Jan 31, 2012

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U.S Extreme Weather Events in 2011

No matter what stands out to each of us about 2011, a common thread shared by many was the severity of nation’s weather. Varied, atypical, and at times both devastating and tragic, 2011 was an exceptionally active year for major-impact weather events in the US.

The National Oceanic & Atmospheric Administration identified no fewer than a dozen events with economical damage exceeding a billion dollars. The events are listed in chronological order below. How many of these “billion-dollar disasters do you recall?

1.Groundhog Day Blizzard, Jan 29-Feb 3, 2011, 1-2+ feet of snowfall, OK to MI to New England

2.Midwest-Southeast Tornadoes, Apr 4-5, 2011, 46 tornadoes, LA-AR-KY-OH eastward to interior east coast states

3.Midwest-Southeast Tornadoes, Apr 14-16, 2011, 177 tornadoes (EF0-EF3), TX-OK-KS eastward to east coast

4.Southeast-Ohio Valley-Midwest Tornadoes, April 25-28, 2011, 343 tornadoes, 321 fatalities, TX-AR-MO-MI eastward to east coast

5.Midwest-Southeast Tornadoes, May 22-27, 2011, 180 tornadoes, 177 fatalities, (including EF5 Joplin, MO ,158 dead), Gt. Plains to Appalachians

6.Midwest-Southeast Tornadoes, Severe Wind and Hail, June 18-22, 2011, 81 tornadoes, widespread severe wind and hail, high plains to east coast

7.Exceptional/Extreme Drought and Heat Wave, Spring-Fall 2011, Southwest-Southern Plains-Gulf Coast

8.Mississippi River Flooding, Spring-Summer 2011

9.Upper Midwest-Plains Flooding, Summer 2011

10.Hurricane Irene, Aug 20-29, 2011, NC to NY & New England

11.Southwest Wildfires, Spring-Fall, 2011, TX-NM-AZ

12.Pre-Halloween Nor’easter Heavy Snowfall, October 29-30, 2011, 1-2+ feet of snowfall, northeastern PA to southern ME

2011 – Record Breaking Year for Tornadoes

Arguably, the most notorious weather events from 2011 were tornadoes. In fact, 2011 was a record breaking year for confirmed tornadoes in the US. Five spring-time severe storms events, totaling 827 tornadoes, resulted in nearly 500 fatalities with at least a billion dollars in losses caused by each event. Some of these tornadoes were long-track storms that were on the ground for prolonged periods. 84 tornadoes were rated as strong and violent, and was the second largest number of these potentially most destructive tornadoes that have occurred since 1950 (Fig.1).

Fig. 1. Tornadoes are rated on a scale (Enhanced Fujita scale) from 0-5. The potentially most destructive tornadoes (strong to voilent; EF3-EF5) from March-August in the US since 1950-2010 are shown above (countrsey NOAA). The 84 strong-voilent tornadoes in 2011 were the second highest total since 1950 and the most since 1974.

Fig. 2. Deadly tornado (EF-5) strikes Joplin, MO on 22 May 2011 (NOAA).

Tornadoes 2012 ?

So, what were the factors that drove the exceptional 2011 tornado season? Are those factors discernable in the climatological data, and to what extent might they again occur in 2012? These are topics for our next discussion, coming in February 2012.

Rod Gonski, Author

Kermit Keeter, Editor

Jeremy Gilchrist, Reviewer

EARLY ALERT, INC.