August 18, 2011 in Washington Voices

Atmospheric pressures raise El Niño prospects

 

Last week, I wrote that La Niña, the cooler than normal sea-surface temperature event was gone. Recently, the National Weather Service issued a forecast that put the odds at 50/50 that a new La Niña would form by fall. I’ve received numerous emails from readers wondering if La Niña was coming back. As we know, during La Niña years, our region typically has above normal snowfall and colder temperatures. That was evident with the heavy snow years of 2007-’08, 2008-’09 and 2010-’11. The winter of 2009-’10 was an El Niño year, the warmer than normal sea-surface temperature event, as we had much less snow.

Australian scientists, the ones that watch the formations of El Niño and La Niña like a hawk, stated that current atmospheric pressures are slightly favoring a new El Niño. But, it’s still too early to tell.

For over a month, Japanese and Australian scientists have stated that La Niña, the cooler than normal sea-surface temperature event in the south-central Pacific Ocean, is gone.

The latest information shows that sea-surface temperatures along the equatorial regions were warming to near normal levels over the past several months. Earlier in August, there were small areas of warmer than normal ocean waters emerging near the west coast of South America. This new trend was beginning to look like the birth of a new El Niño, but those waters have cooled over the past week. However, there are still plenty of colder than normal sea-surface temperatures along the U.S. West Coast that may influence North American weather patterns in the upcoming months.

Right now, it looks like we have a “La Nada,” or in between the La Niña and El Niño. Based on the current data, I still believe La Nada should be with us through at least early fall. But a new El Niño, or even a new La Niña, could form rapidly. It could go either way.

In terms of our local weather, after a wet and cool spring, upper-level jet stream patterns have changed dramatically. We’re finally enjoying nice summer weather with lots of sunshine. We haven’t seen a drop of rain at the Spokane International Airport since July 25.

Temperatures will be warm to hot this weekend and at least into early next week. The best chance for any moisture would be at the end of this month. With this type of warm weather pattern, we sometimes receive scattered afternoon showers or a thunderstorm on the back side of heat waves, but the chances are slight that we’ll see any significant moisture this month.

Contact meteorologist Randy Mann at randy@ longrangeweather.com.

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