Volume 6, Number 16 - July 13, 2006
brought to you online by Pinedale Online
Wyoming on drought watch
While fall and winter snowfall brought a measure of drought relief to most of Wyoming, below-average spring precipitation and warmer-than-average temperatures have contributed to a general drying trend inrecent months, according to Wyoming State Climatologist Dr. Stephen Gray.
“Abnormally dry to moderate drought conditions now exist in all but the western most portions of the state,” Gray said in his recently released Wyoming Drought Watch. “The worst impacts of this dryness have been somewhat localized or confined to a few sectors of the state’s economy, especially ranching and agriculture. The current outlook calls for warmer-than-average temperatures to continue throughout the summer.”
Gray pointed out that one area of concern is a marked drop in soil moisture over large parts of southern and eastern Wyoming. With estimated soil moisture values now ranging from 20-30 percent of normal in several counties, Gray reported that adverse effects on livestock production and agriculture are expected.
Stream flows in central Wyoming are also generally below-average for this time of year, and in many cases the high-elevation snowpack that feeds these streams had melted by the end of May, so relatively low flows will continue throughout the summer.
Temperatures for much of Wyoming have been above average this calendar year, with the month of May being especially warm. This late spring warming contributed to an early melt-out of many snow basins.
According to Gray, historically, the late winter and spring have produced a large percentage of total annual precipitation across Wyoming, and the months of April through June are usually the wettest time of year on the eastern plains. This year, however, April through June has been markedly dry in all but the far northwest and, to some degree, northeast corners of Wyoming
Climatologists look to several indicators to monitor drought situations. While conditions may be better in the higher elevations in the county, the lower elevation southern portion of the county hasn’t received normal precipitation in the last few months. Some areas of Sublette County have dropped below 25 percent of normal in the last 90 days.
Based on observations at U.S. Geological Survey gages, streamflow for the majority of far western Wyoming is near normal. Over the past two weeks, however, streamflows at many gages in Sublette, Sweetwater and Fremont counties (Upper Green and Wind River Basins) have dropped below the 25th percentile.
Reservoir conditions are generally good in the Upper Green River Basin, with that snowmelt helping to fill reservoirs. By the end of June, Big Sandy was 88 percent full; Fontenelle was 82 percent full, and Flaming Gorge was 83 percent full.
Current federal drought monitoring parameters places most of Wyoming, as well as Montana, South Dakota, Nebraska and Colorado in the abnormally dry to moderate drought category.
Gray pointed out that current forecast models point to a significant chance for warmer-than-average temperatures for July through September in Wyoming.
For the seasonal outlook from a national perspective, the U.S. Drought Outlook indicates that the recently-worsening drought affecting parts of the northern Plains and the Upper Mississippi Valley should continue, and may even expand across eastern Montana, Minnesota, the Dakotas and parts of Iowa. To the south, drought should persist over much of the central and southern Plains. In the Southwest and Colorado, heavy rains over the short term should ease drought conditions and reduce the danger from wildfires. However,long-term drought is likely to continue. Additional drought relief should visit southern and coastal Texas, but the outlook is less positive to the east. The drought affecting the northern Gulf Coast from Louisiana into Alabama and northwest Florida should benefit from periodic rains, although major improvement is not expected at this time. The drought in Georgia that extends into the western portions of the Carolinas may see improvement.
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