Keep an eye on weather advisories, warnings
It was another interesting year weatherwise across North Idaho. Despite having one of the driest summer and early fall seasons for the second year in a row, our annual precipitation total of rain and melted snow ended up at 29.21 inches at Cliff’s station in northwestern Coeur d’Alene. The normal precipitation total since 1895 is at 26.77, so we were a little above the average.
In Spokane, however, its final moisture total of rain and melted snow stood at 15.95 inches, a little below the average. Its normal annual precipitation is about 16.50 inches at the airport with slightly higher average totals near the city.
We are now in a pattern of wetter-than-normal weather across the region. A series of Pacific storms will continue to move across the Inland Northwest and provide more rain and snow in the lower elevations, with mostly snow in the higher mountains — which is good news for skiing and snowboarding.
However, we’re in an El Nino-type weather pattern. Ocean temperatures in the south-central Pacific Ocean continue to be well above normal. As Cliff and I have been saying for quite some time, during El Nino years, our seasonal snowfall total is often lower than normal because much of the moisture will fall as rain. This has certainly been the case so far, but we’ve managed to get over 16 inches of snow since the start of the season. The normal to date is about 33 inches, so we’re “going to have to work for the snow” for the rest of the season.
The rest of this month looks wetter than normal with rain and snow in Coeur d’Alene and across the rest of the Inland Empire. As we get into the mid to late portion of February and March, moisture totals are expected to drop off a bit. A lot depends on how strong this new and expected El Nino will get in the next few months. Most scientists are predicting a weak warm-water event in the south-central Pacific Ocean. Even if the El Nino is weak, it’s expected to be with us into at least the spring season. As usual with this pattern, only time will tell.
With the increasing rain and snow activity across the Inland Northwest and other parts of the western portions of the country, it’s a good idea to know what’s in store weatherwise, especially if one is planning to hit the roadways to go to the mountains or visit friends and relatives. The mountain passes, especially over the Cascades, can change very quickly and the roads can quickly become extremely slick.
For much of the Inland Northwest, the mountains generally refer to any elevation above 3,000 feet. A Winter Weather Advisory, Snow Advisory, Winter Storm Warning, or Heavy Snow Warning are usually the most common statements issued by the National Weather Service, sometimes days in advance.
A Winter Weather Advisory is issued when a precipitation mix of snow, sleet, freezing rain and strong wind events is expected. The advisory is upgraded to a Winter Storm Warning if snowfall in the valleys is expected to exceed 4 inches in a 12-hour period in addition to the sleet, freezing rain or wind.
In the mountains, the expected snowfall must exceed 8 inches in that time frame to prompt a warning. If the precipitation is expected to be all snow, a Snow Advisory is issued when 2-4 inches is likely in a 12-hour period. When more than 4 inches of snow is forecast for the valleys (8 inches in the mountains) in a 12-hour period, we’ll see a Heavy Snow Warning. For early or late season storms in the mountains, like in April or October, lesser snow amounts can also prompt warnings.
Another type of advisory one might see, especially during an El Nino year, when sea-surface temperatures are warmer than normal, is the Freezing Rain or Sleet Advisory. These are issued any time the surface becomes hazardous due to those types of precipitation. When more than a half inch of sleet is expected, a Heavy Sleet Warning is issued.
An Ice Storm Warning is issued when the area is threatened by more than a quarter inch of ice. A Blizzard Warning is rare in the Inland Empire, but is issued when visibility due to blowing snow is reduced to a quarter mile or less and winds are 35 mph or stronger. Also, we can have blizzard-type conditions even after it has stopped snowing, especially if strong winds reduce visibility.
Keep an eye to the sky and Cliff and I hope everyone has a safe 2019.
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Randy Mann can be contacted at randy@longrangeweather.com