Summary: August 7, 2018
2018's song of ice and fire (TM?) continues for Colorado and the Upper Colorado River Basin. Smoke from the Mendocino Fire Complex in California has been common throughout the region, as well as smoke from our own fires. Over a dozen wildfires are currently burning on the west slopes of Colorado according to Inciweb. A handful more continue to burn in Arizona with several lingering in New Mexico and Utah.
Meanwhile, yesterday, large hail fell in southeast Colorado with some stones threatening to at least tie Colorado's state record for hailstone diameter (4.5"). Large areas of Pueblo and Las Animas County received over two inches of precipitation, with one gauge in northern Las Animas County recording over 8".
Temperatures over the last week were cooler for much of the Intermountain West than as of late. Areas east of the Continental Divide were generally below average. Locations west of the Continental Divide were still mostly above average, but closer to normal than many recent weeks.
2018 continues to be a rough year for surface water supplies in the Upper Colorado River Basin. The dry conditions have shifted more to the northwest since the conclusion of the snowpack season. Reservoir supplies have tanked in the southern UCRB. Lake Powell, McPhee Reservoir, and Blue Mesa Reservoir are now below 10th percentile storage for this time of year. Both McPhee and Blue Mesa reservoirs filled to capacity in 2017. 75% of stream gages in the Upper Colorado River Basin are reporting below the 25th percentile for this time of year, and 10% are reporting record low flows. The NASA SPoRT soil moisture model shows most of the basin with below normal soil moisture with some pockets of normal or above normal interspersed through the basin.
Looking forward, temperatures over the next two weeks are more likely than not to be higher than normal in the northern part of the Intermountain West, and lower than normal in the southern portion. Monsoonal moisture is forecast to continue dumping on New Mexico and southeast Arizona with some higher totals extending into the San Juans and Sangre de Cristos in Colorado. The best moisture appears likely to stay to the south through the 8-14 day period as well. This pattern is likely to lead to continued degradation in the northern reaches of the UCRB, but could lead to further drought amelioration in New Mexico and Arizona, perhaps even southern Colorado.
UCRB: It is recommended that D3 be upgraded to D2 in western Garfield County and Piute County in southern Utah. These areas have seen above average rainfall in July and early August, which has been sufficient for improving long-term SPIs.
It is recommended that a closer look be taken at western Box Elder County, UT and eastern Elko County, NV. We had a phone call from a concerned rancher in the area. He is having a hard time keeping his cattle herd. The Goose Creek fire is substantial as well. Sage brush in the area is extremely dry. This area is a bit out of our comfort zone for making recommendations, and there is a dearth of long-term weather station data available through COOP or NRCS.
Eastern CO: A 1 category improvement is recommended in Otero, Bent, and Crowley Counties, eastern Prowers County, eastern Las Animas County, north and east Pueblo County, eastern Fremont County, southern Teller County, and southwest El Paso County. Following some strong thunderstorms over the past seven days, SPIs have come clearly out of the extreme and exceptional drought range for the water year to date.
It is recommended that D1 and D0 be scaled back in western Larimer County, CO, and south-central Albany County, WY. A wetter than average July has improved conditions in the region. Closely nearby, it is recommended that D1 and D2 be expanded in northern Jackson County, CO, and southern and central Carbon County, WY. Here July was hot and dry.
Visit the U.S. Drought Monitor