A storm system will bring widespread areas of snow to the Cowboy State today and tonight. Some of the mountainous areas of the west have already received a foot of snow overnight on Saturday into Sunday morning. These areas of snow are spreading east through the day today.
So why did it snow so much in the west and where can we expect the most snow?
An Arctic cold front is sinking south from Canada today. As of late this morning, the front was roughly draped from the Northwest corner to the Southwest corner of the state. True to it's description, this front has some arctic air behind it. As this cold air settles into place, warm moist air will move in from the Pacific and fall into this cold air. This set-up is appropriately referred to by Meteorologists as "overrunning snow."
The overrunning is further enhanced by the mountains, which act as their own boundary, much like a cold front. Boundaries, whether made of rock or cold air, force the incoming moist air aloft making the cloud layer deeper and therefore a more efficient snow producer. These areas are shaded on the Infrared Satellite image and are commonly referred to as "enhanced" areas of cloud cover. These clouds appear colder on the infrared satellite image because they reach higher into the atmosphere.
In addition to the radar image, which has limited coverage beyond a 40 mile radius, Meteorologists look for areas of enhanced cloud cover in the satellite image to predict where areas of heavier snow may be falling.
So in a nutshell...Heavier snow has fallen in the western mountains today because we have moist westerly flow that has become enhanced by the mountains, which provide a nice, predictable, focused boundary. These areas have a Winter Storm Warning for heavy snow in effect until Midnight tonight. Heavy snow will fall east of the mountains today because of overrunning along the Arctic front. The exact location of the heaviest snow will be harder to predict east of the divide because heavier snow bands tend to set up wherever they please, hence the Winter Weather Advisory that has been issued for the rest of the area. The snow fall in these areas will generally be less than in the western mountains, but an isolated area or two of heavy accumulation is possible.
If you would like to see if you can anticipate a heavier snow band moving toward you, check the radar (click here for help interpreting radar imagery); if you do not live close to a radar (click here to locate the closest radar to you), now you know to check the Infrared Satellite Image for enhanced cloud cover moving your way! And as always...keep an eye on our Homepage for updated watches, warnings, advisories, and on our Weather Story for updates on the current weather system.