Posted: Nov 7, 2012 10:23 AM by Meteorologist Matt Elwell
Updated: Nov 7, 2012 10:26 AM
We continue to track the first major winter storm of the season as it approaches Montana. The National Weather Service out of Great Falls has issued a Winter Storm Warning for northern Montana effective Thursday morning through Saturday morning. The Winter Storm Watch is in effect in southwest Montana starting Wednesday evening through Saturday morning. We can expect this Watch to be upgraded to a warning as the system continues to move into the area.
While the models continue to be very consistent (which can be a rarity with these early season storms) there are a few details on this storm that have yet to come together. The two that stand out the most are closely related.
1) Exact timing of the cold air - We anticipate rain changing to snow, but the exact timing of that cold air is still a little hard to predict. Some models are pushing the cold air into place in the early evening on Thursday, while other computer models are bringing it in overnight. This can mean the difference between a layer of ice and snow.
2) The snow amounts in the valleys - The basic number are still pretty firm (between 5" and 10") for the storm. The timing of the cold air could greatly change those numbers. If the cold air slows down, we could easily see ice freezing on the roadways before we see the snowfall strike. That would change driving conditions from dangerous to treacherous in a hurry. The other scenario would be an early arrival of the cold air making higher snow amounts.
The best estimates on the snowfall associated with the storm remains between 5 and 10 inches for the valleys and between 1 to 2 feet across the mountains.
The strength and size of this particular system does lend itself to very windy conditions on Friday, which means blowing and drifting snow to compound the situation. The NWS is monitoring the possibility of blizzard conditions during this storm. Even if we don't hit the criteria for a blizzard warning, you should probably treat this storm as such if you venture out into the elements. Blowing and drifting snow combined with frigid air and high wind speeds will mean that you can't be unprotected outdoors for long before frostbite sets in.
A few other thoughts on preparation the approaching storm:
1) Get a winter survival kit ready for your car before you head out.
2) Make sure you have snow shovels, plows and ice scrapers ready to go.
3) Put on your snow tires and get chains ready.
4) Don't forget to finish those winterization projects (garden hoses, campers and boats)
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