FXUS62 KCHS 181840 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 240 PM EDT Wed Mar 18 2026
.WHAT HAS CHANGED...
Key Message 1, the Aviation section, and the Marine section have all been updated. Key message 2 has been added.
&&
.KEY MESSAGES...
- 1) Frost is expected to develop overnight into Thursday,
impacting sensitive vegetation.
- 2) Rain-free conditions and warming temperatures into
the weekend.
&&
.DISCUSSION...
KEY MESSAGE 1: Frost is expected to develop overnight into Thursday, impacting sensitive vegetation.
Out ahead an approaching surface ridge axis, another overnight period with low temperatures in the 30s is expected. This is due to weak cold-air advection at first, which then transitions over to radiational cooling as winds weaken and the boundary layer decouples. Widespread temperatures in the mid 30s are thus expected away from the coast and when combined with the weak winds, areas of frost are expected to form across the region prompting a Frost Advisory for inland zones. Those along the coast have been kept out of the Frost Advisory given the expected overnight lows in the upper 30s to lower 40s.
KEY MESSAGE 2: Rain-free conditions and warming temperatures into the weekend.
The southeastern states will remain under the influence of broad troughing along the Eastern Seaboard until the end of the week when the troughing pushes into the Atlantic waters. Then, through the weekend, ridging will build into the region aloft from the southwest. At the surface high pressure will dominate, centered over the southeastern states. This synoptic pattern will yield quiet weather with gradually warming temperatures into the weekend. High temperatures Thursday in the 60s will warm to the low to mid 80s by Sunday. The next chance of rain across the region will be Monday as a weak cold front advances towards the region.
&&
.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
18Z TAF: VFR conditions will prevail through the period. Winds will shift to become more northerly throughout the day while remaining light, further decreasing overnight. Winds pick up tomorrow morning bringing some marginally gusty winds for a few hours, decreasing into the afternoon.
Extended Aviation Outlook: VFR conditions are expected to prevail.
&&
.MARINE...
Rest of Today through Sunday: Overall, wind and sea conditions are expected to remain below Small Craft Advisory thresholds through Saturday. The exception for this in the near-term are the outer Georgia waters, where wind gusts of 25 to 30 knots are possible as the surface pressure gradient tightens tonight into Thursday. In addition to the winds, 6-7 foot seas are expected to form and linger in the outer Georgia waters, subsiding below SCA criteria overnight into Friday morning.
A dissipating front may briefly bring winds back up to near 20 knots Saturday morning, with winds picking up on Sunday ahead of an approaching cold front, bringing the next chance for a Small Craft Advisory. NBM 5.0 probabilities for wind gusts greater than 25 knots are currently in the 40-60% range for the nearshore waters, closer to 70% in the outer Georgia waters though the southern extent remains unclear.
&&
.EQUIPMENT...
Radome panel replacement maintenance has started at the KCLX radar and is scheduled to continue through Friday March 20th. The radar will be down during this time. Users are encouraged to use data from the following nearby radar sites during the maintenance outage:
KCAE - Columbia, SC KLTX - Wilmington, NC KJAX - Jacksonville, FL KVAX - Moody AFB, GA KJGX - Robbins AFB, GA
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Frost Advisory from midnight tonight to 9 AM EDT Thursday for
GAZ087-088-099>101-114>116-137-138.
SC...Frost Advisory from midnight tonight to 9 AM EDT Thursday for
SCZ040-042>045-047.
MARINE...Small Craft Advisory from 8 PM this evening to 5 AM EDT Friday
for AMZ374.
&&
$$
APT/CPM