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Demise of El Nino a likely factor in weather change – to La Nada

THURSDAY, OCT. 18, 2012

Our region finally received some much-needed moisture as our major new moon weather pattern change arrived on schedule.

An impressive 0.42 inches of rain fell at Spokane International Airport earlier this week. Since Jan. 1, 14.38 inches of rain and melted snow has fallen in Spokane. Despite the long dry spell, the airport is about 3 inches above normal. More showers are expected into next week. It also looks like the air may be cold enough to produce some measurable snow in the higher mountains.

One possible reason for this big change is the recent demise of El Niño, the warmer than normal sea-surface temperature event in the south-central Pacific Ocean. The latest sea-surface temperature data indicate that ocean temperatures off the west coast of South America and along the equatorial regions are now slightly below normal levels. For the last several months, sea-surface readings were above average, indicating a weak El Niño. Based on the current data, it looks like we’re back in what I would call a La Nada, the in-between El Niño and La Niña events.

New computer model projections indicate that we may see sea-surface temperatures rebound to the warmer side during the upcoming winter. However, if El Niño springs back to life, it should be rather weak. Toward the middle to the end of 2013, it looks like there will be another round of cooling that would lead to a La Niña.

Across the Inland Northwest, our best chances for snow occur when we have a weak to moderate La Niña. With El Niño gone, at least for now, the odds go up for more snow across our region. However, I’m not expecting heavy totals like what we’ve seen during recent record years. I’ll have my annual winter forecast, including projected snowfall totals, in early November.

Ocean temperatures are also below normal in the Gulf of Alaska and east of the Hawaiian Islands. As these readings moderate, as some computer forecasts suggest, moisture should increase in the dry areas of our region and the Great Plains over the next several months. However, despite the added rainfall, drought conditions are expected to continue across much of the central portions of the country through at least the end of this year.

Also, sea-surface temperatures are much warmer than normal, up 4 to 5 degrees, in the Arctic region, near the coast of Japan and along the northeastern coastline northward toward Greenland. The warmer waters in the Arctic may explain some of the melting of Arctic ice that we’ve heard so much about.

If you have any questions or comments, you can contact Randy Mann at wxmann, or go to www.longrange for additional information.

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