AFD_CHS

FXUS62 KCHS 151146 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 646 AM EST Thu Jan 15 2026

.WHAT HAS CHANGED...

The aviation section has been updated for the 12z TAF issuance. A Fire Danger Statement is in effect for southeast Georgia and the South Carolina Lowcountry from 10 AM this morning until 7 PM this evening. A Cold Weather Advisory is then effect from 8 PM this evening to 9 AM Friday morning. The chance for measurable precipitation has increased for Sunday morning and afternoon, while confidence on any frozen precipitation remains low.

.KEY MESSAGES...

- 1) Dry and breezy conditions today, with dry conditions

persisting into Friday.

- 2) Very cold temperatures will occur Friday morning, with lows

in the upper teens to lower 20s away from the beaches.

- 3) A developing coastal low on Sunday will bring a possibility

of snow mixing with rain Saturday night into Sunday morning.

.DISCUSSION...

KEY MESSAGE 1: Dry and breezy conditions today, with dry conditions persisting into Friday.

A strong cold front is timed to reach the GA/SC coast around sunrise, pushing east over the Atlantic through the rest of the day. Near term guidance indicates strong CAA through the day, with H85 temperatures falling to -5 to -10C by this afternoon. The air mass will be further dried by downslope flow in the lee of the southern Appalachians and deep mixing to 4.5 to 5.5 kft. As a result, sfc dewpoints will fall through the daylight hours today, dropping into the single digits to low teens. RH values between 20 to 25 percent should be common. The combination of gusty northwest winds, low RH, and mostly sunny conditions should rapidly dry fine fuels from yesterday's light rainfall. To highlight the enhanced wildfire risk, a Fire Danger Statement has been issued for southeast Georgia and the South Carolina Lowcountry from 10 AM this morning until 7 PM this evening.

The center of the dry air mass will build across the Southeast U.S. on Friday. Dewpoints could be as low as the single digits at a few locations mid-day Friday, most areas between 10 to 15 degrees. As temperatures reach around 50 degrees Friday afternoon, RH values may range from the upper teens to around 20 degrees west of I-95, to the mid to upper 20s to the east. Fortunately, the weak pressure gradient should only support winds around 10 mph. No Fire Danger Statements are expected for Friday.

KEY MESSAGE 2: Very cold temperatures will occur Friday morning, with lows in the upper teens to lower 20s away from the beaches.

A Cold Weather Advisory is now in effect from 8 PM this evening to 9 AM EST Friday morning. Surface high pressure over southern LA/ MS Thursday evening will quickly move east and center across northern FL by Friday morning. This will allow winds to go calm across all of coastal GA and SC. PWATs will also be around 0.10" (or daily minimum values) and with skies clear, near ideal radiational cooling conditions are forecast. Expect low temperatures in the upper teens west of I-95 and in the typical colder spots. Along and east of the I-95 corridor to about US Highway 17, expect low temperatures in the lower to mid 20s. Along the beaches, expect low temperatures in the upper 20s (including the Charleston Peninsula). Temperatures will be below freezing for 8 to 12 hours.

KEY MESSAGE 3: A developing coastal low on Sunday will bring a possibility of snow mixing with rain Saturday night into Sunday morning.

A Rex Block will gradually loose cohesion as a wave situated over the eastern Pacific approaches from the west. In response to this downstream effect, a substantial shortwave trough will dive southeast out of Manitoba and approach the region on Sunday morning. The shortwave will also start to take on a negative tilt as it approaches coastal SC and GA. As this occurs, surface cyclogenesis is forecast to commence off of the South Carolina Coast. Based on the latest guidance, there are 3 main potential scenarios.

(1) Coastal low forms along the SC/ NC coastline * Model Support? The latest run of the GFS (deterministic) and

GEFS (GFS ensemble) shows a much wetter and slightly warmer solution. This is due to the coastal low forming right along the SC coast. This would support a cold rain across most of coastal SC and GA, with some frozen precipitation across the Midlands and Upstate of SC.

* Precipitation Type: mostly plain rain. A small window is

possible for a rain/ snow mix well inland.

(2) Coastal low forms off of the SC/ NC coastline * Model Support: The latest run of the ECMWF and 18z EPS (ECMWF

ensemble) as well as the GEPS (CMC ensemble) support this solution. Here the coastal low is far enough away from the coast to help tap the colder air already in place, while also not to far away to keep the region dry.

* Precipitation Type: plain rain along coastal SC and GA. A

rain/ snow mix possible away from the beaches with a brief transition to all snow possible inland.

(3) Coastal low forms to far east/ northeast of SC/ GA * Model Support: Limited number of model guidance is still

showing this solution. The trend away from this solution started Wednesday morning.

* Precipitation Type: plain rain, or none.

The 14.12z WPC Cluster Analysis also shows ensemble guidance becoming less and less dispersive (e.g., 72% of the EPS being contained in Cluster 1). Taking a look at the WPC Ensemble Sensitivity Analysis webpage reveals that dueling shortwaves (on the western and eastern flanks of the rex block) accounting for most of the variance in model solutions. This type of setup typically has low confidence. The probabilistic Winter Storm Severity Index (WSSI-P) continues to show a 5-10% chance of experiencing minor impacts from winter weather on Sunday. Again, caution should be exercised here as the forecast can change, and will likely change over the next couple days.

Behind the cold front, temperatures will again be seasonably cold Monday with low temperatures in the mid 20s. Ahead of the approaching high pressure, winds may remain just strong enough (near 5 knots) where wind chills may dip into the 15 to 20 degrees range, with highest probabilities again for the furthest inland areas. A Cold Weather Advisory may be needed.

.AVIATION /12Z THURSDAY THROUGH MONDAY/...

VFR conditions will prevail at KCHS, KJZI, and KSAV through 12z Friday. Prior to the 12Z TAFs, a strong cold front was located near the coast, pushing to the east. In the wake of the front, winds will veer from the west and then northwesterly, becoming gusty. Frequent gusts into the 20-25 knot range are expected beginning shortly after sunrise this morning and continuing through this afternoon. Skies will clear out by mid morning, remaining clear through the rest of the TAF period.

Extended Aviation Outlook: VFR conditions will continue for KCHS, KJZI and KSAV through late week. Another system could impact the region late this weekend.

.MARINE...

The marine zones will remain between a strong cold front pushing across the western Atlantic and high pressure centered over the southern Mississippi River Valley today. This pattern will support gusty northwest winds between 25 to 30 kts and elevated wave heights today into late tonight. Wave heights will build through today, peaking between 3-5 ft across the nearshore with 6-8 ft beyond 20 NM this evening. Small Craft Advisories will remain in effect for all marine zones outside the CHS Harbor today into tonight.

The center of a large area of high pressure will arrive on Friday and may linger into Saturday, supporting winds around 10 kts with 1- 2 ft seas. An area of low pressure is forecast to develop off the coast Saturday night into Sunday, with gusty winds and building seas, possibly reaching Small Craft Conditions across a portion of the waters. High pressure should settle over the region early next week, allowing conditions to remain less than Small Craft Advisory criteria.

.CHS WATCHES/WARNINGS/ADVISORIES...

GA...Cold Weather Advisory from 8 PM this evening to 9 AM EST

Friday for GAZ087-088-099>101-114-115.

SC...Cold Weather Advisory from 8 PM this evening to 9 AM EST

Friday for SCZ040-042>044-047.

MARINE...Small Craft Advisory until midnight EST tonight for AMZ350-352-

354. Small Craft Advisory until 4 AM EST Friday for AMZ374.

Haines/NED