Monthly Climate

The Monthly Climate: April 2011

Extreme Weather in the U.S. and Beyond

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Drought. Wildfires. Wind. Hail. Tornadoes. Flooding.

April 2011 was a month defined by extreme weather conditions, particularly in the United States. Texas followed its driest March in over 100 years with its fifth driest April. Higher temperatures and absent rainfall were blamed for power outages at refineries, a spike in rabies reports, and wheat crop losses. By month’s end, 94% of the state was experiencing severe to exceptional drought conditions. The state has received a mere 1.68 inches of rain since February 1, easily besting its driest February-April period in history by nearly an inch. The deepening, months-long drought was accompanied by over 6,000 new wildfires that burned a record 1.79 million acres across the country during April and 2.2 million acres since January in Texas alone. The extreme conditions lead Texas governor Rick Perry to proclaim three days in April as “Days of Prayer for Rain”.

U.S. Precipitation Rankings - April 2011

Six states experienced record setting precipitation while record drought continued in Texas. Image credit: NOAA

The month also witnessed violent storm fronts that brought record precipitation, severe wind, and hail the size of golf balls and larger. Illinois, Indiana, Ohio, Pennsylvania, Kentucky, and West Virginia all reported their wettest April in history. Kentucky received an average of 11.88 inches of precipitation — nearly three times its long-term average for the month — breaking the state’s previous record by more than four inches. Up to 20 inches of rain, nearly half the normal annual amount, fell in some areas resulting in record flooding in the Ohio valley, and the Red River in Minnesota reached major flood stage for the third straight spring. The previous one-day record for severe wind reports of 455 was broken twice during the month. The storms of April 19 generated 575 severe wind reports, but even that number paled in comparison to the staggering 1,318 preliminary severe wind reports resulting from the storms of April 4.

But it was the tornadoes of April that truly made history. The 30-year-average for April tornadoes nationwide is 135. The monthly record was 542.

The preliminary number of tornadoes reported in April 2011 is 875.

U.S. Preliminary Tornado Reports - April 2011

April 2011 easily set a new record for tornado outbreaks. Image credit: NOAA

Single day events saw Wisconsin experience its largest monthly April tornado outbreak in history on April 9, and an EF-4 twister ripped a 21-mile path across the city of St. Louis on April 22. But it was the multi-day outbreaks that generated the most devastation. From April 14 to April 16, there were 329 preliminary tornado reports across 16 states with the final tally expected to be around 155, making it one of the largest outbreaks of any month in history. States of emergency were declared in Alabama, Mississippi, Oklahoma, and North Carolina. North Carolina bore the brunt with at least 30 confirmed tornadoes destroying hundreds of homes and businesses and resulting in at least 24 deaths, marking the three days as the largest tornado outbreak to ever hit the state, and the second deadliest outbreak on record for North Carolina.

April 25th through the 28th saw another massive amount of tornadic activity. An estimated 305 tornadoes hit from Texas to New York during the 4-day period, with 190 of them touching down over just 24 hours on the 27th and 28th. The outbreak included three EF-5, 12 EF-4, and 21 EF-3 tornadoes and killed nearly 350 people, mostly in the state of Alabama, making it the deadliest tornado outbreak since 1936. A strong EF-4 tornado packing winds of 190 mph devastated the cities of Tuscaloosa and Birmingham. This single cyclone tore a path as much as 1.5 miles wide and was on the ground for more than 80 miles causing an estimated 65 fatalities and over a thousand injuries.

Adelie penguins

Adelie penguin populations declining in warming Antarctica. Image credit: Peter Prokosch

Allstate, the nation’s largest publicly held personal lines insurer, announced $1.4 billion in estimated catastrophe losses for the month with over 100,000 claims reported to date in the affected areas. Risk-modeling company AIR Worldwide estimated the tornadoes caused $3.7 billion to $5.5 billion in insured losses industrywide. The years 2008 through 2010 were already the industry’s costliest for thunderstorm damage—which includes hail, tornadoes and other severe storms—with a total tab of $30 billion, said Robert Hartwig, president of trade group Insurance Information Institute, via a Wall Street Journal report, but 2011 is on track to exceed any of those three.

Meanwhile, half way around the world, Thailand experienced massive flooding that impacted nearly a million people. In what is normally the dry season, some areas received more than 50 inches of rain bringing mudslides and widespread damage to crops.

Research Examines Carbon Sinks and Ecological Impacts

Observational research from the scientific community continued to explore the ongoing reaction of natural environments and processes to changing conditions. Under a warming climate, Antarctica is becoming greener as grasses are finding better conditions under which to take root while warming waters and declining krill populations are resulting in declining penguin populations. An analysis of glaciers in the southern half of South America finds them melting at the fastest pace in the last 350 years. And earlier spring blooms are impacting the timing of ecological cycles while changes in rainfall patterns are influencing the migratory habits of some bird species.


USFS: Heavily deforested coastal mangroves are immense carbon stores. Image credit: Theo Allofs/Corbis

Separate studies focused on different global carbon sinks with researchers at Duke University concluding an 18-year study and finding the growth and seed-production abilities of several species of trees to be considerably more sensitive than previously thought to climatic changes such as earlier springs and summer droughts. The U.S. Forest Service found that coastal mangrove forests, which have been the targets of heavy deforestation, store more carbon than almost any other forest on Earth. And the longevity of underwater kelp forests was determined to be hindered by wave damage accompanying increased storm strength and frequency. Lastly, satellite data from NASA revealed lowered plant productivity in several of Earth’s larger ocean currents.

GOP Continues Opposition to EPA Regulation of Greenhouse Gases

In the political arena, carbon pricing remained a contentious subject in Australia while the U.S. Supreme Court signaled a likely rejection of a lawsuit brought by six states attempting to limit greenhouse gas emissions by a myriad of power companies around the nation. The court indicated a preference for such regulations to be handed by the Environmental Protection Agency (EPA), an organization facing its own challenges.

San Rafael Glacier

South American glaciers melting at fastest rate in 350 years. Image credit: Neil Glasser

The Republican party in the United States continued its multi-pronged attack on the EPA throughout the month. A bill aimed at blocking the EPA from using the Clean Air Act to regulate greenhouse gas emissions easily passed in the House of Representatives, but a companion bill failed in the U.S. Senate. And, in a budget deal compromise to avoid a government shutdown, the Republicans won significant environmental provisions that reduce the EPA’s budget by $1.6 billion, remove gray wolves in the northern Rockies from the endangered-species list, and defund the Interior Department’s Wild Lands initiative, which would have inventoried federal lands for their wilderness characteristics.

Meanwhile a study focusing on methane releases from hydraulic fracturing, an increasingly controversial process used in the drilling extraction of natural gas, found that such releases may contribute as much or more than coal to global warming. Natural gas has been gaining widespread favor amongst politicians in both parties in the U.S. considering its large natural stores in the country, relatively easy access, minimal regulation, and lower costs particularly when compared against rising oil prices.

Selected Significant Climate Anomalies and Events, April 2011

Selected Significant Climate Anomalies and Events, April 2011. Image Credit: NOAA


“Whereas, throughout our history, both as a state and as individuals, Texans have been strengthened, assured and lifted up through prayer; it seems right and fitting that the people of Texas should join together in prayer to humbly seek an end to this devastating drought and these dangerous wildfires”

– Rick Perry, Governor, State of Texas
Proclamation for Days of Prayer for Rain
April 21, 2011





  1. Pingback: The monthly climate report: April 2011 | SeaMonster - May 30, 2011

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The Consensus

173 professional scientific organizations (and counting) around the world acknowledge the global impact of rising emissions of greenhouse gases from human activities

The Indicators

Climate Change Indicators Climate Change Indicators NASA GISS - Global Annual Mean Surface Air Temperature ChangeGlobal Temperature Sea level change from 1993 to the present day Global Sea Level Northern Hemisphere Sea Ice Anomaly, 1979-Present Arctic Ice Melt Glacial Retreat, 1980-2010 Glacial Retreat Atmospheric CO2 Concentrations, Mauna Loa Atmospheric CO2 Level
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