Denver Ties Record For Summer Bad Air Days As Threat For Severe Weather Returns

DENVER (CBS4) - Wildfire smoke will be less prevalent along Colorado's Front Range on Friday but high levels of ozone will keep the air unhealthy and therefore another Air Quality Alert in effect. It's the 52nd alert of the summer which ties the record set in 2018.

Friday also marks the 40th consecutive day with an Alert going back to July 5th.

With ozone now being the only air quality problem, the alert is now limited to just Denver and the Front Range. Other parts of the state have been left out of the alert because p[pollution  and ozone is less of an issue.

The decrease in wildfire smoke it attributable to a shift in the upper level winds over Colorado. Instead of coming from the west they have been most of the week, Friday's upper level winds will be from the northwest which has effetely shut off the smoke plume from Northern California.

As the same time, the northwest flow will help transport thunderstorms that develop in the Colorado mountains (mainly east of the Continental Divide) toward Denver and the I-25 corridor Friday afternoon.

The best chance for thunderstorms in the Denver metro area is 3-8 p.m. During this time, one or tow storms may producing hail up to 1 inch in diameter and wind gusts up to 60 mph. There is a higher threat for severe weather in northeast Colorado including Greeley, Fort Morgan, and Sterling later in the evening.

By sunset, most of the storm activity should be east of the metro area where it could linger through midnight on parts of the Eastern Plains.

In addition to the chance for hail and wind, the thunderstorms will be capable of producing very heavy rain similar to what happened in the Highlands Ranch area Thursday night. Between 10 p.m. Thursday and 1 a.m. Friday, parts of Douglas, Jefferson, and Adams Counties were hit with torrential rain. A Flash Flood Warning was issued for most of Highlands Ranch due to 2-3 inches of rain falling over a very short period of time. There were reports of standing water on some roads in Douglas County trough 8 a.m. Friday.

For the weekend, plan on a very small chance for thunderstorms on Saturday (mainly in the mountains) followed by a better chance for thunderstorms in the high country on Sunday that have a 30% chance for of reaching Denver and the Front Range Sunday afternoon and evening.