Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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137 FXUS62 KCHS 030526 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1226 AM EST Wed Dec 3 2025 .SYNOPSIS... Low pressure will exit the region tonight. High pressure will them prevail through middle of this week before another frontal system impacts the area Friday into the weekend. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... High pressure centered across the Ohio River Valley will slowly expand east across the Mid-Atlantic and Southeast, supporting dry and cooler air spreading across the local area within a west- northwest wind this evening, then north wind after midnight. Cold air advection will help keep low-lvl wind fields somewhat mixed, while lingering low-lvl moisture supports some degree of low clouds across the region. The setup favors overnight lows in the mid 30s inland to low-mid 40s across coastal counties. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY/... Surface high pressure will extend into the region on Wednesday. Quieter weather is expected with highs leaning on the cooler side of normal. On Thursday, high pressure will largely persist. Meanwhile, low pressure will begin to take shape over the northern Gulf. Moisture will begin to increase from the southwest, and models hint at weak shortwave energy passing through later in the day. Latest NBM indicates only a small chance (20%) of measurable rainfall (>0.01") Thursday afternoon over interior southeast Georgia, but by and large, most areas will remain dry through the daylight hours. The aforementioned low is expected to lift northeast from the Gulf and into the region Thursday night into Friday. The atmosphere will continue to moisten with PWats expected to surge to near 1.5 inches which is well above normal for this time of year per SPC sounding climatology. This will coincide with an increase in isentropic ascent and large scale forcing which will lead to increasing coverage of showers through the day. Looking at QPF clusters, majority of ensemble members show the entire area receiving beneficial rainfall through the daytime hours, but it`s worth noting that a small contingent (~20% of members) shows the bulk of rainfall focused more inland/over the Midlands through 00z. For now, our QPF indicates 0.25-0.75". Otherwise, there could be a notable temperature gradient between inland (cooler) and coastal locations (warmer) with a wedge set-up evolving. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... The first half of the weekend will remain active with the axis of deeper moisture still oriented over the area. Model consensus indicates the area will remain ahead of a mid level trough axis and the area will also become positioned in the favorable right entrance region of the upper jet. These conditions would support another wave of precipitation developing on Saturday into Saturday night. There remains uncertainty on when rainfall will end, but at least half of ensemble members currently indicate dry conditions returning for Sunday and beyond. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... Prior to the 6Z TAFs, nighttime microphysics indicated a large area of MVFR ceilings across the terminals. The restrictive ceilings should remain until a sfc trough or weak backdoor front pushes across KCHS and KJZI around dawn. The passage of the trough will result in light winds to shift from the northeast along with lifting of cloud bases. Based on satellite trends, conditions over KCHS and KJZI are forecast to improve to VFR by 14Z. The sfc trough may push south, slowing or becoming stationary near the Savannah River by late this morning. As a result, MVFR ceilings over KSAV may linger until early this afternoon. Also, winds at KSAV may remain from the northwest through the TAF period. Extended Aviation Outlook: Flight restrictions, possibly to IFR or lower, are expected in low clouds and rain Friday into the weekend. && .MARINE... Tonight: Conditions will steadily improve over the waters overnight as low pressure exits the area. The Small Craft Advisory for the South Santee-Edisto Beach nearshore leg was cancelled as seas have dropped below 6 ft there based on report from 41004 and the Charleston Harbor Pilot Buoy. The advisory continues for a bit longer for the Georgia offshore leg. Wednesday through Sunday: No marine concerns through mid week. Northerly winds will average around 10 knots or less with seas 2-3 feet. Low pressure is expected to pass across the region Friday into Friday night. Winds should turn more southerly ahead of it and increase in speed, but conditions are currently forecast to stay below small craft advisory criteria. Another wave of low pressure could pass through later in the weekend. && .TIDES/COASTAL FLOODING... Astronomical tides will continue to rise with the morning high tide cycles through Friday and remain elevated through the weekend. Coastal Flood Advisories will likely be needed for morning high tide cycles, primarily at Charleston Harbor (Charleston and Coastal Colleton counties) through late week. There is concern for minor coastal flooding to occur from Beaufort county south across the Georgia coast with the morning high tide on Friday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION...NED MARINE...