Global winds could explain record rains, tornadoes

[OKIsItJustMe]

http://www.news.wisc.edu/20095

Global winds could explain record rains, tornadoes

Dec. 5, 2011

by David Tenenbaum

Two talks at a scientific conference this week will propose a common root for an enormous deluge in western Tennessee in May 2010, and a historic outbreak of tornadoes centered on Alabama in April 2011.

Both events seem to be linked to a relatively rare coupling between the polar and the subtropical jet streams, says Jonathan Martin, a University of Wisconsin-Madison professor of atmospheric and oceanic sciences.

…

Studies of the Tennessee floods, the Alabama tornados, and an odd October storm in Wisconsin showed “that when the subtropical jet is pushed poleward under the influence of strong thunderstorms in the western Pacific, it seems to result in these intense storms in the U.S. midsection,” Martin says. “It’s a really fascinating global connection that occurs seven to 10 days later.”

…

“There is reason to believe that in a warmer climate, this kind of overlapping of the jet streams that can lead to high-impact weather may be more frequent,” Martin says.

…

[Bob Wallace]

1. Well...

Toss in the extra 4% moisture in our now-hotter atmosphere. Extra moisture evaporated from a warmer ocean, held by warmer air until it hits conditions which cause rain and snowfall.

What goes up must come down upon us....

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Here's an interesting read about how warming may be bringing more wildness to us outside our melting Arctic...

"A comprehensive international report on the state of the Arctic climate system, released last week, makes clear that Arctic climate change has not only tipped the entire polar region into a fundamentally different state, but that the changes there may be having spillover effects elsewhere - including the mid-Atlantic region.

As I’ve previously written, the steep decline in Arctic sea ice extent and thickness during recent years alters the flow of heat between the Arctic Ocean and the air. The past five years have seen the five lowest sea ice extent recordings during the satellite era. Since the dark ocean surface absorbs more incoming solar radiation than sea ice does, increasing areas of open water during fall can have a dramatic influence on Arctic air temperatures, and this in turn can alter atmospheric circulation.

Specifically, the report notes that warmer air leads to higher atmospheric pressure surfaces over the Arctic Ocean, and this can weaken the high-altitude winds that circle the North Pole from west to east, known as the “polar vortex.”

A weaker polar vortex can provide greater opportunities for Arctic air to flow southward, into areas like the U.S. and parts of Europe, while the Arctic experiences warmer-than-average conditions. The polar vortex also influences the phase of the Arctic Oscillation, which has a major influence on winter weather in the Washington area, as I detailed in a story last week."

http://www.washingtonpost.com/blogs/capital-weather-gang/post/unusual-winter-weather-may-be-connected-to-rapid-arctic-climate-change-report-warns/2011/12/04/gIQAUdQYUO_blog.html

[OKIsItJustMe]

2. More on the Arctic

http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=318828&mesg_id=319041