NOAA predicts mixed drought outlook for U.S.

Nearly a year after the United States Corn Belt had its driest June-July in 75 years, a U.S. think tank says moderate or exceptional drought covered more than half the continental U.S. last week.

Meanwhile, the National Weather Service is predicting an “elevated chance” of below-average precipitation this spring for parts of the southern and western U.S.

The U.S. Drought Monitor said on April 9 that “moderate to exceptional drought covers 50.8% of the contiguous United States,” though this was down from 51.9% the previous week.

Drought Monitor, which is produced by a partnership comprised of the National Oceanic and Atmospheric Administration (NOAA), the federal agriculture department and the University of Nebraska-Lincoln, noted last week there were recent improvements due to several storm systems in the midwest, south and southeast. That report predicted wet weather across much of the eastern U.S. until April 20.

“Light to moderate precipitation (0.5 to 1.5 inches), with pockets of heavier amounts (more than 2 inches), fell across the western Corn Belt, providing some relief in areas where there was no snow cover and the soil had thawed,” Drought Monitor stated of the midwest region, noting that the National Weather Service’s frost tubes “showed that the last of the frozen soils in northern and central Iowa had thawed, and that some farm tiles were running in eastern Iowa and northern Illinois, indicating more subsoil moisture than previously thought.”

But three weeks ago, NWS had suggested this spring could see below average precipitation in some areas.

“The precipitation outlook for (April, May and June) 2013 indicates elevated chances for below median accumulated precipitation for sections of western and southern (Continental U.S.),” according to a prognostic discussion of long-lead seasonal outlooks issued March 21 by the NOAA’s  climate prediction centre.

“Enhanced chances of above median precipitation exist for the central Mississippi Valley northward into the Great Lakes region for the Ohio (River) valley and sections of the midwest. During (May through September) there are enhanced odds for below-median precipitation from northwestern Texas to sections of the northwest.”

In 2012, the U.S. Corn Belt experienced its hottest and driest period since 1936, according to a Dec. 28 report from A.M. Best, titled As Drought Lingers, Crop Insurers Face Worst Underwriting Results in 25 Years. That report estimated gross underwriting losses, as of the third quarter of 2012, would be about U.S. $15.5 billion for firms offering multiple peril crop insurance in the U.S.

For its part, Aon Benfield estimated total insured losses from the 2012 drought and heat wave in the U.S. were US$20 billion, while it estimated economic losses were US$35 billion.  That report, published in January by Aon Benfield’s Impact Forecasting unit, noted insured and economic losses in 1988 were $1.9 billion and $74.1 billion respectively, in 2012 U.S. dollars.

On April 4, NOAA published its Seasonal Drought Outlook, a map plotting areas under drought conditions where drought is either ongoing with some improvement, will persist or intensify, or is likely to improve with impacts eased. It also plots areas where drought development is likely, such as several sections of California, Arizona, Oregon and Nevada.

The outlook notes drought is ongoing, with some improvement, through most of Kansas, Nebraska and South Dakota. The map shows drought is “likely to improve, impacts eased” in eastern Oklahoma, eastern Kansas and most of Iowa and Minnesota, plus central Florida.

Areas where drought will persist or intensify include most of Arizona, much of the southwest, Wyoming and southern Montana.

NOAA has five designations for drought intensity, ranging from D0 (abnormally dry) through D4 (exceptional).

The April 9 drought monitor noted the D1 (moderate drought) and D0 designations were removed from several sections of Georgia over the previous week. Much of the southeast had received 0.5 to 1.5 inches of rain, with the southern sections of Louisiana, Mississippi, Alabama, and Florida recording more than two inches. Rain also fell on areas of Texas, Oklahoma and Nebraska that were designed D2 (severe drought), D3 (extreme drought) and D4, Drought Monitor noted.

“In Texas, 1 to 3 inches of rain was measured in north-central, central, and southeastern Texas, providing a one category improvement many areas,” according to Drought Monitor. “Unfortunately, little or no rain was observed in western and extreme southern Texas, and some degradation was made.”

On the other hand, most of Kansas did not experience heavy rain.

“In extreme northeastern Kansas, however, a small band of heavier rain (1.5 to 2.5 inches) was enough to diminish deficits and ease drought from D2 to D1.”