Updated Thu Jul 26, 0001 11:30am MST | Published Tue Jul 26, 2022
- Cooler this week. Widespread, heavier storms in southern Colorado (the San Juans and Sangres). Scattered afternoon thunderstorms in the central mountains and parts of the northern mountains.
- Severe storm potential for the I-25 corridor and high plains on Wednesday evening.
- Warmer by the weekend, but still quite stormy. Again, southern Colorado is generally favored.
- Drier air doesn’t really arrive until Monday. There could be some smoke from California and Idaho wildfires arriving with this airmass.
Lightning Risk Grids
This weekend provided a welcome cooldown and some widespread rain and thunderstorms, particularly to eastern Colorado, which has largely missed out on the moisture this season.
Sunday was particularly hairy, as we were expecting. Satellites detected cloud-to-ground lightning strikes in some Colorado mountain ranges as early as 10am, though the heavier early morning moisture largely stayed north of I-70. Widespread precipitation later in the day caused flash flooding.
Despite the cooldown, the past few days have still been warmer than average thanks to the near-record temperatures preceding the weekend’s cold front.
Some large fires in California and Idaho have been dumping smoke into the atmosphere over the western United States.
Colorado has been picking up a small amount of this residual smoke, but has largely been spared. With the unfolding mid-atmospheric pattern this week, we’re afraid that may change by the weekend.
The ridge over the western United States has broken down, with Colorado getting some good relief from scorching temperatures. We’ll stay cooler through the work week thanks to a series of weak cold fronts today and Wednesday.
The pattern this week is pretty classic for monsoon season – low pressure over the Sonoran Desert / northwest Mexico, high pressure over the southern central plains. This establishes a conveyor belt of winds near the surface that will draw in lots and lots of moisture into the desert southwest and southern Colorado.
In addition to that stream of low-level moisture, we’re also getting some moisture in higher levels of the atmosphere from zonal flow across the area, thanks to the lack of strong ridging and a decent shortwave trough sweeping across the northern United States. This is kicking down the cold front today (with a secondary one tomorrow) and providing an additional source of lift and moisture. We’re thinking that Wednesday evening could get very interesting across eastern Colorado, even along the I-25 corridor – severe storms.
Thus, the story this week is widespread storms in the mountains, particularly in southern Colorado. Just about every afternoon into the coming weekend looks like a washout in the San Juans. Northern Colorado should fare better, but definitely not a good idea to hang out above treeline in the afternoon.
The above map shows that the San Juans, Sangres, and parts of the Front Range are likely to pick up copious amounts of moisture. Aside from northwestern Colorado, it should be a particularly wet week.
Much of this precipitation will come in the form of afternoon thunderstorms – so there still could be some sore losers. In the San Juans, be on the look out for low cloud decks, gloomy skies, residual showers, and isolated embedded cells in the mornings as well.
Ridging finally starts to reestablish itself for the weekend, though another shortwave could keep things interesting before the start of next week.
Generally though, high pressure looks to establish itself to our west which will cut off the flow of moisture into Colorado by Monday. This could also start drawing smoke into the region from our western and northern neighbors.
- Today: Widespread thunderstorms in southern Colorado, more isolated in central Colorado and northwards. A few severe storms on the plains.
- Wednesday: More of the same. The potential for another cool front our boundary to push down the Front Range opens the door for severe storm potential in the urban corridor and high plains after 4pm.
- Thursday-Friday: Again…more of the same. Widespread thunderstorms in southern Colorado and central Colorado. Temperatures remain cooler. Scattered thunderstorms in the northern mountains and on the plains.
- Saturday: A little more even distribution of storms across Colorado – scattered to widespread coverage in most mountain ranges. Starting to warm up a bit.
- Sunday: Warmer, with a drier airmass overhead. The drier air will be located over northern Colorado, so again, thunderstorm coverage favors the southern Colorado mountains. Still enough moisture most everywhere for decent storm coverage.
- Monday: Significantly drier, but likely enough moisture over southern Colorado for some isolated storm issues in the San Juans.