Mild winter, wet spring due to warm sea-surface

For the last several months, there has been a moderate El Niño. El Niño is the warmer-than-normal sea-surface temperature along the equatorial regions in the south-central Pacific Ocean.

Most winters in the Inland Northwest during this event are milder and a bit drier. Our region often receives less snowfall as many Pacific storms head southward into California. This has certainly been the case this winter.

In the last several weeks, El Niño has been decreasing in strength. I expect many scientific experts to declare this phenomenon “weak” within the next two to four weeks.

Despite the weakening of El Niño, there are still warmer-than-normal sea-surface temperatures near the west coast of South America westward across the equatorial regions. Readings south of the Hawaiian Islands along the equator are still 2 to 3 degrees above normal. But, concentrated regions southwest of the Hawaiian Islands are as much as 4 to 5 degrees above normal.

This phenomenon appears to be decreasing in strength as sea-surface temperatures near the west coast of South America cool down. Readings along the coast south of the equator are now averaging between 2 to 3 degrees below normal. This cooling trend is evidence that El Niño is weakening.

It appears that this warm-water phenomenon has peaked but will still be influencing global weather patterns at least until early spring. But, it’s possible that we may be talking about a new La Niña, the cooler-than-normal sea-surface temperature, toward the middle to the end of 2010.

If El Niño falls apart, that could mean a cooler-than-normal spring for the Inland Northwest. Average precipitation totals are expected to be above normal as copious amounts of precipitation move across the Inland Northwest. The main jet stream aloft, which directs many of our storm systems from the Pacific Ocean, is expected to move from California into our region.

We may see some snow in the lower elevations from late February into early March, and again in late March into early April. However, snowfall totals for the season will likely end up well below normal across the Spokane and Coeur d’Alene area.

The cooler and wetter weather this spring should last until early to mid-June. Then, the last two weeks of that month, as well as July and August, will be warmer and drier than normal.