Highpoint Weather Blog

Retrospective

Two systems brought snow to Colorado over the past week. From Wednesday to Saturday, a strong closed low produced heavy bands of snow across much of the stated.

We fretted about the small-scale forecast as banding and instability would produce localized booms and busts. Overall, our forecast was conservative so almost everywhere came into range (except parts of central Colorado), with a few booms where the best banding set up.

One of these booms was the Front Range, where a few strong bands jumped the Divide and brought several inches of snow to Denver and Boulder, where we were only expecting a couple inches. Summit County also saw some of the best banding from this storm and totals were better than expected.

On Saturday, another trough to our north brought northwesterly flow which ended up being quite productive -- we didn't cover this (we're still writing a bunch of code to get our models and visualizers set up for this season) which was a shame as quite a few more inches of snow fell across northern Colorado.

Estimated Snow Total Maps

Here are some estimated snow totals from the two systems. The Sangres are a little too high as radar-estimated precipitation was fairly messed up.

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We're doing well so far this season, with most of Colorado's mountains holding onto a deeper snowpack than average. This is one reason why we don't tend to speculate too much about La Niña and other climatology, as a good storm or two will completely upset the balance. However, we'll see where we are come mid-December -- climatology would suggest a slower start to the season, particularly in central and southern Colorado.

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Forecast Discussion

Colorado is currently experiencing temperatures 5-15 degrees above average as a strong storm impacts the Pacific Coast.

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This storm is currently stalled over the coast and digging southwards. Some western mountain ranges (such as the Sierra Nevadas) are expecting feet of snow, and temperature anomalies in the northern Rockies are as extreme as 50 degrees below average.

Unfortunately, this storm will lift quite a bit when it eventually begins its eastward journey towards us.

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Unless this digs quite a bit further south (which models agree wont happen), Colorado will be in an unfavorable jet quadrant as the system approaches, with upper level dynamics only looking decent from Wednesday evening to Thursday morning.

On top of that, there isn't much moisture to work with -- a narrow plume of deeper moisture will be advected across Colorado during that Wednesday evening to Thursday morning timeframe, with much drier air in place outside of that window.

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This setup favors western Colorado, but overall, it may be a matter of 6" vs 3".

That said, there will be northwesterly flow in place into Saturday, which is why our snow forecast extends out to that date -- but this likely be very unproductive, with only some pockets of light snow which may add another inch or two to the final total over the course of late Thursday through Friday.

Perhaps more significant will be the winds associated with this storm, especially on Wednesday. Gusts of 50-80mph are expected across the mountains. Gusts of 40-80mph will hold on along the Divide into Friday.

Thursday will be quite cold as the system's airmass enters the state, with lows well into the negatives in the mountains on Thursday and Friday night.

With that in mind, here are our snow forecast maps:

Snow Forecast Maps

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The Weekend

The weekend will remain on the cold side (highs in the 20s to low 30s in the mountains) with some lingering wind, but generally drier. We're seeing a weak shortwave that could impact Colorado on Sunday, which may bring a couple inches of snow to northern Colorado that night.

Next Week

Models are in strong disagreement about what may happen early next week. By strong disagreement, we mean operational runs are showing anywhere from literally nothing at all to over a foot of snow.

Ensembles are showing a weak troughing signal for early next week which means it's likely we'll see some sort of storm on Monday night. Guidance leans towards this being a southwesterly flow event with the San Juans favored, but this almost entirely speculative as guidance is all over the board right now.

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Let's see how guidance improves after this encroaching storm clears our region -- but the takeaway is that we may get some healthy snow by mid next week, and the pattern remains unsettled.