textproduct: Charleston

WHAT HAS CHANGED

All sections have been updated.

KEY MESSAGES

- 1) The risk for coastal flooding and significant coastal hazards continues.

- 2) Seasonable temperatures and generally dry conditions are expected through Thursday.

- 3) The National Hurricane Center (NHC) has identified a tropical depression (TD9) in the southwestern Gulf. Regardless of development, heavy rainfall could develop over the Southeast United States by this weekend.

DISCUSSION

KEY MESSAGE 1: The risk for coastal flooding and significant coastal hazards continues.

Coastal Flooding: Strong northeast winds, high astronomical tides and departures currently running ~1.2 ft support minor coastal flooding (~7.2 ft MLLW) along Charleston and Coastal Colleton Counties with the upcoming high tide at 5:59 AM. A Coastal Flood Advisory has been issued for Charleston and Coastal Colleton Counties between 4 AM to 8 AM.

Strong/persistent northeast winds associated with a wedge of high pressure inland and low pressure offshore in combination with high astronomical tide levels will likely support additional coastal flooding issues during high tide cycles through Thursday, and possibly into Friday. The tide of most concern will occur during the late afternoon/early evening hours later today where minor to potentially low-end moderate flooding is possible. Otherwise, minor coastal flooding is possible with remaining high tides.

Rip Currents/High Surf/Beach Erosion: The setup remains highly favorable rip currents today with breezy/windy northeast winds expected. A High Risk is highlighted for the Georgia beaches with a Moderate Risk for the South Carolina beaches today. In addition, seas will remain elevated across nearshore waters, with 4-6 ft breakers occurring in the surf zone (largest along coastal Georgia) this morning into early afternoon. A High Surf Advisory remains in effect through early this afternoon along the entire coast. Beach erosion is possible during the high tide cycle this morning.

KEY MESSAGE 2: Seasonable temperatures and generally dry conditions are expected through Thursday.

As we remain between a surface high pressure to our north and a stationary front to our south, winds may become breezy later this morning and into the afternoon. Breeziest winds are expected along the coastline (near 30 mph in SE GA, to near 25 mph in SE SC) while areas inland may see gusts to 20 mph. Otherwise, despite partly to mostly cloudy skies, temperatures continue to moderate today into the upper 70s to lower 80s. Dry conditions are expected, though an isolated shower can't be ruled out near Darien, GA. Weak ridging builds on Thursday with dry northeasterly surface flow keeping the region dry, resulting in an overall rather pleasant mid-October day with highs in the upper 70s to lower 80s and light winds.

KEY MESSAGE 3: The National Hurricane Center (NHC) has identified a tropical depression (TD9) in the southwestern Gulf. Regardless of development, heavy rainfall could develop over the Southeast United States by this weekend.

A tropical depression highlighted by NHC across the southwestern Gulf (TD9) is forecast to slowly shift east/east-northeast, becoming more organized and strengthening while passing north of the Yucatan Peninsula during the next day or two, and then while turning north and tracking across the central/northern Gulf Friday. Regardless of development, deep tropical moisture (PWATs exceeding 2 inches) will likely be drawn northward across the Southeast United States as this system approaches the northern Gulf Coast early weekend, setting up the risk for heavy rainfall locally within a widespread isentropic lift scenario between a wedge of high pressure across the Carolinas and Georgia and a weak front/coastal trough nearby starting early weekend. Widespread showers and embedded thunderstorms are possible late Friday through Sunday as the setup remains quite favorable for deep moisture transport feeding across the region between a mid-lvl pattern featuring a broad closed low over the Southern Plains and a ridge centered across the western Atlantic. This could pose an elevated risk for minor/flash flooding locally as PWATs approach 2.5 inches and rounds of precip activity occur across already wet grounds. In addition, New Moon high tides with elevated astronomical tides will occur this weekend. Any elevated rainfall rates during high tides may lead to flooding of coastal areas, including Savannah and Charleston.

AVIATION /07Z WEDNESDAY THROUGH SUNDAY/

VFR conditions are expected at CHS/JZI/SAV terminals through 06Z Thursday. Northeast winds could gust to around 15 kts mid morning into late afternoon, before weakening considerably this evening.

Extended Aviation Outlook: VFR through Thursday. The risk for flight restrictions returns over the weekend with widespread showers and/or thunderstorms.

MARINE

Today: The pinched pressure gradient will continue the breezy conditions this morning, with gusts of 25 to 30 knots across all near and offshore zones not including the Charleston Harbor keeping Small Craft Advisories in effect. Buoys continue to report wave heights of 5 to 7 ft across nearshore zones and up into the 6 to 8 ft range in the offshore zones, with waves starting to ease as winds decrease throughout the afternoon hours. While winds dip below Small Craft Advisory levels (25 knot gusts) throughout the afternoon and evening hours, gusts will remain in the 10 to 20 knot range throughout the overnight hours, strongest across the SE GA waters. Wave heights will similarly decrease, with Small Craft Advisories expiring from north to south.

Thursday: The last remaining 6 foot waves move out of the marine zone from Savannah to Altamaha Sound, GA 20-60nm offshore near daybreak, allowing for the Small Craft Advisory to expire. While the surface high pressure continue to weaken, the pressure gradient remains elevated with the stalled front to our south, continuing wind gusts generally in the 15 to 20 knot range.

Friday through Sunday: See NHC forecast for the latest on Tropical Depression 9. The pressure gradient will increase between a coastal trough and high pressure inland. Winds should strengthen through the period, with small craft advisories possibly needed by Friday afternoon as 25+ knot gusts move in, with gale wind gusts possible by Saturday. Strengthening winds should drive sea higher, with 6-9 ft wave heights possible on Saturday. Elevated conditions will likely persist through the rest of the weekend.

EQUIPMENT

The Metter, GA, NOAA Weather Radio Station (WWH-25) will be offline from mid-morning Wednesday, October 7, through the afternoon of Thursday, October 8. The transmitter is being relocated.

CHS WATCHES/WARNINGS/ADVISORIES

GA...High Risk for Rip Currents through this evening for GAZ217-219-239- 241. High Surf Advisory until 2 PM EDT this afternoon for GAZ217- 219-239-241. SC...High Surf Advisory until 2 PM EDT this afternoon for SCZ148>151. Coastal Flood Advisory until 8 AM EDT this morning for SCZ149- 150. MARINE...Small Craft Advisory until 5 PM EDT this afternoon for AMZ360. Small Craft Advisory until 8 PM EDT this evening for AMZ362. Small Craft Advisory until 2 AM EDT Thursday for AMZ364. Small Craft Advisory until 8 AM EDT Thursday for AMZ384.