTY WATERS, AND THE OUTER GEORGIA WATERS. THEN
OVERNIGHT BEHIND THE FRONT, WINDS WILL BECOME NORTHWESTERLY AND
REMAIN ELEVATED CLOSE TO ADVISORY LEVELS. CONDITIONS WILL THEN
BECOME MUCH CALMER STARTING MONDAY AS HIGH PRESSURE BUILDS IN, WELL
BELOW ADVISORY THRESHOLDS THROUGH THE LATTER PART OF THE WEEK.
CLIMATE
RECORD HIGHS FOR FEBRUARY 24...
KCHS: 81/2017 AND PREVIOUS
KCXM: 81/1930 KSAV: 86/2012
RECORD HIGH MINS FOR FEBRUARY 24...
KCHS: 60/1992 AND PREVIOUS
KCXM: 63/2018
KSAV: 64/1980
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...DENSE FOG ADVISORY UNTIL NOON EST SUNDAY FOR AMZ352-354.
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