Updated Thu Jun 23, 2022 4:00pm MST | Published Thu Jun 23, 2022
- Tough weekend above treeline due to extensive subtropical moisture and large-scale lift from a disjointed upper-level system. Lots of lightning potential.
- Significant cold front, especially east of the Divide. For the weekend, highs along the I-25 corridor may top out in the 70s, with the coolest temperatures on Sunday.
- Upslope precipitation associated with this front makes widespread thunderstorms and precipitation along and east of the Divide fairly likely on Saturday and Sunday afternoons.
- Lesser impacts to the north of Denver.
- Otherwise, greatest thunderstorm chances remain in the San Juan mountains and Sangres. New Mexico is expected to pick up copious amounts of precipitation.
- Similar forecast through the following weekend – quite the start to the monsoon!
Lightning Risk Grids
Retrospective and Current Conditions
As much of the United States bakes under unseasonably hot weather, Colorado (at least west of the Divide) and New Mexico are enjoying cooler, wetter weather.
You’ll also notice cooler temperatures over the Great Basin (Nevada) and the Pacific Northwest. These are a result of a disjointed upper-level low that will swing through the western United States this weekend and bring a significant cold front to Colorado and enhanced thunderstorm chances.
As it stands, high pressure to our east has allowed for subtropical moisture to surge northwards into the desert southwest. A tropical storm has developed off the coast of Mexico which is helping keep that high pressure where it is in addition to providing another source of moisture.
This week, the biggest beneficiary has been New Mexico. A large proportion of the state has received over an inch of liquid precipitation over the past few days.
The rain and high humidity has helped quell New Mexico’s largest recorded wildfire (Hermits Peak fire), with current fire activity limited to areas of smoldering. Containment and control is far from over, but the situation looks much less dire than it did earlier this month.
Some of that precipitation made it into far southern Colorado, but only barely. In our past forecast we had hoped it would make it a bit further north.
Forecast Discussion: The Weekend
Another stormy weekend is on tap as a significant moisture plume remains planted over the desert southwest.
Again, New Mexico will likely be the biggest beneficiary. For Colorado, the largest impacts will continue to be in the San Juan mountains and Sangres, with more isolated to scattered activity in the rest of the high country.
A disorganized upper-level wave is currently moving across the western United States, with a couple of closed lows embedded in it.
A potent cold front associated with this system will push into Colorado on Friday night / Saturday morning. The most notable cooldown will be east of the Divide. By Sunday, the cold airmass will have made it all the way into New Mexico.
In the lower elevations of the Front Range, Saturday’s high temperatures may still get into the upper 70s and 80s. However, cold air is expected to continue to work its way into the region and by Sunday, high temperatures in Denver may only top out in the low 70s! Ensembles and blended guidance suggest it may be more like the mid 70s – we’ll see.
There’s a good chance that parts of the high country could get below freezing at night. In general, stronger storms at higher elevations may leave a dusting of snow to contend with this weekend.
Model guidance shows widespread precipitation on Saturday afternoon across the Front Range as a moist easterly upslope sets up behind the front.
The Blend suggests decent agreement for this idea across various models and ensembles.
In short – another nice weekend of rain and lightning for New Mexico and parts of Colorado and Arizona, with impacts continuing into next week.
Lift ahead of the approaching system makes for an interesting thunderstorm scenario on Friday in western and northern Colorado. There is good model agreement suggesting isolated strong thunderstorms could be mature well before noon especially near the Flat Tops, Park Range, and West Elk mountains.
Otherwise, thunderstorm coverage looks fairly scattered and evenly distributed across Colorado’s high country. The I-25 corridor’s convective environment doesn’t look that great, so likely not too much action, but there is potential for severe storms along a dryline in eastern Colorado.
On Saturday, the action is focused on southern Colorado (due to the moisture plume) and along the Divide (due to the upslope and cold front). We’re not expecting areas much further north than the Denver metro area to see much activity.
If you plan on recreating above treeline, the western ranges (Elk Mountains, Flat Tops, Park Range) are your best bet. Use extra caution in the San Juans, Sangres, and Front Range.
A lot more uncertainty in the Sunday forecast, but likely similar to Saturday, though most of the impacts may be south of the Palmer Divide.
Again, use extra caution in the San Juans, Sangres, and Front Range if you’re going above treeline.
Forecast Discussion: Next Week
We’ll launch into next week with a pattern that continues to promote monsoonal moisture surges like what we’ve been experiencing.
Currently it looks like high pressure to our east may move westward a bit. By mid next week, this will push the best moisture further west, into Arizona, Utah, and southern Nevada, so relatively less thunderstorm activity is expected in Colorado on Tuesday.
High pressure then looks to move back east a bit (or possibly break down some) and reposition subtropical moisture squarely back over New Mexico and Colorado for following weekend.
There’s good support in the ensembles for the desert southwest to remain rainy and cooler than average into the start of July.
However, we’re finally seeing some more tangible disagreement in the longer-term forecast. Some guidance has this pattern breaking down as we progress into July, but that notion seems to currently be in the minority.
We would continue to plan for decent impacts from the monsoon over the next few weeks, but it’s likely that those of us to the east of the Divide may not get much of that – warm and dry could generally be the prevailing conditions along the I-25 corridor beyond some weak thunderstorms here and there.