In past La Niña winters, area received 26 percent more snow

The beautiful fall weather over the past week, which included a mixture of mild, sunny days followed by lawn-quenching rains, has probably kept most people’s minds off the dire predictions of a snowy upcoming La Niña winter.

I thought I’d bring the subject up again, however, since the National Weather Service recently put out some interesting statistics about La Niña, El Niño, and seasonal snowfall totals. La Niña winters are typically cooler and wetter across the Inland Northwest. This is due primarily to a predominant weather pattern, which includes a blocking ridge of high pressure that forms over the Gulf of Alaska, and a more northern position of the subtropical jet stream.

The ridge of high pressure puts the Inland Northwest under cooler northwest flow, and the position of the jet stream (which is farther south and aimed at California during El Niño years) steers storm systems in our direction. Using data for Spokane, average seasonal snowfall totals for all years is about 49 inches. Looking at all La Niña winters over the last 60 years, the average snowfall is about 61 inches, an increase of about 26 percent. For El Niño winters, the average snowfall is about 29 inches, and for neutral years (neither La Niña nor El Niño) the average snowfall is about 51 inches. Those numbers may put things into better perspective than just looking back at the winters of 2007-’08 and 2008-’09, which were record- or near-record setting years for snowfall.

Outside the Inland Northwest, and down south in northern Arizona near Flagstaff, many folks had more immediate concerns than what La Niña might mean for them this winter. A rare severe weather outbreak hit the area last Wednesday morning, which brought heavy rains, damaging winds, large hail, and at least four tornadoes.

While this type of weather is typical late in the day in the warm humid air of the spring and fall in the Midwest, it was definitely not that kind of environment in Flagstaff, where high temperatures that day were only in the mid-50s. What made some of the tornadoes even more rare was the fact that they occurred between 5 and 7 a.m. Train cars were derailed, windows were smashed out, and homes were damaged, but fortunately no one was injured. Arizona averages four tornadoes per year, about two more than is usually seen in Washington or Idaho.