Tropical system could bring flood threat

This is a quick post, as I'm trying to handle a few other stories early this afternoon.  I'll try to post something more in-depth later in the day.

But the bottom line is that we'll have to watch for a possible significant heavy rain threat Thursday and Friday across the Charlotte region. The culprit will be a tropical system forming near Florida, but there are other players involved.

A moist pattern already is established across the area.  We saw that with the 4-inch rainfall late Sunday and early Monday in parts of the Charlotte region.

By Thursday, it looks as if moisture will be streaming northward from the tropical low.  The question is exactly where the heaviest precipitation will fall, and that depends on the track and strength of the low.

A strong and well-organized tropical low will bring heavy rain near the storm's center.

A less-organized system -- which is what's expected -- will spread the heavy rain over a wider area.

Most of the computer models predict the system will go up the Carolinas coast, which would mean widespread heavy rain in the eastern half of the state.  But some pockets of flood-producing thunderstorms would develop in the Piedmont.

Further complicating the picture is a cold front that is forecast to cross the mountains by Friday. That would add lift in the atmosphere and possibly bring strong storms to the mountains and foothills.

One of the models, the NAM, predicts rain of 4 to 6 inches Thursday and Friday in the Charlotte region. The NAM forecasts the tropical low will take an inland route across the Carolinas.

Justin Lane, a meteorologist at the National Weather Service's office in Greer, S.C., says the NAM has a history of predicting tropical systems will veer too far inland.

But one or two other models are trending more inland with the storm's track.

Stay tuned.