Most folks missed our brief bout with the frozen precipitation unless you were up very early Wednesday morning.
Moisture began to fall into our chilly air mass around 4 a.m. with a mixture of ice pellets and freezing rain. It wasn’t long before things began to get slick.
Fortunately, temperatures warmed just above freezing, allowing the morning commute to proceed without a major disaster. The rest of the day it was just a chilly rain as a slight drift of easterly wind kept our highs from reaching the mid 40s like much of the west side of the Cascades.
So now I am thinking more rain or showers later today and Friday, with a very strong cold front moving in and once again lowering snow levels where we could see a mix or even some wet snow showers about, certainly in our surrounding foothills.
After that, it gets cold again as east winds reappear, ushering in some modified arctic air that will linger all of next week.
We will then have to keep a weather eye out for the possibility of significant snowfall midweek.
With a “wintry mix” in our recent forecast, I have had several inquiries as to the definition of the various types of frozen precipitation.
Direct from the National Weather Service glossary, I offer this:
• Freezing rain: Rain that freezes on objects such as trees, cars and roads, forming a coating or glaze of ice. Temperatures at higher levels are warm enough for rain to form, but surface temperatures are below 32 degrees Fahrenheit, causing the rain to freeze on impact.
• Ice pellets: Precipitation of transparent or translucent pellets of ice, which are round or irregular, rarely conical, and which have a diameter of 0.2 of an inch (5 mm) or less. There are two main types: hard grains of ice consisting of frozen raindrops, and pellets of snow encased in a thin layer of ice.
• Sleet: Raindrops that freeze into ice pellets before reaching the ground. Sleet usually bounces when hitting a surface and does not stick to objects. Forms when snow enters a warm layer of air above the surface and melts and then enters a deep layer of sub-freezing air near the surface and refreezes.
Pat Timm is a local weather specialist. His column appears Tuesdays, Thursdays and Sundays. Reach him at http://weathersystems.com.
