Forecast news: ‘Going back to 1905, we’ve never seen this [ENSO neutral after double-dip La Niña]’ Klaus Wolter #CODrought


From the Summit County Citizens Voice (Bob Berwyn):

The centerpiece of Tuesday’s webcast was a seasonal outlook from NOAA meteorologist Klaus Wolter, who offered some hope. Despite the fact that La Niña is fading, the overall combination of ocean temperatures and global circulation may bring at least normal moisture to the high country.

“What we have to play with … shows a slight preference for a little bit wetter conditions on the West Slope, but it’s not a strong signal,” said Wolter, who studies climate with the Earth Systems Research Laboratory in Boulder.

The combination of a weak El Niño, a cold phase of a large-scale Pacific oscillation known as the PDO, as well as atmospheric patterns in the Atlantic could combine push storms across the central Rockies, he said.

The El Niño Southern Oscillation is one of the best indicators for developing long-term precipitation outlooks, but it looks like the Pacific Ocean will be in a near-neutral state this winter, and perhaps slip back into a La Niña phase (cooler than average sea surface temps in the equatorial eastern Pacific) by next year.

Wolter said having a “neutral” year after a douple-dip La Niña is almost unprecedented. Almost always, after a two-year La Niña phase, the Pacific rebounds to at least a weak El Niño.

“Going back to 1905, we’ve never seen this,” Wolter said.

The last time the Pacific stayed in a La Niña to neutral phases for an extended time was in the late 1990s and early 2000s, culminating in the 2002 drought. In general, Wolter said some of Colorado’s historic long-term droughts have coincided with similar conditions.

“If you look at the big, long droughts … going back to 1910, they were all associated with conditions like we’re seeing; this is the big concern,” Wolter said, adding that he does expect at least a bit of a rebound from last winter’s epic low snowfall.

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