textproduct: Columbia

WHAT HAS CHANGED

Precipitation chances trending downward over the next few days ahead of a cold front this weekend.

KEY MESSAGES

- 1. Daily shower and thunderstorm chances continue through the week, with isolated flash flooding possible.

DISCUSSION

Key Message 1: Daily shower and thunderstorm chances continue through the week, with isolated flash flooding possible.

Showers and thunderstorms have started to weaken and diminish over the region with conditions winding down as we head into the early morning hours. A warm and moist air mass will remain in place as most of the southeast continues to be under a deep southerly flow regime between the Bermuda High and and upper low over the Mid-South. PWATs remain anomalously high, with current mesoanalysis indicating above values at or above 1.5 to 2 inches. This moisture plume will continue to feed into a stationary front to our north.

The pattern changes a bit starting today with an upper trough strengthening over the eastern US which will start to weaken the ridge just offshore, leading to lower moisture with more westerly flow over the FA. Each afternoon and evening could still have the chance for showers and thunderstorms due to moderate destabilization remaining in place, however, coverage will likely be more isolated when compared to previous days. While the severe potential should remain limited, deeper convection could produce heavy downpours dropping a quick inch or two, and isolated minor flooding. Seasonably hot and humid conditions will persist through the end of the week.

Rain chances will increase as a front approaches the area this weekend leading to more widespread showers. It is then expected to stall in the vicinity through the majority of the weekend, with the potential for a weak surface low to develop along the front. Cooler temperatures generally expected as well, although there remains significant spread in blended guidance owing to uncertainty in the location of the front. Drier conditions may briefly return, but there is not a signal for more robust drying until at least after Sunday.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

Ceilings will trend downward early this morning with showers tapering off.

Light showers will continue to move through the area early this morning but are expected to diminish through 12Z. Abundant low- level moisture will support another round of cig restrictions with IFR or LIFR conditions possible. Highest confidence in MVFR ceilings at all sites after 09Z with lowest cigs around 12Z. Patchy fog is also expected but should be a secondary impact to aviation.

Ceilings should slowly improve from 12Z to 15Z, with VFR returning by 18Z along with southwest winds from 5-8 kt. Another round of convection will develop during the afternoon but overall coverage is expected to be lower than the past few days. Highest confidence remains at OGB which will be closer to the sea breeze and the greater projected activity. Storms should linger into the evening. With continued moisture over the region, early morning fog and/or stratus will remain possible on Thursday morning.

EXTENDED AVIATION OUTLOOK...Morning fog/stratus possible each day this week. Scattered, diurnally driven convection expected through Thursday until a front moves into the region significantly increasing rain chances.

CAE WATCHES/WARNINGS/ADVISORIES

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