textproduct: Columbia

WHAT HAS CHANGED

Scattered showers and thunderstorms return later this afternoon and evening, with a few storms capable of becoming strong to marginally severe. Aviation discussion updated for 12z TAFs.

KEY MESSAGES

- 1. Chances for showers and storms continue each day this week as temperatures hover around average. A couple strong to marginally severe storms possible today.

DISCUSSION

- 1. Chances for showers and storms continue each day this week as temperatures hover around average. A couple strong to marginally severe storms possible today.

A closed upper level low is developing just southwest of the forecast area. Deep tropical moisture will continue streaming into the region, with the greatest moisture remaining east of the area and closer to the coast. Guidance remains consistent in keeping the upper low in place through at least midweek, supporting above-normal coverage of diurnal showers and thunderstorms each afternoon and evening. Wrap-around moisture will remain in place today, while cooler and drier air aloft will help steepen lapse rates and increase instability. Combined with modest wind shear, the environment will support scattered thunderstorms this afternoon and into the late evening as forecast CAPE profiles near 2000-2500 J/kg with DCAPE values around 800-1200 J/kg. A few storms could become strong to severe, with damaging wind gusts as the primary concern. Repeat days of convection has resulted in a slowly-increasing risk of localized flash flooding, especially in locations that received multiple rounds of heavy rainfall or training storms over a short period of time.

By Wednesday, an approaching upper-level trough will begin to weaken and lift the upper low out of the southeast. While weak troughing lingers through the end of the week, the overall threat for stronger storms appears lower. Daily afternoon and evening showers/thunderstorms will remain likely. A robust ridge near the NAEFS climatological max builds off the East Coast this weekend. The ridge should allow deep southerly to southwesterly flow to persist late in the week, keeping PWAT's during this period near 2" with seasonable temperatures.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

Restrictions expected this morning through 15z.

Light winds and abundant low level moisture this morning has brought another round of low stratus and patchy fog. This means mvfr/ifr restrictions at most sites at issuance time. Most guidance begins breaking the clouds out and bringing conditions back to vfr by 15z, and have generally trended in that direction. Light south or southeast winds are expected through the day. With weak moisture convergence over the area, we expected another afternoon of scattered showers and thunderstorms. Coverage should support PROB30 groups for thunderstorms during the afternoon through 02z tonight, similar to previous days. As for tonight, latest models showing mainly vfr conditions through the night, but if conditions don't change much over the next 24 hours, can not rule out another night of restrictions forming at all sites.

EXTENDED AVIATION OUTLOOK...Diurnal thunderstorms expected this week with early morning restrictions likely.

CAE WATCHES/WARNINGS/ADVISORIES

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