textproduct: Columbia

WHAT HAS CHANGED

Removed today verbiage from Key Message and updated for recent convective trends. 00Z Aviation Discussion Updated.

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.

Radar this evening shows a line of showers and thunderstorms moving into the northwestern Midlands. A few other showers and thunderstorms are popping up along the sea breeze boundary in the southeastern Midlands. Convective activity should diminish quickly with the loss of daytime heating and remain below severe limits with a quiet, albeit muggy, overnight period expected and forecast lows in the mid to upper 70s.

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 /00Z WEDNESDAY THROUGH SUNDAY/

VFR conditions likely through the 24 hr TAF period.

Shortwave moving northward and into the western Midlands, along with some sea-breeze activity, could bring a few isolated showers to the central Midlands through 02z. Mentioned a Prob30 at cae/cub/ogb, and can not rule out a brief low end vfr or upper end mvfr visibility restriction if a heavier shower impacts any of those sites. Outside rain, conditions will remain vfr. Clouds will be on the increase this evening, mainly in the upper levels as convective blow-off from storms along a slowly moving cold front well off to our north streams into our region. This should keep any visibility issues late tonight to a minimum, especially since winds will not go calm overnight either as the front continues to slowly move southward. The front is still expected to remain to our north through the end of the current TAF period. Winds on Wednesday will once again pick back up and become rather gusty by late morning, with gusts back over 20 kts possible. 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.