Savannah, GA to Altamaha Sound, GA including Grays Reef National Marine Sanctuary Marine Forecast
| Tonight...Ne Winds 15 To 20 Kt With Gusts To 25 Kt. Seas 4 To 6 Ft. Wave Detail: Ne 6 Ft At 6 Seconds. A Chance Of Showers With A Slight Chance Of Tstms Early This Evening, Then A Slight Chance Of Showers Late This Evening. A Chance Of Showers Late. |
| Sun...Ne Winds 20 To 25 Kt With Gusts To 30 Kt. Seas 5 To 7 Ft. Wave Detail: Ne 7 Ft At 8 Seconds. A Chance Of Showers With A Slight Chance Of Tstms. |
| Sun Night...Ne Winds 20 To 25 Kt, Diminishing To 15 To 20 Kt After Midnight. Seas 5 To 7 Ft. Wave Detail: E 7 Ft At 9 Seconds. A Chance Of Showers With A Slight Chance Of Tstms. |
| Mon...Ne Winds 15 To 20 Kt. Seas 5 To 7 Ft, Subsiding To 4 To 6 Ft In The Afternoon. Wave Detail: E 7 Ft At 10 Seconds, Becoming E 6 Ft At 11 Seconds. A Chance Of Showers. |
| Mon Night...N Winds 10 To 15 Kt. Seas 4 To 5 Ft, Subsiding To 3 To 4 Ft After Midnight. Wave Detail: E 5 Ft At 11 Seconds, Becoming E 4 Ft At 10 Seconds. A Chance Of Showers, Mainly In The Evening. |
| Tue...Ne Winds 10 To 15 Kt. Seas 3 To 4 Ft. Wave Detail: E 4 Ft At 10 Seconds. A Slight Chance Of Showers. A Slight Chance Of Tstms In The Afternoon. |
| Tue Night...E Winds 5 To 10 Kt, Becoming S After Midnight. Seas 2 To 3 Ft. A Chance Of Showers With A Slight Chance Of Tstms. |
| Wed...W Winds 5 To 10 Kt. Seas 2 To 3 Ft. A Slight Chance Of Showers And Tstms. |
| Wed Night...S Winds 5 To 10 Kt. Seas 2 To 3 Ft. A Slight Chance Of Showers And Tstms. |
| Thu...N Winds 5 To 10 Kt. Seas 2 To 3 Ft. A Slight Chance Of Showers. |
| Thu Night...Sw Winds 5 To 10 Kt. Seas 2 To 3 Ft. Winds And Seas Higher In And Near Tstms. |
| Area Forecast Discussion National Weather Service Charleston SC 1054pm EDT Sat September 14 2024 Synopsis High pressure will remain over the region into next week. Low pressure will develop offshore of the Southeast U.S. coast this weekend and will impact parts of the Carolinas Monday night into Tuesday night as it moves inland. Near Term - Until 6am Sunday Morning Tonight: A wedge of high pressure will persist across the region while low pressure develops well offshore along a stationary front. Although precipitation coverage remains fairly sparse overnight, persistent and moist northeast surface winds could support a few showers locally while mid level vort energy associated with an upper level low meanders across the region. Instability remains rather low heading through the night, so any thunderstorms that try to develop should remain off the coast. The pressure gradient should tighten late between the wedge over land and low pressure offshore, favoring breezy conditions (20-25 mph wind gusts) closer to the coast for a few hours prior to daybreak. Despite the northeast wind, some clouds and winds should help keep overnight lows in the upper 60s inland to low-mid 70s closer to the coast. Short Term - 6am Sunday Morning Through Tuesday Sunday and Monday: A pronounced Rex blocking pattern will persist across eastern CONUS on Sunday with a cut off low associated with the remnants of Hurricane Francine over the Deep South and upper ridging across the Northeast. At the surface, cyclogenesis will be well underway along a stalled front located offshore of the Southeast U.S. coast. Forecast confidence for both days remains fairly low as much of the forecast will hinge on the size, track, intensity and character of the eventual cyclone offshore. There remains considerable spread on a number of elements in the various guidance, including whether the system will be baroclinic, tropical or subtropical as well as its track and timing. Phase evolution diagrams still suggest the low could begin transitioning from a baroclinic system into a subtropical or tropical entity by Sunday night/Monday morning as a warm-core tries to form as the low meanders near/over the warm Gulf Stream waters. Refer to the latest NHC Tropical Weather Outlook on the probability of this system becoming a tropical or subtropical cyclone. Locally, a strong wedge of surface high pressure will maintain its influence across the Carolinas and Georgia as the parent high holds over the Gulf of Maine/Georges Bank. Guidance is mixed on how much rain will develop/spread inland Sunday with the surface low positioned well offshore and the drier inland wedge forecast to strengthen with time. Although PWATs (Precipitable Waters) are just under 2", we continued to trend the forecast drier with POPs around 30-50% Sunday thinking most of the heavier rainfall will remain offshore with little in the way of forcing. Spotty light rains look most favorable over land with weak isentropic lift and overrunning of the wedge. As for Monday, we maintained a 20-40% chance. Thunder probabilities looks low with little in the way of instability, although a slight chance of thunder was retained for Sunday. Highs both days will warm into the upper 70s to lower 80s with overnight in the mid to upper 60s inland and lower 70s at the beaches. A tight pressure gradient will result in gusty conditions along the coast with gusts 25-30 mph possible Sunday. Additionally, gusts across Lake Moultrie could top out around 25-30 kt Sunday night, which would require a Lake Wind Advisory. Breezy conditions could persist into Monday as well with up to 20-25 mph mainly across the Charleston County coast. Tuesday: General model consensus positions the low to our north, however still much uncertainty in regards to its proximity to the forecast area. We capped POPs around 30% with deeper moisture still lingering to the north. Highs should reach the low to mid 80s as we anticipate the return of potentially bouts of partial sunshine, t least across the southern counties. Long Term - Tuesday Night Through Saturday General consensus is for a weakening area of low pressure to our north to track toward the Mid-Atlantic states Tuesday night into Wednesday before dissipating. Rain chances will trend lower for the middle of next week as drier air filters southeast in the wake of the departing surface low. Closer to the end of the week, we could see the return of a surface wedge pattern. Temperatures will start out in the mid 80s and trend slightly cooler each day next week. Marine Tonight: Marine conditions will slowly deteriorate through the night between strong high pressure over land and low pressure developing off the Southeast Coast. A strong pressure gradient between these two features along with strengthening 1000mb geostrophic winds late night will support northeast winds gusting to 25-30 kt at times, highest outside the Charleston Harbor. Additionally, seas will build to 5-8 ft, largest beyond 10 NM off the Charleston County Coast and across offshore Georgia waters. As a result, Small Craft Advisories will remain in effect across all waters through the night. Sunday through Monday night: Dangerous marine conditions will persist across the waters into Monday as the pressure gradient between a wedge of high pressure inland and developing low pressure offshore strengthens. Small Craft Advisories continue for all marine zones, including the Charleston Harbor. Northeast winds 20-25 kt with gusts to 30 kt will be common for much of the period with seas steadily building, peaking 6-10 ft across the nearshore waters (highest South Santee to Savannah out 20 NM) and 8-11 ft over the Georgia offshore waters out 20-60 NM. There is increasing probability for gale force winds across the nearshore Charleston County waters Sunday/Sunday night, which may need upgrading to a Gale Watch/Warning in the near future. The forecast still remains uncertain as much will hang on the track and nature of the offshore low pressure area as it approaches the Southeast U.S. coast. There is potential for tropical or subtropical development, but regardless mariners can expect hazardous conditions to persist through Monday. Tuesday through Thursday: We expect improving marine conditions with most, if not all, headlines pulled by Tuesday morning. The general consensus is for the low to be positioned to our north, however still much uncertainty in regards to its proximity to the local waters. Regardless, winds and seas should continue to gradually decrease with no additional marine concerns through the period. Rip Currents The risk for dangerous rip currents will linger into Sunday as gusty onshore winds combine with 3-6 ft breakers in the surf zone and 10-11 second period swells. A high risk for rip currents is highlighted for all beaches Sunday. An elevated risk for rip currents will persist into early next week with gusty northerly winds and favorable swell activity. High Surf: Breaking waves are expected to peak around 4-6 ft Sunday through Sunday night along the southeast South Carolina beaches. A High Surf Advisory has been issued. Georgia beaches should see breakers shy of 5 feet, peaking around 3-4 ft, which does not meet the criteria for a High Surf Advisory. Due to a combination of elevated water levels and powerful breaking waves, significant beach erosion is likely, especially along east and northeast facing beaches. Tides / Coastal Flooding Charleston and Coastal Colleton Counties: Persistent and strong onshore winds will lead to elevated tidal departures into Monday during the early evening high tide cycle. The potential for coastal flooding will remain next week with the approach of the full moon and perigee. Both high tide cycles could be of concern next week. The tide of most concern is the Sunday evening high tide where levels could reach the moderate flood threshold (7.5 ft MLLW). While some guidance certainly points to levels reaching the major flood category (8.0 ft MLLW), there is too much uncertainty on how the low pressure offshore will evolve to support forecasting a major flood at this time. A series of Coastal Flood Advisories will likely be needed over the coming days. If the risk for major flooding increases, then a Coastal Flood Watch/Warning could be needed. Beaufort County, SC, south to McIntosh County, GA: Tides should largely remain below minor flood thresholds for the next several days. However, there is a low-end risk that water levels could reach minor flooding at Fort Pulaski with the Sunday and Monday evening high tides. Coastal Flood Advisories could be needed. NOAA Charleston SC Office: Watches - Warnings - Advisories GA...High Risk for Rip Currents through Sunday evening for GAZ117-119- 139-141. SC...High Risk for Rip Currents through Sunday evening for SCZ048>051. High Surf Advisory from 8am Sunday to 8am EDT Monday for SCZ048>051. Marine Small Craft Advisory until 1am EDT Monday for AMZ330. Small Craft Advisory until 2am EDT Tuesday for AMZ350-352-354. Small Craft Advisory until 8am EDT Tuesday for AMZ374. |
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