Bitterly cold air has swept into North-central Montana, and it is expected to continue its advance into the Southwestern United States.
Overnight and into Wednesday morning, areas of light snow are expected to return. Another bout of light snow is expected throughout the whole area on Thursday, as warmer air from the Southwest starts to move back into the region.
Storms with blowing snow are expected to develop throughout the Rocky Mountain Front Thursday night and into Friday morning.
Cold Wind Chills
North-central Montana has been engulfed by Arctic air mass, with a 1034Mb surface high positioned northeast of Great Falls. The skies have become clear over most of the region.
This evening, temperatures will plummet rapidly from roughly -15 to -30 degrees due to the accumulation of new snow and the continuation of frigid advection.
This afternoon, a weak mid-level low-pressure system was moving over southern Alberta and into Saskatchewan, bringing light snow to the Havre region and bringing in the second surge of colder air from the north.
Wind chill values of -40 to -50 degrees will be produced by northerly winds of 5 to 15 mph, triggering a wind chill warning for the Hi-Line counties. Wind chill warnings are in force for the remainder of the state of Montana, particularly in North-central Montana.
Winter Weather Advisory Issued
The cold front has moved south of I-90 in southwest Montana, bringing rain and snow with it.
At this point, the front seems to have come to a complete standstill, with little more southerly movement anticipated.
It is expected that a fresh upper-level disturbance will rise over this stalled frontal zone over the overnight period, which will bring snow to Southwest Montana.
Minor traffic disruptions are predicted in this region beginning early Wednesday, causing a Winter Weather Advisory to be issued until Wednesday morning.
Associated with this passing shortwave disturbance, a spell of very light snow is also likely tonight across North-central Montana and the surrounding areas.
Warm Front on Wednesday; Blowin
Following another very cold day on Wednesday and into the night and early morning hours of Thursday, we'll see a warm front begin to organize and rise over the area by Thursday afternoon.
Even as temperatures continue to climb and the cold airmass is eroded from the southwest and west, a widespread light snowfall is expected through the day on Thursday, according to the National Weather Service.
Winterstorm in the Rockies
Currently, a winter storm warning has been issued for the Rocky Mountain Front, where heavier snowfall rates and a longer duration of snow are forecast in the westerly flow.
A surface trough forms on Friday as a result of the snow accumulation, resulting in high winds and a period of significant blowing snow for this region Thursday night into Friday morning.
The Rocky Mountain Front, and in particular the Blackfeet Nation, should be prepared for potentially challenging circumstances in the form of blowing snow on Friday morning, according to the National Weather Service.
Warmer Temperatures on Friday
Overall, temperatures will rise temporarily on Friday, but a cold front will sweep southward again on Saturday, bringing with it some light snowfall and a return to cooler temperatures.
Following the departure of this front to the northward on Sunday, a period of near/above-normal temperatures is likely to develop across the area from Monday into Tuesday, accompanied by mostly dry weather.