US NOVEMBER: Storminess Increases, Wild Temperature Swings

Written by on October 18, 2012 in North and South America, United States of America with 0 Comments

In the past 10 days the US and overall North America pattern has changed from back through August, September and early October. Since July’s heat, there was at least 3 significant shots of cold during August, Sept and early October with the trough dropping straight into the Central and Eastern states. However in the past 10 days, this shift has taken place with Pacific storms now able to strike the West Coast bringing much need rains to the Pacific Northwest and now, that ridging in the West has broken down and shifted. Storms are on the increase and the split jet with the El Nino-like setup will allow more fun and games during November. This setup supports more frequent cold shots which will grow more intense throughout the month and I could see some major storms driving into the West Coast and crossing the country.

In my opinion, November should see the mean trough centred from the Interior Northwest to Plains and it’s the kind of pattern also which could support below normal temperatures across the North and warmer than normal across the South but right now I’m seeing more ridging from the Southeast up to New England. The pattern currently is showing a significant cold shot dropping into the Interior Northwest and Rockies which slides east into the Plains between Oct 27 through Nov 7. Whether it slides all the way to the East Coast will be interesting to see.

I expect above normal precipitation in the West with a good start to the ski season for the Intermountain West. Some good wind storms also from Seattle down to San Francisco. As for the East, I can see some big rains combined with fairly mild weather for a good part of the month. Pacific systems look likely to strike the West Coast, drop into the Southwest, perhaps Southern Plains and then lift northeast, entering Canada over the Great Lakes, perhaps New England. This would keep the milder air over the East Coast, not so much cold.

Mid month, a period of very mild, Pacific air could flood the country with the pattern turning zonal. This would allow time for the NAO, AO to turn more positive and remember, we need to see this happen for a few weeks to allow the pole to see it’s cold reservoir build.

During November I believe the NAO will bounce from negative to positive and we will see a series of strong storms drop into the PNW from the Gulf of Alaska. At least 2 of these could support significant cold blast for the Western States into the Plains while southwest winds and ridging brings warm air into the East. This whole pattern should progress east through the month and by months end I think the mean trough will be more towards the East while milder weather starts to influence the West more.

By December, the cold expands and becomes more prevalent in the East. Heads up from South-Central states to New England, a long and tough winter is looking likely.

Here’s the latest Jamstec for this upcoming winter.

My official US Winter forecast will be released Oct 31. Stay tuned.

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