textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 12Z forecast.

KEY MESSAGES

- 1. Increasing moisture this weekend leading to chances for rain and storms through Monday when a front moves through.

DISCUSSION

Key Message 1: Increasing moisture this weekend leading to chances for rain through Monday when a cold front moves through.

8am Update: Scattered showers and embedded t-storms have developing across northern SC. Expect these to continue through 9-10am.

Strong convection has developed well to the west early this morning near Texarkana and will continue to shift into the Deep South through the day. This MCS to the west will likely continue to propagate southeasterly with highest instability along the Gulf coast which will likely limit significant convection occurring within the forecast area. Heaviest rain and highest thunderstorm coverage has trended southward for today among CAMs. However, moisture over the forecast area has gradually increased and is expected to continue to increase with HREF mean PWATs generally around an inch and a quarter to the north to an inch and a half in the south. With HREF probability of sbCAPE above 500 J/kg around 60-70% this afternoon, scattered convection still remains likely, favoring the southern portion of the forecast area. Models have generally trended stronger with a 500mb trough to the west for Sunday which may shift some drier air into the northern area and keep strongest forcing to the south. As a result, pops have trended downward for the day Sunday, although still have kept slight to chance pops in the southern portion of the forecast area. Highest confidence in widespread showers and storms continues to be Monday with an approaching cold front. Slightly slower timing of the front has led to blended guidance a bit more unstable with probability of sbCAPE greater than 1000 J/kg around 40-60%. Forecast soundings indicate profiles with long, skinny CAPE. This would favor moderate to potentially heavy rain at times, although likely limit the severe weather threat, although some ML guidance has indicated at least a low end threat so it is worth monitoring. Drier conditions arrive Tuesday has we eventually end up within the northwest flow regime of the persistent troughing.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Mix of VFR-IFR conditions likely this morning as showers and low cigs roll in.

Increasing moisture across the region is pushing some MVFR-IFR cigs into the area. Generally the Columbia terminals should remain MVFR, maybe briefly dipping to IFR, but confidence is low in that. AIK and the Augusta terminals will likely remain IFR periodically through 14z roughly. A few showers are likely within this plume of increasing moisture, with some increasing chances for showers mainly before 18z. Rain chances generally decrease after 18z for the entire area with cigs and vsby expected to remain VFR until early Sunday morning.

EXTENDED AVIATION OUTLOOK...Another system brings a chance for restrictions with showers and thunderstorms this weekend into Monday.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.