Marine Weather and Tide Forecast for Goose Creek, SC

KEY MESSAGES
- 1) Scattered showers and thunderstorms could impact portions of southeast South Carolina and southeast Georgia today. The best chance for locally heavy rainfall will be along the coast.

- 2) Coastal flooding is expected at least through the middle of the week, especially along portions of the southeast South Carolina coast.

DISCUSSION
KEY MESSAGE 1: Scattered showers and thunderstorms could impact portions of southeast South Carolina and southeast Georgia today. The best chance for locally heavy rainfall will be along the coast.

With high pressure to the north and weak low pressure near the northeast FL coast, northeast will will prevail across the area today. By mid to late morning we should start to see either showers and storms develop over the coastal waters or along the coast. These showers and storms should be scattered in coverage and move to the southwest and west-southwest within the aforementioned flow pattern. By the afternoon, we should start to see some lower precipitable water values push in from the northeast (~1.5 inches) while areas down across the lower SC coast and southeast GA sit within a more moist environment (~2 inches). There will be some potential for locally heavy rainfall, primarily along the coast from around Beaufort County south to the Altamaha. The overall flood risk is relatively low but it is possible a few locations could pick up 1-2 inches of rain. If this locally heavy rain were to occur around the time of the late afternoon high tide (~5:45 pm) the flood risk could be slightly enhanced along the coast.

KEY MESSAGE 2: Coastal flooding is expected at least through the middle of the week, especially along portions of the southeast South Carolina coast.

Astronomical tide levels will continue to rise through the middle of the week thanks to the recent lunar perigee (9/6) and the upcoming new moon (9/11). These factors will push astronomical tides as high as 6.55 ft MLLW at Charleston Wednesday evening, setting the stage for coastal flooding potential with each evening high tide cycle. Northeast flow will strengthen along the coast today and persist into Tuesday night which is expected to drive increasing tidal departures. The first round of coastal flooding is expected to occur with the upcoming late afternoon high tide at Charleston (~5:45 pm) and we are currently forecasting a peak tide value of 7.3 ft MLLW.
The potential for moderate coastal flooding (7.5ft MLLW or higher) will increase with the Tuesday and Wednesday evening high tides as tidal departures likely build within the persistent northeast flow. Coastal Flood Advisories will almost certainly be needed for Charleston and coastal Colleton counties with each late afternoon and early evening high tide cycle through at least Wednesday.

For the rest of the coast from Beaufort County south including the southeast GA coast, tidal departures would need to exceed 1 ft to reach the minor coastal flood threshold (9.5 ft MLLW) at Fort Pulaski. Therefore, coastal flooding is less likely along this part of the coast but can't be ruled out especially with the late afternoon and early evening high tide cycle on Tuesday and Wednesday.

AVIATION /12Z MONDAY THROUGH FRIDAY/
The 12z TAF period begins with mostly IFR conditions around the area. KCHS and KSAV are currently IFR while KJZI has been a bit more variable over the last few hours. IFR stratus should lift to MVFR by around mid to late morning, transitioning to MVFR for a bit before VFR. Also, northeast winds are expected to become breezy with gusts up to around 20 knots starting around mid morning. Regarding shower and thunderstorm potential, we expect to see activity either spread inland from the coastal waters or develop along the coast and then track to the west-southwest.
Current thinking is that most of the activity should just scoot by KCHS and KJZI to the south, meaning that KSAV likely has the best chance of seeing a shower or thunderstorm. We have maintained the PROB30 at KSAV in the 18-21z time period.

Extended Aviation Outlook: Scattered thunderstorms could impact the terminals again on Tuesday. Northeast winds will be breezy on Tuesday as well.

MARINE
Today and tonight: Northeast flow will continue to surge across the local waters this morning with the strongest flow across the SC nearshore waters. A solid 15-20 knots is expected across all waters, with frequent gusts to around 25 knots in the SC nearshore waters and for a shorter period of time in Charleston Harbor. Seas will build in response, becoming 3-5 ft across the SC waters and 3-4 ft for the GA waters. Small Craft Advisories are in effect for the SC nearshore waters and Charleston Harbor.
Overnight, winds should diminish just a bit in the early morning hours which will allow for the ongoing Small Craft Advisories to likely come down. But we still expect to see persistent 15-20 knots of flow.

Tuesday through Friday: Northeast flow across the local waters is expected to surge a bit on Tuesday with gusts to 25 knots becoming more frequent across all the nearshore waters and possibly even Charleston Harbor. The ongoing Small Craft Advisories will either need to be extended in time or new advisories will be needed for much of the waters through Tuesday evening. The gradient will begin to weaken and diminish Tuesday night through Wednesday. For Thursday and Friday we expect to see a return to southwest flow.

Rip Currents: Persistent and gusty northeast winds and building seas will support a Moderate Risk of rip currents at all beaches along the southeast SC and southeast GA coast today.
Then for Tuesday, increased swell energy and continues gusty northeast winds will result in at least a Moderate Risk of rip currents again. There is even some support for a High Risk.

CHS WATCHES/WARNINGS/ADVISORIES
GA...None.
SC...Coastal Flood Advisory from 4 PM this afternoon to 8 PM EDT this evening for SCZ149-150.
MARINE...Small Craft Advisory from 11 AM this morning to 7 PM EDT this evening for AMZ340.
Small Craft Advisory from 11 AM this morning to 2 AM EDT Tuesday for AMZ360-362.