Hot, dry summer may not mean cold, snowy winter

The summer of 2006 will certainly rank as one of the driest summer seasons in recorded history, despite the recent showers and the 0.24 inches of moisture that fell on Aug. 27 at the Spokane International Airport. This is Spokane’s sixth driest summer on record. So far, it’s Coeur d’Alene’s most arid period in history.

Not only has this summer been dry, it’s also been very hot. Since May 15, the airport has recorded 30 days with highs at or above 90 degrees. Coeur d’Alene has gauged a remarkable 38 days. Both are nearly double the normal number of days.

During an average summer season, we typically see 19 days at the airport and about 22 days in the Spokane Valley area at or above 90 degrees. July was certainly a torrid period with almost half of that month (14 days) recording those temperatures at or above 90 degrees. In fact, July 23 was the hottest day with a high of 102 degrees. We actually saw three days in a row with highs at or above the century mark – mighty hot indeed.

Recently, I’ve been asked by many folks as to what type of weather patterns normally follow an extremely hot and dry summer. In other words: How much snow will fall this winter and will the skiing be as good as last season? Despite what you may have heard, an extremely hot summer doesn’t always mean a snowy winter season.

Our winter weather patterns seem to be affected by a particular sea-surface temperature event in the warm waters of the Pacific and the upper-level jet stream flows, and not what kind of summer we experience.

For example, when there is a moderate to strong El Nino (the abnormal warming of sea-surface temperatures along the equatorial regions of the Pacific), many of the potent Pacific storms tend to head south of our region into California. That was the case during the winter of 2004-05, when Spokane received only 25.8 inches of snow and California was hit with major flooding.

The heaviest snows in this area often occur when we’re at the end of a La Nina (the abnormal cooling of sea-surface temperatures along the equatorial regions), or when we’re seeing “normal” ocean temperatures in that part of the world.

Out of the previous 10 hot summers since 1888, only four subsequent winter seasons would be described as unusually snowy. The other six winters tended to be drier than usual with wide temperature variations. The total seasonal snowfall amounts ranged from a meager 15.9 inches in 1929-30, which was also the driest summer ever with .07 inches, to 52.7 inches in 2000-01. The normal snowfall for Spokane’s International Airport is 40.9 inches with 66.7 inches for Coeur d’Alene.

The snowiest winter after a hot and dry summer was in 1968-69. The airport measured 77.9 inches. January of 1969 was also Spokane’s snowiest month ever with an amazing 48.7 inches of the white stuff. Coeur d’Alene picked up an all-time monthly record of 82.4 inches and finished the season with a whopping 117.8 inches of snow.

So, what do I actually predict as far as snowfall is concerned for this upcoming winter?

We have a rather weak El Nino event in the south-central Pacific. If this phenomenon intensifies, then snowfall might become rather scarce in our region. But if El Nino falls apart within the next few months, as many computer models predict, then we could see between 40 to 50 inches of snow in the Spokane region, 50 to 60 inches in the Spokane Valley, 60 to 75 inches in Coeur d’Alene and close to 300 inches of snow for the skiers and snowboarders in the mountains. Stay tuned.