Summary: December 10, 2019
Over the last week the Intermountain West received some beneficial precipitation, especially in the Colorado higher elevations. Some areas to note include the San Juan Basin up north thru the Gunnison Basin received 1.01-2.00” of precip with NE Montezuma County seeing 2.01-3.00”, Routt and Jackson Counties received 0.51-2.00” and southwest Utah saw 1.01-2.00”. This precipitation over the last week has helped increase SWE in SW Colorado. For instance, Gunnison River Basin is now 111% of median and San Miguel River Basin is 131% of median. However, recent precipitation was not enough to make up the huge deficit from the lack of Monsoon season. For instance, looking at the two examples given precipitation at Gunnison River Basin is 77% for the water year and San Miguel River Basin is at 65%.
Temperatures were mostly above normal across much the IMW, with the exception of NW Utah and SW Wyoming where it was 0 to 3 degrees below average. The whole state of Colorado experienced above average temperatures of at least 3 to 9 degrees with some pockets of 9 to 15 degrees above average in south central CO.
Streamflows across the Upper Colorado River Basin are running above normal for the most part. Reservoirs in the Upper Colorado River Basin are retaining adequate winter storage. Lake Powell, of course, is still below the long-term average. Most major reservoirs, however, are retaining near-normal to above normal storage thanks to last year's great snowpack.
Forecast outlook is showing some spotty/higher elevation precipitation in northern Utah and western Colorado. It appears the most significant precipitation will occur along the Wyoming/Idaho boarder where they are forecasting up to 3.00”. Southern Utah, most of Wyoming, and eastern Colorado are expected to see little to no precip this upcoming week. Temperatures are expected to be below average for Utah, normal temperatures forecasted for the rest of the IMW, and above average temperatures expected in eastern Colorado.
Utah: Status Quo. We are in agreement with the Utah drought representatives on status quo. Last week’s precipitation was not enough to improve the deficit. Some specific observations include:
Wasatch Front: rainfall at lower elevations rather than more useful snowfall
Emery County: lower elevations typically green up with Sept/October rains, that didn't happen this year; producers are still hauling water. PRISM data in Emery County is consistently not representative of conditions. We hypothesize that this is due to the sparsity of weather stations in the area and the stations that do exist being located at high elevations.
Four Corners: Status Quo. While much of the IMW saw beneficial precip, including the four corner region, it was not enough to improve a full drought category. However, recent precipitation is pushing us in the right direction. A few weeks ago we were teetering on the edge of downgrading from D2 to D3 and now we are teetering on an improvement from D2 to D1 but we are not quite there yet. 30-day SPIs are showing great improvement in the four-corners/San Luis Valley area however, fast forward to 90-day, 120-day, and the 6 month timeframes and the SPIs deteriorate significantly. Precipitation is still behind for the water year in much of this area. Mesa Verde NP, for example, is still tied for its record driest July 1 - present precipitation accumulations, and running at a 5-inch deficit.
Eastern Colorado: Status Quo. Most of eastern Colorado was dry over the last week with the exception of the northern Front Range. 30 day SPIs are showing improvement around Teller County but this area did not receive precipitation and experienced above average temperatures over the last week. We decided to hold off on improvements in this area but will keep an eye on things for next week.
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