Marine Weather Net

Savannah, GA to Altamaha Sound, GA including Grays Reef National Marine Sanctuary Marine Forecast


20 - 25


5 - 10


5 - 10



The Marine Weather Forecast In Detail:
AMZ354 Forecast Issued: 612 AM EDT Wed Mar 29 2023

Today...N Winds 20 To 25 Kt With Gusts To 30 Kt, Becoming Ne 10 To 15 Kt By Late Morning. Seas 3 To 4 Ft.
Tonight...E Winds 5 To 10 Kt. Seas 2 To 3 Ft.
Thu...Ne Winds 5 To 10 Kt. Seas 2 To 3 Ft.
Thu Night...E Winds 10 Kt. Seas 2 To 3 Ft.
Fri...Se Winds 10 To 15 Kt. Seas 2 To 3 Ft.
Fri Night...S Winds 15 To 20 Kt With Gusts To 25 Kt. Seas 3 To 4 Ft, Building To 4 To 5 Ft After Midnight.
Sat...Sw Winds 15 To 20 Kt. Seas 4 To 5 Ft. Showers And Tstms Likely.
Sat Night...W Winds 10 To 15 Kt. Seas 3 To 4 Ft. A Slight Chance Of Showers And Tstms.
Sun...N Winds 10 To 15 Kt. Seas 2 To 3 Ft.
Sun Night...E Winds 5 To 10 Kt. Seas 2 Ft. Winds And Seas Higher In And Near Tstms.
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Area Forecast Discussion
National Weather Service Charleston SC
624am EDT Wednesday Mar 29 2023

A cold front will move south of the region early today, followed by High pressure through Friday. Another cold front will cross through the area Saturday, followed by high pressure into early next week.

Near Term - Through Tonight
Early Wednesday morning: Ongoing forecasts remain on track and required only minor adjustments. A strong cold front had pushed south of the forecast area, and much cooler/drier air had spread across our region. Until later this morning, north/northeast winds will gust 20-30 mph, Then, winds should gradually diminish as high pressure settles over the region. Meanwhile, persistent low- level moisture could support areas of low clouds this morning, especially over SC counties including the Charleston Tri-County region. Then, subsidence/drying should eliminate low clouds by late morning or early afternoon, leaving sunshine filtered by cirrus. Otherwise, expect a cooler day with highs ranging from the lower to middle 60s north to 65-70F south.

Tonight: High pressure overhead and mostly clear skies will promote excellent radiational cooling. By daybreak Thursday, temperatures should bottom out around 40F well inland; no frost is expected. Elsewhere, expect lows in the middle 40s across a wide swath of territory away from the immediate coast. On the beaches, northeast winds/a persistent marine influence will hold temperatures in the 50s.

Short Term - Thursday Through Friday Night
Thursday: A potent mid-level wave will be exiting New England east towards the Canadian Maritimes. On the back side of the exiting wave, a strong upper level jet streak will drive the wave east with strong ageostrophic convergence centering over the Ohio River Valley. This will make for a chilly start across the region Thursday morning with widespread temperatures in the lower 40s (and perhaps an upper 30 degree reading). During the day Thursday, bright sun and rising 850 MB temperatures (around 6 degrees C) will support highs in the low to mid 70s. Thursday night into Friday morning, surface high pressure will exit off the Mid-Atlantic coast with a weak inverted coastal trough setting up just off the GA/ SC coast. Lows Thursday night/ Friday morning will be about 10 degrees warmer than the previous night with temperatures around 50 degrees. Towards the GA/ SC beaches expect lows near the 60s.

Friday: Surface high pressure will be located over Bermuda with southerly flow establishing itself across the region. A warm front will sweep north with dewpoints rising into the lower 60s for all coastal zones. Low level thermal profiles will warm rather rapidly as 1000/850 mb thicknesses approach 1380 m in places across GA. Expect high temperatures in the lower to mid 80s with winds gusting to 25 MPH at times. No precipitation is expected. Friday night, clouds will continue to increase in coverage with winds continuing to gust 20 to 25 MPH. This will keep low temperatures rather warm or in the mid 60s for most of the area.

Long Term - Saturday Through Tuesday
A potent upper level low will be located near the central United States Saturday morning with the wave well underway to becoming barotropic/ vertically stacked. When this happens, the cold front south of the wave is usually slower to clear than initially forecast, and latest model guidance supports that this morning. Yesterday, global guidance had the cold front clearing the coast late Saturday afternoon and now it appears to be a early Sunday morning timing. This means that Saturday looks windy across the region with wind gusts of 30 to 35 MPH forecast (thanks to a potent warm conveyor belt/ LLJ of 40 to 50 kt) with the morning hours being dry. The delayed frontal passage will also result in high temperatures in the 80s.

Late Saturday afternoon into early evening a line of showers and thunderstorms will approach the region from the northwest. If any robust updrafts are able to get established, severe weather will be possible. For now this remains uncertain as mid-level moisture appears in question.

Sunday into Monday high pressure will dominate the region with mostly clear skies and no precipitation expected. On Tuesday, a warm front will lift north across the area ushering in much higher dewpoints and a return of a few showers and thunderstorms.

Wednesday, a robust mid-level anticyclone will bulge northeast ahead of the next approaching wave with mid-level heigheights nearing 586 dam. Global ensemble guidance is rather robust in its support of this, with the GEFS/ GEPS/ and EPS all showing mid-level heigheights +1 to +2 SD anomalies by the middle of next week.

Today And Tonight
Ongoing Small Craft Advisory event will wind down as winds diminish by late morning most areas, except later today across the outer GA waters. Seas as high as 6 feet will then persist across AMZ350 until mid to late afternoon and across AMZ374 until later this evening. Elevated but sub-SCA (Small Craft Advisory) NE winds and seas 3-5 feet will persist through the overnight hours.

Thursday and Friday: Surface high pressure will center across the Mid-Atlantic Thursday with seas diminishing 2 to 4 ft. By Friday, high pressure will translate offshore with seas and winds slowly starting to increase.

Saturday: Winds veering around from the southwest with SCA (Small Craft Advisory) gusts likely over all waters. Seas 5 to 7 ft.

Sunday: A cold front will cross the waters early Sunday morning with winds and seas relaxing below SCA (Small Craft Advisory) criteria around or just after sunrise.

NOAA Charleston SC Office: Watches - Warnings - Advisories
GA...None. SC...None.

Small Craft Advisory until 11am EDT this morning for AMZ330- 352-354. Small Craft Advisory until 3pm EDT this afternoon for AMZ350. Small Craft Advisory until 9pm EDT this evening for AMZ374.