Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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242 FXUS62 KCHS 201737 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 137 PM EDT Fri Sep 20 2024 .SYNOPSIS... An area of high pressure is expected to gradually strengthen across the region through early next week. A weak cold front may approach from the west around the middle of next week. && .NEAR TERM /THROUGH TONIGHT/... Latest visible satellite indicated densely packed cumulus cloud streets across the forecast area. The 12Z KCHS observed sounding indicated a convective temperature around 85 degrees with an inversion around 590 mb. However, a mid-level vort max was indicated on satellite water vapor, tracking south across the forecast area. By this afternoon, the combination of a weak sea breeze, passage of vort max, and CAPE around 1000 J/kg should support isolated showers along the GA coast this afternoon. High temperatures are on track to peak in the mid to upper 80s. Tonight: Mid level trough axis will advance off the coast with upstream ridging expanding into the southeast states, and inland high pressure wedging become better defined. Any convection that develops this afternoon will fade quickly this evening with clear to partly cloudy skies dominating overnight. Lows dip back into the middle to upper 60s, warmer along the coast. && .SHORT TERM /SATURDAY THROUGH MONDAY/... The synoptic pattern will remain largely unchanged through the period with a large upper ridge across the Deep South. Surface high pressure will remain over the Southeast U.S., providing subsidence and generally quiet weather conditions through the period. Mostly sunny skies are expected each day through Monday. Any potential for convection will be largely suppressed due to relatively dry air aloft and the lack of significant forcing mechanisms. No mentionable rainfall chances have been included in the short term forecast. Temperatures will trend warmer due to the ridge aloft with highs in the mid to upper 80s Saturday, increasing to the upper 80s/low 90s Sunday and Monday. Lows will start somewhat cool Saturday night, dipping into the mid to upper 60s for most locations. Sunday night will feature lows in the upper 60s inland and low 70s near the coast. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... The long-term forecast features continuing dry conditions initially, with increasing chances of afternoon showers and thunderstorms around the middle of next week. The region will see a slight uptick in moisture with surface high pressure shifting offshore Tuesday, followed by the upper ridge axis. Slight chance POPs return Wednesday with peak rain chances anticipated to occur mid to late week as an upper trough and cold front approach. Temperatures will remain seasonable with highs generally in the mid 80s and lows in the mid to upper 60s, with an ever so slight cooling trend through the week. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... Prior to the 18Z TAFs, satellite indicated densely packed cloud streets over KCHS and KSAV, bases just above 3 kft. Cloud bases should lift through the rest of the afternoon, reaching between 050-060 kft this afternoon. Winds are forecast to remain generally from the ENE through the TAF period, between 5-10 kts during the day and around 3 kts at night. KSAV could see some ground fog or patchy fog during the pre-dawn hours Saturday morning, highlighted with a TEMPO from 10-12Z. Extended Aviation Outlook: VFR conditions expected to prevail. && .MARINE... Light offshore winds will be in place to start the day but will veer north/northeasterly later this morning and this afternoon. Speeds 10 knots or less anticipated and seas 3 feet or less. Saturday: Inland high pressure with a coastal trough off the southern Florida Peninsula will result in northeast winds between 10- 15 kt with gusts around 20 kt Saturday. Seas will average between 2- 4 ft with some 5 foot seas in the outer Georgia waters from 20-60 nm. Conditions are expected to be below Small Craft Advisory criteria. Sunday through Wednesday: As the coastal trough to the south subsides and high pressure begins to migrate offshore, the pressure gradient will relax bringing northeasterly to southeasterly winds around 10 kt or less. Seas will decrease to around 1-3 ft with 4 foot seas beyond 40 nm. && .TIDES/COASTAL FLOODING... Minor coastal flooding is possible along the Colleton and Charleston County coast with this evening`s high tide. Positive tidal anomalies and high astronomical tides from the recent full moon will lead to elevated tides through the weekend. Although the astronomical high tides start to lower Saturday and Sunday, minor to moderate coastal flooding is likely with each high tide cycle along the Charleston and Colleton county coasts. Further south and along the Georgia coast, minor coastal flooding is likely with the morning high tide cycle. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...BRM LONG TERM...BRM AVIATION...NED MARINE...Adam/BRM