#Drought news: D0 (Abnormally Dry) expanded over Front Range

Click here to go to the US Drought Monitor website. Here’s an excerpt:

Summary

An upper-level ridge of high pressure maintained its grip across the contiguous U.S. (CONUS) during this U.S. Drought Monitor (USDM) week. The ridge kept temperatures warmer than normal from coast to coast, with the highest temperature departures from the High Plains to Mid-Atlantic States. Weather systems moving in the jet stream flow rode over the top of the ridge, taking their surface lows and Pacific fronts along a northerly track into a trough over the eastern CONUS where they stalled out across the Midwest. Showers and thunderstorms developed as the fronts moved across the northern Plains and into the Midwest, but rainfall amounts were mostly below normal. Above-normal precipitation fell in places along the North Dakota/South Dakota border, from northeast South Dakota to northern Illinois, from the Ohio Valley to Mid-Atlantic States, and across parts of Nebraska and Kansas. Above-normal precipitation fell across parts of the southern Plains to Southeast as afternoon heating triggered convective storms, and a front near the end of the week sagged south. The Southwest Monsoon continued this week, bringing above-normal precipitation to much of the 4-Corners States and contracting drought and abnormal dryness. But drier-than-normal weather dominated the rest of the West, most of the Plains, much of the Midwest and South, and parts of the Mid-Atlantic and New England. Soils continued to dry out and crops suffered as drought and abnormal dryness continued to expand or intensify across the Plains, Midwest, northern Rockies, and Virginia…

High Plains

Half an inch or more of rain fell across parts of the Dakotas this week, but the rain did little to improve drought conditions, only holding off drought expansion or intensification. D0-D3 were pulled back in parts of South Dakota where rainfall amounts totaled 2 inches or more, D0 was pulled back in southeast North Dakota and southwest Minnesota, and D0-D1 were pulled back in parts of north central and south central Nebraska and north central Kansas.

But expansion occurred in other parts of the region. Much of Montana and parts of the Dakotas, Nebraska, and Kansas had no rain this week; some areas have been drier than normal for the last 2 to 3 months; and some drought indicators reflect dryness for the last 12 months. D3-D4 were expanded in northeast Montana, and D3 expanded in northwest South Dakota and was added in southeast South Dakota, where the Standardized Precipitation Index (SPI) was consistently at those dry levels for the last 1 to 9 months. D1-D4 expanded in northwest North Dakota where the SPI was consistently at those dry levels for the last 1-6 months. D0-D2 expanded across much of Nebraska, with collateral expansion of D1-D2 in adjacent South Dakota, D1 in adjacent Iowa, and D0-D1 in southeast Wyoming, and D0 expanded in parts of eastern Kansas and northeast Colorado, due to 30-90 day precipitation deficits and high evapotranspiration caused by excessive heat. Governors provided much-needed response to the dire drought impacts. Montana Gov. Steve Bullock issued an executive order declaring a drought disaster in 28 counties and five Indian reservations in the eastern part of the state. Nebraska Gov. Pete Ricketts issued an emergency proclamation, allowing the state Emergency Management Agency to address unmet drought needs, particularly those related to wildfires. According to July 23rd USDA reports, 92% of the topsoil moisture and 88% of the subsoil moisture were rated short or very short in Montana, 82%/81% of the topsoil/subsoil moisture was short or very short in South Dakota, 71%/66% in Nebraska, 67%/62% in North Dakota, 61%/58% in Wyoming, and 45%/41% in Colorado. More than half of the pasture and rangeland were rated in poor to very poor condition in North Dakota (75%), South Dakota (73%), and Montana (56%). In South Dakota, 37% of the corn crop, 34% of soybeans, 57% of sorghum, and 76% of the spring wheat were in poor to very poor condition. In North Dakota, 23% of the corn crop and 39% of the spring wheat were in poor to very poor condition. In Montana, 55% of the spring wheat was in poor to very poor condition. According to media reports, as of July 25th, the Lodgepole Complex wildfire in Montana was the largest wildfire in the CONUS…

West

In the Southwest, several inches of rain fell with monsoon showers and thunderstorms in much of Arizona and parts of New Mexico, with 1-2 inches common across parts of western Colorado. With SPI indicators in Arizona wet at several time scales from 1 to 6 months and longer, D1 in Yavapai County was deleted and D0 or D1 were pulled back in parts of the west and south. D0 or D1 were trimmed in parts of western New Mexico and southern Nevada. But other areas were not as fortunate, with below-normal precipitation common this week across parts of New Mexico, northern Nevada, and northern Utah, where D0 was expanded. USDA statistics indicate topsoil/subsoil moisture was short or very short in 62%/60% of New Mexico, 52%/42% of Utah, 35%/25% of Nevada, and 75%/75% of California, and 41% of the pasture and rangeland was in poor to very poor condition in New Mexico. No change to the depiction was made in California.

No rain fell this week across most of the Northwest and northern Rockies, with only a tenth of an inch or two tenths recorded at coastal stations in Oregon and Washington, and at a few stations in the Rockies. The continued dryness further eroded soil moisture, with USDA reports indicating topsoil/subsoil moisture short or very short across 71%/44% of Washington, 62%/51% of Oregon, and 52%/47% of Idaho. A fifth of the pasture and rangeland was rated in poor to very poor condition in Washington (22%) and Oregon (20%). D0 was added to the interior coastal area of Washington where streamflow and modeled soil moisture were below normal, and D0 expanded across western Montana and parts of north central Idaho, and D1 added to the mountains of northwestern Montana, where 2-3 month dryness was acute and growing worse. Numerous large wildfires have broken out in this area…

Looking Ahead

In the 2 days since the Tuesday morning cutoff time of this week’s USDM, heavy rains moved across parts of the northern and central Plains and Midwest, and monsoon showers and thunderstorms brought additional rain to parts of the Southwest. For July 27-31, 1-2 inches of rain is forecast for parts of the Midwest to Mid-Atlantic region, coastal Southeast, and Southwest to southern High Plains. Rainfall amounts may be locally as high as 3 inches from the Midwest to Mid-Atlantic, as high as 5 inches in the coastal Southeast, and as high as 6 inches in the central Rockies to southern High Plains. Less than an inch is predicted for much of the Plains, Northeast, Great Lakes, and Lower Mississippi Valley, while no rain is expected for most of the Far West and parts of the northern and southern Plains. Temperatures are predicted to be warmer than normal in the West and cooler than normal in the East. For August 1-9, odds favor drier-than-normal weather in the Northwest, northern Plains, and Upper Mississippi Valley, and wetter-than-normal weather across the Southwest, southern Plains, and Southeast, as well as parts of Alaska. The Northeast likely will start out drier than normal but end up wetter than normal. Odds favor warmer-than-normal temperatures for Alaska, the West, northern Plains, and parts of the East Coast, and cooler-than-normal temperatures for the southern Plains to Ohio Valley.

So what do the prognosticators think is in store for Colorado for the next 3 months? Hot with above average precipitation in W. Colorado and equal chances for average precipitation E. of the Great Divide.

Three month temperature outlook through October 31, 2017 via the Climate Prediction Center.
Three month precipitation outlook through October 31, 2017 via the Climate Prediction Center.

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