Hail, sleet, snow - oh my!

Last month started out drier than normal, but November is turning out to be different. A series of storms has been moving through the Inland Northwest and more wet weather is on the way.

As of the weekend, it looked like we had a good chance of seeing some snow in the lower elevations through the early portion of this week. Then, we’ll have a brief break before more rain and snow arrives next week.

I received an email asking about the difference between sleet, hail and freezing rain. As our new snowfall season starts to pick up the pace in the coming weeks, I think it would be a good time to answer that question.

In terms of hail, the Inland Northwest normally sees that type of frozen precipitation in the spring and summer months from thunderstorm activity. However, there have been rare occasions when there are thunderstorms during the winter season that produce snow.

On average, Coeur d’Alene and surrounding regions usually have just three or four days a year with hail, mostly small pea-sized, but there are rare occasions when hailstones will be the size of golf balls. That was the case back in 2006 when Post Falls had a strong thunderstorm leading to reports of damaged gardens as flowers were literally flattened by the storm. It was a fast-moving storm that pushed northward into Canada in a matter of a few hours.

Cliff tells me that the largest hailstone he’s ever measured while watching the weather in Whitefish, Mont., Hayden Lake and Coeur d’Alene was a 3.1-inch tennis ball-sized stone. He photographed the large chunk of ice on his front porch in Whitefish on June 2, 1971.

Hail will consist of balls or irregular lumps of ice that will form in thunderstorm-type clouds called cumulonimbus. It forms when there are strong, upward motions of air and the water in the cloud will freeze as moves up into the cloud.

With updraft wind speeds as high as 110 mph, the hailstone can move up and down in the cloud. As it descends through the cloud, it receives another layer of supercooled water droplets. Then, as it moves up the cloud, the water droplet freezes once again and the hailstone becomes bigger. The ball of ice falls to the ground when it becomes too heavy in the cloud.

According to Wikipedia, the heaviest hailstone was 2.25 pounds and fell at Gopalganj District in Bangladesh on April 14, 1986. The largest diameter officially measured was 7.9 inches at Vivian, S.D., on July 23, 2010. That particular hailstone had a circumference of 18.622 inches.

But the largest circumference, the distance around the ice, was 18.74 inches, which fell at Aurora, Neb., on June 22, 2003.

Snow is formed when the air from cloud to ground is generally below freezing. It’s amazing to know that of all the trillions of snowflakes that fall, it’s believed that no two are exactly alike. The form and shape of each snowflake depends on the air temperature and the moisture content of the cloud.

Snowflakes are white when they fall, but according to The National Snow and Ice Data Center, snow can occasionally look blue, especially in deep crevasses as it travels below the surface. Snow has also been noted to turn pink from red clay and dirt in the sky or black or grey from industrial elements in the air like coal dust.

Most snowflakes are small, but there have been occasions when the snow becomes much bigger, sometimes the size of silver dollars. The world’s largest snowflake was reported at Fort Keough, Mont., on Jan. 28, 1887 when it was measured to be about 15 inches wide and close to 8 inches in thickness.

Sleet is formed when the moisture falls as rain and then freezes to ice before hitting the ground. Freezing rain is one of the worst events as the air above the ground is above freezing, but the surface is at or below 32 degrees. This will turn the rain to ice once it comes in contact with buildings, power lines or other objects that are below freezing.

In November 1996, about an inch and a half of rain fell on the frozen surface in North Idaho. There was also freezing fog, snow and mist. It was a mess as trees and branches were coming down due to the heavy weight of the ice.

Ice-covered power lines and transformers were exploding as over 100,000 people lost power. Other structures like homes, buildings and vehicles were caked with layers of ice up to an inch thick. Damage was about $22 million in Spokane and Kootenai County.

One of the worst ice storms to ever hit the U.S. occurred from Jan. 5-9, 1998, across northern New England and southeastern Canada. Total damage was around $1.4 billion in the U.S. and over $3 billion in Canada. Over 500,000 homes lost power in northern New England and some went without electricity for months.

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Contact Randy Mann at randy@longrangeweather.com