textproduct: Columbia

WHAT HAS CHANGED

Updated 12z 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 /12Z SATURDAY THROUGH WEDNESDAY/

IFR/LIFR Ceilings in place with improvement to VFR expected this afternoon.

Widespread IFR/LIFR ceilings visible on satellite imagery this morning with lingering low level moisture and a stalled weak front. Ceilings will slowly improve after sunrise with restrictions hanging into the afternoon. Patchy visibility restrictions possible as well but the dominant restrictions will be low ceilings. Isolated storms possible this afternoon but confidence is too low to include in TAFs at this issuance as drier air aloft will continue to move into the area. Widespread restrictions tonight appear unlikely, although will need to monitor how quickly drier air moves into the area.

EXTENDED AVIATION OUTLOOK...Isolated storms each afternoon with higher coverage of storms expected by midweek.

CAE WATCHES/WARNINGS/ADVISORIES

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