A developing winter storm is taking aim at Colorado, and it has the potential to be the biggest snowstorm of the season so far, for Denver. The El Niño weather pattern has delivered storms right into our ‘sweet spot’ a few times since November, but Denver has only officially registered more than 3 inches of snow three times.
It will take about 8 inches to take the title. That would beat the 1-day storm total from the middle of December.
Denver’s only storms this season to measure more than 3 inches of snow:
7.7" December 15
4" November 16-17
3.5" January 7-8
This storm has great potential, but it comes with several uncertainties. The available moisture is high, and the storm track is projected to be in just the right location, but any course deviation by the storm will change the areas of greatest snowfall. In the coming days, as the storm takes shape, specific details will become more evident.
February is Denver’s 5th snowiest month, averaging 7.5 inches of snow. We have a good chance to get that on the first day this year.
The end of this winter is shaping up to be well above average for snowfall, and that just leads us right into Denver's real snow season, the spring. Twelve of Denver’s top 24 snows of all-time have come in March and April, and those are the two snowiest months on average. The El Niño pattern increases the chance of above-average precipitation in the spring, and lends itself to large scale events, instead of gradual accumulation. So you may hear plenty more hype about approaching storms over the next 3 months.
In the fall, FirstAlert Weather meteorologists reported that the El Niño would favor southern storm tracks. These tracks favor snow on the Colorado Front Range. The I-25 corridor is actually on the lee side (dry side) of the Rocky Mountains, so we need an easterly wind (upslope) to counter that general flow of wind in the U.S.
It’s called a ‘4-Corners Low’ by most meteorologists. The counter clockwise flow wrapping around that low pressure is what delivers that upslope wind. The projected path of this storm is really in the perfect spot, so why don't we just come out and say Denver will get 18 inches?
I wish it were just that easy, but it’s not. There is a whole symphony of variables that also must come together. How deep will the low be, or how tall, in other words? If the surface low works in conjunction with the upper low, there is stronger upslope. Speed. If the storm moves slowly across the bottom of Colorado, we will have a longer period of time to create snow showers, so more snow. If the low tracks just 50 to 100 miles further south, which isn’t much on this scale, those easterly winds don’t get to push up against the Colorado Rockies. Just to name a few.
Global or long range forecast models are relied upon for early development. Those computer models are calling for a lot of moisture. A spread anywhere from 6 to 12 inches in the Denver metro, and 12 to 24 in the mountains. Models are also calling for a huge coverage area. Giving most of Colorado at least 3 inches of snow. The bulk of the storm will be Monday and Tuesday for the lower elevations.
As the storm actually starts to take shape, meso-scale models or short-term models will come into play. Along with satellite imagery, surface plots, and upper air soundings. This is the stuff that starts to happen about 48 hours away from the storm impact. Confidence in the forecast increases dramatically in this period.
There is certainly enough information now to warrant some precautions or even some planning changes for folks that live in northeastern Colorado. Travel anywhere in the state will be difficult, especially on Monday.