Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 27. lokakuuta 2010 klo 15:09 (GMT)
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. So far, it appears the lowest reading (now official) was a pressure of 28.21" (955.2 mb) reduced to sea level reported from Bigfork, Minnesota at 5:13pm CDT. Other extreme low pressures from Minnesota during yesterday's storm included 28.22" (956 mb) at Orr at 5:34pm CDT, 28.23" at International Falls (3:45pm), and 28.23" at Waskuh at 5:52pm. The 28.23" (956mb) reading from International Falls yesterday obliterated their previous record of 28.70" set on Nov. 11, 1949 by nearly one-half inch of mercury--a truly amazing anomaly. Duluth's 28.36" (961 mb) reading smashed their old record of 28.48" (964 mb) set on Nov. 11, 1998. Wisconsin also recorded its lowest barometric pressure in history yesterday, with a 28.36" (961 mb) reading at Superior. The old record was 28.45" (963.4 mb) at Green Bay on April 3, 1982. The previous state record for Minnesota was 28.43" (963 mb) at Albert Lea and Austin on Nov. 10, 1998.
Figure 1. Visible satellite image of the October 26, 2010 superstorm taken at 5:32pm EDT. At the time, Bigfork, Minnesota was reporting the lowest pressure ever recorded in a U.S. non-coastal storm, 955 mb. Image credit: NASA/GSFC.
Yesterday's records in context
Yesterday's 28.21" (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. The modern Pacific Coast record is 28.40" (962mb) at Quillayute, Washington on Dec. 1, 1987. An older reading, taken on a ship offshore from the mouth of the Umpqua River in Oregon during the famous "Storm King" event on January 9, 1880, was 28.20" (954.9 mb)--slightly lower than the 2010 storm.
The lowest non-hurricane barometric pressure reading in the lower 48 states is 28.10" (952 mb) measured at Bridgehampton, New York (Long Island) during an amazing nor'easter on March 1, 1914 (see Kocin and Uccellini, "Northeast Snowstorms; Vol. 2., p. 324, American Meteorological Society, 2004.) The lowest non-hurricane barometric pressure reading from anywhere in the United States was a 27.35" (927 mb) reading at Dutch Harbor, Alaska on Oct. 25, 1977. The lowest hurricane pressure reading was the 26.34" (892 mb) recorded in 1935 during the Great Labor Day Hurricane.
Figure 2. Storm reports received by NOAA's Storm Prediction Center from the October 26, 2010 superstorm.
The six most intense storms in history to affect the Great Lakes
According to the Chicago branch of the National Weather Service and Christopher C. Burt, our Weather Records blogger, the following are the six lowest pressures measured in the U.S. Great Lakes region:
1. Yesterday's October 26, 2010 Superstorm (955 mb/28.20")
2. Great Ohio Blizzard January 26, 1978 (958 mb/28.28")
3. Armistice Day Storm November 11, 1940 (967 mb/28.55")
4. November 10, 1998 storm (967 mb/ 28.55")
5. White Hurricane of November 7 - 9, 1913 (968 mb/28.60")
6. Edmund Fitzgerald Storm of November 10, 1975 (980 mb/28.95")
So, the famed storm that sank the ore carrier Edmund Fitzgerald in 1974, killing all 29 sailors aboard, was weaker than the current storm. Indeed, I wouldn't want to be on a boat in Lake Superior today--sustained winds at the Rock of Ages lighthouse on Isle Royale were a sustained 68 mph, gusting to 78 mph at 3am EDT this morning!
Yet Another Remarkable Mid-latitude Cyclone so far this Year!
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.
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.
A low pressure system (Invest 90L) in the middle Atlantic Ocean has developed a broad circulation, but has very limited heavy thunderstorm activity. NHC is giving 90L a 10% of developing into a tropical depression by Friday. Another area of disturbed weather a few hundred miles west of 90L is disorganized, and is also being given a 10% chance of developing.
I'll have an update on Thursday morning. I'm at the National Hurricane Center in Miami this week, as part of their visiting scientist program, and hopefully the weather in the rest of the country will slow down enough so I can write about goings-on here at the Hurricane Center!
Christopher C. Burt is responsible for most of the content of this post, with the exception of the commentary, which I wrote.
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