Source: US Drought Monitor
Map valid May 30, 2019 | Data valid May 28, 2019
This week’s drought summary: During this U.S. Drought Monitor (USDM) week, a strong high pressure ridge was anchored over the southeastern contiguous U.S. (CONUS) while an upper-level trough dominated the West. This pattern set up a southwesterly flow across the central part of the country, which funneled moist and unstable air from the Gulf of Mexico into the Plains. Pacific weather systems moving in the jet stream flow plunged into the western trough, bringing precipitation and cooler-than-normal temperatures to much of the country from the Rockies westward. The weather systems intensified as they moved into the Plains, triggering another week of severe weather and heavy flooding rains. Two or more inches of precipitation occurred across the Plains to Midwest and in upslope areas of Montana and Wyoming, with locally 5 inches or more. Weekly precipitation was wetter than normal across much of the Southwest, and from much of the Great Plains to Great Lakes. Half an inch to locally 2 inches was observed from the central Appalachians to New England, but these amounts were mostly below normal. The week ended up drier than normal across western Washington, northern Idaho and northern Montana, southern Arizona, most of New Mexico, and central to southern Texas. The subtropical high kept the Southeast drier and warmer than normal, with record high temperatures reported. As a result of this weather pattern, drought contracted in Oregon, Wyoming, and the central Plains, but expanded in the northern Rockies, Texas, the Tennessee Valley, and the Southeast.
South: Precipitation amounts in the South ranged from zero in parts of Texas, Louisiana, Mississippi, and Tennessee, to over 5 inches in northern Oklahoma. D0 expanded in central Tennessee where 90-day precipitation deficits were noteworthy, pockets of D0 expanded or were introduced in southern Texas along the Rio Grande or along the coast, and D1 was added to Zavala County in Texas where dryness was evident for the last 7 days to 6 months. According to USDA reports, 21% of the topsoil moisture in Tennessee was short or very short, up from 3% last week. The last couple weeks have been very dry, hot, and windy in southern Texas as the subtropical ridge continued to build and dry out the atmosphere. There have been reports of significant evaporation of Cameron County retention ponds with fields and lawns showing some browning. Some producers in Dimmit County, Texas were hauling water and supplemental feeding in some areas.
Looking Ahead: Next week (May 30-June 4), an upper-level weather system will move across the eastern CONUS while another takes up residence over the Southwest. The high pressure ridge over the Southeast gradually shifts to the Plains. During this process, fronts and low pressure systems will trigger heavy rains again across the Plains to Midwest, with 1 to locally over 3 inches progged from northern Texas to Illinois, and from Illinois to Pennsylvania. An inch or more of precipitation is expected over much of the Northeast. Little to no precipitation is forecasted for much of the Southeast, most of California, the western half of the 4 Corners States, western Oregon, much of Washington, the High Plains of Wyoming and Montana, most of North Dakota, and northern Minnesota.
Above-normal temperatures will continue in the Southeast for much of this period, and spread from the Pacific Northwest into the northern and central Plains, while cooler-than-normal temperatures will linger in the Southwest and from the eastern Great Lakes to New England.
For June 5-12, odds favor above-normal precipitation from the 4 Corners States to the southern Appalachians, eventually spreading across the Southeast; along most of the Mississippi River; and over the northern half of Alaska, including the panhandle. Statistical odds favor drier-than-normal weather over the Great Lakes to Northeast, from northern California to the northern High Plains, and over southwestern Alaska.
Cooler-than-normal weather is expected across New Mexico to western Texas, over Washington State, from the Great Lakes to New England, and over central Alaska. There is a high probability for warmer-than-normal weather over the northern to central Plains stretching into California, over the Southeast stretching to the Gulf of Mexico coast and Mid-Atlantic coast, and over southern and northern Alaska.