More rain visited the U.S. over the past Drought Monitor period, resulting in various improvements across the Eastern two-thirds of the country, drought change maps show.
Much of that wet weather impacted Texas and the Plains, and based upon estimated monthly state rainfall totals, May 2015 was the wettest month ever in Texas and Oklahoma. This ended the region's long-term drought within 4-6 weeks, but causing widespread flooding.
Dry conditions and increasing temperatures returned to the Southwest after an unseasonably cool and wet May, and in the Midwest, weather has been favorable in alleviating drought conditions in Minnesota and Wisconsin.
About 43.3% of the contiguous U.S. is in some form of drought or dryness currently, compared to 50.7% last week and 48% one year ago. About 3.1% is in the most extreme rating, compared to 3.1% last week and 3% one year ago.
This week's Drought Map author, NOAA's David Miskus, said moisture, combined with a cold front in the Northeast brought improvements across the region and halted any drought expansion. Since this was the first decent widespread rainfall event in New England in a while, only the areas with the heaviest rains were improved by one category.
As of June 2, instantaneous and daily average USGS stream flows quickly rebounded from near- to record low levels to much above normal, but 7-, 14-, and 28-day average flows were still below the tenth percentile.
Scattered showers and thunderstorms were a daily occurrence across most of the Southeast during the 7-day drought map period, and after a week's worth of rainfall, significant totals (more than 2 inches) were measured across most of Arkansas, Louisiana, Mississippi, Alabama, central Tennessee and Kentucky, northern and western Georgia, west-central Florida, western Carolinas, and northern Virginia.
In contrast, much lighter amounts (less than 0.5 inches) fell on southeastern Virginia, and eastern sections of the Carolinas, Georgia, and Florida.
Since much of the area under D0 was short-term dryness, the moderate to heavy rains were enough to eliminate D0 in central Kentucky and Tennessee, northern sections of Alabama and Georgia, central Alabama, and southwestern Georgia.
Drought expanded in Central North and South Carolina, as well as the very tip of Florida.
Another week of widespread moderate to heavy showers and thunderstorms provided a fitting end to a wet May in the Midwest.
More than 1.5 inches of rain fell on northwestern and southern Minnesota, northern Iowa, central Missouri, most of Wisconsin, Illinois, Michigan, and the northern halves of Indiana and Ohio, allowing for a one-category improvement across much of the region, Miskus' report said.
The rains effectively eliminated abnormal dryness in most of Wisconsin, southern Minnesota, Michigan, northern Indiana and Ohio, and central Missouri, and D1 was improved to D0 in northwestern and east-central Minnesota, and in central Wisconsin.
Where the weekly totals were lower (less than 1 inch) or short-term deficits initially greater, D0 and D1 remained, and this included northern Minnesota, west-central Illinois, northern and southeastern Indiana, and south-central lower Michigan.
Overall Midwest major crop progress (planting and emergence) were close to the five-year average, and crop and pasture conditions were generally favorable, Miskus' report said.
The incredible southern Plains drought relief continued this week, although the weekly rainfall amounts "decreased" from copious to heavy, and clear skies finally prevailed later in the period.
Still, more than 2 inches of rain fell on parts of the Dakotas, western Nebraska, western and eastern Kansas, eastern Oklahoma, and most of Texas except for the Panhandle and southwest.
With the continued moisture, decreasing or eliminated long-term deficits, and increasing short-term surpluses, one-category improvements were made across much of Texas, Oklahoma, western and southern Kansas, southeastern Colorado, eastern South Dakota, and northeastern and southwestern North Dakota.
Where lighter rains fell (north-central Oklahoma, south-central Kansas, eastern Nebraska, and south-central South Dakota), conditions were maintained. D0 was slightly expanded in northwestern North Dakota (Mountrail County) where long-term dryness still lingered.
Seasonably drier and warmer weather returned to the West after unseasonably cool and unsettled conditions occurred during the first three weeks of May. As a result, May recorded above-normal precipitation (except along the Pacific Coast) and well below-normal temperatures (except in the Pacific Northwest).
An unusual effect of the cool and wet May weather was a green-up of pasture and range vegetation in southern and eastern California and Nevada where extreme to exception drought is widespread and ongoing.
Although California and Nevada pasture and range conditions were rated 35% and 50% good or very good on May 31 by the USDA, no improvements were made to the drought depiction as long-term (4-year drought) hydrologic conditions remained dire. In fact, Miskus says the green-up of vegetation and sprouting of grasses will most-likely provide extra fuel for wildfires once the vegetation dies off later this summer.
Source: David Miskus/ The U.S. Drought Monitor is produced in partnership between the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration.