Charleston Harbor Marine Forecast
| Today...Ne Winds 10 To 15 Kt With Gusts To 20 Kt. |
| Tonight...Ne Winds 15 Kt With Gusts To 20 Kt. |
| Thu...Ne Winds 10 To 15 Kt, Becoming E 15 To 20 Kt In The Afternoon. Waves 1 To 2 Ft. A Slight Chance Of Showers In The Afternoon. |
| Thu Night...E Winds 10 To 15 Kt With Gusts To 20 Kt. A Chance Of Showers, Mainly In The Evening. |
| Fri...E Winds 10 To 15 Kt. A Chance Of Showers With A Slight Chance Of Tstms. |
| Fri Night...Ne Winds 10 To 15 Kt. A Chance Of Showers With A Slight Chance Of Tstms. |
| Sat...Ne Winds 10 To 15 Kt. Showers Likely With A Slight Chance Of Tstms. |
| Sat Night...Ne Winds 10 To 15 Kt. A Chance Of Showers With A Slight Chance Of Tstms. |
| Sun...Ne Winds 10 To 15 Kt. A Chance Of Showers With A Slight Chance Of Tstms. |
| Sun Night...Ne Winds 10 To 15 Kt. A Chance Of Showers With A Slight Chance Of Tstms. Winds And Waves Higher In And Near Tstms. Unless Otherwise Noted, Waves 1 Foot Or Less. Charleston Harbor Water Temperature 78 Degrees. |
| Area Forecast Discussion National Weather Service Charleston SC 720am EDT Wednesday September 11 2024 Synopsis High pressure will remain over the region through mid week. Hurricane Francine is expected to make landfall west of the Mississippi River later today. Moisture associated with Francine will build over the area on Thursday and linger into the late week. A wave of low pressure could develop off the Southeast coast over the weekend into early next week. Near Term - Through Tonight Today: We start the day with extensive high level cloudiness streaming overhead from Hurricane Francine, which makes landfall later today in Louisiana. Meanwhile, our region remains under the control of high pressure from New England which stretches into the Southeast, while a weakening ridge is found aloft. Most of the area will get by with another day free from rain, with the exception of places south of I-16, where isolated to scattered showers will take place. This occurs in the region where we find the best low level moisture convergence from off the ocean, and where the best MLCAPE of maybe 500-750 J/kg is found. Given the placement of the upper jet stream, considerable high level clouds will dominate, along with scattered to perhaps broken cumulus/stratocumulus developing within the easterly low level flow. Simulated satellite, cross-sections, and soundings point toward only limited insolation, and this will play a huge part in actual max temperatures. Trended toward the lower side of guidance, which still might be too warm. In addition, gusty east-northeast winds from off the Atlantic within a fairly tight gradient and sufficient mixing will produce speeds as high as 20-25 mph over the coastal corridor. Tonight: Francine looks to move through Louisiana and into Mississippi, with the local vicinity still under the influence of high pressure centered off New England. Ridging aloft gives way to more of a cyclonic flow to the west during the overnight period. But large scale subsidence persists across a large part of the area, with the best moisture still confined over far southern areas and southward. We currently have no more than isolated to scattered showers south of I-16, where we find subtle isentropic ascent in tandem with the best low level moisture convergence. Extensive cloud cover and winds never fully decoupling will yield a warmer night than the past couple of nights, with lows in the mid and upper 60s inland, lower and middle 70s closer to the ocean, where gusty east-northeast winds will persist. Short Term - Thursday Through Saturday Surface high pressure will continue to ridge south into the region Thursday into Friday. Concurrently, Francine will be slowing and weakening while moving up the Mississippi River Valley. It appears that the ridge will hold firm, but a front near the Gulf coast could make northward progress but will likely stall south of the local area. Deep tropical moisture will steadily overspread the region. Scattered to numerous showers, and possibly a couple thunderstorms, are expected over southeast Georgia on Thursday, with lesser coverage further north where drier air will hold the longest. Friday should see higher coverage on the whole and Probability of Precipitation peak in the 60-70% range. Highs will be in the low to mid 80s, with lows mainly in the upper 60s to lower 70s. High pressure will persist inland on Saturday, while a coastal trough or potentially an area of low pressure develops well offshore. Aloft, vort energy associated with the remnants of Francine will pass across the region. Scattered to numerous showers with perhaps a few embedded thunderstorms are forecast. High temperatures generally around 80 or in the lower 80s. trong> High pressure will continue to extend south into the region early next week. Models indicate that an area of low pressure could be located well offshore along a stalled front. The evolution of this feature is still uncertain, so there is lower confidence in the forecast at this juncture, but the low could take a track back towards the Southeast coast later in the period. Maintained chance PoPs each day, generally in the 30-40% range. Marine Today: High pressure to the north band a stationary front to the south will yield a modest pressure gradient across the local waters, leading to Small Craft Advisories all marine zones outside of Charleston Harbor. Easterly winds will be as strong as 15-20 kt with gusts at least as high as near 25 kt to occur. This favorable onshore fetch will produce seas reaching up to 6 feet on the waters out 20 nm from the South Santee River to the Altamaha Sound, and up to 7 feet further out. Charleston harbor will experience gusts near 20 kt at times, but not enough for any advisory. Tonight: Once again the pressure gradient remains rather pinched, and Small Craft Advisories will continue for all waters except the Charleston Harbor. Winds and seas will be very similar to what they were during the daylight hours. Thursday through Monday: A ridge of high pressure inland will drive persistent northeast to east flow over the coastal waters through much of the period. Speeds of 15-20 knots and seas of 6 feet on Thursday will settle a bit late week, allowing the ongoing Small Craft Advisories to come down. However, it will likely be fairly short-lived as conditions could again increase over the weekend into early next week as a coastal trough or potentially an area of low pressure develops offshore. Still uncertainty on the evolution of this feature, so forecast is lower confidence late in the period. Rip Currents Moderate to strong onshore winds, small swells, plus elevated tides will lead to an enhanced risk of rip currents all beaches today. Local tabulations and the Rip Current MOS point toward a Moderate Risk on the South Carolina beaches, with a High Risk along the Georgia beaches. In addition, there will likely be a strong northeast to southwest parallel current due to the winds. Gusty NE winds along with swell of 3-4 feet every 8 seconds favors a Moderate Risk for rip currents for South Carolina beaches and a High Risk for Georgia beaches on Thursday. An elevated risk for rip currents will persist into the weekend. Tides / Coastal Flooding Persistent and strong onshore winds will lead to elevated tidal departures this week. Tide levels could reach minor flooding thresholds along the Charleston and Colleton county coasts, beginning as early as Thursday, with the afternoon high tide cycle. The threat for coastal flooding will increase next week as we approach the full moon and perigee. NOAA Charleston SC Office: Watches - Warnings - Advisories GA...High Risk for Rip Currents through this evening for GAZ117-119-139- 141. SC...None. Marine Small Craft Advisory from 5pm this afternoon to 8pm EDT Friday for AMZ350. Small Craft Advisory from 11am this morning to 8am EDT Friday for AMZ352. Small Craft Advisory until 8am EDT Friday for AMZ354. Small Craft Advisory until 8pm EDT Friday for AMZ374. |
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