Jan. 29 - Feb. 3: 'Groundhog Day Blizzard' – A massive winter storm dubbed the "Groundhog Day Blizzard" struck several states across the southeast, central and northeast United States, paralyzing travelers, knocking out electricity and killing 36 people. Total losses approached $2 billion.
April 4-5: Tornadoes in Midwest, Southeast – During the first week of April, 46 tornadoes struck 10 central and Southern states, causing nine deaths and nearly $3 billion in damage. The twisters tore the roof off this manufacturing plant near Hopkinsville, Kentucky. The region saw more damaging tornadoes in the weeks that followed.
April 8-11: More tornadoes strike the U.S. – An estimated 59 tornadoes pummeled nine states in the central and southeastern United States, damaging more than 60% of the small town of Mapleton, Iowa, pictured here. There were no deaths, but this twister outbreak caused more than $2.2 billion in damage.
April 14-16: A third week of twisters – The cycle of deadly tornadoes continued in mid-April when an outbreak of 177 tornadoes struck 10 central and Southern states, killing 38 people. The power of the twisters bent over this tree in Camp Lejeune, North Carolina. Total property losses exceeded $2 billion.
April 25 - 28: Tornado 'super-outbreak' – In the last five days of April, a "superoutbreak" of more than 340 tornadoes hit the central and Southern states, killing 321 people -- most of them in Alabama. One mile-wide twister tore through Tuscaloosa, Alabama, pictured here, devastating the city. Total losses exceeded $10 billion.
May 22-27: Another tornado outbreak – On May 22, an extremely powerful tornado struck Joplin, Missouri, part of a six-day tornado outbreak of 180 twisters in more than a dozen states that caused 177 deaths, most of them in Joplin. The town is still rebuilding, as shown in this photo taken four months after the tornado -- the single deadliest twister in U.S. history. Total losses exceeded $9 billion.
Spring - Summer: Mississippi River flooding – Heavy rains combined with melting snow triggered major flooding along the Mississippi River in May 2011. To alleviate the overflowing Mississippi and its tributaries, the U.S. Army Corps of Engineers opened spillways, like the Bonnet Carre spillway -- pictured here -- just north of New Orleans. At least two people died and the estimated economic loss ranges from $3 billion to $4 billion.
Summer: Upper Midwest flooding – In June, the melting mountain snowpacks dumped massive amounts of water into the Missouri and Souris rivers, causing record flooding in the Upper Midwest. About 11,000 people were forced to evacuate Minot, North Dakota, pictured here, and thousands of acres of farmland flooded along the Missouri. Five people were killed and estimated losses exceed $2 billion and counting.
Spring - Fall: Southwest wildfires – A dangerous combination of drought, hot temperatures and zero-percent humidity created the perfect storm for wildfires in parts of Arizona, New Mexico and Texas, including the Bastrop wildfire -- the aftermath of that blaze is pictured here. The Bastrop wildfire burned for more than a month near Austin, Texas, destroying more than 1,500 homes. More than 3 million acres were burned across Texas. The wildfires in all three states caused more than $1 billion in direct losses and resulted in five deaths.
Spring - Fall: Southern drought, heatwave – Dry weather and high temperatures have wreaked havoc on the farms and pastures in Texas, Oklahoma, New Mexico, Arizona, southern Kansas and western Louisiana. So far, the direct losses to crops, livestock and timber are approaching $10 billion and the amount is expected to rise as the drought continues.
August 20-29: Hurricane Irene – On August 28, Hurricane Irene became the first hurricane to make landfall in the state of New Jersey in more than a century. The storm -- which had already pummeled the Caribbean islands and North Carolina's Outer Banks -- flooded streets, like this one in Wallington, New Jersey, knocked out electricity and inflicted more than $7 billion in damages. At least 45 people were killed in the storm.