Colorado Weather Forecast | Apr. 27 — May 2, 2021
Snow and severe thunderstorms from Tues afternoon to Weds morning, warm weekend.
Hello everyone. Hopefully the return to spring was a welcome change after a rather dreary week (at least in the Front Range). Some parts of northern Colorado picked up quite a decent amount of snow before the weekend began, and the skiing — or climbing — conditions were truly wonderful. Spring provides so many options!
Here’s a basic overview of the storm chances we will discuss in this article:
On the Front Range, we’ve likely hit our maximum snowpack for the year, unless tomorrow’s storm truly delivers, which may happen.
Elsewhere, the melt has continued fairly unabated. For instance, in parts of the San Juans, we’re almost halfway melted out!
The snowpack anomaly chart (blue = above average, red = below average) shows consistently below-average snowpack across the state. However, the mountains on the east side of Summit County, including A-Basin, Loveland, and Winter Park (circled), look to have more snow than usual.
The other blue areas are mostly just lower elevation slopes that usually have little to no snow this time of year, but picked up some snow from our recent storms. We also see some higher elevation spots of above-average snowpack near the Aspen resorts and in the Wet Mountains, Ruby Range, West Elks, Cimmarons, and far northern Sangres.
Our weather for the week and weekend features two main events.
A closed low dropping well to our south brings precipitation chances from Tuesday afternoon to Wednesday morning, and then a very strong ridge builds over the Mountain West as we get into the weekend.
Temperatures should come as no surprise: a midweek cooldown, followed by almost record high temperatures for the weekend.
Parts of Colorado have the potential to get into the 90s on Sunday, with 80s for the urban corridor. Even the high elevation mountain towns could hit the low 60s.
We are getting ahead of ourselves. That closed low on Tuesday should cause a center of low surface pressure to deepen in southeastern Colorado. This will drive a decent upslope snow storm for the Front Range which would last from Tuesday afternoon to Wednesday morning.
We aren’t seeing enough cold air being drawn in for snow accumulation to be a major concern east of the foothills, though the Palmer Divide (Castle Rock) is a bit of a mystery. Right now, the Blend mostly calls for entirely rain east of the foothills.
The HRRR does bring a few inches onto the Palmer Divide, and we’re a little more inclined to go with its guidance.
Regardless of precipitation type, a respectable amount of water will fall across northeastern Colorado. Like our recent storms, the Front Range foothills and mountains near the Divide will likely pick up the best totals, especially when it comes to snow.
Some of those higher totals in far northeastern Colorado reveal our potential for severe storms tomorrow. The Storm Prediction Center has issued a “Marginal” risk (the first of the season) for the region, which means there’s a small chance of damaging hail and even a tornado or two.
This will become a more regular phenomenon as we get into May. Thunderstorms are very likely across the entire state, thanks to an unstable atmosphere, but severe storms will be limited in size and quantity by the lack of convective inhibition that helps them build up their energy before explosively releasing it.
On Tuesday, we have a few things occurring before the upslope storm really starts:
- Jet dynamics and strong southwesterly upslope will get snow going in the San Juans early Tuesday morning.
- The frontal boundary could kick off some strong thunderstorms in northeastern Colorado (just east of the urban corridor) before noon, as early as 10am.
- Widespread thunderstorm development occurs over the mountains by noon, with precipitation falling as snow at the higher elevations
By the late afternoon or early evening, the northeasterly upslope begins to kick in as lee cyclogenesis strengthens low pressure to the east of the Divide.
As a whole, it should be quite the display! By Wednesday afternoon, we’ll just be left with some isolated thunderstorms.
Snow totals should be quite decent for many areas in the foothills and the Divide. The snow exceedance chart below is fairly loaded, considering this is primarily a 12–18 hour event.
The Blend’s deterministic snow forecast is even more optimistic, with 12–24" throughout the foothills and 5–15" for most mountains.
This is likely a bit overdone, as we don’t think the storms earlier in the day on Tuesday will be consistently productive, and we also think the wraparound moisture is being over-forecasted. Still, some areas have very good chances at exciting snow totals.
Here’s what we’re thinking:
- Winter Park, Berthoud Pass, Jones Pass: 8–15"
- A-Basin, Loveland: 6–12"
- Breck (Ski Resort), Copper: 5–10"
- Longs Peak: 10–20"
- Mt. Evans, Mt. Bierstadt: 7–13"
- Hidden Valley: 5–10"
- Cameron Pass: 6–12"
- Buff Pass: 4–8"
- Hoosier Pass: 5–10"
- Vail Pass: 4–9"
- Independence Pass: 4–8"
- Red Mountain Pass: 3–6"
- Denver, Boulder, Ft. Collins, Colorado Springs: 0–1"
- Foothills: 6" (above 6000ft) — 18" (below 10,000ft)
Note that some of this snow will come after resorts report their morning totals.
We quickly warm back up for the rest of the week, with minimal clouds and thunderstorm chances in the forecast until the weekend. Some gustier conditions are possible on Thursday as warm air advects back into the state, but overall, winds will be fairly light through the weekend, besides the outflow gusts from isolated storms.
We do see some isolated thunderstorm chances this coming weekend, mostly for the Front Range mountains — keep this in mind if you’re heading above treeline.
Be aware of gustier conditions on Sunday as a weak jet max crosses over the state ahead of a weak trough which brings snow and more widespread thunderstorms back into the forecast for early next week. Stay tuned.
Thomas Horner (Twitter: @thomaschorner)
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