The State of the Atmosphere: Sunday, October 28, 2018

An overall cooler and more unsettled week ahead for northeast Colorado with the exception of Monday.

MOS guidance has temperatures in the upper 70s for Denver on Monday ahead of a rather dramatic cool down for Tuesday. Highs Tuesday will likely top out in the mid 40s, with rain and snow showers possible across the region.

The ridge that is well established over Colorado today and Monday...

Is replaced by a large upper level trough racing through the Rockies Tuesday:

At 850mb we see those anomalously warm temperatures on Monday across eastern Colorado...

Replaced with below average temperatures Tuesday across eastern Colorado:

With the chilly air flooding the heart of the country through the end of the week into next weekend:

Along with the cooler temperatures expected for much of the week, we should see a couple chances for rain and snow across the region as well.

The first chance comes Tuesday through Wednesday. This is not a too terribly exciting a setup for the northern urban corridor, but we'll need to keep an eye on things –– mainly Tuesday night into Wednesday.

If you live across the southern Denver metro area, especially south across the Palmer Divide, the chance of accumulating snowfall Tuesday evening through Tuesday night looks greater than for those of us living in Denver and north. If you live, or plan to travel between Denver and Colorado Springs Tuesday night, expect some tough travel conditions, with heavy snow at times. Greatest potential for this heavier snowfall at this time looks to be between Castle Rock and Monument, with some models pulling that heavier snowfall a bit further south into Colorado Springs proper. If we look at the GFS forecast for early Wednesday morning, we see some rain and snow for the greater Denver area, but heaviest precipitation focused in the foothills and then south:

This is largely predicated on the assumption the best energy associated with this trough will be too far south Tuesday night for northern Colorado to see too much of the action. A shift in that track and we may end up bumping up snow chances for Denver/Front Range foothills a bit.

As for how much snow to expect? At the moment there's not much support for accumulation in Denver proper, perhaps 0 - 2" from Tuesday evening through Wednesday morning, mainly on the south side. If you live across the Palmer Divide, or in the foothills southwest of Denver, it could be you see several inches during this period –– perhaps in the 3 - 7" or 4 - 8" range. Here is a look at the EURO probabilities for an inch or more of snow through Wednesday:

And here's for three inches or more, the probabilities really drop off outside of the western Palmer, southern Front Range foothills:

Something to keep an eye on to start the week, but probably not a huge deal for most of us north of C470, aside from the chilly weather change and perhaps some rain and snow showers Tuesday PM through Wednesday AM. Good news is, whileWednesday looks chilly (highs in the 40s again), it'll likely dry for trick or treating! 🎃

The flow aloft remains northwesterly through the end of the week and into next weekend. This will keep us on the cool side, with perhaps some more unsettled weather as disturbances embedded in the flow move through. The next system to keep an eye on looks to arrive Thursday evening. For now this again doesn't look like too big of deal... but perhaps some more rain and snow showers, and likely some good snow on the way for the north-central mountains. Let us hope!

Brendan Heberton

Brendan is founder of Weather5280. He is co-founder of FreshyMap, and develops software for geospatial data analysis and visualization.

Denver, Colorado
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