Summary: June 2, 2020
May in the Intermountain West Region saw the beginning of the summer precipitation pattern with the bulk of the precipitation showing up in eastern Colorado and eastern Wyoming. Less precipitation fell in the Upper Colorado River Basin, the rest of Utah and much of Arizona and New Mexico. Northeastern Colorado saw the best precipitation for the month with near normal conditions. Southeastern Colorado though, continued the dry pattern when precipitation should be increasing, which is not great for an already dry area. Western Colorado, most of Utah, and much of Wyoming are also continuing the dry trend.
Not helping the dryness in the IMW was the much above normal temperatures seen in May. Most of the IMW region saw 2-4 degrees warmer than normal and much of western Colorado and eastern Utah seeing 4-6 degrees above normal. There were a few spots with near normal temperatures, which include northeastern Colorado and northeastern Wyoming. The warm temperatures drove up evapotranspiration rates further drying out a region that has little water to give.
It appears streams and rivers in the Upper Colorado River Basin have seen their peak flow with flows starting to drop. The basin saw an overall drop in streamflows, with the number of streamgages seeing above normal flows dropping and the number of gages seeing below normal flows increasing. The three main sites in the basin appear to be peaking now or have peaked with flows in the Colorado and Green River fighting to stay in the normal range. The San Juan River seems to be fighting to stay in the below normal range.
As expected, soil moisture is dropping and vegetation health is mainly in the drought categories.
The outlook for the next week is hopeful for precipitation through Utah and western Colorado, with a nice bullseye in the parched San Juan Mountains. Little to no precipitation is in the forecast for eastern Colorado and most of New Mexico and Arizona. Unfortunately, beyond next week, it looks like the dry trend is back with increased chances of below normal precipitation through the IMW region.