South Santee River to Edisto Beach, SC Marine Forecast
| Today...Sw Winds 10 To 15 Kt With Gusts To 20 Kt. Seas 3 Ft. Wave Detail: S 3 Ft At 4 Seconds And Se 3 Ft At 9 Seconds. |
| Tonight...Sw Winds 10 To 15 Kt. Seas 3 Ft. Wave Detail: S 3 Ft At 4 Seconds And E 2 Ft At 9 Seconds. |
| Fri...Sw Winds 10 To 15 Kt. Seas 3 Ft. Wave Detail: S 3 Ft At 5 Seconds And E 2 Ft At 9 Seconds. |
| Fri Night...Sw Winds 10 To 15 Kt. Seas 2 To 3 Ft. Wave Detail: S 2 Ft At 5 Seconds And Se 2 Ft At 9 Seconds. |
| Sat...Sw Winds 10 To 15 Kt. Seas 2 To 3 Ft. Wave Detail: S 2 Ft At 5 Seconds And Se 2 Ft At 8 Seconds. |
| Sat Night...S Winds 10 To 15 Kt. Seas 3 To 4 Ft. Wave Detail: S 3 Ft At 5 Seconds And Se 2 Ft At 8 Seconds. |
| Sun...Sw Winds 15 To 20 Kt. Seas 3 To 4 Ft. |
| Sun Night...N Winds 20 To 25 Kt With Gusts To 30 Kt. Seas 4 To 5 Ft. |
| Mon...Ne Winds 20 To 25 Kt With Gusts To 30 Kt. Seas 4 To 6 Ft. |
| Mon Night...Ne Winds 15 To 20 Kt. Seas 3 To 4 Ft. |
| Area Forecast Discussion National Weather Service Charleston SC 226am EDT Sat September 5 2026 .WHAT HAS CHANGED... All sections have been updated. .KEY MESSAGES... - 1) Hot and humid conditions expected this weekend. - 2) Numerous to widespread thunderstorms are expected to develop across the region Sunday afternoon into Sunday night. These thunderstorms are expected to bring a risk for damaging wind gusts as well as locally heavy rainfall and flooding. - 3) The potential for coastal flooding will increase starting early next week with the threat continuing at least through the middle of the week. KEY MESSAGE 1: Hot and humid conditions expected this weekend. Aloft, the eastern extent of high amplitude ridging centered across the central CONUS will reach into the region today. Then by Sunday this eastern extent of the ridge will retreat to the west as troughing spreads into the area. At the surface, the forecast area will sit ahead of a cold front approaching from the north today, with the front expected to arrive late Sunday. For today, temperatures are forecast to peak in the mid 90s. Dewpoints are forecast to be in the mid to upper 70s along much of the coastal corridor while mixing out a bit into the low to mid 70s inland. This combination is expected to yield heat indices up to around 105 degrees everywhere, with values as high as 110 degrees across an area that includes nearly all of southeast SC and potentially even across the Savannah River and into Effingham and Chatham counties. The ongoing Heat Advisory looks to be well placed, and some areas within it will be quite marginal to reach the advisory threshold of 108 degrees. Therefore, there is no strong support to expand the Heat Advisory. Looking ahead to Sunday, another hot and humid day is expected ahead of an approaching cold front. Temperatures are forecast to peak in the mid 90s, with some upper 90s possible across southeast GA. With dewpoints again in the mid to upper 70s along the coast and low to mid 70s inland, the setup will again likely yield heat indices into the 105-110 degree range. We could again see marginal Heat Advisory conditions likely along the entire coast and even some of inland southeast GA. However, we expect to see thunderstorm coverage increase quickly in the afternoon which could complicate the heat index forecast. KEY MESSAGE 2: Numerous to widespread thunderstorms are expected to develop across the region Sunday afternoon into Sunday night. These thunderstorms are expected to bring a risk for damaging wind gusts as well as locally heavy rainfall and flooding. A cold front is forecast to approach the forecast area from the north Sunday afternoon and then pass through Sunday night. Ahead of the front, numerous to widespread thunderstorms are expected to develop in the afternoon and impact the entire forecast area into the evening. These thunderstorms will bring the risk of damaging wind gusts as well as intense rainfall. Severe Weather: Temperatures are forecast to warm into the mid (and possibly upper) 90s with dewpoints pooling in the mid to upper 70s along the coast. This will yield moderate to strong instability within a very moist environment. The front will provide sufficient convergence to support strong updrafts and despite the lack of any significant deep layer flow there will be the potential for clusters of strong storms capable of producing damaging wind gusts. The severe potential will be highest where outflow boundary interactions enhance updrafts. There is little to no confidence in where the best severe potential will reside spatially, but with the anticipated coverage the threat will exist across all of southeast GA and southeast SC. As far as timing, guidance suggests that convective initiation will take place in the mid afternoon and the threat will persist until the environment gets worked over later in the evening. Heavy Rain: The environment will be quite moist with precipitable water values in the 2-2.25" range. With strong convection expected and some enhanced convergence with the presence of the front, pockets of very intense rainfall are expected with thunderstorm clusters. Storm motion will not be particularly fast, likely around 15 knots. The risk for heavy rain will be highest where clusters track over the same areas and where boundary interactions produce persistent development. The 05/00z HREF suggests there will be pockets of 30-50% probabilities of 3+ inches in a 3 hour period, which will bring the risk of flash flooding to the area. The risk will be highest in urbanized areas and will extend through the evening. The potential for locally heavy rain will decrease into Monday as less coverage is expected and less instability will be available. KEY MESSAGE 3: The potential for coastal flooding will increase starting early next week with the threat continuing at least through the middle of the week. Astronomical tides will continue to rise through the middle of next week thanks to the lunar perigee (9/6) and the upcoming new moon (9/11). These factors will push astronomical tides as high as 6.55 ft MLLW at Charleston with the Wednesday evening high tide, setting the stage for the coastal flooding potential with meteorological support. A cold front will push through Sunday night and an extended period of elevated northeast flow is expected from Monday into Wednesday which will drive increased tidal departures. Coastal flooding will be favored during the evening high tide cycles at Charleston and could begin as early as the Monday evening high tide. While minor coastal flooding is the most likely scenario, the potential for moderate coastal flooding will increase with the Tuesday and Wednesday evening high tides. Coastal Flood Advisories will likely be needed for Charleston and coastal Colleton counties. For the rest of the coast for Beaufort County and the southeast GA coast, tidal departures would need to exceed 1 ft to reach the minor coastal flood threshold (9.5 ft MLLW) at Fort Pulaski. So, coastal flooding is less likely in this area but still can't be ruled out especially if the northeast flow behind the passing cold front turns out a bit stronger than currently forecast. Marine Today through tonight: Light westerly flow this morning will turn more southerly with the onset of the sea breeze this afternoon and evening along the land/sea interface. Then through the overnight, southwest flow will prevail across the local waters. Wind speeds should mostly be in the 10-15 knot range, but could gust up to around 20 knots at times in the evening and the first part of the overnight with some modest nocturnal surging. Seas are expected to be in the 2-3 ft range through the period. Sunday through Wednesday: A cold front is expected to drop southward through the waters Sunday night. Behind the front, a solid surge of northeast flow is expected. Winds will peak Monday through Tuesday with sustained wind speeds around 20 knots and gusts around 25 knots. Seas will steadily build in the persistent northeast flow as well, with 5+ ft expected everywhere and even 6-7 ft spreading across much of the waters. This combination of winds and seas will almost certainly bring the need for Small Craft Advisories beginning Monday morning and continuing through Tuesday and possibly even Tuesday night. Charleston Harbor will likely be included in these advisories as well, especially with some diurnal surging in the afternoon and evening Monday and Tuesday. Along the front, there will be the potential for strong thunderstorms across the local waters Sunday and Sunday night. These storms will bring the potential for strong wind gusts in excess of 35 knots as well as frequent lightning. NOAA Charleston SC Office: Watches - Warnings - Advisories GA... Heat Advisory from 11am this morning to 8pm EDT this evening for GAZ101-218-219. SC... Heat Advisory from 11am this morning to 8pm EDT this evening for SCZ042>045-147>152. Marine None. |
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