U.S. drought coverage increases sharply in November
Dec 1, 2016
By Brad Rippey, USDA Meteorologist, Office of the Chief Economist, World Agricultural Outlook Board, Washington, D.C.
During the 4-week period ending on November 29, 2016, contiguous U.S. drought (D1 to D4) coverage increased sharply from 26.80 to 31.46 percent—up 4.66 percentage points. Since reaching an autumn minimum of 18.34 percent of the country in drought on September 13, coverage has increased 13.12 percentage points. Other subsets of drought coverage also increased between November 1 and 29: exceptional drought (D4) increased from 1.71 to 2.68 percent, extreme to exceptional drought (D3 to D4) increased from 4.86 to 8.66 percent, and severe to exceptional drought (D2 to D4) increased from 10.95 to 16.60 percent.
The increases in drought coverage were driven by rapidly worsening conditions in the Southeast. However, substantial rain arrived across much of the southeastern drought area November 28-30. Record-setting streaks without measurable rainfall ended abruptly in locations such as Tuscaloosa, Alabama (71 days from September 18 to November 27), and Atlanta, Georgia (43 days from October 17 to November 28). Before the late-month rainfall, on November 27, USDA rated topsoil moisture 100 percent very short to short in Alabama, along with 98 percent in Georgia, 81 percent in Tennessee, and 76 percent in Kentucky and Mississippi. On the same date, USDA rated pastures at least three-quarters in very poor to poor condition in Alabama (95 percent), Georgia (81 percent), and Tennessee (79 percent). Ironically, one of the most visible and tragic drought-related impacts occurred on November 28 as rain approached and began to fall across the Great Smoky Mountains of eastern Tennessee. That afternoon and evening, in advance of a cold front, wind gusts of 40 to 60 mph or higher fanned and spread the 5-day-old Chimney Tops fire, which rapidly expanded to encompass more than 17,000 acres in and near Gatlinburg, Tennessee. In the ensuing tragedy, there were at least seven fatalities and approximately 700 structures destroyed.
By November 29, exceptional drought (D4) covered nearly one-third (33 percent) of Alabama and Georgia, along with 14 percent of Tennessee, 6 percent of South Carolina, 4 percent of North Carolina, and 3 percent of Mississippi. Extreme drought (D3) or worse blanketed 97 percent of Alabama, 71 percent of Mississippi, 62 percent of Georgia, and 60 percent of Tennessee. The southeastern drought has lasted long enough to begin affecting water supplies. In northern Georgia, the surface elevation of Lake Lanier dipped to 1060.7 feet by late November, 10.3 feet below full pool and 9.7 feet below a year ago. Lake Lanier’s lowest level on record occurred in December 2007, when the surface elevation fell to 1050.8 feet.
Meanwhile, late-autumn precipitation provided parts of the Northeast with drought relief. Northeastern regional drought coverage peaked at 55 percent—the highest since 2002—on November 22. Despite recent precipitation, topsoil moisture was rated 85 percent very short to short in Connecticut on November 27, along with 66 percent in New Hampshire and 46 percent in Vermont. By November 29, a ribbon of lingering extreme drought (D3) stretched across southern New England, covering 44 percent of Connecticut, 41 percent of Massachusetts, and 5 percent of New Hampshire.
Although 58 percent of the U.S. winter wheat crop was rated good to excellent on November 27, there were some drought-related issues (e.g., uneven emergence, poor establishment) on the central and southern High Plains, and 27 percent of the U.S. winter wheat production area was in drought on November 29, up from an early-autumn low of 8 percent. In five of the Plains states (CO, KS, NE, OK, and TX), the portion of the wheat crop rated very poor to poor on November 27 ranged from 12 to 16 percent. By November 29, severe drought (D2) covered more than 10 percent of Kansas—all in the southwestern part of the state where late-November topsoil moisture was rated 80 percent very short to short.
On November 1, drought was affecting 32 percent of the U.S. cattle inventory, up from 14 percent in early autumn. Similarly, 33 percent of the nation’s hay area was in drought, up from 14 percent as recently as mid-September. Some of the most visible drought impacts on cattle and hay have been reported in the southeastern drought area, where surface water has become scarce and supplemental feeding of livestock has been ongoing for weeks or months because of abysmal pasture conditions.
Drought coverage in the Northwest remained minimal during November because of ongoing showery weather. A few northwestern areas, including eastern Oregon, continued to grapple with long-term water supply issues. In California, statewide drought coverage stood at 73 percent on November 29—the lowest in more than 3.5 years, since April 30, 2013. Nearly all of California’s drought-free area was in the northern part of the state, but extreme to exceptional drought (D3 to D4) still covered 43 percent of the state. A recent report from USDA stated that aerial surveys have indicated that there are more than 100 million dead trees in California, with the majority located in ten counties in the central and southern Sierra Nevada.
Short-term weather outlook: A brief period of generally tranquil conditions will soon be replaced by a return to active weather. On Friday, precipitation will develop across the south-central United States and overspread the Pacific Northwest. During the weekend, rain will become heavy across parts of the South, while showery weather will engulf the northern half of the West. Five-day rainfall totals could reach 2 to 6 inches across the South, excluding the southern Atlantic region; 1 to 4 inches in the Pacific Northwest; and 1 to 3 inches in the northern Rockies. Higher Northwestern elevations will receive significant snow. In contrast, mostly dry weather will prevail into next week from southern California into the Desert Southwest, and from the central High Plains into the upper Midwest.
Please Note: The next issuance of this drought update will be Thursday, January 5, 2017, unless conditions warrant an earlier release.
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