textproduct: Charleston

WHAT HAS CHANGED

The Aviation Section has been updated for the 12Z TAF issuance.

KEY MESSAGES

- 1) Dry conditions and above normal temperatures will continue through Thursday.

- 2) Frost/freeze conditions are possible Friday night through Sunday night.

DISCUSSION

KEY MESSAGE 1: Dry conditions and above normal temperatures will continue through Thursday.

Today: High pressure will continue to dominate the weather pattern across the Southeast United States, supporting dry conditions and above normal temperatures, despite an increase in mid-high clouds across the region. High temps should peak in the mid-upper 70s this afternoon. Overnight lows will also trend warmer with cloud some cloud cover lingering and a light west-southwest wind through the night. In general, low temps should range in the low-mid 50s inland to upper 50s/around 60 near the beaches.

Thursday: A breezy southwesterly flow is expected to develop across the region as a mid-upper lvl trough forces a sfc cold front across the Appalachian Mountains early morning, then toward the local area late afternoon into evening hours. Gusts up to 25-30 mph will be common by afternoon hours as sfc temps warm into the mid-upper 70s one last day this week. Latest soundings continue to indicate substantially dry low-mid levels through cold fropa, which leads to a dry forecast for the entire area. Strong cold air advection occurs in wake of the front overnight with a west-northwest flow bringing noticeably cooler air across the local area. Overnight lows should generally range in the low-mid 40s inland to around 50 at the beaches during predawn hours Friday.

KEY MESSAGE 2: Frost/freeze conditions are possible Friday night through Sunday night.

Much cooler air begins to move in behind the front, with early morning temperatures on Friday expected to start off in the lower 40s inland up into the lower 50s along the coast. Despite the sky being clear, cold air advection (CAA) will keep afternoon highs limited to the lower to mid 60s. Wind speeds have come down a touch, though the afternoon hours will likely still see gusts into the upper teens to lower 20s.

With the cold air continuing to funnel down into the region, Friday night into Saturday will be our first night where concerns for frost formation return to the area. As mentioned previously, wind speeds have come down, and with overnight lows in the mid 30s across portions of inland southeast South Carolina and southeast Georgia, frost formation can't be ruled out. The highest chances for frost will be Saturday night into Sunday morning, with the immediate coastal zones being excluded. Areas west of I-95 in southeast Georgia and along/west of I-95 in the Lowcountry have a chance of reaching freezing temperatures. Another chance for frost/freeze returns into Monday morning as cold temperatures linger.

Nov 11 01z NBM 10km neighborhood probabilities for emergency management warming shelter planning:

Friday Night/Saturday Morning: Inland Areas Coastal Corridor Temps 35 degrees or colder: 20-40% <5% Temps 32 degrees or colder: 5-10% <5% Temps 30 degrees or colder: <5% <5%

Saturday Night/Sunday Morning: Inland Areas Coastal Corridor Temps 35 degrees or colder: 70-90% 20-50% Temps 32 degrees or colder: 20-40% 5% Temps 30 degrees or colder: 10-30% <5%

Sunday Night/Monday Morning: Inland Areas Coastal Corridor Temps 35 degrees or colder: 40-70% 10-30% Temps 32 degrees or colder: 20-30% 5-10% Temps 30 degrees or colder: 10-20% <5%

Frost Advisories, Freeze Watches and Freeze Warnings may eventually be needed, especially for areas roughly inland of US-17 in the Lowcountry and I-95 in Southeast Georgia.

Detailed information on first freeze dates for the area can be found online at: https://www.weather.gov/media/chs/climate/AverageFirstLastFreezeDates.pdf

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

VFR conditions are expected to prevail at CHS/JZI/SAV terminals through 12Z Thursday.

Extended Aviation Outlook: Breezy southwesterly winds will be strengthening throughout the day on Thursday, producing gusts up to near 25 knots. A cold front moves through overnight into Friday, swinging winds around to become out of the west-northwest.

MARINE

Today and Tonight: High pressure will dominate the weather pattern through tonight, but the pressure gradient is anticipated to strengthen well in advance of large-scale trough and associated cold front late day and overnight. In general, south/southwest winds around 10 kt or less this morning will gradually increase to around 15 kt this afternoon, then continue to increase to 15-20 kt across most local waters during the night. There is a chance of gusts to briefly touch 25 kt across offshore GA waters after midnight, but coverage and duration do not support a Small Craft Advisory issuance at this time. Seas will slowly build from 1-3 ft today to 2-4 ft tonight.

Thursday into Sunday: Winds increase out of the southwest Thursday ahead of an approaching cold front, becoming gusty to near 30 knots. Likewise, wind-driven seas will build, with 6 foot seas likely limited to the offshore (20-60nm) zones. Small Craft Advisories will likely be needed for our waters starting Thursday, though with timing concerns wanted to allow for more model runs before issuing. Winds shifts to become out of the west-northwest overnight into Friday, with a brief period of weakening winds during the morning/afternoon, before wind gusts pick up again overnight into Saturday to near 25 knots. This looks to primarily impact the waters 20-60nm offshore from Edisto Beach, SC to Altamaha Sound, GA, with weaker winds elsewhere. Winds decrease Saturday as surface high pressure builds in, remaining in the 10 to 15 knot range with gusts to 20 knots at times into Sunday.

CHS WATCHES/WARNINGS/ADVISORIES

GA...None. SC...None. MARINE...None.