Well, well, well ... I'm sitting pretty here in Denver. Right now, temps are in the 50's and air is descending off the mountains giving us some strong southwesterly winds. There is some turbulence in the lee of the mountains giving us a few clouds, but mostly we're just enjoying a partly cloudy and reasonably warm day.
Other places aren't fairing so well. I'm "nowcasting", if you will, for my parents, who are driving from Boise, Idaho to Butte, Montana today. They just encountered a strong snow band north of Idaho Falls which is attributed to a strong surface low there (it's quite wrapped up on visible satellite). The road ahead won't be anything easy, however, as most observations along the path are between 4 and 7" of new snow ... and a howling north to northeast wind. In fact, temperatures in southwest Montana have dropped below zero.
Meanwhile, in Eastern Montana, the storm is just cranking up. I checked in with my cousins in Billings and they report plenty of new snow and plenty of wind. Earlier today, SPC issued a "blizzard" mesoscale discussion for the area. In fact, most of Montana and the Dakotas are under a blizzard warning for the next day or so.
In the wake of this storm, which should continue to pound the northern tier, the cold air will settle in. Many locations will see -20ºF to -30ºF with wind chills even lower. This looks to stay around for a while as well, especially if the GFS verifies. The upper level pattern really doesn't modify in the 180hour time frame, with the persistent trough in the west and ridge in the east allowing the cold air masses to advect down along the eastern slope of the Rockies and the northern plains. Even at the end of the week, the GFS is showing lows in Montana back to -30ºF again.
A little further to the south, Colorado may see a few quick inches tonight and brief showers of snow in the coming days as little perturbations ripple in the flow. However, the western slope seems to have more heavy snow potential.
Chase forecast update 7 - for May 16
4 days ago