Extreme Weather in US Triggers Large Losses

29-Apr-11

Extreme weather in the eastern US has caused a historic outbreak of tornadoes. With hundreds of touchdowns, some tornado tracks reported to be almost a mile wide and tens of miles long causing hundreds of fatalities, insured losses from the most recent outbreak of tornadoes are expected to be in the range of $2 to $5 billion. The 2011 Tornado Season has just begun and it is already setting many records.

The same extreme weather patterns causing tornadoes are leading to heavy rainfall in the Midwest. This runoff is leading to serious flood conditions with many roads and highways blocked, thousands of acres of agricultural land inundated, and many towns already underwater. Rainfall is beginning to taper off, but runoff into streams and rivers is expected to lead to cresting of the floods over the next few days.

Winds of 30 mph and more in drought-stricken west Texas this month has contributed to multiple fires that so far have burned more than a reported 1.6 million acres of brush and forest land. Most of the fires have been in remote areas and the number of buildings burnt from this event number only into the hundreds. Insured losses from the fires in Texas have probably already exceeded $100 million, with a forecast of critical fire conditions extending into next week generating expectations for these losses to grow.

Record Setting Tornado Activity

Tornado activity in April is putting 2011 into the record books. The US National Weather Service report of cumulative tornado activity compared to historical activity shows that this year’s is about 30% higher than the historic recorded maximum. The weather service produces an “inflation adjusted” data set to account for under- and over- reporting of tornadoes in the historical set, and 2011 is a very active year.

Annual Tornado Trend - April 29, 2011

Source: National Oceanic and Atmospheric Administration (NOAA)

There have been more than 350 reported tornado landfalls in the last 10 days. The most deadly tornadoes appeared yesterday (April 27) and caused significant damage in and between Tuscaloosa, AL and Birmingham, AL. More than 130 fatalities have been reported in Alabama, 30+ each in Mississippi and Tennessee, and more than 10 fatalities each in Georgia, Virginia, and Arkansas. One fatality has been reported in Kentucky. These reports are indicative of the urban landfalls of these events.

With initial reports of buildings destroyed approaching 10,000, property insurance losses are expected to range from $2 to $5 Billion. The current weather outlook is for this current outbreak of tornadoes and accompanying hail storms to end tonight.

Weather Outlook - April 29, 2011

Source: Google Maps

Mississippi River Flooding Following Large Rains

River flows in several basins are at major flood stage (purple in the figure below). Both the Mississippi and Ohio Rivers are at a major flood stage, leading to a significant buildup of river flow at Cairo, Illinois, the juncture of the two rivers, and further downstream along the Mississippi. The general area has received from 6 to 12 inches of rainfall this month, although some areas have received more, and this is contributing to the current risk. Rainfall remains in the forecast for the area and will contribute to a continued risk of flooding.

River Flows - April 29, 2011

Source: National Oceanic and Atmospheric Administration (NOAA)

The Mississippi River in Southern Missouri is already beginning to flood areas along the river and is threatening many riverside communities. Reports are that many state highways have already been closed and several interstate highways are being closed as well. The river is at very high flood conditions between Cairo, IL and New Madrid, MO.

Cairo, Illinois - Apri l 29, 2011

Cairo, Illinois is expected to see a cresting of river elevations this weekend at a stage higher than has ever been recorded. The prior record of 59.5 feet was set in February of 1937. The US Army Corps of Engineers has received approval to breach the Mississippi River levee at Birds Point, MO, which is expected to reduce the flood pressure on Cairo by directing part of the Mississippi River flow onto nearby farmland.

Ohio River at Cairo - April 29, 2011

Source: National Oceanic and Atmospheric Administration (NOAA)

The current flood stage is expected to abate over the next week, although rainfall forecasts bring an expectation of continued regional flood risk into May.

Texas Fires

A drought in Western Texas has led to large areas with extremely dry underbrush and ground cover. Current weather conditions have included persistent 20 mph and greater winds that have contributed to severe fire weather conditions in the area, and many have fires have occurred in West Texas this month. Total area burned is estimated to be in excess of 1.6 million acres, and more than 250 buildings are estimated to have been lost. The areas of the fires are very sparsely populated and leading to the very low level of building losses. The disruption to local farming and livestock production is expected to be more significant.

Texas Fires - April 29, 2011

Source: Texas Forest Service

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