924
FXUS62 KCHS 152347
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
647 PM EST SAT FEB 15 2025
SYNOPSIS
A STRONG COLD FRONT WILL IMPACT THE AREA SUNDAY, FOLLOWED BY
HIGH PRESSURE FOR MONDAY AND TUESDAY. A LOW PRESSURE SYSTEM
WILL MOVE ACROSS THE REGION DURING THE MIDDLE OF NEXT WEEK.
HIGH PRESSURE WILL THEN RETURN LATE NEXT WEEK.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
REPORTS FROM SURFACE OBSERVATIONS, THE SAVANNAH PILOT OFFICE,
AND AREA WEBCAMS, INDICATE THAT FOG IS DEVELOPING, IN LINE WITH
SOME OF THE GUIDANCE. SINCE IT IS DUE TO LOW CLOUDS THAT ARE
BUILDING DOWN AND SEA FOG, IT COULD BE HARD TO GET RID OF. BUT
WITH THE INCREASE IN WINDS THROUGH THE NIGHT IN WAKE OF A WARM
FRONT LIFTING NORTH, WE HAVE IT DISSIPATING BY 12 MIDNIGHT. FOR
NOW WE INCLUDED MENTION OF AREAS OF FOG, SOME OF WHICH COULD BE
DENSE OVER COASTAL COUTNIES OF GEORGIA AND LOWER SOUTH
CAROLINA. WE ADDED MENTION OF PATCHY FOG ACROSS CHARLESTON AND
EASTERN BERKELEY COUNTY DURING THAT SAME TIME PERIOD. THE
EVENING UPDATE ALSO INCLUDED SOME ADJUSTMENTS TO TEMPERATURES
BASED ON LATEST TRENDS.
TONIGHT: A POTENT MID-LEVEL WAVE WILL APPROACH THE AREA FROM
THE WEST TONIGHT WITH THE WAA WING/ ISENTROPIC UPGLIDE
TRANSLATING EAST. THIS MEANS THAT THE SHOWERS FROM THIS
AFTERNOON WILL ALSO ADVECT NORTHEAST. HOWEVER, ANOTHER WEAK
POCKET OF PVA IN THE SOUTHWEST FLOW IS ALREADY CAUSING FURTHER
DEVELOPMENT OVER NORTHERN FL, AND THIS WILL LIKELY TRANSLATE
ACROSS GA THROUGH THE EVENING HOURS. AFTER MIDNIGHT, THE
PRECIPITATION WILL COME TO AN END FOR MOST OF THE REGION WITH
SOUTHERLY WINDS INCREASING.
SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/
SUNDAY: A POTENT UPPER LEVEL WAVE WILL ADVECT EAST SUNDAY
MORNING WITH A SEASONABLY STRONG 250 MB JET STREAK APPROACHING
THE AREA (140 - 150 KT). AT 500 MB, THE MID-LEVEL WAVE WILL BE
OVER THE SOUTHERN OHIO RIVER VALLEY AROUND SUNRISE WITH 200 M
HEIGHT FALLS APPROACHING. THE WAVE WILL THEN BEGIN TO TAKE ON A
NEGATIVE TILT AS IT EJECTS NORTHEAST WITH THE CORE OF THE DCVA
AND HEIGHT FALLS MOVING ALONG THE SPINE OF THE APPALACHIANS.
ACROSS SC/ GA 80/100 M HEIGHT FALLS WILL STILL MOVE EAST OVER
THE REGION. AT 850/ 925 MB, THE PGF IS FORECAST TO TIGHTEN
THROUGH THE MORNING PERIOD WITH THE LLJ PEAKING AT 50 TO 60 KT
OVERHEAD. AT THE SURFACE, A COLD FRONT AND ASSOCIATED LINE OF
SHOWERS (WITH A RUMBLE OF THUNDER POSSIBLE) WILL BE APPROACHING
THE WESTERN ZONES BETWEEN 6 AND 8 AM.
TIMING-- SEVERE WEATHER LINE:
* I-95 BETWEEN 9 - 11 AM
* THE GA/ SC COAST BETWEEN 11 AM - 1 PM.
SUNDAY SEVERE THREAT: THE MAIN CONCERN FOR SUNDAY WILL BE THE
CHANCE FOR SEVERE WEATHER/ STRONG TO LOCALLY DAMAGING WIND
GUSTS. CLOUD BEARING SHEAR VALUES ARE AROUND 50 KT ALONG THE
LINE, HOWEVER INSTABILITY IS EXTREMELY LIMITED (ONLY AROUND 100
J/KG OF MU CAPE). AS MENTIONED ABOVE THOUGH, 50 - 60 KT OF WIND
IS FORECAST TO BE IN THE 925/850 MB LAYER AND WITH ANY DOWNWARD
MOMENTUM TRANSFER, LOCALLY DAMAGING WIND GUSTS WILL BE
POSSIBLE. THE GREATEST INSTABILITY, IS TOWARDS SOUTHERN GA AND
THEREFORE SPC HAS INTRODUCED A SLIGHT RISK FOR SEVERE WEATHER
ACROSS GA, AND CONTINUED A MARGINAL RISK FOR SC.
WIND THREAT: A WIND ADVISORY IS ALSO IN EFFECT FOR ALL ZONES
FROM 5 AM THROUGH 6 PM SUNDAY. AHEAD OF THE COLD FRONT, WINDS
WILL START TO APPROACH WIND ADVISORY CRITERIA AND REMAIN GUSTY
AFTER THE LINE PASSES AND A COLD FRONT SWEEPS ACROSS THE REGION.
LATEST FORECAST SOUNDINGS SHOW WIND GUSTS BEHIND THE COLD FRONT
AROUND 30 KT (VIA MOMENTUM TRANSFER TECHNIQUES), OR JUST SHY OF
WIND ADVISORY CRITERIA. GIVEN THE STRONG CAA THOUGH, HAVE OPTED
TO KEEP THE WIND ADVISORY UNTIL 6 PM SUNDAY.
MONDAY AND TUESDAY: SURFACE HIGH PRESSURE WILL BUILD OVER THE
REGION FOR MONDAY AND TUESDAY. QUIET AND DRY WEATHER IS
EXPECTED. THERE WILL BE PLENTY OF SUNSHINE, ALTHOUGH CLOUD COVER
WILL BE ON THE INCREASE DURING THE LATTER HALF OF THE DAY
TUESDAY. SEASONALLY COOL TEMPERATURES MAINLY IN THE MID 50S ON
MONDAY WILL MODERATE CLOSER TO NORMAL FOR TUESDAY. LOWS MONDAY
NIGHT WILL RANGE FROM THE LOW 30S INLAND TO UPPER 30S/AROUND 40
CLOSER TO THE COAST.
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
FOCUS FOR THE EXTENDED PERIOD WILL BE ON MID-WEEK AS THE NEXT
WEATHER SYSTEM IMPACTS THE REGION. SURFACE LOW PRESSURE IS EXPECTED
TO DEVELOP OVER THE NORTHERN GULF AND THEN LIFT NORTHEAST, PASSING
NEAR/ALONG THE SOUTHEAST COAST WEDNESDAY INTO WEDNESDAY NIGHT. AMPLE
FORCING FOR ASCENT ALONG WITH PWATS RISING TO WELL OVER AN INCH WILL
RESULT IN A FAIRLY WET DAY WITH WIDESPREAD SHOWERS CURRENTLY
FORECAST. THIS SYSTEM HAS THE POTENTIAL TO BRING 1-2 INCHES OF RAIN
TO THE AREA. INSTABILITY PROGS ARE PRETTY MEAGER, SO NO THUNDER IS
MENTIONED IN THE FORECAST AT THIS TIME. RAIN CHANCES SHOULD DECREASE
WEDNESDAY NIGHT.
THE AFOREMENTIONED LOW WILL LIFT AWAY FROM THE AREA ON THURSDAY,
ALLOWING CHILLY AND DRY HIGH PRESSURE TO BUILD FOR LATE WEEK.
TEMPERATURES WILL BE NOTABLY COOLER, WITH LOWS DIPPING WELL INTO THE
20S. WILL NEED TO MONITOR THE POTENTIAL FOR A COLD WEATHER ADVISORY
(WIND CHILL 20F OR COLDER) THURSDAY NIGHT.
AVIATION /00Z SUNDAY THROUGH THURSDAY/
TONIGHT: IFR/LIFR CONDITIONS WILL OCCUR AT KSAV THE FIRST PART
OF THE NIGHT, WITH MVFR TRANSITIONING TO IFR AT KCHS AND KJZI.
ALL SITES WILL ALSO EXPERIENCE SOME LIGHT FOG OR SHOWERS EARLY
ON WITH A DISTURBANCE PASSING THROUGH ALOFT. OVERNIGHT INTO
EARLY SUNDAY WITH THE PASSAGE OF A 45-55 KT LOW LEVEL JET,
SURFACE WINDS WILL INCREASE. BUT THERE REMAINS ENOUGH OF A
DIFFERENTIAL BETWEEN WINDS AT THE SURFACE AND 2000 FEET TO
INCLUDE LLWS FROM 06-15Z.
SUNDAY: A COLD FRONT WILL CROSS THE ZONES IN THE MORNING WITH A
LINE OF SHOWERS AND POSSIBLY A RUMBLE OF THUNDER. WIND GUSTS OF
30 TO 50 KT ARE POSSIBLE WITH THE PASSAGE OF THIS CONVECTIVE
LINE WITH SOME LOCALIZED HIGHER GUSTS. THE LINE OF SHOWERS WILL
THEN RAPIDLY CLEAR THE COAST LATE SUNDAY MORNING AND BE CLEAR OF
THE TAF SITES BY 18Z SUNDAY.
EXTENDED AVIATION OUTLOOK: VFR WILL RETURN FOR MONDAY AND TUESDAY.
FLIGHT RESTRICTIONS ARE POSSIBLE WEDNESDAY INTO WEDNESDAY NIGHT AS A
LOW PRESSURE SYSTEM PASSES ACROSS THE REGION.
MARINE
REPORTS FROM SURFACE OBSERVATIONS, THE SAVANNAH PILOT OFFICE,
AND AREA WEBCAMS, INDICATE THAT FOG IS DEVELOPING, IN LINE WITH
SOME OF THE GUIDANCE. SINCE IT IS DUE TO LOW CLOUDS THAT ARE
BUILDING DOWN AND SEA FOG, IT COULD BE HARD TO GET RID OF. BUT
WITH THE INCREASE IN WINDS THROUGH THE NIGHT IN WAKE OF A WARM
FRONT LIFTING NORTH, WE HAVE IT DISSIPATING BY 12 MIDNIGHT.
HOWEVER, UNTIL THEN, VISIBILITIES COULD BE DOWN TO UNDER 1 NM ON
THE GEORGIA AND LOWER SOUTH CAROLINA NEARSHORE WATERS. SO WE
OPTED FOR A DENSE FOG ADVISORY. FURTHER NORTH THE CONDITIONS ARE
NOT AS FAVORABLE FOR MORE THAN PATCHY FOG, BUT WE CONTINUE TO
MONITOR.
TONIGHT: WINDS AND SEAS WILL START TO INCREASE AS THE PGF
RAPIDLY BEGINS TO TIGHTEN WITH 850/925 MB WINDS APPROACHING 40
KT. AT THE SURFACE, EXPECT WIND GUSTS UP TO 30 KT WITH SEAS
BUILDING 5 TO 7 FT.
SUNDAY: A COLD FRONT WILL BE APPROACHING THE WATERS FROM THE
WEST AND SWEEP ACROSS THE MARINE ZONES IN THE EARLY AFTERNOON.
OUT AHEAD OF THE COLD FRONT, THE CORE OF THE 60 KT JET WILL BE
JUST OFF THE SC COAST. SOME HIGH RES GUIDANCE IS INDICATING THE
POSSIBILITY OF STORM FORCE GUSTS, BUT GIVEN THE TEMPERATURES OF
THE SHELF WATERS HAVE OPTED FOR A GALE WARNING WITH GUSTS
PEAKING AT 45 KT. SEAS WILL ALSO BE DANGEROUS SUNDAY AND PEAK 8
TO 12 FT. A HIGH SURF ADVISORY WAS CONSIDERED, BUT WE OPTED TO
HOLD FOR NOW GIVEN THE COASTLINE PARALLEL WAVE ENERGY. HOWEVER
THIS MIGHT NEED TO BE RE-EVALUATED.
MONDAY THROUGH THURSDAY: MARINE CONDITIONS WILL SUBSIDE ON MONDAY AS
HIGH PRESSURE EXPANDS ACROSS THE AREA AND THE PRESSURE GRADIENT
RELAXES. WINDS WILL TURN NORTHERLY AND EVENTUALLY MORE
NORTHEASTERLY WITH NO CONCERNS THROUGH TUESDAY. A LOW PRESSURE
SYSTEM IS EXPECTED TO IMPACT THE REGION WEDNESDAY INTO WEDNESDAY
NIGHT WHICH WILL BRING THE NEXT CHANCE FOR SMALL CRAFT
ADVISORIES. WINDS COULD STAY ELEVATED ON THURSDAY BEHIND THE
SYSTEM AS HIGH PRESSURE BUILDS INTO THE AREA.
CHS WATCHES/WARNINGS/ADVISORIES
GA...WIND ADVISORY FROM 5 AM TO 6 PM EST SUNDAY FOR GAZ087-088-
099>101-114>119-137>141.
SC...WIND ADVISORY FROM 5 AM TO 6 PM EST SUNDAY FOR SCZ040-042>045-
047>052.
MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 7 AM EST
SUNDAY FOR AMZ330.
GALE WARNING FROM 7 AM TO 3 PM EST SUNDAY FOR AMZ330.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR AMZ350-352-354.
GALE WARNING FROM 7 AM TO 6 PM EST SUNDAY FOR AMZ350-352-354-
374.
DENSE FOG ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR AMZ352-354.
SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR AMZ374.
NEAR TERM...
SHORT TERM...ETM/HAINES
LONG TERM...ETM
AVIATION...
MARINE...
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