textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 00z TAFs.

KEY MESSAGES

- 1. Above average temperatures and chances for showers and storms early this week.

- 2. Much cooler conditions expected Wednesday onward, with periods of showers mainly Wednesday and Thursday.

DISCUSSION

KEY MESSAGE 1: Above average temperatures and chances for showers and storms early this week.

One more day of a stagnant pattern today with a shift beginning late Tuesday. Upper low over northwest Florida will continue to draw moisture into the state over the next 24 hours. This disturbance should finally lift northeast off our coastline Tuesday in response to an approaching upper trough moving through the Midwest. Highs today will still peak in the low 90s with isolated showers and thunderstorms as a result of the strong heating. Better coverage of precip can be anticipated Tuesday as better forcing associated with the upper low grazes the forecast area. Another shortwave moves across the region from the west while a surface front moves south then sink across the Midlands Tuesday night with scattered to widespread showers and storms.

KEY MESSAGE 2: Much cooler conditions expected Wednesday onward, with periods of showers mainly Wednesday and Thursday.

Models are generally converging now high pressure over the northeast will push a wedge front through our forecast area late Tuesday into Wednesday. The ongoing showers and cloud cover Wednesday morning will likely limit daytime heating, especially with cold advection occurring at the surface. There remains some uncertainty regarding how far south the wedge front will go, and it is expected to have a tight temperature gradient setting up somewhere across the southern Midlands Wednesday afternoon. All said, the temperature drop of 10 to 15+ degrees between Tuesday and Wednesday will be very noticeable north of the front. There will also be some breezy northeast winds accompanying this airmass change. Blended guidance struggles in these scenarios and so NAM/GFS data was blended in and collaborated to better capture the expected temperatures. It can be noted that we may still be too warm for Thursday, and future packages may continue to drop temperatures as appropriate.

An upper trough Thursday will work to scour out the wedge through some portion of the day, with drier northwest flow eventually moving into the area. High pressure will continue to be in place at the surface and keep temperatures on the cooler side. But the drier air aloft will bring precip-free conditions back by Friday with highs starting to rebound back a bit closer to normal. Highs should generally reach into the upper 70s and low 80s, with overnight lows in the upper 50s to low 60s. Overall, this should provide our first real taste of fall with a refreshing change in temperatures arriving just as astronomical autumn begins on Tuesday!

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Fog possible Tuesday morning, scattered thunderstorms expected in the afternoon.

Although models are again suggesting fog development tonight, based on the verification from the past few days it seems unlikely that widespread IFR fog will develop. Therefore we trended the TAFs towards a more optimistic outlook limiting MVFR fog to the fog prone sites AGS and OGB between 9Z and 12Z similar to what occurred the previous morning.

East winds will pick up around 7 kts after 15Z Tuesday. The environment will support higher convective coverage in the afternoon with scattered thunderstorms expected to develop around 18Z. Thunderstorms are likely to continue into the evening past the end of the 00Z TAF period.

EXTENDED AVIATION OUTLOOK...Widespread restrictions and higher rain chances expected early Wednesday through Thursday as wedge conditions set up across the region. Drier conditions expected beginning Friday.

CAE WATCHES/WARNINGS/ADVISORIES

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