June 9, 2011 in Washington Voices

La Niña may be on way out, El Niño returning

Randy Mann

Over the past year, the Inland Northwest has been influenced by La Niña, the cooler-than-normal sea-surface temperature phenomenon along the equatorial regions. Conditions in our region have been cooler and wetter than normal since late last year.

During recent La Niña years, snowfall totals have been near or at record-breaking levels in three of the last four winters. The cooler ocean waters have also been blamed, at least in part, for the unusually high tornado activity east of the Rockies and the heavy rainfall that has led to historic flooding along the Mississippi River.

Heavy flooding is also possible in the lower elevations near the Rockies in Montana, Colorado and Utah. Snowpacks were measured at 200 to 250 percent above normal with some parts of the northern Utah mountains reporting snow totals near 400 percent above average last month.

Temperatures in this area were as much as 10 to 20 degrees below average. Eventually, readings will start warming to normal or even above-normal levels that will melt much of that snow. The last time the West had a prolonged winter was in 1983 when there was massive flooding. During that time, the Colorado River went absolutely wild for about a month.

Sea-surface temperatures along the equatorial regions have been warming to near-normal levels over the past four to six weeks. There is still an area of cooler waters in the mid-Pacific regions, but it does appear that La Niña is almost gone. And, ocean temperatures near the South American coastline have warmed to above normal levels. It’s too early to tell, but this could be a sign of the formation of a new El Niño, the warmer than normal sea-surface temperature event, by the end of this year.

In terms of our local weather, June has started with a mix of showers and cool temperatures combined with sunny days and warm afternoons.

It’s beginning to look like we’re finally going to see more sunny days and warmer temperatures beginning next week. It’s not going to be rainless, but we should see less rain between now and early July.

With La Niña rapidly weakening, I still believe our upcoming summer will be warmer and drier than normal. During this cycle of wide weather extremes, places that are wet and cool often turn warm and dry. This will likely be the case for our region this summer and perhaps into the fall as well.

Contact meteorologist Randy Mann at randy@ longrangeweather.com.

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