Massive Winter-Like Storm

Even though it’s still autumn, a major storm system will result in a wide array of intense winter-like weather to the western part of the country during the next couple of days. Winter storm warnings and watches are in effect for parts of the Rockies, where greater than two feet of snow will accumulate in the higher elevations, and high wind watches and warnings extend as far westward as California. 

Sometimes pictures are better than words, so here is a National Oceanic and Atmospheric Administration (NOAA) map showing the watches and warnings as of early Tuesday:

NOAA map of weather watches and warnings on October 27, 2009

While our inclination might be to believe that it’s too early for storms like this, it’s not. The Rockies are notorious for heavy snow in spring and fall, including October and April, and this is something that I highlighted in Weather Whys.

During the winter, the jet stream, which is the fastest layer of wind in the upper levels of the atmosphere that pushes storms along, is often too strong for storms to linger; that’s not the case during the fall in spring, and the result is often a slow-moving storm that lasts for a couple of days, brings intense weather from the West Coast to the Plains, and turns Halloween into a bright, white holiday in the Rockies.

NOTE: This storm is likely to produce widespread intense thunderstorms in the Plains this week–a classic example of the second severe weather season that I talked about last week.

–Paul Yeager

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