textproduct: Columbia

WHAT HAS CHANGED

Removed a Key Message to focus more on the approaching front. Guidance continues to trend toward a slower frontal progression.

KEY MESSAGES

- 1. A slow-moving front will approach late tomorrow into Thursday, bringing scattered to widespread rain/storm chances. Active weather persists into the late week.

DISCUSSION

Key Message 1: A slow-moving front will approach late tomorrow into Thursday, bringing scattered to widespread rain/storm chances. Active weather persists into the late week.

Slightly drier air has filtered into the area today with lower PWATs and dewpoints mixing out into the upper 60s to lower 70s. As a result, forcing remains limited with afternoon temperatures climbing into the mid-90s. CAM guidance continues to indicate limited coverage, with a modest cap in place and high LFCs suppressing storm development. That said, cannot completely rule out isolated pulse showers/t-storms this evening.

A weak front will settle toward the area on Wednesday, bringing increasing low-level convergence and improved large-scale forcing. However, guidance continues to trend toward a slower frontal progression, resulting in a slightly warmer forecast with only isolated to scattered convection expected during the late afternoon. Rain and thunderstorm coverage should increase Wednesday night into Thursday as the front moves in. The primary uncertainty remains the later timing, which would reduce the overlap between the strongest forcing and peak instability. If trends continue, the severe threat may continue to diminish.

As the front stalls out on Thursday, another round of stronger convection may develop. Regardless, the greater concern appears to be the potential for heavy rainfall from late Wednesday through Thursday. PWATs exceeding 2" and relatively skinny CAPE profiles will favor efficient rainfall rates, while the stalled boundary could support training convection. The ECMWF remains the most aggressive solution, with the overall environment supporting a heavy rainfall setup. That said, it remains uncommon for a front to push this far south in late July, so continued downtrends are anticipated but this will be monitored.

The boundary is expected to linger across much of the area through Friday, as another shortwave approaches maintaining scattered to widespread shower and thunderstorm chances. Forecast confidence decreases into the weekend, but the overall pattern remains favorable for unsettled weather.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

VFR conditions likely through the 24 hr TAF period.

With drier air over the region today, convective coverage will be low enough to limit the chance of showers or storms at any of the TAF sites. Expect breezy SW winds today with gusts around 20 kts. Gusts should subside around 03Z but winds will stay up around 5 to 10 kts overnight as a front slowly approaches the Southeast. The front will remain to our north through the end of the TAF period. SW winds will pick up once again Wednesday morning with gusts around 20 kts. A few patches of MVFR ceilings may be around on Wednesday morning but VFR conditions remain the most likely scenario. Much of the convective activity associated with the front should remain north of the TAF sites through the end of the TAF period.

EXTENDED AVIATION OUTLOOK...Restrictions from showers and thunderstorms likely beginning Wednesday night through late this week.

CAE WATCHES/WARNINGS/ADVISORIES

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