Colorado Weather Forecast #187: May. 14, 2022 - May. 22, 2022

Colorado remains mostly dry into the weekend and next week, but an impactful snow storm for the Front Range is possible next weekend, though perhaps not likely. We'll take a look at the current uncertainty and what would need to happen.

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Updated Fri May 13, 2022 2:30pm MST | Published Fri May 13, 2022

By Thomas Horner

Forecast Discussion - Next 7 Days

Windy and dry… We’ve been waiting for the hills around Golden to start really greening up, but that’s not happening. Quite the contrast from May of last year, which saw an impressive amount of precipitation and verdant hillsides that lasted into the start of summer.

Though the next week doesn’t feature any moisture-laden storm systems for our region, we are seeing some support for isolated thunderstorms as we progress into the third week of May. Here are a few visualizations from the Blend showing thunderstorm potential creeping up for northern and eastern Colorado:

Looking at global models, this doesn’t appear to add up to much. The Euro ensemble shows that most of Colorado has less than a 50% chance of seeing any precipitation over the next five days or so.

(via WeatherBell)
(via WeatherBell)

Still, high resolution modelling has been sniffing out better dynamics than the global models, so it’s likely this may be a little pessimistic. Even so, it would be hard to imagine we would be overcoming a precipitation deficit of this magnitude:

(via WeatherBell)
(via WeatherBell)

The melt-off is real right now, and with some added dust and plenty of sunshine, our snowpack seems to be disappearing at a rate faster than usual for this time of year.

Get your turns in while you can…

Potential Storm: May 21st-ish

Weather models have been sniffing out an impactful upper-level trough for next weekend which would swing through the western United States. Here’s a very idealized take on the potential setup:

(via WeatherBell)
(via WeatherBell)
(via WeatherBell)
(via WeatherBell)

Many deterministic model runs have been playing around with the possibility of lee cyclogenesis resulting in low pressure which could possibly be centered over southeastern Colorado. This would provide a nice upslope for the Front Range and help draw down some frigid air.

(via WeatherBell)
(via WeatherBell)

The above image shows the Euro ensemble for May 21st and the locations of centers of low pressure across its various ensemble members. The pink arrow shows roughly where we want this low pressure to be centered. You can see that it has quite a few model members with low pressure in that area, but lots of members which have it elsewhere (such as up near Denver) – quite a lot of disagreement and uncertainty.

Forecasts beyond 5 days are unreliable, so no surprise that we can’t get too much info about a potential system that is nearly 10 days out, and we are being careful to not explore any scenarios with too much detail as anything from a non-event to a decent snowstorm remains on the table.

That said, with most ensembles showing some general troughiness for the area by that weekend, it’s a fairly safe bet that Colorado, especially northern Colorado, will at least see a cooldown and more widespread precipitation chances. It’s also likely that eastern Colorado and the midwest could see some escalated severe storm threats.

As of now, we haven’t ruled out the upside scenario of a foot of snow in parts of the northern Colorado mountains, and some accumulating snow in the Front Range (including the I-25 corridor).

In fact, we’ve seen some pretty fun scenarios – these are HIGHLY UNLIKELY but worth mentioning if only for entertainment purposes – the caveat being that the current chance of snow in Denver has been hovering around 0%:

(via WeatherBell)
(via WeatherBell)

On the Euro ensemble, the control run has 10” of snow for Denver airport, which is an almost unbelievable scenario. The average of its ensemble members comes in at less than 2”, which considering snow-liquid ratios and melting, would be a negligible amount of accumulating snow. Still, just over half of the members are calling for at least a bit of snow, which bodes well for the possibility of colder temperatures and widespread precipitation.

Turning to the GFS ensemble, we’d like to make a shoutout to member #30 which has a 27” snow forecast for Denver airport:

(via WeatherBell)
(via WeatherBell)

That would easily crush Denver’s May snowstorm record, if it were even remotely possible…which it isn’t. More realistic is that the control run has a 0” forecast and the average across ensemble members also comes out to a negligible amount of snow. Overall, this ensemble is less optimistic about the chances for colder temperatures and precipitation.

If we consider these ensembles, in addition to the Canadian ensemble and some deterministic runs, we don’t get a particularly exciting picture. Namely, chances of accumulating snow in the lower elevations of the Front Range are basically nil when considering this morning’s model runs. That’s congruent with climatology for the region, at least.

In Denver, there have only been a few particularly significant snowstorms on record in the second half of May. Most recently was May 20-21, 2019 (3.7”) and May 26-27, 1950 (10.7”).

A lot of things need to come together for this to happen, but most importantly, the snow needs to fall during the nighttime hours. Even if we get a potent system lined up, if most of the precipitation comes during the day, it becomes extraordinarily unlikely to get accumulating snow down in the urban corridor.

In parts of the mountains, the picture is a little more solid. If we look at the Blend’s snowfall product, there is strong enough support for an upslope across various models that we’re actually already seeing some decent snow totals near and east of the Divide:

Most of the mountains further the west of the Divide remain more of a mystery, but areas from central Colorado and north could see some nice totals if this system pans out.

However, the above map has an important caveat: it is a blended average. When it generates the snowfall forecast, it takes an average of the input models. If there are models that are super snowy (which there are), this will bias the forecast towards an unrealistically snowy scenario.

So let’s take a look at the median. This would be the scenario if we threw out all the most and least snowy scenarios:

Not exciting at all, and belies the high likelihood that this system could just be a quick, glancing blow.

If there’s one takeaway from this: powder is certainly possible next weekend, but it’s anything from a sure bet at this point. Still, plan for a potentially impactful break from the heat and sun across northern Colorado.

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