textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 12z TAFs.

KEY MESSAGES

- 1. Diurnal showers and thunderstorms, some strong, each day.

- 2. Increasing heat and humidity is expected next week.

DISCUSSION

- 1. Diurnal showers and thunderstorms, some strong, each day.

More of the same pattern is expected through the weekend and well into next week. Onshore surface flow, in conjunction with a strong Bermuda high over the western Atlantic will continue to provide significant low-level moisture to the region. Shower and thunderstorm coverage should begin to decrease this weekend, with the focus shifting closer to the coast as the ridge begins to flatten. However, dewpoints are expected to remain in the low to mid 70s over the next several days. Daily SBCAPE values should also remain more than sufficient to support diurnal chances for showers and thunderstorms, so the potential for additional convection will remain despite the overall decrease in coverage. Strong storms are capable each day, as sufficient CAPE will support the potential for wet microbursts within the strongest convection.

Upper-level ridging is expected to strengthen by next week, which should help keep shower and thunderstorm coverage generally isolated, though daily storm chances will remain possible. There is also a signal, albeit an inconsistent once, that a deeper trough could move into the eastern CONUS towards the end of next week, potentially increasing storm coverage once again.

- 2. Increasing heat and humidity is expected next week.

A low amplitude upper level ridge is forecast to begin developing over the next several days, with 90th percentile 500 hPa heights overspreading the area by Sunday. With southwesterly flow common and afternoon storm coverage expected to lower a bit by early next week, afternoon highs are forecast to bump up into the mid 90s. With persistently high dewpoints in the low to mid 70s, LREF guidance continues to indicate a high likelihood of daily, peak heat index value exceeding 100F. While this isn't at heat advisory criteria, it isn't crazy to think we may have a day or two next week where we approach 105F-108F for afternoon heat index values. Be sure to practice good habits when dealing with the heat next week!

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Brief restrictions possible this morning.

Satellite imagery is indicating patchy fog and stratus across the region over the last couple of hours. It appears to be increasing in coverage, but isn't impacting all of the TAF sites currently. Will leave in a tempo group to account for some briefly reduced CIGS/VSBYs for the next couple of hours. Given the lack of rain at the terminals yesterday, expect restrictions to quickly ease back to VFR for much of the rest of the day. Calm winds are expected to increase to light SE 5 to 10 kts into this afternoon. Shower and thunderstorm coverage today seems to be less than the past few days, with the best chance at OGB. Have handled the potential for -TSRA with a PROB30 there, and only VCSH at the other terminals where confidence is lower. Guidance is hitting the restrictions a bit harder for tonight, but it may again be dependent on where any heavier pockets of rain fall today. Hedged only slightly on some reduced VSBYs tonight at AGS, but this may expand to the other terminals with subsequent forecasts.

EXTENDED AVIATION OUTLOOK...A seasonal pattern of early morning restrictions and diurnal thunderstorms is likely through much of the extended.

CAE WATCHES/WARNINGS/ADVISORIES

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