Nothing in the evening data to suggest we're headed for a bust, as snowfall probabilities are highest since March blizzard tonight across Northern Colorado. In fact, some models are pulling heavier snow south into Denver, Castle Rock, and even northern/western Colorado Springs tonight.
We showed the HRRR forecast earlier today and it certainly caught the band of heavy snowfall across the northern urban corridor we've seen so far this afternoon/evening. Snowfall rates from 2 to 3" an hour have been common under this band, with totals upwards of 6" already being reported for some communities to Denver's north.
Bands of HEAVY snowfall will continue to move through overnight. The SPC has issued a mesoscale discussion calling for rates of 3" per hour for the urban corridor:
The HRRR shows the heaviest snowfall staying to the north through much of the evening, here's its 10 pm outlook:
But by midnight heavier snow starts to fill in across the Denver area:
With the heaviest getting east by early Tuesday, but still, some persistent snow along and west of I-25, likely really stacking up in the Front Range foothills:
For totals, it's a bit late in the game to be changing things up. That said, high-end potential is on the table pretty much across the board... UNLESS we get inundated by dry air overnight, something these systems have been wont to do AND we've seen show up in modeling from time to time. Should this happen, Denver and points east and south would see the greatest hit to snowfall totals, especially given the heavy snow already falling across the northern urban corridor.
For the region we've been focused on for several days now (Boulder, Loveland, Fort Collins) and points west, it's easy to see some areas breaking 20" by the time all is said and done.
For the foothills to the west, 1 to 3 feet still looks like a good bet.
For Denver, 6 - 12" should cover well enough. The NAM came in tonight and puts a good 10 - 14" over the city, so if its right... well, we'd bust:
The HRRR through 9 am, on the other hand, has about 6 to 12" for the city (6" east, 12" for the west side). While it's still snowing at this time, this model would generally look much better for our forecast:
- BOTH models show higher potential for the Palmer and Colorado Springs. Not hard to see 3 - 6" or even 5 - 10" now for some of the western and northern areas outside of downtown Colorado Springs, which is notable change to our earlier thinking. IF winds shift to the north quicker than evening data currently seems to be indicating, then our forecast should hold down here okay. If you live south of Denver, the potential for higher-end totals should be something you're on the lookout for tonight and early Tuesday.
In the end, a high impact event unfolding across Northeast Colorado tonight. This does not change whether some areas boom or some bust. Travel is already a mess and will only continue to become more difficult, if not impossible, as the night progresses. It's all about the impact, and whether you get 6" or 20", this will be a memorable Thanksgiving week storm!
Our advice? Stay home, enjoy, and send us your snow reports!