textproduct: Columbia

WHAT HAS CHANGED

Updated the Key Messages to reflect seasonal summer conditions expected this week. Updated 06z Aviation discussion.

KEY MESSAGES

- 1. Seasonal temperatures with afternoon thunderstorm chances.

DISCUSSION

KEY MESSAGE 1: Seasonal temperatures with afternoon thunderstorm chances.

Persistent upper ridging that was in place the last week will give way to troughing over the eastern US. This will lead to more seasonal temperatures with blended guidance highs in the upper 80s and low 90s and lows in the upper 60s and low 70s. Relatively high confidence in the temperature forecast with a limited interquartile range within blended guidance.

Drier air is beginning to work its way into the area with northwest flow strengthening through today. This will limit convective coverage, although lingering low level moisture, especially in the eastern portion of the forecast area will support isolated storms with moderate instability and HREF sbCAPE approaching 2000 J/kg. By Sunday, NAEFS mean indicates PWATs will be around the tenth percentile, around an inch and while can't completely rule out a stray storm with a strong moisture gradient near the southern portion of the forecast area, expected mostly dry conditions. While isolated diurnally driven storms will be possible early this week, increasing moisture mid to late week will likely lead to higher coverage of storms each afternoon with LREF probabilities around 50- 70% of PWATs greater than 1.75 inches Wednesday through the end of the week and weak shortwaves leading to increased forcing.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

VFR conditions are present at all sites sans OGB. IFR and potentially LIFR ceilings likely await us later tonight...

High, debris cloudiness is present across the area as convection wanes across the southeastern CONUS. Beneath this, observations reveal a deck of stratus beginning to develop and push southward out of the northern Midlands. Orangeburg is already seeing IFR ceilings and CUB/CAE have flirted with ceilings over the last hour or two. Expecting widespread ceiling restrictions to overspread the sites over the next 3-4 hours, persisting through late morning across the area. We should see clouds break by late morning/early afternoon, with isolated showers/storms possible this afternoon. Coverage is far less certain than it was yesterday, so have opted to keep mention of precip out of the TAFs for now.

EXTENDED AVIATION OUTLOOK...Thunderstorm chances remain into the weekend, with scattered to widespread convection expected.

CAE WATCHES/WARNINGS/ADVISORIES

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