August 11, 2020 (UT, WY, CO)
- During July, drier- and warmer-than-normal conditions over most of the region led to an expansion of drought coverage and increased drought severity. New areas of D3 drought emerged in Utah and Wyoming. Over 95% of the region is experiencing drought or abnormally dry conditions. An El Niño event is unlikely to develop this winter; it is likely that La Niña or neutral conditions will occur in winter and spring 2020-21.
- Precipitation during July was below normal for much of the region, especially in Utah and Wyoming. Less than 50% of normal precipitation fell over most of Utah and Wyoming. Isolated areas of above-average precipitation occurred in south-central Utah and northeastern Wyoming. Precipitation was much below normal in northwestern and north-central Colorado, while above-average precipitation fell in much of southern and eastern Colorado.
- Regional temperatures during July were at least slightly warmer than normal for most of the region, with slightly cooler than average temperatures in northern Utah and western Wyoming. Temperatures were 2-4° F above normal in eastern Wyoming and 2-6° F above normal in eastern Colorado. Overall, the pattern of regional temperature anomalies was very similar in July compared to June, but July temperatures were generally not as warm relative to the average.
- With the snowpack now entirely melted, streamflow in the region is at baseflow levels. Most gages across the region are reporting near-average or below-average streamflow. More sites in Wyoming are reporting below and much-below average streamflow compared to Colorado and Utah. Despite the below-normal runoff this spring, most large reservoirs in the region have near-average or above- average storage for this time year except for Lake Powell (50% full; 65% of average), Blue Mesa Reservoir (65% full, 79% of average), and McPhee Reservoir (60% full; 72% of average). Medium to large reservoirs in Utah are also near-average to above-average for August 1st, except for Echo Reservoir (49% full; 86% average).
- Drought or abnormally dry conditions expanded to cover the entire region except for a small portion of western Wyoming . Drought conditions remained the same or worsened by one category in Utah and Wyoming while conditions in Colorado improved in some areas and worsened in other areas. In portions of eastern and southern Colorado, drought conditions improved by one category, including the removal of D4 conditions. Much of northern Colorado saw a degradation of drought conditions and emergence of D0 and D1 conditions. In Wyoming, D2 expanded significantly in the central portion of the state and three areas of D3 emerged. Drought in Utah worsened and D1–D3 now covers 94% of the state. Two new areas of D3 emerged in western and southwestern Utah.
- Pacific Ocean temperatures remained slightly below normal during June . It is unlikely that El Niño conditions will emerge this winter. During fall and early winter there is a slightly higher probability for La Niña conditions to occur compared to neutral conditions . By late winter and spring, there is a high probability of neutral ENSO conditions. The NOAA one-month outlook predicts a higher probability for above average temperatures and below average precipitation in Utah, western Colorado and southwestern Wyoming . On the three-month timescale, it is more likely that above average temperatures will prevail for the entire region and below average precipitation is more likely for the entire region except for northern Wyoming .
- A significant heat wave occurred in northern Utah from July 30th to August 3rd. Salt Lake City saw temperatures above 100° F on five consecutive days for only the fifth time. Record daily high temperatures were recorded on of 104° (July 31), 105° (August 1), and 105° F (August 2). The all-time high temperature for Salt Lake City is 107° F. In Ogden, the all-time high temperature of 104° F was tied on August 2nd.
