Edisto Beach, SC to Savannah, GA Marine Forecast
|Today...N Winds 15 To 20 Kt With Gusts To 25 Kt, Diminishing To 10 To 15 Kt Late. Seas 3 To 4 Ft.|
|Tonight...N Winds 15 To 20 Kt With Gusts To 25 Kt. Seas 3 To 4 Ft.|
|Tue...N Winds 15 To 20 Kt With Gusts To 30 Kt. Seas 3 To 4 Ft.|
|Tue Night...N Winds 20 To 25 Kt With Gusts To 35 Kt. Seas 4 To 5 Ft, Building To 4 To 6 Ft After Midnight.|
|Wed...N Winds 20 To 25 Kt, Becoming Ne 15 To 20 Kt In The Afternoon. Seas 4 To 6 Ft.|
|Wed Night...Ne Winds 15 To 20 Kt With Gusts To 25 Kt. Seas 4 To 5 Ft.|
|Thu...Ne Winds 15 To 20 Kt. Seas 4 To 5 Ft.|
|Thu Night...Ne Winds 10 To 15 Kt. Seas 3 To 4 Ft. A Chance Of Showers.|
|Fri...E Winds 10 Kt. Seas 3 To 4 Ft. A Chance Of Showers.|
|Fri Night...S Winds 10 To 15 Kt. Seas 3 To 4 Ft. Showers Likely.|
Area Forecast Discussion|
National Weather Service Charleston SC
439am EST Monday Jan 20 2020
High pressure will build across the area through midweek, then weaken late week in advance of a low pressure system impacting the region this weekend. High pressure will then return late weekend and persist into early next week.
.NEAR TERM Through Tonight
Pre-dawn: Clear skies overnight with much colder air continuing to advect into the region. Temps overnight have been rather homogeneous as surface winds have remained elevated both inland and coast. Readings should continue to fall per low level thermal progs and advection profiles.
Lake Winds: Conditions have been close to advisory thresholds on Lake Moultrie overnight. We initialized our forecast with North Winds 15-20 kt and waves 1-2 ft.
Today: The mean upper trough across the eastern half of the country will continue to deepen as upper waves dig southeast from the midwest to the southeast states. While modified continental polar air arrives, surface high pressure will continue to build into our forecast area. Deep layered dry air will result in sunshine today, some increase in high clouds probable this afternoon as a strong upper jet slices through the region. 850 MB temps will continue to plummet with the zero degree isotherm going south of our entire forecast area by late afternoon. We have not altered high temps much with max temps in the mid 40s north to upper 40s south.
Tonight: Freezing conditions are likely to the beaches of SC with the GA barrier islands possibly reaching 32 degrees degrees right off the Atlantic. Winds will likely continue to stir overnight in most areas as gradient remain tight as a potent mid level low at 500 MB takes shape over the southeast U.S. Wind chills are expected to dip to the upper teens to lower 20s by daybreak on Tuesday.
Short Term - Tuesday Through Thursday
Tuesday: Dry and cold high pressure will prevail at the surface while a mid-level low rounds the southern base of a broad trough of low pressure across much of the East Conus. Strong cold air advection associated with the mid-level low in combination with northerly surface winds will limit overall temps under mostly sunny skies. In general, temps will struggle to reach the low/mid 40s during peak diurnal heating. Winds could also be breezy along the coast, peaking between 15-20 mph at times. Overnight, temps will be chilly under little clouds and within a persistent northerly surface wind. The pressure gradient will remain quite strong along the coast, suggesting winds in the 20-25 mph range during the night. These winds in combination with overnight lows in the mid/upper 20s inland to lower 30s near the coast should support wind chill values in the upper teens, but conditions are expected to remain above Wind Chill Advisory criteria for all areas. Another concern during the overnight period will be gusty winds across Lake Moultrie where warmer waters promote strong mixing in the low levels as cold air advection occurs aloft. A Lake Wind Advisory could be needed across Lake Moultrie Tuesday night into Wednesday.
Wednesday: Breezy northerly winds (15-20 mph) could persist along coastal areas through much of the morning as the pressure gradient remains enhanced between low pressure offshore and high pressure centered to the north. Conditions will be dry, but temps will struggle to warm significantly as high pressure remains wedged southward across the Carolinas into Georgia. In general, temps will peak in the lower 50s under mostly sunny skies. Overnight, temps will remain slightly warmer than the previous night due to clouds spreading across the area after midnight. In general, temps will dip into the lower 30s inland to mid/upper 30s closer to the coast.
Thursday: A wedge of high pressure should hold across the area through much of the day, but will begin to show signs of weakening as a coastal trough begins to develop along the Southeast Coast late. Surface winds will turn more northeast as the surface trough develops and temps will be warmer than the previous day under a ridge of high pressure extended across the region in the mid-lvls. In general, high temps should range in the mid/upper 50s, but a few locations could reach 60 degrees south of I-16 in Southeast Georgia.
Long Term - Thursday Night Through Sunday
A coastal trough should linger near the Southeast Coast Thursday night into Friday before lifting north and dissipating in advance of a low pressure system approaching from the west. A cold front associated with this system is anticipated to track across the area Friday night into early Saturday, producing scattered to numerous showers for most locations when moisture is deepest and forcing is strongest. Dry high pressure will then build across the area late weekend and become centered across the Southeast early next week.
In regards to temps, conditions will remain mild ahead of the cold front this weekend, with afternoon highs ranging in the mid/upper 60s Friday and lows ranging in the upper 40s to lower 50s Friday night. Temps will be a degree or two cooler on Saturday with frontal passage ongoing, then remain around 60 degrees for highs Sunday and Monday afternoons and in the upper 30s/lower 40s Sunday and Monday nights.
SCAs (Small Craft Advisories) ongoing all waters this morning as strong cold advection and drier air advecting over the area, resulting in steeper low level lapse rates and excellent mixing profiles. We have SCAs (Small Craft Advisories) for the Charleston Harbor and near shore GA/SC waters through 10 AM. Winds will remain gusty at times late day, however winds and seas should be below SCA (Small Craft Advisory) criteria into the early evening. Later tonight, the gradient will tighten once again and we will likely need to reintroduce SCAs (Small Craft Advisories) for all near shore waters, but probably not the CHS Harbor. We have extended the SCA (Small Craft Advisory) through tonight and beyond for 20-60 NM GA waters as warmer waters well offshore likely to result in stronger wind gusts and higher seas.
Tuesday through Saturday: A strong pressure gradient is expected to develop across the coastal waters heading into Tuesday between high pressure building from the north and low pressure deepening offshore. The enhanced gradient along with the strongest period of cold air advection associated with a mid-level low shifting offshore will likely support Small Craft Advisory conditions across offshore Georgia waters by Tuesday morning and most coastal waters starting Tuesday afternoon. Winds/seas should peak Tuesday evening into Wednesday when the pressure gradient is most enhanced within a chilly northerly wind. Latest guidance even supports gale force wind gusts for a portion of the coastal waters and a Gale Watch/Warning could eventually be needed (especially across northern South Carolina waters and offshore Georgia waters). In general, north- northeast wind speeds could gust upwards to 25-35 kts while seas build as high as 4-7 ft across nearshore waters and 8-11 ft across offshore waters Tuesday night and Wednesday.
Marine conditions should gradually improve on Thursday, but Small Craft Advisory level conditions should persist as north/northeast surface flow prevails across all coastal waters. Conditions should then continue to improve Thursday night into Friday as winds turn more onshore in association with a coastal trough along the Southeast Coast. By Friday night, southerly flow returns across all waters in advance of a low pressure system advancing toward the coast from the west. A cold front is expected to shift offshore Saturday, before high pressure builds across the waters late. Conditions will become elevated post frontal passage. but should remain below Small Craft Advisory levels across all waters.
Tides / Coastal Flooding
Cold high pressure will build across the area mid-week while low pressure deepens offshore. Strong north-northeast winds between these two features will help produce elevated tide levels a few days before the upcoming new moon (Jan 24). Tide levels could reach 7.0 FT MLLW along the Southeast South Carolina coast during the Wednesday morning high tide and a Coastal Flood Advisory could eventually be needed.
NOAA Charleston SC Office: Watches - Warnings - Advisories
Small Craft Advisory until 10am EST this morning for AMZ330- 350-352-354. Small Craft Advisory until 3am EST Saturday for AMZ374.