AFD_CHS

FXUS62 KCHS 230729 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 229 AM EST Mon Feb 23 2026

.WHAT HAS CHANGED...

Minor changes made to Key Message 1 in regards to ongoing cold weather this morning and return tonight. Added Key Message 2 to reflect hazardous conditions across Lake Moultrie. Added Key Message 3 to reflect breezy winds and low RH supportive of a Fire Danger Statement today. Updated the Aviation Section for the 06Z TAF issuance. Updated to Marine Section to reflect ongoing Gale Warnings and Small Craft Advisories today into tonight.

.KEY MESSAGES...

- 1) Cold weather with sub-freezing temperatures continues early this

morning with another round to return tonight.

- 2) Gusty winds expected to produce hazardous conditions across Lake

Moultrie this morning.

- 3) Breezy winds with low relative humidity values enhances

fire weather concerns late morning through the evening.

.DISCUSSION...

KEY MESSAGE 1: Cold weather with sub-freezing temperatures continues early this morning with another round to return tonight.

A modified arctic airmass will continue to filter into the region this morning as sprawling high pressure builds southward from south- central Canada. This will yield well below-freezing temperatures this morning and tomorrow morning as wind chills drop into the upper teens to low 20s southeast South Carolina and southeast Georgia. NAEFS ESAT minimum temperature anamolies hint at these below-average temperatures well with values ranging from -3 to -5 for this morning through tomorrow morning.

Temperatures began to fall this previous afternoon as breezy west- northwesterly winds soared through the region, and will continue to drop into the low to mid 20s inland and upper 20s to low 30s along the coastline. These breezy winds will make it feel like low to mid 20s area-wide, with upper-teens inland. Hence, a Cold Weather Advisory has been issued until 8AM this morning for all of the South Carolina Lowcountry and southeast Georgia. It's important to note that it will be marginal for the coastal zones as wind chill values bottom out near 20F, but an advisory seemed warranted considering the near record to record warmth that has been experienced recently.

High temperatures will struggle to reach 50F (more than 15 degrees below normal for Feb.) today as this arctic airmass continues to filter into the region. Also, lingering northwesterly winds will make it feel closer to the upper 30s to low 40s, which is a big change compared to the last couple days. The coldest period is expected tonight into tomorrow morning, with lows in the low 20s inland and mid to upper 20s near the coastline. Similar to this morning, wind chill values will fall into the low to mid 20s, with a few upper teens possible across the inland counties. Additionally, the 01Z.NBM minimum temps. forecast for tomorrow morning indicate a IQR range of 1-2 degrees, reflecting a tightly clustered distribution and reinforcing a high degree of confidence in the forecast. Hence, a Cold Weather Advisory will likely be warranted across the inland counties for tonight into tomorrow morning, however it will be marginal for the coastal zones as wind values bottom near 20F again. The need for an advisory will be reassessed again today. Highs on Tuesday will moderate slightly, reaching into the low to mid 50s.

KEY MESSAGE 2: Gusty winds expected to produce hazardous conditions across Lake Moultrie this morning.

Cold high pressure continues to spread across the region early this morning with gusty northwest winds in the 20-25 kt common across and nearby Lake Moultrie. Water temps in the mid 50s will continue to promote low-lvl mixing supportive of gusts around 25 kt into mid morning hours today, resulting in a Lake Wind Advisory until 9 AM. Some guidance suggests gusty winds continuing into afternoon hours prior to the pressure gradient weakening late day. Should trends and sfc obs support higher gusts, the Lake Wind Advisory could need to be extended into mid-late afternoon hours today.

KEY MESSAGE 3: Breezy winds with low relative humidity values enhances fire weather concerns late morning through the evening.

Sustained northwesterly winds of 15 to 20 mph with gusts up to 25-30 mph are expected late this morning through the evening as a low pressure system shifts farther away and surface high pressure builds into the region. This downslope flow regime will continue to usher in a drier airmass and yield relative humidity values between 25-30% this afternoon. Despite the measurable precipitation this past weekend, these conditions will support elevated fire weather concerns today. Therefore, a Fire Danger Statement has been issued from 11AM until 7PM (after sunset).

.AVIATION /07Z MONDAY THROUGH FRIDAY/...

VFR conditions will prevail at CHS/JZI/SAV terminals through 06Z Tuesday. However, gusty northwest/west winds (around 20-25 kt) will continue at the terminals early morning and afternoon, before weakening early evening.

Extended Aviation Outlook: An approaching front could bring flight restrictions late Thursday into Friday.

.MARINE...

Today and Tonight: Cold high pressure will continue to spread across coastal waters, with sufficient low-lvl mixing into 35-40 kt 1000mb geostrophic winds supporting frequent gusts to gale force across nearshore SC/GA waters and offshore GA waters. A Gale Warning remains in effect until 9 AM as a result, before winds slowly decrease late morning through the afternoon. A period of Small Craft Advisories will follow Gale Warnings as well, and could persist through much of tonight with winds still gusting to around 25 kt across nearshore and offshore waters. Seas will subside with a continued offshore flow present, eventually reaching the 2-4 ft range across nearshore waters by sunset while holding in the 4-6 ft range across offshore GA waters for much of the night.

In the Charleston Harbor, a Small Craft Advisory will remain in effect until early afternoon, although could need to be extended into late evening should gusty winds persist around the harbor into mid-late afternoon hours.

Tuesday through Friday: High pressure will prevail across local waters through mid-week with no marine concerns expected. However, winds and seas should increase/build with the approach of a cold front early weekend, which could support Small Craft Advisories across a majority of local waters Thursday and Friday. High pressure should then return during the weekend.

.CHS WATCHES/WARNINGS/ADVISORIES...

GA...Cold Weather Advisory until 9 AM EST this morning for GAZ087-

088-099>101-114>119-137>141.

SC...Cold Weather Advisory until 9 AM EST this morning for SCZ040-

042>045-047>052. Lake Wind Advisory until 9 AM EST this morning for SCZ045.

MARINE...Small Craft Advisory until 1 PM EST this afternoon for AMZ330.

Gale Warning until 9 AM EST this morning for AMZ350-352-354- 374.

Dennis/DPB