Fading El Niño Means A Wet Spring, Possible Snowpack Bump For Colorado
The El Niño that brought record warm winter temperatures to much of Colorado will continue into April, meaning more precipitation than usual — especially along the Front Range.
“It’s hanging in there, just barely, which means that we have that setup that’s favorable for a wet spring… It has been wet in the northern and central mountains,” said University of Colorado-Boulder climatologist Klaus Wolter.
“And the wrinkle in this, in 2016, is that it’s a bit warmer than it used to be so at the lower elevations you get maybe not as much snow, but higher up, the snowpack could continue to be above normal conditions.”
The 2015/2016 El Niño has broken records. Data from buoys in the Pacific show that for about two weeks in November sea surface temperatures were the warmest recorded.
Now that we’ve moved past the El Niño’s peak, sea surface temperatures are decreasing, making the weather patterns weaker. But, it should still generate more storms and cooler temperatures. These spring storms could dump huge amounts in some areas, and leave others relatively untouched - making the location of the storm key.
“This is the time of year where there is more of a tendency for those storms to cut off, which makes the forecasting game bit more interesting… they are not any different from storms you can get other times of the year, they are just more common and maybe a little juicier if they sit in the right spot.”
Even though each El Niño is different, Wolter, a climatologist for over 20 years, was surprised by the record warm temperatures mid-winter.
“February was the most unusual month of this El Niño. You could even argue that it looked more like a La Niña. That was when California dried up. March was the sixth wettest in northern California since 1920 and it filled up the reservoirs, that was very good. So that was a bit of a surprise in February.”
The majority of California’s reservoirs are located in the northern half of the state, but Wolter found that this El Niño didn’t keep to the storm track he predicted earlier.
“In general, things have been shifted a bit to the north, meaning that places like Seattle had a very wet winter, and southern California, Los Angeles and San Diego had a very dry winter. That’s not supposed to happen. Same in Arizona; Phoenix was exceptionally dry.”
That dry zone from southern California through Arizona and northern New Mexico extended into southeast Colorado. The southern river basins —including the Arkansas and the Rio Grande — are currently at 86 percent of normal snowpack for this time of year, according to early April 2016 SNOWTEL survey data [.pdf].
Overall, Colorado sits at 96 percent of normal snowpack for as of April 4, 2016.
The El Niño, which began in spring of 2015, may keep Colorado’s snowpack at average levels going into spring melt - good news for the millions of people who depend on water from the state’s rivers, both in Colorado and much of the West.
“If we continue into May with that pattern, that would be a bit less common. There have been El Niño years where it kept going all the way into June, the most recent was 1995… 1983 was like that too, another Super El Niño.
“Right now we are on this glide path towards probably neutral conditions in the Pacific in probably June or July and then the data will show that the event [El Niño] is over.”
Climatologists are debating what will happen next. Usually, a La Niña has the tendency to follow up a big El Niño, but Wolter isn’t convinced. Even with the best weather models, we’ll just have to wait and see.