Video: Drought: the ‘new normal’?

  1. Closed captioning of: Drought: the ‘new normal’?

    >>> good evening from this global gathering here in london where tonight as quickly we turn our sights back to the united states specifically the tripling and history making drought we are in the midst of and the news that came out just today a measure of just how bad it is and how much it is going to impact us. we begin with our chief environmental affairs correspondent, anne thompson .

    >> reporter: this is america land of the dry. rivers barely moving, farmland cracked and parched by a persistent stubborn drought. today the u.s. department of agriculture reports nearly half of the counties have been declared a disaster because of the drought. much of the west, midwest and southeast bathed in red having endured a severe drought for eight or more weeks. the fear in colorado county , texas is potential wildfires fueled by the trees killed in last year's drought.

    >> we may have lost between 100 and 500 million trees.

    >> reporter: it's been so hot in minnesota even famous lakes provide little relief.

    >> temperatures of 95 degrees.

    >> reporter: causing fish kills in at least 25 lakes. withering in fields the price of corn hit a new high. there is other trouble, too. 37% of the soybean crop is rated very poor to poor. 66% of the hay fields are in drought. so is 73% of the cattle land.

    >> this could be the new normal in the united states . we need to plan ahead because we know and science tells us that under a changing climate droughts will be more frequent and more intense.

    >> reporter: 60% of the states have no plan. tomorrow the government will issue its weekly drought monitor detailing the extent of a crisis that could stretch into fall, a crisis that is expected to impact food prices as much of the nation remains stuck in a very dry place.

updated 8/2/2012 10:15:15 AM ET 2012-08-02T14:15:15

There were only 24 tornadoes throughout the United States last month, according to preliminary data from the National Oceanic and Atmospheric Administration, by far the fewest for a July since records began in the 1950s. This shatters the record low of 42 tornadoes set in July 1960.

Why so few twisters?  "The one-word answer is drought," said Bob Henson, a meteorologist and science writer for the National Center for Atmospheric Research in Boulder, Colo. Fewer rainstorms means fewer chances for tornadoes, which form only in thunderstorms. "If you don't have thunderstorms, you can't get a tornado," Henson told OurAmazingPlanet.

Record drought has gripped much of the country, with nearly two-thirds of the 48 contiguous states in some stage of drought. Part of the reason for the drought — and hence the lack of tornado-producing storms — is the presence of a high-pressure "heat dome" over much of the country.

The year started out differently, with unusually high tornado activity. In March, for example, there were 151 tornadoes, well above average, Henson said. These deadly storms made up the first billion-dollar disaster of the year.

But tornadoes grew scarcer as drought started to take hold in mid- to late April. From May through July, there were 231 tornadoes, the fewest in this span since high-quality record-keeping began in the 1950s, according to the U.S. Storm Prediction Center in Norman, Okla.

In many years, a large percentage of tornadoes occur on a handful of days when conditions are right, such as strong upper-level winds and unstable air near the ground. This year was no different, with 153 twisters –  a third of the year's current total  –  occurring on just three days: Feb. 29, March 2 and April 14. [Infographic: Tornado! How, When & Where Twisters Form ]

A significantly greater number of tornadoes can be recorded now than in decades past due to the increased number of storm chasers and the ease of sharing photos or video of twisters, which makes this July's record all the more impressive. Researchers have created "inflation-adjusted" stats that reflect how many tornadoes likely occurred in years past.

After 2012, the most tornado-starved Julys were in 2002, 2006 and 2007, according to the adjusted data. The Julys of 2002, 2006 and 2012 also were among the nation's warmest months in the last century, Henson said. When a summer month is unusually hot, the polar jet stream generally has been pushed well to the north by domes of high pressure. That leaves less upper-level energy to fuel tornado-creating thunderstorms. Non-tornadic storms (which rely less on wind shear and more on heat and moisture) may still pop up, assuming drought hasn't taken hold, Henson said.

With the jet stream pushed to the north, Canada had more tornadoes than the United States last month, which is very unusual, Henson said.  

Reach Douglas Main at Follow him on Twitter @Douglas_Main. Follow OurAmazingPlanet on Twitter@OAPlanet. We're also onFacebookand Google+.

© 2012 OurAmazingPlanet. All rights reserved. More from OurAmazingPlanet.


Discussion comments


Most active discussions

  1. votes comments
  2. votes comments
  3. votes comments
  4. votes comments