U.S. drought coverage increases as conditions deteriorate in Southeast
During the 4-week period ending on November 1, 2016, contiguous U.S. drought (D1 to D4) coverage increased sharply to 26.80 percent—up 7.36 percentage points. Other subsets of drought coverage also increased between October 4 and November 1: exceptional drought (D4) increased from 1.17 to 1.71 percent, extreme to exceptional drought (D3 to D4) increased from 3.14 to 4.86 percent, and severe to exceptional drought (D2 to D4) increased from 8.37 to 10.95 percent.
The increases in drought coverage have been driven by rapidly worsening conditions in the Southeast. Measurable rain has not fallen in parts of Alabama and Mississippi since mid-September, accompanied by chronically and unusually high temperatures. By October 30, USDA/NASS rated at least one-half of the pastures in very poor to poor condition in Tennessee (65 percent), Georgia (63 percent), and Alabama (52 percent). USDA/NASS also indicated that topsoil moisture was at least three-quarters very short to short in Mississippi (83 percent), Georgia (80 percent), Louisiana (79 percent), Tennessee (78 percent), and Alabama (76 percent). Due to dryness, winter wheat planting is substantially behind schedule in several southeastern states, including Alabama (15 percent planted on October 30 vs. the 5-year average of 30 percent) and Louisiana (9 percent planted vs. 27 percent).
Exceptional drought (D4) has developed across parts of the Southeast in recent weeks and currently covers 15 percent of Alabama, 14 percent of Georgia, and 5 percent of Tennessee. Extreme drought (D3) or worse is affecting 52 percent of Alabama and just under 50 percent of Georgia. Other southeastern states reporting D3 or worse are Mississippi (27 percent), Tennessee (15 percent), South Carolina (12 percent), and North Carolina (5 percent). The southeastern drought has lasted long enough to begin affecting water supplies. In northern Georgia, the surface elevation of Lake Lanier dipped to 1,062.3 feet in early November, 8.7 feet below full pool and 6.7 feet below a year ago. Lake Lanier’s lowest level on record occurred in December 2007, when the surface elevation dipped to 1050.8 feet.
Meanwhile, autumn precipitation has provided much of the Northeast with some drought relief. Northeastern regional drought coverage peaked at 53 percent—the highest since 2002—on October 18, but has fallen 2 percentage points in the last 2 weeks. Northeastern extreme drought (D3) coverage fell to 1.37 percent by November 1, down from an autumn peak of 6.68 percent. However, northeastern pastures have been slow to recover, with 82 percent rated very poor to poor in Maine on October 30, along with 55 percent in Massachusetts, 45 percent in New Hampshire, and 44 percent in Vermont.
Although 58 percent of the U.S. winter wheat crop was rated good to excellent on October 30, there were some drought-related issues (e.g., uneven emergence, poor establishment) on the central and southern High Plains. By the first of November, 15 percent of the U.S. winter wheat production area was in drought, up from an early-autumn low of 8 percent. In Texas, 17 percent of the winter wheat was rated very poor to poor on October 30, according to USDA/NASS.
On November 1, drought was affecting 25 percent of the U.S. cattle inventory, up from 14 percent in early autumn. Similarly, 27 percent of the nation’s hay area was in drought, up from 14 percent as recently as mid-September.
In the last 4 weeks, the portion of the U.S. corn and soybean production areas in drought has increased—from 2 to 9 percent for corn and from 3 to 15 percent for soybeans. Most of the change has been driven by the escalating southeastern drought. However, with the exception of late-planted soybeans, crops were mostly mature when conditions deteriorated. Still, many southeastern row crops had been hurt by an earlier round of heat and drought during the summer.
Exceptionally wet weather covered the northwestern half of the western U.S. during October. As a result, nearly all drought was eradicated from the Northwest, except for some lingering, long-term water supply issues. Some of the improvement reached northern California, helping statewide drought coverage to dip to 75 percent by November 1, down from 84 percent a month ago. However, extreme to exceptional drought (D3 to D4) remains deeply entrenched across 43 percent of California, owing to massive 5-year precipitation deficits and related impacts across central and southern portions of the state.
Short-term weather outlook: A cold front will push eastward, clearing the Atlantic Coast (except Florida’s peninsula) by Friday, but the tail of the front will stall across the Deep South. Specifically, a multi-day rain event could result in 1- to 4-inch totals from eastern Arizona to Texas, providing significant relief from short-term dryness. Most of the remainder of the United States, except the Pacific Northwest, will receive little or no precipitation during the next 5 days. In addition, late-season warmth will continue to dominate the country, except for cool conditions along the Atlantic Seaboard. In particular, record-setting warmth can be expected across the northern Plains and upper Midwest.
Please Note: The next issuance of this drought update will be Thursday, December 1, 2016, unless conditions warrant an earlier release.
– National Drought Mitigation Center