518
FXUS62 KCHS 162327
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
627 PM EST THU JAN 16 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL THROUGH THE WEEK. AN AREA OF LOW
PRESSURE AND ASSOCIATED COLD FRONT WILL IMPACT THE REGION THIS
WEEKEND. ANOTHER LOW PRESSURE SYSTEM COULD IMPACT THE REGION
EARLY TO MID NEXT WEEK.
NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
TONIGHT: THE SURFACE FRONT/TROUGH WILL SHIFT OFFSHORE BY THE
EARLY MORNING HOURS, AS HIGH PRESSURE SETTLES IN ACROSS THE
REGION BY SUNRISE FRIDAY. UNTIL THE FRONT/TROUGH GETS OFFSHORE,
THE GRADIENT WILL HELP TO MAINTAIN ELEVATED WESTERLY FLOW. THEN
AS SUNRISE APPROACHES, THE GRADIENT RELAXES AND WINDS COULD EVEN
GO CALM FOR MUCH OF THE AREA. SKIES WILL REMAIN CLEAR AND THE
FORECAST IS DRY WITH PRECIPITABLE WATER VALUES OF 0.25" OR LESS
BY LATE TONIGHT. LOWS ARE FORECAST TO FALL INTO THE LOWER 30S
INLAND, WITH MID TO UPPER 30S AS YOU GET CLOSER TO THE
IMMEDIATE COAST.
SATELLITE IMAGES DO SHOW NUMEROUS FIRES STILL ONGOING IN AND
NEAR PARTS OF THE AREA. UTILIZING THE HRRR, AND A CONTINUATION
OF SOME MIXING THROUGH MUCH OF THE NIGHT, THERE WILL BE SMOKE
NOTICED IN SOME PLACES. THERE HAS NOT BEEN ANY VISIBILITY
REDUCTIONS PER SURFACE OBSERVATIONS, BUT WITH THE FORMATION AND
STRENGTHENING OF THE NOCTURNAL INVERSION OVERNIGHT, THERE MIGHT
BE A FEW PLACES WITH VISIBILITIES LOWERING AT THE SURFACE.
LAKE WINDS: WINDS ACROSS LAKE MOULTRIE COULD INCREASE AGAIN
BETWEEN 9 PM AND 3 AM AS A 30-35 KT LOW LEVEL JET PASSES
THROUGH. SOME GUIDANCE SUGGESTS CONDITIONS COULD GET CLOSE TO
ADVISORY THRESHOLDS, AND WE CONTINUE TO MONITOR.
SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/
HIGH PRESSURE WILL GIVE WAY TO AN APPROACHING COLD FRONT
SATURDAY AS A SERIES OF NORTHERN STREAM SHORTWAVES PROPAGATE
ACROSS THE NORTHERN CONUS. RAIN CHANCES WILL INCREASE QUICKLY
SATURDAY AHEAD OF THE COLD FRONT AS BUILDING MOISTURE
CHARACTERIZED BY PWATS >1" COMBINE WITH FORCING GENERATED BY
PASSING SOUTHERN STREAM SHORTWAVE ENERGY AND THE LEFT EXIT
REGION OF A POWER 150 KT SUBTROPICAL JET. IT APPEARS MOST AREAS
WILL RECEIVE A SOLID 0.75-1.50" INCH OF RAIN WITH THIS SYSTEM
AND CATEGORICAL POPS 90-100% WERE MAINTAINED. FLOODING IS NOT
ANTICIPATED TO BE AN ISSUE. RAIN CHANCES WILL SLOWLY DIMINISHING
SATURDAY NIGHT INTO SUNDAY AS THE FRONT PUSHES OFFSHORE. HIGHS
EACH DAY WILL WARM INTO THE UPPER 50S/LOWER 60S AWAY FROM THE
COAST WITH OVERNIGHT LOWS DROPPING INTO THE MID-UPPER 30S FRIDAY
NIGHT WITH UPPER 40S/LOWER 50S SATURDAY NIGHT.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
THERE REMAINS MUCH UNCERTAINTY THE SYSTEM THAT WILL IMPACT THE
REGION DURING THE MID-WEEK AS A COLD, ARCTIC AIRMASS SETTLES
OVER THE REGION. WHAT IS KNOWN IS THERE IS HIGH PROBABILITY FOR
TEMPERATURES TO AVERAGE WELL BELOW NORMAL LEVELS FOR MID-JANUARY
WITH HIGHS BOTH TUESDAY AND WEDNESDAY LIKELY REMAINING SOLIDLY
IN THE 30S WITH MINIMUM WIND CHILLS FALLING INTO THE 10-20
DEGREE RANGE AT NIGHT. THIS IS WELL WITHIN COLD WEATHER ADVISORY
CRITERIA (11-20 DEGREES). IN FACT, THERE ARE SIGNALS THAT SOME
LOCATIONS COULD SEE WIND CHILLS DROP BELOW 10 DEGREES WHICH IS
DIPPING INTO EXTREME COLD WARNING TERRITORY (10 DEGREES OR
COLDER).
WHAT IS MORE UNCERTAIN IS HOW THE PRECIPITATION PATTERN WILL
EVOLVE MONDAY NIGHT THROUGH WEDNESDAY MORNING WHEN TEMPERATURES
WILL BE AT THE COLDEST. MUCH WILL BE DEPENDENT ON HOW FAR SOUTH
AND OFFSHORE LOW PRESSURE TRACKS OFF THE SOUTHEAST U.S. COAST IN
RESPONSE TO AN IMPRESSIVE UPPER TROUGH PROPAGATING ACROSS THE
EASTERN CONUS. GIVEN THE AMOUNT OF COLD AIR IN PLACE, IT REMAINS
QUITE REASONABLE THAT VARYING DEGREES OF ACCUMULATING WINTER
WEATHER COULD OCCUR OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST
GEORGIA WITH SPECIFICS ON P- TYPES, INTENSITY AND POSSIBLE
ACCUMULATIONS REMAINING HIGHLY UNCERTAIN THIS FAR OUT. WHILE A
FEW OF THE OPERATIONAL RUNS OF THE VARIOUS LONG-TERM GUIDANCE
HAVE TRENDED DRIER OVER THE PAST FEW CYCLES, MANY OF THEIR
ACCOMPANYING ENSEMBLE COUNTERPARTS REMAIN QUITE WET AND COLD.
ALL NUMBER OF OUTCOMES REMAIN PLAUSIBLE RANGING FROM LITTLE TO
NO PRECIPITATION TO A FULL BLOWN WINTER STORM WITH SIGNIFICANT
IMPACTS; HOWEVER, NET ACCUMULATING SNOW AND FREEZING RAIN
PROBABILITIES ARE CREEPING UP WITH EACH FORECAST CYCLE. THE
OFFICIAL FORECAST REMAINS FAIRLY STEADY STATE WITH SOME MINOR
UPWARD ADJUSTMENTS IN POPS, SHOWING VARIOUS DEGREES OF A MIX OF
SNOW, FREEZING RAIN AND RAIN IN THE MONDAY NIGHT TO WEDNESDAY
MORNING TIME FRAME. RIGHT NOW, SLEET LOOKS THE BE THE LEAST
LIKELY P-TYPE TO OCCUR.
MOST OF THE PRECIPITATION SHOULD END WEDNESDAY MORNING. THERE
ARE SIGNALS THAT A WEAK WAVE OF LOW PRESSURE COULD DEVELOP
OFFSHORE WEDNESDAY NIGHT INTO THURSDAY AND WITH TEMPERATURES
STILL COLD, SOME LINGERING POCKETS OF FREEZING RAIN COULD OCCUR.
AVIATION /00Z FRIDAY THROUGH TUESDAY/
VFR CONDITIONS WILL PREVAIL AT KCHS, KJZI, AND KSAV THROUGH 00Z
SATURDAY.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS ARE LIKELY
SATURDAY AS WIDESPREAD RAINS MOVE THROUGH IN ASSOCIATION WITH A
COLD FRONT. THE RISK FOR RESTRICTIONS IN LOW VSBYS AND CEILINGS
WILL RETURN MONDAY NIGHT INTO WEDNESDAY MORNING AS A POTENTIAL
WINTER STORM IMPACTS THE REGION. THERE IS A CHANCE FOR FREEZING
OR FROZEN PRECIPITATION IMPACTING ALL TERMINALS DURING THIS
TIME.
MARINE
TONIGHT: GUSTY WEST-SOUTHWEST WINDS WILL PEAK THROUGH MUCH OF
THE NIGHT, THEN DIMINISH CLOSER TO SUNRISE FRIDAY AS THE WIND
DIRECTION TURNS MORE TO THE NORTHWEST. SOLID SMALL CRAFT
ADVISORY CONDITIONS WILL CONTINUE FOR ALL WATERS OTHER THAN THE
CHARLESTON HARBOR AND THE NEARSHORE GA WATERS, WITH SOME GUSTS
UP TO 30 KNOTS POSSIBLE. THESE ADVISORIES ARE SCHEDULED TO COME
DOWN EARLY FRIDAY MORNING. FOR CHARLESTON HARBOR, WINDS WILL
MOSTLY BE 10-15 KNOTS, ALTHOUGH THERE COULD BE A PERIOD LATE
THIS EVENING AND FOR SHORT TIME AFTER MIDNIGHT WHERE WINDS ARE
BIT STRONGER. IN THE NEARSHORE GA WATERS WINDS SHOULD MORE
CONSISTENTLY REMAIN IN THE 10-15 KNOT RANGE, WITH GUSTS UP NEAR
20 KNOTS TO OCCUR. SEAS WILL PEAK IN THE EARLY MORNING HOURS,
WITH UP TO 5 FEET POSSIBLE IN THE CHARLESTON COUNTY WATERS AND
THE OUTER GA WATERS.
FRIDAY THROUGH TUESDAY: NORTHWEST WINDS WILL SURGE BEHIND A
COLD FRONT SUNDAY NIGHT WITH SPEEDS REACHING 15-25 KT WITH GUSTS
TO 30 KT. SMALL CRAFT ADVISORIES ARE LIKELY DURING SUNDAY NIGHT
INTO MONDAY MORNING. SEAS WILL PEAK 3-5 FT OVER THE NEARSHORE
WATERS OUT 20 NM AND 4-6 FT OVER THE GEORGIA OFFSHORE WATERS OUT
20-60 NM. ANOTHER SURGE WILL OCCUR MONDAY NIGHT INTO TUESDAY AS
THE PRESSURE GRADIENT TIGHTENS BETWEEN INLAND HIGH PRESSURE AND
A DEVELOPING LOW OFFSHORE. NORTH TO NORTHEAST WINDS 20-25 KT
WITH GUSTS TO 30 KT WILL OCCUR DURING THIS TIME WITH SEAS 2-4 FT
WITHIN 20 NM AND 4-6 FT OVER THE GEORGIA OFFSHORE WATERS OUT
20-60 NM. SOME WINTER PRECIPITATION COULD FALL OVER THE COASTAL
WATERS MONDAY NIGHT INTO TUESDAY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR AMZ350-352-374.
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
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