El Nino may mean fall rain, less winter snow
Today is the first full day of fall across the Inland Northwest. Temperatures have certainly cooled down considerably, with some locations recently receiving “substantial rains” that were needed to put a big dent in our summer drought and help put out the many wildfires, the worst in 45 years in some areas.
Some folks actually loved the weather over the last few months while some are now happy to see the return of wetter conditions. This week, parts of North Idaho received more than a half-inch of rain with about a quarter-inch of moisture measured in Spokane and the Spokane Valley. But, the summer of 2006 will certainly be remembered as a hot and dry one across much of the United States.
For example, Great Plains in the central part of the country,. had the hottest summer since the Dust Bowl days of the 1930s. More than 2,300 weather records were smashed. The torrid conditions extended all the way into southern Canada as parts of South Dakota recorded highs of 120 degrees in July. There were also long stretches of 110 degree-plus temperatures in parts of the central Great Plains. Despite the tremendous heat, the summer of 1936 was still hotter than 2006, by about three to four degrees.
Moisture also was very scarce, especially in the panhandle of Oklahoma and northern Texas. Crop yields were some of the lowest in recorded history. That particular weather pattern was part of a 70-year drought cycle dating back for hundreds of years.
July was also the hottest month in California’s history as temperatures in the agriculturally-rich central valley topped 115 degrees during the height of the summer season.
We’re now hearing about the onset of this new El Nino event forming in the warm waters of the south-central Pacific Ocean. As I mentioned last week, the phenomenon is the abnormal warming of sea-surface temperatures along the West Coast of South America and along the equatorial regions. This ocean warming directly affects the upper-level jet stream patterns that usually determines whether we see wetter or drier weather conditions.
No one is certain as to why ocean waters warm up and cool down. I believe that short and long-term climatological cycles and underwater volcanic activity may play a big part to the formation of an El Nino and La Nina (the abnormal cooling of sea-surface temperatures).
The latest sea-surface temperature data does indicate that El Nino is gaining strength, which would be bad news for those of us who wish for lots of winter snow.
During this event, western United States is often warmer than normal, especially during the winter season. Snow levels will rise to 6,000 feet or higher as lowland snows are often far below normal levels.
Despite the new El Nino, there is some hope. About 70 percent of the time, the fall season is cooler and wetter than normal. This means we should see above normal moisture from now until Thanksgiving with some Indian summer weather around early October. As we head into December, and if El Nino hangs on, Pacific storms should start moving into California and we typically get what’s left over. But by the late winter and early spring season the wet weather is expected to return to our region.
Although the milder and drier winters are usually the result of El Nino, there have been a few exceptions to the rule as we’ve experienced a few snowy winters during this event like in 1982-83 and 1957-58. And, this summer pattern we just came through strongly resembles the one in 1936. (Remember the 70-year drought cycle?) Well, during the winter of 1936-37 the Inland Northwest saw lots of snow, but we didn’t have an El Nino back then.
It’s still possible, however, that the current El Nino may fall apart prematurely or the main storm track takes a more northerly path into the Pacific Northwest, which happens approximately 30 percent of the time. So there’s always hope for snow. We’ll just have to wait and see what Mother Nature has in store.