Summary: May 26, 2020
The previous week’s weather was true to early summer form over the Intermountain West. The Colorado River watershed stayed dry save for the far northern reaches of the Upper Green Basin. Areas east of the Continental Divide received several rounds of showers, amounting to 0.50-1.00″ of moisture. Isolated severe storms struck southeast Colorado last Tuesday and Thursday, the 19th and 21st. More widespread moisture hit eastern Colorado on Sunday the 24th. Temperatures stayed cooler than normal for the Upper Colorado River Basin, but it was a warm week for the Eastern Plains, with temperatures anywhere from 2-8 degrees above normal.
While the Arapahoe Basin Ski Resort is reopening, this move is not reflective of the broader snowpack scenario. Northern basins, such as the South Platte and Yampa/White watersheds, are holding onto normal snowpack for this time of year. Over 90% of the season’s peak snowpack has already melted from SNOTEL measurement sites in the San Juan and Rio Grande Basins. As we reach peak streamflow season, we are seeing a mix of above and below normal flows. Streamflows are below normal on the San Juan and Gunnison River Channels. This is troubling, since these areas have nearly no snowpack remaining at SNOTEL sites. Reservoir storage is falling into the below normal range in southwest Colorado as well.
While recent moisture in eastern Colorado is helpful, long-term drought indicators, and vegetative health indices are still paining a grim picture over much of the region. The Vegetative Drought Response Index is showing moderate-to-severe drought conditions across all of southern and eastern Colorado, all of northern and central Utah, and now, much of Wyoming as well. Field condition reports are also discouraging, particularly in areas where severe drought already exists. Impacts include dry soils, lack of green vegetation, inability to drill and plant crops, and cattle being taken to auction early.
The seven-day precipitation outlook shows some shots for moisture mainly over the high terrain. This moisture will come in the form of thunderstorms. Temperatures are forecasted to be well above normal as high pressure air builds over the region. Both medium and long-range outlooks suggest increased chances for above normal temperatures across the region with less certainty with regards to precipitation.