Summary: August 15, 2017
Last week, much of the Upper Colorado River Basin received less than 0.50 inches of new precipitation. The exceptions were the Uintah Mountains and south into the Duchesne Basin in northeastern Utah, were at 0.50 inches to 2.00 inches of precipitation fell, the higher amounts in the higher elevations. Western Colorado saw areas of mainly 0.50 inches to 1.00 inches of new precipitation in Montrose, northern Gunnison, Garfield, southern Rio Blanco counties and along the Divide. SPIs in the Basin are near normal for the past 30-days between -1 and +1. More dry SPIs show up on the 90 day SPI in the basin and most of Utah and Colorado are dry for the past 6 months, with a few near normal SPIs. The northern Uintah Mountains are showing wet SPIs on all time scales, this could bring some reduction of D0.
Western Colorado has seen beneficial precipitation, however this near normal precipitation hasn't been enough to erase the dryness from the past 6-months.
East of the Divide saw at least 0.50 inches in eastern Colorado. Higher amounts of 1.00 - 2.00 inches fell along the Front Range from Larimer to Fremont counties. El Paso, southern Elbert, southern Lincoln, parts of Otero, Las Animas, Baca and Prowers counties all received greater than 2.00 inches of new precipitation. Southeastern Colorado, mainly Otero County saw severe storms with crop damaging hail last week.
Weld, Adams and eastern Boulder counties, where D0 still shows up was drier than surrounding areas last week, only seeing between 0.50 - 1.00 inches last week and 1.00 - 2.00 inches for the month. This area seems to be on the edge of improvement. With SPIs in the area showing above normal precipitation, soil moisture showing wet conditions and vegetation health in good shape, there seems to be justification to remove D0. There is a similar argument for the D0 in Jackson County, however some longer term dryness still shows up, so the D0 is justified.
Temperatures for the entire region were below normal with the most below normal were seen in eastern Colorado.
UCRB: A slight reduction of D0 in the Uintah Mountains in northeastern Utah and southwestern Wyoming is being recommended. This area has seen above normal precipitation in July and 1.00 to 2.00 inches so far this month. This will leave a fairly tight gradient between D nada and D1. With the differences in precipitation amounts in the area, due to topography, this gradient is justified. The rest of the UCRB should remain status quo. With the recent precipitation in Western Colorado, so D0 trimming could be justified, however recent near to slightly above normal precipitation has not offset the dryness of the past 6 months.
Eastern Colorado: Removal of the D0 northeast of the Denver Metro area is recommended. This area is on the edge of improvement. Given SPIs and soil moisture are showing up wet should give justification for the improvement.
Some slight improvement of the D0 in northeastern Colorado in Phillips County is also recommended. This area saw above normal precipitation in July and has received at least 2.00 inches of precipitation this month.
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