Blizzard Warning Is In Effect For Parts of Montana, But No New Snow Is Expected
Published: February 13, 2018
When many people think of blizzards, images of heavy snow falling in strong winds comes to mind. Although it may seem odd, blizzard warnings do not actually mean that additional snow will be accumulating.
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This is the case in portions of Montana through Tuesday evening. A blizzard warning is in effect for part of northern Montana, including Glacier National Park, where wind gusts up to 65 mph will cause whiteout conditions in blowing snow, likely resulting in blizzard conditions. This is sometimes referred to as a ground blizzard.
In addition, winter weather advisories are also in effect east and south of the blizzard warning, including the Cut Bank, Great Falls and Helena areas. Wind gusts up to 45 mph are expected in the advisory areas, which may cause areas of blowing and drifting snow and consequently poor visibility and slick roadways.
Blizzard warnings are shown in red, while the turquoise indicates winter weather advisories on the morning of Feb. 13, 2018.
So if snow does not have to be falling, what exactly is a blizzard?
The National Weather Service defines a blizzard when the following conditions are met for at least three hours: sustained winds or frequent gusts to at least 35 mph and considerable falling and/or blowing snow that frequently reduces visibility to less than a quarter-mile. Blowing snow refers to snow that is picked up by strong winds and reduces surface visibility.
(MORE: The Difference Between Blowing Snow and Drifting Snow)
A blizzard warning means that those severe winter conditions mentioned above are likely, making travel extremely dangerous. In areas where a winter weather advisory was issued today in Montana and not a blizzard warning, the visibility requirement may not be met for at least three hours.
The current setup features Chinook winds in this part of Montana. Chinook winds are the result of a warmer airmass rising over mountain ranges and as the air reaches the ridge tops, it begins to sink and warm as it descends the mountain slopes. The winds that result can be strong and gusty and can also create dramatic temperature changes.
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There is plenty of snow already in the area where the blizzard warning is in effect, with feet of snow on the ground. Farther east, areas from Cut Bank to Great Falls reported about 6 inches on the ground early Tuesday morning.
Estimated snow depth as of 1 a.m. EST Feb. 13, 2018.(NOAA/NOHRSC)
The combination of snow on the ground and the Chinook winds will continue to make for treacherous travel conditions through this evening.
This area of the country is no stranger to blizzard warnings without falling snow. Blowing snow is not that unusual in the northern Plains and mountain West due to the strong winds that can develop here, along with the terrain.
It is important to pay attention to these warnings as conditions can deteriorate here rapidly.
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These hazardous weather conditions have already resulted in numerous road closures in the area due to the very limited visibility.
Blowing snow was also observed on Monday in central Montana.
Widespread blowing and drifting of snow will end Tuesday night, as the snow will become compacted which will limit the amount of snow available to be blown around. Temperatures will also continue to rise during the day, which will also eventually help to limit the blowing and drifting of snow.
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