The State of the Atmosphere: Sunday, December 28, 2014

A lot to get to in this week’s State of the Atmosphere with cold and snow on the way this week. The cold will rival that of our November outbreak and will settle in tonight through at least Wednesday. Snowfall will generally be light with this system, but a few locations could see several inches over the next three days.

The Cold
While the cold coming has been well advertised, that doesn’t do much to reduce its impact. Highs today may just break freezing in Denver, but if we do, that’ll be the last time until about Thursday. The coldest day of the week looks like it’ll come Tuesday, when highs may struggle to climb above 0 degrees F for highs. The latest GFS continues to show temperatures 30 to 40 degrees below normal by midday Tuesday.

WeatherBell Analytics

The culprit? A big arctic high that will slide southward over the next 24 hours. By Tuesday evening the GFS forecasts a 1051 high over east central Wyoming! Tuesday night lows will be well below zero.

WeatherBell Analytics

The Snow
The other story this week will be the return of the snow. While there will be a chance for snow across eastern Colorado tonight through Tuesday night, totals will likely be mostly light (likely in the 2 - 4” range), though a few locations may do better. As is often the case with these types of systems, the cold will likely be the bigger story.

Greatest snowfall totals, at this time, appear to be from Denver’s northern suburbs south, and southwest across the city. Winds will favor southwest Denver and the Palmer Divide with this event, which may put some of these locations at the high end for snowfall totals.

The best chance of snow in Denver looks to come Monday morning through Monday night when several fluffy inches of snow could fall across the metro. It’s important to note that all snowfall totals referenced here are over an extended time period (Sunday night through Tuesday night), so don’t expect it all to come at once.

While latest model runs suggest upwards of 6” will be possible over this three day period, we think this will be the exception, not the rule. Despite very good SWE expected with this this system (likely much higher than 15:1), these cold systems just don’t typically deliver how they may look on paper. Expect bursts of snow over the coming days, very cold temperatures, and quick shots of 0.5” to 1” of snow every so often.

Please be mindful, that even if not a lot of snow falls, the fluffy flakes and bitter cold temperatures will mean an extended period of snow-impacted roadways across eastern Colorado, especially side streets. If you’re out and about over the next several days, please drive carefully.

QPF chart

New Year’s Eve
Temperatures New Year’s Eve will remain very cold, though will moderate a bit from Tuesday’s “highs”. Daytime highs Wednesday are forecast to climb back into the teens, with overnight lows Wednesday night into Thursday back in the single digits. If your New Year’s plans take you out and about Wednesday night, please plan accordingly!

Beyond Thursday things become a bit more messy. We do expect temperatures to moderate for Thursday and Friday a bit, but after that the EURO shows another show of cold(er?) air for next weekend, while the GFS and GEM keep this cold shot at bay until possibly early next week.

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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