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NIDIS Intermountain West
Drought Early Warning System
May 23, 2017


Current U.S. Drought Monitor Depiction


Recommended Changes

Summary: May 23, 2017

Last week, a significant precipitation/snow event impacted much of northeastern Colorado.  Precip amounts of over 2 inches were reported over areas that are currently depicted as D0 (abnormally dry) to D1 (moderate drought).  Much of the higher elevations in the region also received over an inch of moisture for the week.  The cold temperatures and snow accompanying this active weather pattern have helped to keep the snowmelt season slow and steady.  The lower elevations of eastern Utah, where D0 currently shows up on the U.S. Drought Monitor, continues to see a deficit of moisture, where less than half an inch has been reported since the beginning of the month.

Currently midway into the snowmelt season, snowpack numbers throughout the IMW are still in very good condition.  Even for basins that saw lower than average snowpack peaks, snowmelt was not early and some of the snow still remains.  The responding streamflows are in good conditions, with most sites in the Upper Colorado River Basin reporting in the near normal range (and high flows showing up in the Upper Green in southwest WY).  The slower melt rates have helped to minimize flooding.  Reservoirs are responding to the uptick in flows, and we're observing good levels throughout the UCRB.  As of last week, levels at Lake Powell have reached the near normal range for this time of year and continue to rise.

VIC soil moisture gives a good indication of where dry conditions currently exist.  Drier soils are now popping up in eastern UT and western CO.  They also show where short-term dry conditions have been dominating in southern AZ and southern NM.  Areas previously showing dry conditions (along the Front Range urban cooridor in CO) now show wet soil moisture conditions.  VegDRI (the health of the vegetation) also shows the short-term dryness in eastern UT with good moisture showing up in eastern CO.

This active weather pattern, regulating temperatures and bringing moisture to the eastern portion of the region, is forecast to continue over the next couple of weeks.  Unfortunately, this pattern may not bring relief to our dry regions of eastern UT and southern AZ/NM, but it should help keep the rest of the region in good condition as the water supplies increase and the growing season continues.

Recommendations

UCRB: Last week, the U.S. Drought Monitor author expanded D0 in western Colorado.  While we agreed to a limited expansion, D0 was added to higher elevations that are not showing signs of dryness.  While the lower elevations show very dry soils, local reports are that the higher elevations look lush and healthy.  We recommend keeping the D0 in the valleys, but removing it from higher elevations (black contour shows what we think D0 depiction should look like).

Eastern Colorado: This week, the U.S. Drought Monitor author is proposing possible improvements to D0 and D1 conditions along the CO Front Range.  We are in agreement with these recommendations (shown as green and orange contours).

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