Snowy season due in part to La Niña

The frigid weather pattern arrived as temperatures were already near or below zero across much of the region.

Prior to the big chill, more snow fell in the Spokane area – 40.1 inches has fallen at the international airport since winter’s start. The normal snowfall for July 1 through June 30 in Spokane is 45.5 inches. We’re already ahead of last year’s entire 2006-07 season. Only 35.2 inches of snow was observed last winter as most of the moisture fell as rain in the lower elevations.

In Coeur d’Alene, more than 80 inches of snow has fallen so far; the normal is 66.7 inches.

In early December, I was asked if plenty of snow was going to fall in time for Christmas. I’m now hearing folks ask when the snow will end and if spring will come early. This has certainly been one of the snowiest winters we’ve seen in years. Good friends of mine who relocated to Coeur d’Alene three years ago are heading south to California to get away from the wintry weather. (There were other reasons, but this one was in the top-three.)

Despite all the snow, we’re not even close to the 93.5 inches observed in the Spokane area in 1949-50. January 1950 saw 56.9 inches of snow. Although we’ve had above-normal snowfall during the first half of this winter, the second half is not expected to be as snowy. Spokane should end up with approximately 50 inches of snow for the season with nearly 100 inches expected in Coeur d’Alene.

This snowy season is the result, at least in part, of La Niña. This phenomenon is the cooler than normal sea-surface temperature event in the south-central Pacific Ocean. La Niña has been strengthening over the last month. While the Northern Hemisphere is in a deep freeze, the Southern Hemisphere is well into its summer season. During this time we sometimes see El Niño, the warmer than normal sea-surface temperature event, form or expand.

A number of computer forecast models had this La Niña weakening by the early portion of 2008. Several scientists are now calling this phenomenon a “monster” because of its recent strengthening, and La Niña will likely be with us well into the spring season.

As mentioned in previous articles, it’s not clear why we see abnormal warming and cooling of ocean waters in the equatorial regions. I believe that underwater volcanic activity plays a role on whether we see a La Niña or El Niño event.

There’s little doubt that La Niña is influencing weather patterns, especially here in the Inland Northwest. Last week, rare snows were seen in the normally mild southeastern U.S. We’ve already seen above normal snowfall in our region with about six more weeks of winter weather expected.

As this round of cold air moves to the east, milder weather will invade the region around the first week of February, sending highs well into the 40s. Who knows, we may see an isolated 50-degree reading. Another round of mild weather is expected in early March that will ultimately reduce mountain snowpacks, leading to some lowland flooding.

The early March thaw may seem like an early spring, but the mid-March through mid-June period should be cooler and a bit wetter than normal across the Inland Northwest as La Niña continues to influence our weather patterns. We should also see above normal thunderstorm activity during the upcoming spring season as well.