From The Grand Junction Daily Sentinel (Dennis Webb):
The climatological pattern that could contribute to a wetter-than-average winter in Colorado is taking its time becoming an actual thing this season. But the National Oceanic and Atmospheric Administration is still expecting its arrival, hoping that it could help alleviate drought conditions that are particularly severe in the Four Corners region.
That region has been especially dry in recent years, and currently is experiencing the worst drought conditions in the continental United States. It’s ranked as being in exceptional drought, the worst category, with that drought level extending north through Delta and eastern Montrose counties, even crossing into a bit of eastern Mesa County. The rest of Mesa County and the rest of western Colorado are all in lesser stages of drought, with conditions having eased thanks to some fall moisture.
While southwest Colorado also benefited from that moisture, conditions more recently have been drier there. The Natural Resources Conservation Service reported as of Thursday that while statewide snowpack averaged 117 percent of normal, southwest Colorado has fallen below median snowpack, with the Gunnison River Basin at 94 percent, the Upper Rio Grande at 86 percent and the Four Corners basins at just 70 percent. That compares to 133 percent for the Upper Colorado River Basin, 130 percent for the Yampa/White river basins, and around 150 percent for the Arkansas and South Platte basins…
“We still think it will form,” [Mike Halpert] said…
Specifically, the ocean warming needs to alter tropical rainfall patterns, bringing more rain to the central and eastern Pacific and less rain over Indonesia, and it’s that rainfall shift that affects the jet stream and moisture patterns in the United States.
Halpert said he’s expecting such an atmospheric response to happen shortly. Fortunately, he said, in the meantime the short-term forecast over the next few weeks already is for wetter-than-normal conditions. That means a likely wetter-than-average start to winter in the Southwest even before El Niño influences kick in.
Based in good part on that El Niño forecast, the Climate Prediction Center says there are above-average chances for above-normal precipitation in Colorado through March…
It’s also noteworthy that the Climate Prediction Center says there is an above-average chance of warmer-than-normal temperatures this winter in Colorado. Halpert said El Niños used to be associated with colder winters in the southern United States, but in light of a warming climate over the years, forecasters aren’t expecting below-average temperatures this year.
[Royce Fontenot] said the trend of warming temperatures matters when it comes to drought assessment, when taken in context with other factors such as the region and time of year, which can affect things such as levels of evaporation, and of water absorption and release by plants.
[John Berggren[ said that even with an above-average snowpack season, if there is a warm winter and spring, “you can very quickly eliminate those gains … which is unfortunate.”
He said even a weak El Niño is better than no El Niño when it comes to precipitation, particularly in the Four Corners area. That said, “it’s not going to be a gangbusters of a winter, especially with the warmer-than-average temperatures that are expected,” he said.