textproduct: Charleston

WHAT HAS CHANGED

Updated Key Message 2 and Aviation Section.

KEY MESSAGES

- 1) Cool weather will linger into the weekend. Near to slightly above normal temperatures return next week.

- 2) The coastal flood risk ramps up due to persistent northeast winds and high astronomical tides.

- 3) A High Risk of rip currents continues through this evening, followed by a Moderate Risk Friday. The rip current risk could remain elevated through the weekend.

DISCUSSION

KEY MESSAGE 1: Cool weather will linger into the weekend. Near to slightly above normal temperatures return next week.

Fall is here, well false fall but it will feel crisp over the next couple of days as drier continental air moves in from the north. With deep upper troughing and associated surface low off the east coast, dry northwesterly flow has overspread the area. Dewpoints have already dropped into the 50s all the way to the coast and even drier air is expected to move in. While high temperatures will still range in the 70s given ample solar insolation; low temperatures will be certainly cooler with lows dipping into the low to mid 50s across most of the area tonight and again on Sunday night. A few isolated interior locations may even sneak out a low in the 40s. Nonetheless, temperatures will be noticeably refreshing compared to the last few months.

Temperatures will begin to gradually rebound throughout the early part of next week as high pressure overspreads the area and moves east by the mid to late parts of the week. Highs will climb back into the mid to upper 80s with lows in the upper 60s to low 70s along the coast by the weekend.

KEY MESSAGE 2: The coastal flood risk ramps up due to persistent northeast winds and high astronomical tides.

A nor'easter located offshore of the Mid-Atlantic will result in continued breezy northeasterly winds across the region. The combination of these winds with the upcoming full moon (9/26) will yield increased chances of minor to moderate coastal flooding with each high tide cycle through the weekend (esp. for the Charleston Harbor).

In regard to today, expect minor flooding to occur in Charleston and Colleton County with the morning (~7AM) and evening (~8PM) high tide. Thus, plan to issue a Coastal Flood Advisory with this forecast package. Will continue to monitor trends closely this morning, as higher tidal departures could result in moderate flooding instead. Otherwise, could see another round of coastal flooding occur around Saturday morning's high tide.

Fort Pulaski: Latest guidance suggest tidal levels should remain just shy of minor flooding (9.2 to 9.4 ft MLLW) during the morning and evening high tide today. Thus, will hold off on issuing a Coastal Flood Advisory for lower South Carolina and southeast Georgia. However, as noted above, will continue to monitor trends in the event that tidal departures rise higher than expected.

KEY MESSAGE 3: A High Risk of rip currents continues through this evening, followed by a Moderate Risk Friday. The rip current risk could remain elevated through the weekend.

A strengthening area of low pressure offshore will continue to drive strong gusty winds along the coast and the coastal waters today. With long period swells near 10 to 12 seconds, believe this setup will continue to support a Moderate Risk of rip currents at all beaches through this afternoon. An elevated risk could persist into Saturday thanks to lingering swell, with the overall risk expected to become low by Sunday as the aforementioned low drifts further north and loses its influence across the region.

AVIATION /06Z FRIDAY THROUGH TUESDAY/

06Z TAFs: Skies have begun to clear across the area as MVFR ceilings will quickly become VFR. Drier air will move in with winds persisting out of the north around 10 knots gusting to 20 knots throughout the afternoon. VFR conditions should prevail through overnight tomorrow as winds gradually diminish.

Extended Aviation Outlook: VFR conditions are expected to prevail, with lingering northerly gusts possible through the afternoon.

MARINE

Friday through Saturday: Marine conditions are expected to gradually improve on Friday as the offshore low lift northward closer to the New England coast and and the pressure gradient starts to relax across the local waters. The Gale Warning for the outer GA waters will be replaced with a Small Craft Advisory, and the ongoing Small Craft Advisory for the nearshore waters will continue through this evening. By Saturday winds and seas will diminish further and the only remaining headline will likely be the Small Craft Advisory for the outer GA waters into Saturday afternoon.

Sunday through Tuesday: Quiet conditions will return and winds and seas will be well below Small Craft Advisory thresholds.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...Coastal Flood Advisory until 9 AM EDT this morning for SCZ149- 150. MARINE...Small Craft Advisory until 2 AM EDT Saturday for AMZ360-362- 364. Gale Warning until 6 AM EDT early this morning for AMZ380-382- 384. Small Craft Advisory from 6 AM this morning to 2 PM EDT Saturday for AMZ384.