Rain is on the way to the Rock Hill region. How long will it last?

More than 4 inches of rain could fall this week across the Rock Hill area, forecasters say, raising the possibility of flash flooding.

Meteorologists say showers and thunderstorms will move into the region by late Monday afternoon, then continue into Friday.

The culprit, they say, will be a strong upper-level low pressure system that is predicted to drift southward from the Great Lakes on Monday, then stall across Tennessee for several days.

The rain threat is not directly connected with Tropical Storm Arthur, which is expected to pass the North Carolina Outer Banks on Monday.

“It’s going to rain, perhaps excessively, across the western part of the Carolinas on Tuesday and Wednesday,” says National Weather Service meteorologist Pat Moore.

“Waves of rain should be expected to continue into Thursday,” Moore adds.

The government’s Weather Prediction Center has the Rock Hill area in a “Slight” risk of flash flooding Tuesday and Wednesday. That’s the second-highest of four risk levels. The foothills are in a “Moderate” risk zone -- third-highest of the risk levels.

Flood watches are likely to be issued for Tuesday and Wednesday across at least parts of the western Carolinas, meteorologists say.

“The current thinking is that the potential for flooding does not start to rise until after sunrise Tuesday,” Moore says.

As might be expected with the clouds and precipitation, temperatures will retreat over the next several days. Highs are expected to be in the 70s, except Wednesday, when an infusion of cooler air from the north will combine with the clouds to hold high temperatures to the low and mid 60s.

Moore says a break is likely in time for the Memorial Day weekend.

He says the low pressure system is expected to move from the Southeast into New England on Friday, gradually taking rain chances with it. Moore says a few showers and thunderstorms are possible Friday, but a gradual drying trend will take hold.

Sunny skies are forecast for Saturday and Sunday, with high temperatures returning to the 80s.

Steve Lyttle on Twitter: @slyttle

This story was originally published May 18, 2020 at 10:05 AM.