Heavy rainfall, possible flooding forecast for today, Thursday

A flash-flood watch was issued for Southwest Colorado, northwest New Mexico and southeast Utah from noon Wednesday into the evening as thunderstorms with potentially heavy rain move into the region.

The National Weather Service said flash flooding could occur in slot canyons, normally dry washes and small streams, as well as in urban areas with poor drainage. It also warned of the potential for mud and rock slides in mountainous terrain.

Weather forecasters also are predicting excessive rainfall Thursday and Friday across much of the Four Corners as a result of monsoon moisture and instability in the atmosphere.

Forecasters had anticipated issuing the flash-flood watch, and also expect to issue a warning by Thursday, when the heavier rains are expected to fall, said Dennis Phillips, meteorologist with the National Weather Service in Grand Junction.

“This is just kind of a heads-up,” he said Tuesday.

“We’re just kind of getting people aware of what’s coming their way Thursday.”

It was too early to say how much moisture specific areas may receive, but it is likely isolated areas will receive torrential amounts, similar to what Durango experienced Monday afternoon, Phillips said.

“There’s a good chance that it will rain, and when it rains, it’s going to be efficient,” he said.

Montezuma County forecast


Wednesday: Partly sunny and a 70 percent chance of showers and thunderstorms after noon, with a high near 82 degrees and an overnight low of 52.Thursday: Cloudy, with a 60 percent chance of showers and thunderstorms after noon,  a high near 78 and a low of 56.Friday: Mostly cloudy, with a 50 percent chance of showers and thunderstorms,  a high near 77 and an overnight low of 54.Saturday: Partly sunny, with a 30 percent chance of showers and thunderstorms, a high near 78 and a low of 54.Sunday: Mostly sunny with a slight chance of showers and thunderstorms, a high near 81 and a low of 54.Durango received 0.38 inches of rain during the 24-hour period ending at 8 a.m. Tuesday, said Corbin Wrinkle, a local weather observer for the National Weather Service.

The moisture expected later this week will be aided by a “trigger” in the atmosphere, essentially a disturbance or a spin that will help stir thunderstorms.

“It’s just a piece of energy up there that is going to help focus thunderstorms and drive them,” Phillips said.

“It’s like an area of enhanced vorticity.”

The monsoon


The weather service as attributed to rain to the monsoon, a seasonal phenomenon in which winds start coming from the south instead of the west. Then, as high pressure sets up in the Southwest, winds help pull water into the region from the Mexican and Californian gulfs. And because of solar heating, a thermal low develops over the desert Southwest, which helps to pull even more rain into our area. As these two events interact, we get our familiar, seasonal pattern of almost daily thunderstorms.

The (Cortez) Journal contributed to this article.