Marine Weather and Tide Forecast for Goose Creek, SC

KEY MESSAGES
- 1) Dry conditions and below normal temperatures will continue into early next week.

- 2) A significant multi-day coastal flooding event is expected this weekend through at least the middle of next week.

- 3) Strong northeast flow this weekend and into early next week will result in several coastal hazards including rip currents, high surf, and beach erosion.

DISCUSSION
KEY MESSAGE 1: Dry conditions and below normal temperatures will continue into early next week.

Rest of Today and Tonight: Strong high pressure centered to the north of the Great Lakes will dominate through the remainder of today and through tonight. A strong mid-level shortwave trough was analyzed on this morning's 12Z 500mb analysis from the SPC. This feature will help keep temperatures slightly cooler than yesterday, with highs generally in the low to mid 70s away from the beaches.
The pressure gradient will begin to quickly tighten tonight as low pressure begins to organize east of the Southern Bahamas and the strong high pressure wedges south across the Carolinas and Georgia.
An uptick in winds is expected tonight, with breezy conditions developing at the beaches and around the Santee-Cooper lakes.
Despite clear skies, the elevated winds will yield a warmer night in comparison to previous nights this week with lows ranging from the upper 40/lower 50s inland to around 60 at the beaches. Some mid 40s could occur, mainly in the Jenkins- Allendale corridor where winds will be the lightest.

Saturday through Thursday: Surface high pressure will extend across the region through late next week. Over the weekend, the high will strengthen inland while a coastal trough develops offshore.
The air mass will remain quite dry. The pattern will support a rain- free forecast through at least early next week. Despite plenty of sunshine, temperatures will lean on the cooler side of normal, owing to the persistent NE flow. Highs will top out in the lower to mid 70s for the weekend and early next week. Low temperatures will fall into the 40s across many interior locations.

KEY MESSAGE 2: A significant multi-day coastal flooding event is expected this weekend through at least the middle of next week.

Astronomical tides will continue to rise through the weekend and into next week due to the upcoming full moon (10/26) and the lunar perigee (10/28). Large tidal departures are already ongoing, and with an extended period of strong northeast flow this weekend and into next week, these departures will increase in magnitude. The combination of the highest astronomical tides of the year and persistent strong northeast flow will result in a multi-day moderate to major coastal flooding event for the entire southeast GA/SC coast.

Upcoming evening high tide (~6:45 pm): Minor coastal flooding will likely occur at Charleston with the evening high tide cycle. The astronomical high tide is 5.79 ft MLLW and we are currently running a 1.2-1.3 ft departure as we head into the preceding low tide. We currently expect high tide to peak in the 7.0-7.2 ft MLLW range, and a Coastal Flood Advisory is in effect for Charleston and coastal Colleton counties. There are no coastal flooding concerns at Fort Pulaski.

Over the weekend and into the middle of next week, there is increasing potential for multiple rounds of moderate to major coastal flooding at Charleston and minor to moderate coastal flooding at Fort Pulaski. The highest water levels are expected to occur with the Monday, Tuesday, and Wednesday morning high tide cycles. During these cycles, confidence is increasing that Charleston will exceed major flood stage (8.0 ft MLLW) and Fort Pulaski will exceed moderate flood stage (10.0 ft MLLW). There is even concern that Fort Pulaski could reach or exceed its major flood stage (10.5 ft MLLW), which has never happened in its history (records begin in 1935) outside of a tropical system. Coastal flooding will likely occur with both the morning and evening high cycles for several days, though the evening tide will be the lower of the two. Coastal Flood Advisories will definitely be needed, and Coastal Flood Watches/Warnings are very likely for some or all of the coast from Sunday through Wednesday.

KEY MESSAGE 3: Strong northeast flow this weekend and into early next week will result in several coastal hazards including rip currents, high surf, and beach erosion.

Rip Currents: Strong northeast winds and increased wave action will support a period of enhanced rip current risk this weekend. A Moderate Risk for rip currents remains along all beaches this afternoon, followed by a High Risk for all beaches Saturday, and likely again for all beaches on Sunday. An enhanced period of rip currents will likely continue into early next week.

High Surf: Breaking wave heights of 5 ft or higher will be possible this weekend into early next week and High Surf Advisories should be needed. The greatest risk for high surf should occur along the GA coast, where persistent/gusty northeast winds are more directly onshore Saturday afternoon into Monday. The combination of elevated tides, increased wave action, and the persistent/gusty northeast winds will likely produce beach erosion as well, with the most significant impacts occurring around high tide cycles this weekend.

Lake Wind: Gusty northeast winds will pick up across Lake Moultrie and persist through the weekend. There is a chance that winds could gust up to 25 knots early Saturday morning through around 8 AM Saturday, supported by the HRRR. However, given the short duration and low confidence have opted to not issue a Lake Wind Advisory with this afternoon's forecast package. Winds over the lake through most of the day on Saturday will generally be gusting around 15-20 mph.
After sunset Saturday, the pattern flips and winds will rapidly pick up as cold air advection occurs over the warmer lake waters. This will trigger strong mixing, dragging 30 kt wind gusts down to the lake surface. A Lake Wind Advisory will likely be needed starting Saturday night. The combination of steady northeast winds and 2-3 ft waves could yield lakeshore erosion along the southwest side of the lake along with some overwash. This is includes areas from roughly Pinopolis to Blacks Camp near Cross.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
VFR through the 18Z TAF period. Gusty NE winds will develop at KCHS/KJZI/KSAV on Saturday, gusting upwards of 25 knots.

Extended Aviation Outlook: Breezy northerly winds anticipated at CHS/JZI/SAV terminals through Monday morning. Gusts could reach 25- 30 kt, especially during the afternoon hours Saturday and Sunday.
Otherwise, VFR conditions are expected at all terminals through Tuesday.

MARINE
Today through Tuesday: High pressure will continue to strengthen across the Northeast and Mid-Atlantic states while low pressure develops east/north of the Bahamas this weekend.
The setup favors a strong pressure gradient across local waters with marine conditions rapidly deteriorating tonight. Winds/seas will substantially increase during the weekend, likely reaching Small Craft Advisory levels for a period this evening, before gales are prevalent. Gale Watches have been upgraded to Gale Warnings for offshore waters starting tonight, and will likely need to be upgraded for nearshore waters starting around daybreak Saturday. The risk for gale force winds will remain across nearshore and offshore waters through Monday (longest across offshore waters). Additionally, a Small Craft Advisory is in effect for the Charleston Harbor, starting overnight tonight and persisting into Monday. Winds and seas start to trend lower late Monday into Tuesday, but Small Craft Advisory level conditions could persist across local waters outside the Charleston Harbor through the middle of next week.

CHS WATCHES/WARNINGS/ADVISORIES
GA...None.
SC...Coastal Flood Advisory until 9 PM EDT this evening for SCZ149- 150.
MARINE...Small Craft Advisory from 2 AM Saturday to 6 AM EDT Monday for AMZ340.
Small Craft Advisory from 6 PM this evening to 6 AM EDT Saturday for AMZ360-362-364.
Gale Watch from Saturday morning through late Sunday night for AMZ360-362-364.
Gale Warning from 6 PM this evening to 8 PM EDT Monday for AMZ380-382.
Gale Warning from 6 PM this evening to 6 AM EDT Tuesday for AMZ384.