Marine Weather Net

South Santee River to Edisto Beach, SC Marine Forecast


TONIGHT

SW
WINDS
15 - 20
KNOTS

WED

NW
WINDS
10
KNOTS

WED NIGHT

NE
WINDS
10 - 15
KNOTS

THU

NE
WINDS
15
KNOTS

The Marine Weather Forecast In Detail:
AMZ350 Forecast Issued: 611 PM EDT Tue Jun 22 2021

SMALL CRAFT ADVISORY IN EFFECT UNTIL 1 AM EDT WEDNESDAY
Tonight...Sw Winds 15 To 20 Kt With Gusts To 25 Kt, Becoming W 10 To 15 Kt With Gusts To 20 Kt After Midnight. Seas 4 To 6 Ft, Subsiding To 3 To 5 Ft. A Chance Of Showers.
Wed...Nw Winds 10 Kt, Becoming Ne In The Afternoon. Seas 3 To 4 Ft, Subsiding To 2 To 3 Ft In The Afternoon. A Chance Of Showers And Tstms.
Wed Night...Ne Winds 10 To 15 Kt With Gusts To 20 Kt. Seas 2 To 3 Ft, Building To 3 To 4 Ft After Midnight. A Chance Of Showers And Tstms.
Thu...Ne Winds 15 Kt With Gusts To 20 Kt. Seas 3 To 4 Ft. A Chance Of Showers And Tstms.
Thu Night...E Winds 10 To 15 Kt. Seas 3 To 4 Ft. A Chance Of Showers And Tstms.
Fri...Se Winds 10 Kt. Seas 3 Ft. A Chance Of Showers And Tstms.
Fri Night...Se Winds 10 Kt. Seas 3 Ft. A Chance Of Showers And Tstms.
Sat...Se Winds 10 Kt. Seas 3 To 4 Ft. A Chance Of Showers And Tstms.
Sat Night...Se Winds 10 Kt. Seas 3 To 4 Ft. A Slight Chance Of Showers And Tstms.
Sun...Se Winds 5 To 10 Kt. Seas 3 To 4 Ft. A Chance Of Showers And Tstms.
Sun Night...Se Winds 10 Kt. Seas 3 To 4 Ft. A Slight Chance Of Showers And Tstms. Mariners Are Reminded That Winds And Seas Higher In And Near Tstms.
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Area Forecast Discussion
National Weather Service Charleston SC
721pm EDT Tuesday Jun 22 2021

Synopsis
A cold front will move through the area tonight, then stall just off the Georgia coast Wednesday. A coastal trough will persist through early next week.

Near Term - Until 6am Wednesday Morning
Only minor adjustments were needed for the early evening update. probability of precipitation were lowered about 10% area wide as residual shower activity is slowly winding down. Also expanded the mention of patchy fog to include most of southern South Carolina and into the Savannah Metro area per latest condensation pressure deficits progs. The rest of the forecast is on track.

A cold front associated with a broad and deep layered trough that covers much of the eastern half of the country currently extends over central Georgia and South Carolina. The front will pass through the area tonight, before coming to a crawill and stalling just off the GA coast by morning. As the front becomes closer in proximity from the west this evening, areas that have cleared (mainly over the SC Piedmont region) could have destabilized enough to support another round of scattered showers and possibly enough convection to produce a few rumbles of thunder. Also, the co-location of the right entrance region of the Polar Jet will provide weak forcing for ascent in this area. There is a slight decrease in PWATs (Precipitable Waters) tonight, and with further stabilizing influences within the nocturnal environment, we anticipate less activity after dark. Therefore, most of the activity should remain inland and diminish as the front gradually moves east. Chance Probability of Precipitation cover the forecast area this evening will decrease to slight chance overnight.

The saturated atmosphere and winds diminishing to near calm inland, plus low condensation pressure deficits will lead to the formation of stratus build down. Latest projections are that it will not be low enough to produce any significant reduction in visibilities, but we have included patchy fog over the inland GA counties starting after midnight and diminishing around sunrise. Lows tonight will get down close to dew points, which will be in the upper 60s and lower 70s.

Short Term - 6am Wednesday Morning Through Friday
Wednesday: A cold front will stall south of the forecast area Wednesday. However most recent guidance suggests that it's location will be too far to the south to provide the necessary lift/moisture for the development of showers/thunderstorms. Have lowered POPs considerably as a result. Any shower/thunderstorm activity will be limited to the afternoon hours, as the sea breeze may provide just enough forcing to trigger precipitation. With minimal precipitation coverage high temperatures should be able to reach up into the low to mid 80s across the region. Low temperatures are expected to be in the upper 60s inland with low 70s along the coastal counties.

Thursday: The cold front positioned to the south should transition into a coastal trough by Thursday morning, providing slightly more forcing and moisture than Wednesday. Convective parameters are nothing of note, so there is a low risk of severe weather. High temperatures are again expected to reach into the low to mid 80s with overnight lows in the upper 60s inland and low 70s along the coastal counties.

Friday: Atmospheric moisture begins to increase Friday as the coastal trough moves inland accompanied by a weak upper low. Moisture transport increases as PWATs (Precipitable Waters) increase to close to 2 inches across the forecast area. Precipitation coverage looks fairly decent, especially with the sea breeze possibly triggering more convection in the afternoon hours.

Long Term - Friday Night Through Tuesday
High pressure will build into the southeastern states over the weekend, resulting in a typical summer pattern. Maximum temperatures will gradually increase through the period, with each day featuring a risk of afternoon convection.

Marine
Tonight: A pressure gradient remains between the sub-tropical Atlantic ridge and an upstream cold front located over central Georgia. The Small Craft Advisory for the Charleston Harbor and the outer GA waters beyond 20 nm have been cancelled. Gusty winds have lessened to below advisory criteria. The advisories for the SC nearshore waters will remain in effect through late evening until the gradient slackens with the approach of the cold front and as 6 foot seas move out of those zones.

Wednesday through Sunday: With the cold front positioned to the south of the marine zones west winds Wednesday morning should transition to northeast by Wednesday afternoon. As the coastal trough moves onshore Friday they should veer to the east/southeast and persist through Sunday. Winds 10 to 15 knots through the period, with seas averaging 2 to 4 feet.

Tides / Coastal Flooding
A northeast wind will develop on Wednesday and continue through Thursday evening before shifting to the southeast. Tidal anomalies should gradually increase during this period. Given the approaching full moon and the associated increase in astronomical tide levels, when adding another 0.5-0.8 ft departure, we expect to reach minor coastal flooding in Charleston Harbor with the evening high tides Wednesday through Friday.

NOAA Charleston SC Office: Watches - Warnings - Advisories
GA...None. SC...None.
MARINE...
Small Craft Advisory until 10pm EDT this evening for AMZ352. Small Craft Advisory until 1am EDT Wednesday for AMZ350.