Heavy rainfall, tennis ball-sized hail, flash floods possible Thursday across northeastern Colorado, NWS says

DENVER – Morning showers will intensify later in the day, bringing with them the possibility of heavy rainfall, tennis ball-sized hail, flash floods and isolated tornadoes as they move east across the Denver metro area into the plains Thursday afternoon, according to forecasters with the National Weather Service (NWS).

Two separate “waves” of storms will push through the northeast part of the state Thursday, with the first starting at around noon for the mountains to the Foothills, then entering the Urban Corridor and plains by 1 p.m. A second wave will then produce a “short wave” of widespread showers and thunderstorm in the northeast plains through the afternoon and into Friday morning, with the potential of flash flooding and brief heavy rainfall.

Washington and Lincoln counties, from Akron all the way to La Junta and eastward, were at an enhanced risk of flash floods from three or more inches of rainfall, while the rest of the northeast plains, including Denver, were under a marginal or slight risk of flash floods occurring, as 1.5-2.5 inches of rainfall were expected, forecasters said.

A flash flood watch will be in effect for both Lincoln and Washington counties from 2 p.m. through 10 p.m. Thursday.

Burn scar areas, including the Cameron Peak, East Troublesome and Williams Fork burn scars, are under elevated risk of flash floods from widespread showers, the NWS said, with the risk dropping back to limited for Cameron Peak.

The greatest threat of tennis ball-sized hail up to two-and-a-half inches in diameter, very heavy rain and damaging winds, as well as isolated tornadoes were expected east of a line from Akron to Deer Trail to Castle Rock. The Denver metro was under a “slight risk” of these events occurring, according to the latest forecast from the NWS.

National Weather Service in Boulder

“The storms will decrease from northwest to southeast across the region by late this evening, but residual showers/storms may linger over the far eastern plains overnight,” the NWS said in a late morning forecast discussion. “In addition, the models suggest the potential for stratus/fog late tonight, which could impact portions of the urban corridor Friday morning.”

Warmer and drier weather will return starting Friday with only a few afternoon thunderstorms, according to Denver7 meteorologist Lisa Hidalgo.

The weekend should be hot and dry with highs back in the mid 90s.

Heavy rainfall, tennis ball-sized hail, flash floods possible Thursday across northeastern Colorado