Wednesday, June 6, 2012

Chill Today, Not Tomorrow?

Eastern Canada & U.S. Satellite image from Environment Canada

1:15 PM EDT 6/6/12 (Forecaster Mike) In the past several days across the eastern third of the country, a summery feel has been completely absent. It's one of the fickle aspects of June, and this year it's due to a pattern that would more typically set up during the winter season that in pre-summer. 

Hey East: Why Winter Now? - For all the snow-lovers out there, this is the pattern that did not happen once throughout the entire 2011-2012 winter. The primary characterizing factor is the North Atlantic Oscillation(NAO) in the negative phase. For the first time since last summer, the NAO has crashed into the strongly negative phase. This promotes the development of a high pressure near Greenland, something typically only seen in the winter months. With this arrangement having developed, a deep trough has begun to dig over the east, allowing Northwest winds to usher in much cooler air. Additionally, a ridge over the west is helping to amplify the eastern trough. To anyone missing the snow - if the calendar said January and not June, we would be already talking about the snow! 

The results of this pattern will be chilly conditions again on Wednesday, and thus not the best beach weather. Areas like the Virginia Tidewater zone which covers the Virginia Beach area will have highs only in the low to mid 70s! 

Western Ridge - I did mention this ridge building in the west as well, and it will be centered around the front range of the Rockies on Wednesday. The frontal boundary leading out ahead of the ridge will try to flare up some thunderstorms just east of the Rockies, including some scattered thunderstorms hitting portions of the Central Colorado zone. Heat will be holding strong across much of the middle of the country, with highs surging into the humid 80s all up the Great Plains region of the country. 

Have a fantastic Wednesday! 

(This graphic below shows the observed and forecasted NAO since February 7th. As you can see, the NAO has spent very little time below zero throughout the last few months, and before that as well.)

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