Tornado, flood threat looms this week

A slow-moving and massive low pressure system is expected to cause a wide variety of stormy weather across the Carolinas from Monday evening into Wednesday night.

Severe thunderstorms, tornadoes and flash flooding will be threats for the Charlotte region this week, and National Weather Service forecasters say it's a foregone conclusion that the area will be under various severe weather watches and warnings over the next few days.

"This will be a very active weather week," said Scott Krentz, of the National Weather Service office in Greer, S.C.

The severe thunderstorm and tornado threat began Sunday in the Midwest and is expected to shift eastward Monday into the Tennessee Valley and Mid-South. By later Monday, that threat will reach the western Carolinas.

"I think most of the day Monday will be OK, with a few showers around," Krentz said. "But things will start to degenerate around sunset Monday.'
The severe thunderstorm and tornado threat will be at its greatest in the Charlotte region from Monday evening through Tuesday. Forecasters say a warm front that will stretch east to west along the Carolinas border Monday morning will push slowly north during the day and evening. That front will be the focal point for trouble.

"The wind shear will really increase after dark and continue to be high during the night," Krentz said, referring to a weather condition in which winds blow from different directions at various levels of the atmosphere.

Often, especially during the warm season, thunderstorm activity dissipates in the evening, with the loss of daytime heating. That will not be the situation Monday night and early Tuesday, due to the advance of low pressure and the presence of the warm front. Krentz said areas north of Interstate 40 probably will escape the severe threat Monday night, but the warm front is forecast to push northward into Virginia on Tuesday, so all parts of the Carolinas will be at risk then.

The nature of the threat changes as we go through Tuesday, Krentz said. He said severe storm will remain a possibility, but repeated episodes of heavy showers and storms will cause a flooding threat.

"I think that we'll probably be under a flood watch by then," he said, referring to Tuesday and Wednesday.

Krentz said computer models indicate about 3.5 inches of rain will fall in Charlotte from Monday night until precipitation tapers off later Wednesday. About 4.5 inches is expected in the South Carolina Upstate.