Will another snowy winter boost the #ColoradoRiver? It hasn’t happened in this century — AZCentral.com #COriver #aridification

“New plot using the nClimGrid data, which is a better source than PRISM for long-term trends. Of course, the combined reservoir contents increase from last year, but the increase is less than 2011 and looks puny compared to the ‘hole’ in the reservoirs. The blue Loess lines subtly change. Last year those lines ended pointing downwards. This year they end flat-ish. 2023 temps were still above the 20th century average, although close. Another interesting aspect is that the 20C Mean and 21C Mean lines on the individual plots really don’t change much. Finally, the 2023 Natural Flows are almost exactly equal to 2019. (17.678 maf vs 17.672 maf). For all the hoopla about how this was record-setting year, the fact is that this year was significantly less than 2011 (20.159 maf) and no different than 2019” — Brad Udall

Click the link to read the article on the AZCentral.com website (Brandon Loomis). Here’s an excerpt:

The arrival of the winter snow season, which sustains the river and last year bailed out water users facing critically low reservoirs, brings new questions for water managers: Will El Niño conditions in the Pacific Ocean produce a wet winter in the Southwest and parts of the Rockies? And could a second straight wet winter wallop the region with above-average snowfall and again forestall more drastic conservation measures?

[…]

[Jack] Schmidt isn’t predicting the weather, but he has crunched the numbers on the drought or aridification patterns that plunged the Colorado into peril over the last 23 years and they aren’t pretty. Last winter was the second-wettest of that time, behind 2011. There have been a handful of high-snow, high-flow years in that span, but none was followed immediately by another. Each such winter has provided no more than a two-year arrest in the system’s downward slide. Without another one this winter, Schmidt said, the region will be back in crisis despite the states’ agreed cutbacks…And history shows that those who hope another wet winter will forestall tough choices risk disappointment…

Already, the region has used about a fifth of last winter’s windfall, Schmidt said. That’s enough to set water storage back where it was in June of 2021, a time that was better than last year, but still an impending disaster that sent water managers scrambling and forced central Arizona farmers to prepare for a cut off…Like Schmidt, federal forecasters and some water system managers are tamping down optimism for this El Niño…National Weather Service meteorologists reinforced the uncertainty in a Phoenix briefing this week. Their predictions for northern Arizona’s high country, which saw big snows in tandem with the Rockies last winter, amount to essentially even odds…Scanning moderate to strong El Niños in recent decades, [Ken Drozd] found that about half bring wet winters to the state, meaning snow in the north. About 30% are drier than normal, including the winter of 2015-2016. About 20% are near normal. At present, the Weather Service’s Climate Prediction Center gives roughly even odds to all three possibilities: wet, dry and normal.

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