September was drier than normal, with about half the normal amount of rain measured at Spokane Internation Airport. But the El Nino in the south-central Pacific Ocean should bring more precipitation to the Northwest this winter.
The El Nino – the unusually warm ocean temperatures in the equatorial Pacific – is still weak. Much of drought-stricken California and parts of the southern Great Plains are hoping for at least a moderate El Nino pattern. Scientists say that a moderate to strong El Nino is needed to change worldwide weather patterns and possibly offer relief to drought-stricken areas this winter.
Our rather warm and dry summer season in the western U.S. may have also been influenced by the large pool of warm water in the Gulf of Alaska. Ocean temperatures in this region are averaging as high as 5 degrees above normal.
The abnormal warming also extends northward into the Arctic regions. There have been numerous reports of additional ice melting in the Arctic which has raised a new level of concern. The warmer ocean waters could be one reason for the melting. The rise in ocean temperatures near the North Pole may be caused, at least in part, by the undersea thermal vents.
Watching these patterns for many years, I’ve noticed that low pressure systems will usually form or even intensify over regions of warmer waters. As the low pressure forms in the Gulf of Alaska, high pressure will become stronger to the east. This has been the case for the summer and early fall for much of the West Coast as the ridge of high pressure continues to dominate this part of the country blocking most Pacific storms.
The long-range computer models are beginning to show a weakening of the high pressure ridge in our region in the next few weeks. But, it’s still going to be strong enough to keep vital rainfall from entering California.
In the Northwest, precipitation totals are expected to be above normal for the winter. However, the warmer ocean temperatures, including those in the Gulf of Alaska, should decrease snowfall totals. In the mountains, though, it may be cold enough to produce enough snowfall for another good ski season. It’s all about the temperature and a few degrees can make a big difference between rain and snow.
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