Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
750 FXUS62 KCHS 131825 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 225 PM EDT Sun Sep 13 2026 .WHAT HAS CHANGED... All sections updated. && .KEY MESSAGES... - 1) Limited rain chances today and Monday, with record challenging high temperatures forecast Monday. - 2) Cooler and drier conditions expected Tuesday through mid week. - 3) Minor coastal flooding possible with the Tuesday midday high tide along the Charleston and Colleton county coasts. && .DISCUSSION... KEY MESSAGE 1: Limited rain chances today and Monday, with record challenging high temperatures forecast Monday. Despite a PWAT of 2.31 inches with this morning`s 12Z KCHS RAOB Sounding, conditions are forecast to dry out into the afternoon hours as a shortwave trough advances towards the local forecast area. This shortwave can be easily seen on the GOES mid-level water vapor imagery, as of 17Z roughly located just to the west of Jenkins/Screven/Allendale counties. The KCLX radar has begun to detect isolated showers over southeastern GA. These showers are forming just ahead of the shortwave, likely initiating with the assistance of the sea breeze. Most model guidance from this morning paint a rather benign picture of isolated convection this afternoon and any showers/storms diminishing with nightfall. A similar set-up is forecast on Monday, with the shortwave trough pushing through the region overnight. With the arrival of the shortwave PWATs are forecast to drop even lower, with some guidance showing values as low as 1.5 inches. The bigger story with Monday`s forecast will be the hot temperatures. High pressure will build into the forecast area on Monday aloft, centered over the Deep South. At the surface high pressure will briefly build into the region ahead of an approaching front. Guidance points to high temperatures reaching into the upper 90s across most of the forecast area. The 850mb temperatures are forecast to reach as high as 18-20C, which would point to high temperatures in the mid 90s. Surface winds are forecast to shift to the NW on Monday. This direction typically leads to some downsloping influences and drier/warmer conditions over the local forecast area. These temperatures could potentially be record breaking at the local climate sites. See the Climate Section for more details. KEY MESSAGE 2: Cooler and drier conditions expected Tuesday through mid week. A backdoor cold front will drop through the area Monday night, followed by seasonally strong high pressure ridging south into the Carolinas and Georgia for midweek. This will bring temperatures down to more typical September levels, with highs largely in the 85-90 range. Lows are expected to fall well into the 60s over most inland locations. The chance for rainfall should be pretty limited during this time period as PWats are forecast to eventually drop below 1 inch (which is 10-15th percentile of climo). The exception would be on Tuesday across portions of southeast Georgia where low level convergence intersects some lingering deep moisture before the drier air really arrives. Otherwise, it looks to be a pleasant couple of days. Northeast winds could get a bit gusty along the coast. KEY MESSAGE 3: Minor coastal flooding possible with the Tuesday midday high tide along the Charleston and Colleton county coasts. Minor coastal flooding is possible with the Tuesday midday high tide along the Charleston and Colleton County coasts. Strengthening northeast winds are expected on Tuesday which will increase tidal departures. The tide would need ~1 ft departure to reach minor flooding thresholds of 7 ft MLLW in the Charleston Harbor. Most guidance indicates this could be achieved, with tide levels possibly falling somewhere in the 7.0-7.2 ft MLLW range. A Coastal Flood Advisory could be needed. No issues expected further south along the lower SC and southeast GA coasts. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Dry conditions are forecast through the 18Z TAF at KCHS/KJZI while some VCTS are possible at KSAV through the afternoon. Confidence is too low to include restrictions at KSAV due to showers/storms, so have VCTS from 18 to 23Z. Skies are forecast to go SKC Monday morning with winds tipping around to the NW. Extended Aviation Outlook: VFR. Gusty winds are possible Tuesday through Thursday afternoons. && .MARINE... Through Tonight: Weak troughing across inland locations have shifted winds to the SSW. As the troughing weakens winds will tip to the W overnight, generally in the 10 to 15 knot range. Seas will average 2 to 3 ft. Monday through Thursday: No marine concerns on Monday. Winds and seas will increase Tuesday as high pressure ridges south into the region, with conditions remaining elevated into Thursday. Wind gusts are expected to peak in the 25-30 knot range while seas build to 5-7 feet. There is a low-end chance some gusts reach near gale force later Tuesday and again later Wednesday, particularly over the GA waters. However, it looks marginal and short-lived with NBM indicating probabilities for gusts over 34 knots are less than 30%. Will continue to monitor. Pressure gradient should begin to ease on Thursday, with conditions likely falling below advisory levels Friday. Rip Currents: Gusty northeast winds and increasing seas Tuesday into midweek will lead to an elevated risk of rip currents. Latest rip current forecast for Tuesday indicates a Moderate Risk for SC beaches and a High Risk for GA. && .CLIMATE... Record High Temperatures September 14: KCHS: 94/1991 KCXM: 94/1938 KSAV: 96/1991 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ CPM/ETM