Click here to read the briefing:
The latest monthly briefing was posted [January 10, 2018] on the Intermountain West Climate Dashboard. The highlights, also provided below, cover current snowpack and drought conditions, seasonal runoff forecasts, December and annual precipitation and temperature, and ENSO conditions and outlooks.
A winter drought is developing across Utah and Colorado, with very low precipitation and poor snowpack conditions accompanied by very warm temperatures and unusually high evaporative demand. It is unlikely that the snowpack will recover to average conditions by spring, and very low spring-summer runoff is increasingly likely, especially in southern Utah and southwestern Colorado. The snowpack in both Utah and Colorado is at a near-record-low for early January, with statewide SWE at around 50% of normal, and many individual basins in southwestern Colorado and southern Utah well below 50%. Wyoming is faring much better, with above-normal SWE in the northwest basins grading to below-normal SWE in the southern basins. The first official seasonal runoff forecasts, issued in early January by NRCS and NOAA, call for below-average (70-89%) or much-below-average (<70%) April-July runoff for nearly all forecast points in Colorado and Utah, with many points expected to see less than 50% of average runoff. Forecasted runoff for Wyoming is generally above average or near average. La Niña conditions are more firmly entrenched and expected to persist through the winter, with a transition back to ENSO-neutral conditions likely by late spring. Historically, weak to moderate La Niña events are associated with below-normal March-May precipitation for Utah and Colorado. December saw much-below-normal precipitation and very warm conditions for Colorado and Utah, and near-average precipitation but very warm conditions for Wyoming. Calendar year 2017 was the 3rd-warmest on record for both Colorado and Utah, with near-normal annual precipitation in both states, while Wyoming had its 7th-warmest year on record despite much-above-normal precipitation. Since early December, drought conditions have emerged or worsened for nearly all of Colorado, southern and western Utah, and parts of southern Wyoming . As of January 2nd, 61% of Utah is in D1 or D2, and another 29% in D0; in Colorado, 33% is in D1 or D2, and 60% in D0; and in Wyoming, only 2% is in D1, and 23% in D0.