Saturday, December 02, 2006
Weather columnist Kevin Myatt: Early season storm makes for wild weather
Kevin Myatt is The Roanoke Times' weather columnist.
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Tulsa, Okla., had never had more than 4 inches of snow on any November day, or more than 5.6 inches of snow in any November.
Tulsa's average seasonal snowfall is 9.1 inches.
But Thursday, Tulsa got 10.4 inches.
That's just one of many testaments to the fury of a historic early season winter storm over the nation's heartland.
This was definitely not our storm, but we still had considerable effects from it. Its core of energy sailed far to our northwest, passing over the Great Lakes. But even at that distance, it whipped up wind gusts that sometimes exceeded 50 mph on Friday in Southwest Virginia.
Colder air will continue to settle in over the next few days, as conditions return to more typical Christmas shopping weather with cool days and chilly nights. It appears that next week will be mostly dry, but there are a couple of things to keep an eye on. More on that a little later.
This powerful storm system exhibited a wide range of inclement weather, including not only snows of a foot or more in many places from Oklahoma to Michigan, but freezing rain, severe thunderstorms, flooding rains and gusty winds.
Many areas saw significant weather on both the warm side and the cold side of the storm. The National Weather Service in Tulsa issued a blizzard warning for parts of northeast Oklahoma only 24 hours after much of its forecast area was under a tornado watch.
Though collisions of drastically different air masses are not uncommon in late fall and early winter, the depth of both the Arctic air and the subtropical air that became wrapped into this low-pressure system is a bit unusual.
A mass of Arctic air has been building over western Canada for weeks, with some temperatures falling below minus-30 degrees. Persistent storminess from the Pacific continued to pile up the snowpack, helping hold the cold air in at the surface.
Meanwhile, warm air streamed into much of the nation's eastern two-thirds from both the Pacific and the Gulf of Mexico. Above-normal temperatures were common, and some record highs occurred.
Finally, the Arctic air became so dense, it had to move south. The jet stream buckled south, and fast wind energy moving through the jet stream, combined with the intense difference in temperatures, spun up this large winter storm.
It's hard to draw any long-term conclusions from this one storm. A big early season winter storm doesn't necessarily mean there will be more like it, or that some of those will happen much farther east. If this storm's path is any indication of what is to come for the bulk of the winter, we would have a mild winter here in the eastern U.S.
But one thing that's happening as a direct result of this storm is that very cold air is being driven far to the south early in the season, and held in by a large snowpack not only covering Canada but much of the central U.S. This cold-air mass looks to have more staying power than once believed.
Are there any more waves in the jet stream that can kick up something snowy or icy for us?
One moves through late in the weekend. At this time, it looks like it will form a low-pressure system too far to the east to affect us much. Probably we will see no more than a few clouds.
About Thursday or Friday, there seems to be some potential of getting both moisture and cold air involved in a new system crossing the country.
At this distance, the late-week system doesn't look like anything comparable to what the central U.S. just experienced. It could yet turn into rain for us if the low-pressure system again streaks to the northwest of us. But there's some wintry intrigue with it, as temperatures should still be pretty cold.
And that's what this season is about for weather geeks: The next puny disturbance riding the jet stream could be a partly cloudy afternoon, a 33-degree rain or a historic winter storm.




