Another bout of extreme weather.
A satellite picture at this link of the storm looks like there is a giant hurricane covering the eastern U.S.
http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1674
Posted by: JeffMasters, 3:09 PM GMT on October 27, 2010
Tornadoes, violent thunderstorms, and torrential rains swept through a large portion of the nation's midsection yesterday, thanks to the strongest storm ever recorded in the Midwest. NOAA's Storm Prediction Center logged 24 tornado reports and 282 reports of damaging high winds from yesterday's spectacular storm, and the storm continues to produce a wide variety of wild weather, with tornado watches posted for Mississippi, Alabama, and Georgia, a blizzard warning for North Dakota, high wind warnings for most of the upper Midwest, and near-hurricane force winds on Lake Superior.
The mega-storm reached peak intensity late yesterday afternoon over Minnesota, resulting in the lowest barometric pressure readings ever recorded in the continental United States, except for from hurricanes and nor'easters affecting the Atlantic seaboard.
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Yesterday's 28.20" (955 mb) low pressure reading in Minnesota breaks not only the 28.28" (958 mb) previous "USA-interior-of-the-continent-record" from Cleveland, Ohio during the Great Ohio Storm of Jan. 26, 1978 (a lower reading in Canada during this event bottomed out at an amazing 28.05"/950 mb), but also the lowest pressure ever measured anywhere in the continental United States aside from the Atlantic Coast.
Yesterday's superstorm is reminiscent of the amazing low pressures reached earlier this year (Jan. 19-22) in the West, where virtually every site in California, Nevada, Utah, Arizona, southern Oregon, and southern Idaho--about 10 - 15% of the U.S. land area--broke their lowest on record pressure readings. However, the lowest readings from that event fell well short of yesterday's mega-storm with 28.85" (977 mb) being about the lowest recorded at any onshore site.
Commentary
We've now had two remarkable extratropical storms this year in the U.S. that have smashed all-time low pressure records across a large portion of the country. Is this a sign that these type of storms may be getting stronger? Well, there is evidence that wintertime extratropical storms have grown in intensity in the Pacific, Arctic, and Great Lakes in recent decades. I discuss the science in detail in a post I did earlier this year. Here is an excerpt from that post:
General Circulation Models (GCMs) like the ones used in the 2007 IPCC Assessment Report do a very good job simulating how winter storms behave in the current climate, and we can run simulations of the atmosphere with extra greenhouse gases to see how winter storms will behave in the future. The results are very interesting. Global warming is expected to warm the poles more than the equatorial regions. This reduces the difference in temperature between the pole and Equator. Since winter storms form in response to the atmosphere's need to transport heat from the Equator to the poles, this reduced temperature difference reduces the need for winter storms, and thus the models predict fewer storms will form. However, since a warmer world increases the amount of evaporation from the surface and puts more moisture in the air, these future storms drop more precipitation. During the process of creating that precipitation, the water vapor in the storm must condense into liquid or frozen water, liberating "latent heat"--the extra heat that was originally added to the water vapor to evaporate it in the first place. This latent heat intensifies the winter storm, lowering the central pressure and making the winds increase. So, the modeling studies predict a future with fewer total winter storms, but a greater number of intense storms. These intense storms will have more lift, and will thus tend to drop more precipitation--including snow, when we get areas of strong lift in the -15°C preferred snowflake formation region.
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