FXUS62 KCHS 210700 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 200 AM EST Sat Feb 21 2026
.WHAT HAS CHANGED...
Key messages have been updated to reflect severe weather potential this afternoon/evening and cold temperatures early next week. The aviation section has been updated for the 06Z TAF issuance. The marine section has been updated to reflect Gale Watches Sunday afternoon into Monday morning.
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.KEY MESSAGES...
- 1) Strong to severe storms possible this afternoon and evening.
- 2) Sub-freezing temperatures return on Sunday night and persist
into the mid-week.
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.DISCUSSION...
KEY MESSAGE 1: Strong to severe storms possible this afternoon and evening.
A stalled front will linger across portions of South Carolina today as a shortwave trough located over the Mississippi Valley deepens and shifts into the region. Simultaneously, a surface low will develop along the stalled front in the north-central Gulf and then translate across South Carolina by the afternoon. As the upper-lvl trough strengthens, this low is expected to deepen while tracking eastward and eventually offshore by early Sunday morning. Increasing large-scale ascent and low-lvl moisture will support scattered showers and thunderstorms across southeastern Georgia and southeastern South Carolina throughout today and into tonight, with some potential for damaging wind gusts and a brief weak tornado.
Elevated thunderstorms could be ongoing along the front in the early morning as modest heating tries to develop south of this front. As this surface low develops, it should push the front northwards throughout the day and most of southeast Georgia and southeast South Carolina should be situated in the warm sector, however some uncertainty remains on how quickly this front lifts northward. Therefore, if the front struggles to quickly lift northward, the Charleston Tri-County could wrestle to produce any reasonable instability for thunderstorm development. However, moderate instability should build throughout the day as dewpoints climb into the mid to upper 60s. Expect SBCAPE values to range from 500 to 1000 J/kg across the region with some pockets above 1000 J/kg possible across southeast Georgia (esp. in the afternoon hours). Forecast hodographs depict elongated, relatively straight profiles largely parallel to the front, yielding the potential for organized line segments, or clusters to form. However, a brief weak tornado (mainly in southeast Georgia) cannot be ruled out near the breaks of a QLCS and/or bowing line segments as 0-6km bulk shear on the order of 50 to 70 kt will be present. The risk for severe weather remains highest across southeast Georgia between 2PM to 9PM, roughly along/south of I-16 (away from the immediate coastline), and possibly as far north as Beaufort and Hardeeville in southern South Carolina. To reflect this severity, SPC has highlighted the region in marginal risk for severe thunderstorms today. The main uncertainty will be centered around how much instability can develop in the warm sector, as this will determine if the severe weather risk will need to be increased.
Along with the severe weather risk, expect rainfall values from 0.50 to 1.25 inches today through Sun. morning as the scattered to numerous showers and thunderstorms (mainly induced by isentropic ascent and warm-air advection) push across the region. This coupled PWATs climbing above 1.5 inches and the presence of some surface- based instability should easily support some spots receiving over an 0.50 inches over a 6-hour period. This could lead to brief urban, or poor drainage flooding, particularly in the Charleston and Savannah metro areas.
These showers and thunderstorms should gradually shift offshore by late Saturday evening as the front clears off the coastline, followed by veering winds and drying from west to east overnight. Expect cooler and more stable air to filter into the region by early Sunday morning and effectively end the severe weather threat.
KEY MESSAGE 2: Sub-freezing temperatures return on Sunday night and persist into the mid-week.
As a cold front pushes off the coastline on Sunday morning, expect cold surface high pressure to build into the region behind it. This will yield a considerably colder airmass for the 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.
Temperatures will fall Sunday afternoon with breezy northwest winds and continued cold air advection through Sunday night. By Monday morning, lows will reach the upper 20s inland and low 30s along the coastline, but gusty winds will make it feel like low to mid 20s area-wide, with upper teens possible inland. Therefore, a Cold Weather Advisory might be warranted. 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. Another Cold Weather Advisory may be warranted. Highs on Tuesday will moderate slightly, reaching into the low to mid 50s.
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.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions should prevail for the next couple hours at CHS/JZI/SAV terminals through about 08-10Z Saturday, although a line of showers could impact CHS/JZI and produce TEMPO MVFR conditions prior to 08Z. Expect MVFR conditions to develop at CHS/JZI terminals prior to daybreak, then continue to deteriorate to IFR as low clouds and shower activity occur along a front nearby. IFR conditions should then prevail with continued low clouds and shower activity persisting through 06Z Sunday. The risk for a few thunderstorms will also increase late afternoon into early evening. PROB30 groups have been introduced for thunderstorms and lower vsbys between 02-06Z Sunday.
At SAV, the risk for MVFR and even IFR cigs comes sooner (around 08Z), but should remain in the MVFR category for a bulk of the time later tonight and through early afternoon. VFR conditions temporarily return at SAV during mid afternoon prior to shower/thunderstorm activity returning with a cold front approaching from the west late in the TAF period. A PROB30 group for thunderstorms and reduced vsbys has also been added at SAV between 02-06Z, although the risk for thunderstorms should increase late afternoon into early evening.
Extended Aviation Outlook: Periods of flight restrictions will be possible through Sunday morning primarily due to showers and/or low clouds associated with a cold front shifting offshore. VFR conditions should then prevail as high pressure builds across the region next week.
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.MARINE...
Today and Tonight: South/southwest winds should settle into the 10- 15 kt range with seas between 2-3 ft while a front becomes positioned north and inland to the area. There are no wind/seas concerns outside convection at this time. However, a band of showers/tstms could push off of the coast late afternoon and evening hours. These storms could produce localized wind gusts in excess of 34 kt, isolated waterspouts and cloud-to-water lightning. Special Marine Warnings could eventually be needed.
Sunday through Wednesday: A strong cold front will move across the area Sunday morning, resulting in 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. As a result, a Gale Watch has been issued for all nearshore SC/GA waters and offshore Georgia waters Sunday afternoon through Monday morning, with gusts up to 35-40 kt at times. The Charleston Harbor remains out of the Gale Watch for now, but should see Small Craft Advisory level conditions for a period behind the front as well. There could be a 6-hr period of Small Craft Advisories leading into the current Gale Watch Sunday morning/afternoon, which will need to be further refined for a possible issuance. Marine conditions will then gradually improve back below Small Craft Advisory thresholds Monday through Monday night as high pressure builds across the region through the middle of next week.
Sea fog: Some guidance suggests another round of sea fog developing prior to daybreak and lingering through late morning, although increasing winds and shower activity could limit this activity. Conditions will continue to be monitored for possible Marine Dense Fog Advisories.
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.CLIMATE...
Record High Temperatures:
February 21: KSAV: 84/2018
Record High Minimum Temperatures:
February 21: KCHS: 62/2023 KSAV: 63/2023
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...Gale Watch from Sunday afternoon through Monday morning for
AMZ350-352-354. Gale Watch from Sunday afternoon through Monday afternoon for AMZ374.
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Dennis/DPB