Posted: Nov 5, 2012 10:48 AM by Meteorologist Mike Heard
Updated: Nov 5, 2012 4:01 PM
Forecast models have been very consistent in their analysis of a major change in the weather for the latter half of this week. That change brings the first strong Arctic cold front through Montana and Pacific moisture over-running that colder surface air.
This pattern is conducive to producing widespread snow across Montana and heavy snow is possible over the mountain passes and for some lower valleys as well.
The atmosphere is quite warm ahead of this major change and temperatures will continue to stay above normal Tuesday and Wednesday and possibly pushing close to record high levels especially in the wind prone Chinook belts along the Continental Divide and Rocky Mountain Front Tuesday.
Wednesday Pacific moisture will begin to enter the state and late in the day and scattered rain showers are possible for our region. Temperatures will be warm and snow levels will be very high.
The Arctic front will begin to move into NW Montana Thursday morning and push through the state by Friday morning. This will lead to rain changing to snow during that 24 hour period. Forecast models are projecting 1" to 1.5" of liquid precipitation, some of that will be in the form of rain but most of it will be snow and it's possible we could be looking at 3" to 6" of valley snow or more and 6" to 12" of mountain snow or more.
This is a classic over-running event as a warm moist Pacific storm moves from the Pacific NW down into southern Idaho rolls east into Wyoming and then lifts to the northeast in the Dakotas Wednesday through Sunday. As the cold air from the north digs in at the surface across Montana and the wrap around moisture from a low to our south lifts over the colder surface air, look for plenty of snow.
We also expect to see a pressure gradient form as the cold air is associated with a High pressure ridge over Canada and a pacific storm system over the Pacific NW will create gusty east to north winds Thursday and Friday. Look for blowing and drifting snow and reduced visibilities especially in wind prone areas.
The National Weather Service will be issuing winter storm watches and eventually advisories and Warnings as we get close to this weather event.
Temperatures will drop dramatically over the next 5 days with near record highs Tuesday to morning lows falling slightly below zero by Sunday. This temperature drop will produce considerable ice Friday through early next week.
The storm event is still several days away and your STORMTracker weather team will continue to analyze weather computer models and update and refresh the forecast throughout the week.
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