It is weird how western Colorado has missed out this summer. It has rained all summer, except for early-mid July in Western Wyoming. The wettest since 1998.
JACKSON, Wyo. – Rainfall has been heavier and more consistent than usual in Jackson Hole and the Tetons this summer. In fact, the Town of Jackson received more rain from June through August in 2023 than in any other June-August period since 1998. Summer Rainfall The Town of Jackson weather...
buckrail.com
It has indeed been a very different situation this summer in Colorado in comparison to Wyoming.
Although not a complete fizzer, the summer monsoon season in Colorado was drier than normal, with the southwest quarter of the state in particular receiving less than half the rainfall that normally occurs in this period (the map is for August, but June and July showed similar patterns). By contrast, note how wet the Front Range counties from Denver northward continued to be to the east of the Continental Divide, an anomalously wet pattern on the plains that started in May and lasted all summer.
As a result of the poor monsoon, soil moisture at depth is now depleted. Even at the surface things are dry up high - I was above timberline at the summit of Guanella Pass a week ago, and the normally green tundra was dry and crunchy underfoot.
The sub-par moisture in southwest Colorado has also been accompanied by a hotter than normal summer, with air temperatures running from well above normal to record warm from June through August.
This has in turn created high vapor pressure deficits and evaporative demand, as shown in this three-month plot of the Evaporative Demand Drought Index (EDDI). Note the striking contrast between Colorado (and states to the south), where drought prevails, and Wyoming, which has high moisture and low evaporative demand, and is running a moisture surplus. Basically, this summer the further south you went, the drier it got, while the areas to the north in Wyoming, northwestern Utah, and northern Nevada got abundant rainfall (much to the distress of those at Burning Man).
All of this translates to stress on vegetation, which will gladly start to suck up whatever precipitation does begin to fall as we head toward winter. Once again, this stress is most acute in the San Juan, Gunnison and Eagle river basins, but that is also where the majority of the annual runoff that feeds Lake Powell comes from.
The bottom line here is that although we headed into the spring and summer of 2023 in good shape hydrologically due to a good winter snowfall, it did not take long for drought to reassert itself, particularly across southwestern Colorado and the adjacent Four Corners area. Therefore, these summer deficits will play into spring runoff patterns from whatever amount of snowfall the current El Nino winter brings. We are already a month late in terms of significant snowfall above timberline, so winter is not starting early. We are still in more of a fading weak summer monsoon pattern, with no big snow makers on the horizon yet. Given that this will likely go down as the warmest year on record averaged globally, it will be interesting to see how the transition to winter finally plays out, and when.
But this was todays weather. A little different
