textproduct: Columbia

WHAT HAS CHANGED

Showers and thunderstorms have developed across the forecast area and will continue overnight. Aviation discussion updated for 00Z TAF.

KEY MESSAGES

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

DISCUSSION

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

Tonight: Showers and thunderstorms continue to develop over the forecast area in a strongly unstable air mass. PWATs remain anomalously high, with mesoanalysis above indicating above 2 inch PWATs. Storms have been exhibiting occasionally somewhat strong downdrafts with winds generally in the 30 to 40 mph range, well below severe limits, as storm heights remain relatively low with much of the instability in the low levels and skinny CAPE profiles in the mid to upper levels. Flash flooding remain somewhat of a threat. Currently there is a Flash Flood warning across western Orangeburg and Calhoun counties. The possibility remains under some training storms through the remainder of the night before storms diminish early tomorrow morning.

Pattern changes a bit tomorrow with an upper trough strengthening over the eastern US which will weaken the ridge offshore, leading to lower moisture with more westerly flow over the area. While there will still be moderate destabilization each afternoon Wednesday and Thursday, coverage will likely be more isolated each day with seasonably hot and humid conditions. A front will approach the area this weekend leading to the potential for more widespread showers GEFS probabilities of sbCAPE greater than 500 J/kg, on the low side for late May. Cooler temperatures generally expected as well, although there remains significant spread in blended guidance owing to uncertainty in the location of the front.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

A mix of MVFR and VFR cigs this evening as convection moves through. Shower/storm chances diminish overnight, but another round of morning cig restrictions possible.

Scattered showers and storms will continue to move through the area this evening, with the primary hazards being reduced visibilities in heavy rainfall and occasional gusty winds around 25-35 kts. A few thunderstorms cannot be ruled out with a strong line currently moving in and around CAE, CUB, and AIK. For now, a TEMPO group is in there until 04Z. Lingering MVFR ceilings remain at a few places across the CWA. Convection is expected to gradually diminish overnight, with mostly dry conditions anticipated. However, abundant low-level moisture remaining in place will support another round of cig restrictions into early Wednesday morning. Confidence remains a bit uncertain as of now, though at least periods of MVFR cigs appear possible roughly after 06-08Z. Skies should slowly improve, with VFR returning along with southwest winds around 5-8 kt. Another round of showers and storms may develop during the afternoon and evening tomorrow, but confidence remains too low for TAF inclusion at the end of the current forecast period.

EXTENDED AVIATION OUTLOOK...Morning fog/stratus possible each day this week. Scattered, diurnally driven convection expected through Friday.

CAE WATCHES/WARNINGS/ADVISORIES

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