Friday, June 17, 2011

Missouri River flood hits unprecedented flow rates

http://www.wunderground.com/blog/JeffMasters/article.html

By Dr. Jeff Masters
Published: 6:51 PM GMT on June 17, 2011
The most expensive tornado/severe weather disaster in American history is the great May 21 - 26, 2011 storm that spawned the Joplin, Missouri EF-5 tornado. According to catastrophe modeling firm AIR Worldwide, insured damages from that storm will amount to $4 - $7 billion, the greatest damages ever for a spring severe weather outbreak. However, the damages from the huge, slow-moving low pressure system that spawned the Joplin tornado have not yet been fully realized. The powerful storm pumped huge quantities of warm, moisture-laden air from the Gulf of Mexico northwestwards into Montana, where the moisture condensed into record-breaking heavy rain and snow. In portions of eastern Montana, the storm brought a year's worth of precipitation in a week, swelling the tributaries of the Missouri River to unprecedented heights. Billings, Montana recorded 9.54" of precipitation in May, its single wettest month on record, and not far from its annual average precipitation of 14.5". A great 100-year flood has arrived along the Missouri River and its tributaries from Montana to Nebraska. Record spring rains, combined with snow melt from record or near-record winter and spring snows, brought the Missouri River at Williston, North Dakota to 30' today (June 17), two feet above the record crest set in 1912. Tributaries to the Missouri, such as the Souris River in North Dakota and the North Platte River in Nebraska, are also flooding at all-time record heights. With warm summer temperatures and 2 - 5" of rainfall expected over much of the area during the coming week, snow melt and rain runoff will swell area rivers even further, creating an even more dangerous flood.

Flooding along the Missouri River has already broken two levees and closed two portions of I-29, a key trucking route that extends from Kansas City through Iowa, South Dakota and North Dakota to the Canadian border. A 20-mile stretch between Council Bluffs and the Missouri Valley area is closed, as well as a 22-mile section in southwest Iowa and northwest Missouri, causing significant disruptions to the trucking industry.

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Powerful southwest winds of 20 - 30 mph, gusting to 40 mph will continue through Saturday in Eastern Arizona and western New Mexico, making progress containing the region's severe fires difficult. Even worse conditions are begin predicted for Sunday, when NOAA's Storm Prediction Center forecasts forecasts that wind gusts up to 50 mph will occur. With hot conditions and humidity values below 10%, these are likely to be among the worst fire conditions the region has seen this year.

While the exceptional drought gripping Arizona is largely to blame for terrible fire conditions this year, unusually windy and dry weather has also been a significant factor. These windy and dry conditions have been caused, in part, by a stronger-than-average jet stream over the region. According to the National Weather Service in Phoenix, the period April-May 2011 was the 11th windiest and had the 6th lowest average relative humidity value on record in Phoenix. Combined, it was the 3rd windiest-driest April-May on record.

Our weather historian, Christopher C. Burt, has an interesting post on The Worst Wild Fires in World History. Arizona's Wallow Fire, at 750 square miles, has a long way to go before matching the largest fire in U.S. history, the great Peshtigo Fire of 1871. That fire burned 5,938 square miles of Wisconsin and Michigan.

Tallahassee hits 105°, their hottest day on record

On Wednesday June 15 at 307 PM EDT, the Tallahassee Regional Airport in Florida recorded a high temperature of 105 degrees. This temperature breaks the previous all time high temperature record for Tallahassee of 104 degrees, set most recently on June 20th 1933. The period of record for Tallahassee dates back to 1892.
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