By Brad Rippey, USDA Meteorologist, Office of the Chief Economist, World Agricultural Outlook Board, Washington, D.C.
During the five-week period ending on Nov. 3, 2015, contiguous U.S. drought coverage fell sharply to 26.17 percent—a decrease of 5.19 percentage points.
The drop is even more impressive when considering that U.S. drought coverage had increased to 34.78 percent by Oct. 20, at which time heavy rain began to fall across the South. As a result, U.S. drought coverage—on the strength of Southern drought eradication—fell from 34.78 to 26.17 percent, or 8.61 percentage points—between Oct. 20 and Nov. 3. This marked the fourth-largest two-week decrease in D1-4 coverage in the U.S. Drought Monitor’s 16-year history.
Since mid-October, a procession of storms has sharply reduced U.S. drought coverage. Some of the heaviest rain has fallen from Texas to the Mississippi Delta, where two- to four-month precipitation deficits were wiped out in a matter of days. In some of the hardest-hit areas, severe to exceptional short-term drought (D2 to D4) turned suddenly to flash flooding. While it is not possible to blame individual storms on El Niño, the type of weather pattern that we’ve experienced in the last few weeks—featuring strong, slow-moving storms and an enhanced subtropical jet stream across the southern U.S.—are consistent with the atmospheric response to unusually warm water over the central and eastern equatorial Pacific Ocean. In addition, enhanced tropical activity in the central and eastern North Pacific is a hallmark of warm-episode (El Niño) events; thus, it is worth noting that the remnants of record-setting Pacific Hurricane Patricia contributed abundant tropical moisture to one of the southern U.S. storms.
During the two weeks ending Nov. 3 (to reflect the improvement since heavy rain began), statewide drought coverage decreased sharply in Louisiana (from 86 to 2 percent); Mississippi (75 to 8 percent); Arkansas (60 to 22 percent); Texas (50 to 4 percent); Oklahoma (36 to 14 percent); and Alabama (24 to 0 percent). USDA’s topsoil moisture ratings also reflect the dramatic change. In Louisiana, for example, topsoil moisture rated very short to short decreased from 85 to 5 percent during the two weeks ending Nov. 1. Immediately prior to the late-month Southern deluge, record-setting heat, low humidity, and gusty winds contributed to a rash of wildfires.
Even parts of the drought-stricken West benefited from the recent increase in precipitation. Between Sept. 29 and Nov. 3, overall drought coverage fell from 63 to 45 percent in Arizona and from 86 to 82 percent in Idaho. While all of Oregon and Washington remained in drought, coverage of extreme drought (D3) fell from 67 to 61 percent in Oregon and from 68 to 48 percent in Washington during the five weeks ending Nov. 3. California continued to lead the nation in coverage of exceptional drought (D4), although coverage decreased slightly from 46 to 45 percent between Sept. 29 and Nov. 3. Historically, approximately 90 percent of California’s wet-season precipitation occurs after Nov. 1.
On Nov. 3, drought covered 11 percent of the U.S. corn production area and 13 percent of the soybean area. The October increase in drought coverage (values stood at 4 and 5 percent, respectively, on Sept. 29) had no impact on yield potential, since corn and soybeans were mostly mature and in the process of being harvested. By Nov. 1, the U.S. corn harvest was 85 percent complete, ahead of the five-year average of 79 percent. Similarly, soybeans were 92 percent harvested by Nov. 1, four percentage points ahead of the 5-year average.
On Nov. 3, the portion of the U.S. winter wheat production area in drought stood at 22 percent, down from an autumn peak of 29 percent on Oct. 20. However, late-October rain mostly bypassed an area stretching from the east-central Plains into the middle Mississippi Valley, leaving some winter wheat in need of moisture to ensure proper autumn establishment. By Nov. 1, the portion of the wheat crop rated in very poor to poor condition was 14 percent in Kansas, 15 percent in Missouri, and 19 percent in Oklahoma.
Weather outlook: A cold front currently crossing the nation’s mid-section will reach the Southeast by Saturday. Locally severe thunderstorms will develop later today along the cold front and push eastward on Friday. Total rainfall associated with the cold front’s passage could reach 2 to 4 inches in the western and central Gulf Coast States, leading to possible flooding, and 1 to 2 inches in the Southeast. Rainfall will be lighter, generally an inch or less, from the Midwest into the Northeast. Elsewhere, mostly dry weather will prevail from southern California to the southern Plains, but increasing storminess farther north could lead to five-day precipitation totals of 1 to 3 inches in the Pacific Northwest and 1 to 2 inches in the northern Rockies.
PLEASE NOTE: The next issuance of this emailed drought update will be Thursday, Dec. 3, 2015, unless conditions warrant an earlier release. The “U.S. Crops in Drought” products will be produced on a weekly basis, and are available online:
http://www.usda.gov/oce/weather/Drought/AgInDrought.pdf
Archived “U.S. Crops in Drought” files can be downloaded:
http://drought.unl.edu/Planning/Impacts/USAginDroughtArchive.aspx