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Posted at 11:20 AM ET, 06/20/2011

After severe spring, a thin line separates wet from dry in the U.S.

When it comes to weather, there’s a general notion that an extreme event in one location will be “balanced out” by an opposite, extreme event in another location. So if there’s a flood in the Mid-Atlantic, then at the same time you might expect a drought to be occurring on the West Coast of the US, or halfway around the world. And this drought might be connected to the flood in some way.

The interconnected nature of earth’s climate system is starkly evident right now, as much of the Southern US experiences worsening drought conditions and wildfires, while much of the northern tier continues to reel from flooding and severe weather events.

In fact, I’m not sure I’ve ever seen such a prominent contrast between the precipitation “haves” and the “have-nots.” For perspective, all you’d need to do to travel from parched conditions to sopping wet ground would be to take a flight of less than two hours, such as from Austin to Little Rock, or New Orleans to Indianapolis.

The statistics, most of which Jason highlighted in a post last week , are startling.

March to May was the wettest such period on record in 10 northern states, spanning from Washington to Vermont. The Ohio Valley received 300 hundred percent of its normal amount of precipitation from March to May, and 1,300 daily precipitation records were broken across the Midwest and South. An impressive 72 locations reported their wettest day on record for any April, and five set all-time daily rainfall records for any month.


Percent Normal Precipitation (percentage) March-May (High Plains Regional Climate Center)

All of this rain led the Mississippi River to overflow its banks, flooding 6.8 million acres of land. The flooding is estimated to have cost at least $2 to $3 billion in insured losses.

Right now, major flooding is occurring in the Upper Missouri River Basin, fed by above average rainfall and melting snowpack from the Upper Midwest and northern Rocky Mountain states.

At the same time as the northern tier of the country has been submerged, states from New Mexico to Florida have been suffering from varying degrees of drought. It was the driest March to May on record in Texas. In El Paso, Texas, it didn’t rain at all for 110 days, a record dry stretch that ended on May 24th. “Extreme” to “exceptional” drought conditions are prevalent in Arizona, New Mexico, and Texas, with severe drought conditions also popping up along the Gulf of Mexico.

Wildfires have burned about 4.3 million acres so far this year, mainly in Arizona, New Mexico, and Texas, with a record amount of land going up in smoke in April alone.

According to NCDC, Texas ranchers have lost $1.2 billion because their pastures have not greened, and livestock losses may top $1 billion because of shortages in water and feed for cattle.

It’s not an accident that there is such juxtaposition between droughts and floods this year. The prevailing weather pattern throughout the winter and spring, which was influenced by La Nina conditions that finally dissipated earlier this month, steered storms away from the Southwest, and doused the northern states with snow and rain. Also, precipitation extremes are already increasing as the climate warms, as NCDC director Tom Karl pointed out in a media call last week.

“Extremes of precipitation are generally increasing because the planet is actually warming, and more water is evaporating from the oceans,” he said, adding that this “enables rain and snow events to become more extensive and intense [than they otherwise would be].”

Increased instances of drought, and more severe droughts are expected as the climate warms, but Karl said that scientists have not yet detected manmade trends emerging out of the historical record of US drought conditions.

By  |  11:20 AM ET, 06/20/2011

Categories:  Climate Change, Latest, U.S. Weather, Freedman

 
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