Summary: January 16, 2018
While warmer than average conditions still dominated the Intermountain West last week, the high elevation regions of the Upper Colorado River Basin received a healthy bump in snowpack. Basin snowpack values increased between 5% and 10% over the past week. Even with these increases, snowpack is still below average and conditions worsen toward the south. The basins of WY are all near-to-above average, while the northern CO mountains are slightly below average, and UT and southern CO basins are much below average.
Across the IMW, precipitation over the past week ranged from 1-2 inches in the higher elevations to quarter to half inch across the lower elevations. These recent precipitation accumulations have resulted in 30-day Standardized Precipitation Index (SPIs) in the 0 to -1 range. The 90-day SPIs highlight the extreme dryness that most of the region has been experiencing.
The active weather pattern looks to continue over the next couple of weeks. CPC shows an increased chance of below average temperatures for week 2. This is good news for further improving snowpack conditions during this critical time of year, when large accumulations of snow are typical.
At this time of year, it is extremely unlikely that the southern and central Rockies (south of Wyoming) will fully recover from the extreme deficits that have been experienced since the beginning of the snow season. Several healthy snow accumulating events in the next couple of months can help minimize some of the impacts to future water supply, but it is likely many of the sub-basins of the Colorado River will not reach their average peak snow water equivalent for the water year.
Along the eastern plains, warm daytime temperatures and windy conditions have likely been sucking moisture away from the soils and vegetation. Very cold overnight temperatures and lack of conistent snow have had a damaging effect on livestock, and winter wheat crops are starting to show signs of stress. It's still too soon to tell how the winter dryness and temperature anomalies will impact the crops and land in the spring, but the situation is being monitored.
UCRB: Although the higher elevations received decent precipitation last week, areas in central UT are still show extremely large precipitation and snowpack deficits. Following the precipitation and snowpack at SNOTEL sites that are below the 10th percentile, an expansion of D2 (maroon shape) is recommended. A further northward expansion of the D1 (orange shape) and D0 (black shape) into southwest WY are also recommended based on the SNOTEL numbers.
Eastern Colorado: The U.S. Drought Monitor has proposed a slight introduction of D2 into the far southeastern corner of the state (in Baca County) to match up with deteriorating conditions in the Oklahoma panhandle. Other than this change, status quo is recommended following the large changes made to the region last week.
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