Summary: July 16, 2019
Weather has been seasonally normal over the Intermountain West over the last week. Temperatures were largely within 3 degrees of normal, and precipitation came in the form of spotty thunderstorms, primarily east of the Continental Divide. There are some dry pockets in the Upper Colorado River Basin and eastern Colorado to watch, but for the most part, we are still coasting on the high snowpack last winter, and the cool, wet May and start to June.
We can now say with some degree of confidence that streamflows have peaked for the season following peak snowmelt, and are winding down in the direction of base flows. Flash flooding later in the summer could set a higher peak for certain gauges or tributaries, but won't deliver as much water over such a broad area. Reservoirs continue to soak in above average streamflows. Lake Powell has amassed roughly 4 million acre feet over the last four months, and continues to rise. Lake Granby, and McPhee in Colorado are full. Blue Mesa Reservoir will likely fill in the next two weeks. Navajo and Flaming Gorge Reservoirs are also above 70th percentile storage, and still filling.
More flashy drought conditions have been observed across the IMW with grasses drying out due to hotter temperatures and lower precipitation. This is normal for steppe climates. However, Quickdri shows some areas where drying has been greater than normal. Washington, Yuma, Lincoln, and Kit Carson Counties in eastern Colorado are showing moderate drought from Quickdri. Similarly, northern Utah and southwest Wyoming are on the dry side according to Quickdri.
The remainder of the week is expected to be quite hot for the majority of the IMW. Fire danger will be elevated for Utah and western Colorado with warm, dry air aloft Wednesday through Friday. This weekend, temperatures should cool down again at least marginally as cooler air pushes into the northern portion of the region.
The 8-14 day outlook shows increased chances of above average precipitation over the Four Corners and surrounding areas. The monsoon looks to extend northward into Utah and Colorado over this time frame.
UCRB: Status Quo
We're starting to keep a closer watch on southwest Wyoming and northern Utah. Winter was excellent, and water supplies are still in good shape. However recent dryness is evident in SPIs, Quickdri, and impact reports. If this dryness continues, it will be detrimental to rangeland, and make hot weeks more dangerous from a fire standpoint.
Southern New Mexico and Arizona have been drier than normal over the past 120 days, and are eagerly awaiting the arrival of monsoonal moisture. We'll defer to other more local experts on recommendations here.
Eastern CO: Status Quo
Pockets of northeast and southeast Colorado were a little on the dry side this winter and spring. Over the last several weeks, just enough moisture has rolled through to avoid any official recommendations. We are keeping our eyes on Washington and Yuma Counties in northeast Colorado, where water year to date totals are below normal. We are also beginning to watch Huerfano and Las Animas Counties more closely. July is typically one of the rainiest months of the year for the low elevations of southeast and south-central Colorado. To this point, rains have under-delivered in central Las Animas and eastern Huerfano Counties.
Visit the U.S. Drought Monitor