textproduct: Charleston

WHAT HAS CHANGED

Added a new Key Message to address the dense fog this morning.

KEY MESSAGES

- 1) Dense fog will impact southeast GA this morning, with patchy dense fog possible elsewhere.

- 2) The coastal flood risk will linger through the end of this week. Another round of coastal flooding is possible next week. - 3) Above normal temperatures with minimal rain chances expected today and Thursday.

- 4) Unsettled weather will return late week into the weekend with fall-like conditions early next week.

DISCUSSION

KEY MESSAGE 1: Dense fog will impact southeast GA this morning, with patchy dense fog possible elsewhere.

Given the clear skies and light to calm winds early this morning fog has developed across the forecast area. Across southeastern GA the fog has become dense in many locations, with obs showing visibilities ~1/4 mi. A Dense Fog Advisory is in effect for southeastern GA through 9 AM this morning. Patchy dense fog is possible across the SC Lowcountry, however as of this juncture it is not widespread enough to warrant a Dense Fog Advisory.

KEY MESSAGE 2: The coastal flood risk will linger through the end of this week. Another round of coastal flooding is possible next week.

Astronomical tides continue to run higher than normal due to the recent full moon. Combined with the build up of tidal waters across inland waterways, and a possible slowing of the gulf stream, coastal flooding will pose a risk through the end of the week, especially at the Charleston Harbor. Tide levels at the Charleston Harbor are forecast to reach 7.1-7.3 ft MLLW with this morning's ~11AM high tide. Minor coastal flooding is forecast again with the late morning/early afternoon high tides on Thursday and Friday. Coastal flooding is not a concern at Fort Pulaski.

A cold front is forecast to push through the region next week, with high pressure building in behind it. The resulting northeasterly flow will likely trigger another round of coastal flooding, especially at the Charleston Harbor.

KEY MESSAGE 3: Above normal temperatures with minimal rain chances expected today and Thursday.

Ridging aloft will prevail over the southeastern states, yielding a generally rain-free forecast. However the 00Z REFS as well as the HREF and HRRR are showing some isolated showers this afternoon in southeastern GA where PoPs are ~15-20%. Highs will be roughly 5 degrees above normal for late September/early October, with pars out southeastern GA reaching into the low 90s. Lows will gradually warm each night, hovering in the mid to upper 60s inland and low to mid 70s near the beaches.

KEY MESSAGE 4: Unsettled weather will return late week into the weekend with fall-like conditions early next week.

More notable rain chances will return to the forecast late week into the weekend. The upper ridge will still hold some influence on Friday, but increasing moisture will bring the potential for isolated to perhaps scattered showers and thunderstorms. Over the weekend, heights aloft will lower as a larger scale trough shifts into the eastern U.S. At the surface, a cold front will approach and eventually get pushed offshore, though there are inconsistencies with regards to timing. It appears the most active period will be Sunday into Monday as the aforementioned features interact with deep moisture in place across the region (noted by PWats peaking over 2 inches/~95th percentile of climo). Still difficult to pinpoint rainfall amounts but there is potential for an inch or two with this system.

High pressure will build south across the Carolinas into Georgia following fropa early next week, likely resulting in a significant cool down and gusty winds. Rain chances will linger in the forecast.

AVIATION /09Z WEDNESDAY THROUGH SUNDAY/

VFR conditions are expected to prevail at KCHS, KJZI, and KSAV through 06z Thursday. The only real forecast issue is the potential for some shallow ground fog around sunrise. MIFG is featured at all three TAF sites through 13Z this morning.

Extended Aviation Outlook: Flight restrictions in showers and thunderstorms are possible over the weekend into early next week.

MARINE

Quiet marine conditions will prevail across the local waters through the rest of the week and into the weekend. Winds and seas will remain well below Small Craft Advisory thresholds across all marine zones. Winds will surge a bit each afternoon and evening, but speeds should mostly top out in the 10-15 knot range and will be strongest along the land/sea interface.

Main time period of concern looks to be Monday into the middle of next week as high pressure builds south into the Carolinas and Georgia following a cold front. This set-up looks favorable for Small Craft Advisories, with even a potential for gales, particularly on Tuesday.

Rip Currents: A Moderate Risk of rip currents is in place for all southeast South Carolina and southeast Georgia beaches today due to 13 second swell moving in.

CHS WATCHES/WARNINGS/ADVISORIES

GA...Dense Fog Advisory until 9 AM EDT this morning for GAZ087-088- 099>101-114-115-137-216-218-238-240-241. SC...Coastal Flood Advisory from 9 AM this morning to 1 PM EDT this afternoon for SCZ149-150. MARINE...None.