FXUS62 KCHS 220717 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 217 AM EST Sun Feb 22 2026
.WHAT HAS CHANGED...
Added Key Message 1 to address gusty wind potential today into the evening. Minor update to Key Message 2 has been made to reflect cold temperatures through mid week. The Aviation Section has been updated to reflect the 06Z TAF issuance. Minor adjustments have been made to the Marine Section in regards to gale force winds this afternoon through early Monday.
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.KEY MESSAGES...
- 1) Gusty winds expected across all areas late this morning
into evening.
- 2) Sub-freezing temperatures return tonight and persist into
the mid-week.
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.DISCUSSION...
KEY MESSAGE 1: Gusty winds expected across all areas late this morning into evening.
A strong cold front is expected to move across the local area early today, likely shifting off the South Carolina and Georgia coast by mid-late morning and ending light to moderate rain/showers locally. Strong cold air advection in wake of the front will promote ample mixing into 40 kt low-lvl wind fields, favoring west/northwest winds gusting to around 30-35 mph this afternoon into early evening. There is a low risk for gusts to approach 40 mph during peak diurnal heating given the strength of cold air advection and packed pressure gradient associated with high pressure building in, but confidence in coverage/duration of event appears to fall just shy/short of a Wind Advisory for a majority of the area at this time. However, these winds should produce hazardous conditions across Lake Moultrie (gusts up to 25-30 kt), which has led to a Lake Wind Advisory being issued from noon to 8 pm today. Waves between 1-2 ft are possible across the lake, highest along the eastern lakeshore.
KEY MESSAGE 2: Sub-freezing temperatures return tonight and persist into the mid-week.
As a cold front slides off the coastline this morning, expect cold, dry surface high pressure to build into the region behind it. This will yield a considerably colder airmass tonight into early next week with well below-normal temperatures, widespread below freezing temperatures Monday and Tuesday mornings, and wind chills dropping into the upper teens to low 20s for some areas. NAEFS ESAT minimum temperature anamolies hint at these below-average temperatures well with values ranging from -3 to -4 for tonight through Tuesday morning.
Temperatures will begin to fall this afternoon as breezy west- northwesterly winds prevail and cold air advection continues through tonight. By Monday morning, lows will reach the upper 20s inland and low 30s along the coastline, but breezy winds will make it feel like low to mid 20s area-wide, with upper teens possible inland. The 01Z.NBM minimum temps. forecast for Monday morning indicate a IQR range of 2-3 degrees, reflecting a tightly clustered distribution and reinforcing a high degree of confidence in the forecast. Also, the 00Z.HREF indicates 80-90% chance of wind chill values dropping below 20F on Monday morning for inland counties across southeast Georgia (specifically Screven, Jenkins, Candler, Tattnall, Evans, and Bulloch counties) and a Cold Weather Advisory will likely be needed for these areas. Highs on Monday will struggle to reach 50F (more than 15 degrees below normal for Feb.).
The coldest period is expected Monday night into Tuesday morning, with lows in the low to mid 20s inland and upper 20s near the coastline. Despite wind speeds being much lighter, wind chills will still fall into the low to mid 20s, with a few upper teens possible across inland counties of southeast Georgia. Additionally, the 01Z.NBM minimum temps. forecast for Tuesday morning indicate a IQR range of 1-2 degrees, reflecting a tightly clustered distribution and reinforcing a high degree of confidence in the forecast again. Another Cold Weather Advisory may be warranted for portions of southeast Georgia. Highs on Tuesday will moderate slightly, reaching into the low to mid 50s.
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.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
CHS/JZI: Periods of IFR are expected overnight with light to moderate rain/showers occurring until a cold front passes by around 13Z this morning. Conditions will then improve to MVFR behind the front for a few hours, then become VFR as skies clear out with high pressure building across the region. West/northwest winds will become gusty at both terminals late morning and afternoon, peaking between 25-30 kt mid afternoon. Gusty winds should persist through evening hours, but will gradually decrease to the 15-20 kt range.
SAV: Periods of MVFR and TEMPO IFR conditions are expected overnight with light to moderate showers until a cold front passes by around 13Z. MVFR conditions could hold on for a few hours thereafter, but will improve to VFR by around 16Z. West/northwest winds will become gusty post fropa, peaking around 30 kt during afternoon hours. Gusty winds should persist through the evening, but will gradually decrease to the 15-20 kt range.
Extended Aviation Outlook: VFR.
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.MARINE...
Today and Tonight: A strong cold front will move across the area early this morning, likely shifting offshore after daybreak and bringing increasingly hazardous marine conditions across local waters as strong cold air advection post front promotes low-lvl mixing into 40-45 kt 1000mb geostrophic winds. Gale Warnings remain in effect for all nearshore and offshore waters this afternoon into early Monday for gusts up to 35-40 kt at times. A Small Craft Advisory remains in effect for the Charleston Harbor this afternoon and tonight as well.
Monday through Thursday: Marine conditions should gradually improve to below Small Craft Advisory thresholds late morning Monday through Monday night as high pressure builds across the region through mid- week. However, winds and seas could increase/build to near Small Craft Advisory levels mid-week, well ahead of large trough approaching the region late week.
Sea fog: Patchy to areas of fog are possible across nearshore waters, including the Charleston Harbor, until a cold front shifts offshore shortly after daybreak. Ongoing rain/showers should limit a true sea fog event, but vsbys could become reduced to below 1 NM at times through daybreak.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...Lake Wind Advisory from noon today to 8 PM EST this evening
for SCZ045.
MARINE...Small Craft Advisory from 3 PM this afternoon to 8 AM EST
Monday for AMZ330. Gale Warning from 3 PM this afternoon to 8 AM EST Monday for AMZ350. Gale Warning from 1 PM this afternoon to 8 AM EST Monday for AMZ352-354. Gale Warning from 11 AM this morning to 8 AM EST Monday for AMZ374.
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Dennis/DPB