Patchy fog overnight, milder than average temps this week
The region has been under the influence of high pressure for the past several days which has kept us mostly sunny during the day and clear and cold overnight. A byproduct of that is that there are also light winds under the dome of air. During the winter, smoke from chimney fires and pile burns gets trapped in the area under the dome. Several counties in Oregon have been under “air stagnation” advisories. It is as the name suggests, air with little movement (no wind) that allows the smoke to build up leading to poor air quality.
Also, there is a decent amount of moisture at the lower levels of the atmosphere so fog and frost have been developing overnight. The air is cold enough for the fog to become “freezing fog” which is dangerous. It is when the tiny droplets of moisture that make up the fog can freeze on contact and generate some ice. The ice forms on objects like your windshield, back deck, road surfaces and fences. This can be very dangerous when driving or walking around. This will probably happen a lot during the next several months.
As for the forecast, not much change this week other than the afternoon high temps will be warming as the week moves along. Not a lot, just a few degrees each day, but peak by Friday with highs in the middle to upper 50s. Probably middle 50s.
Another feature this week will be the introduction of some cloud cover Thursday, followed by some rain on Saturday. Current forecast models suggest that we will be looking at rain changing to snow Saturday. The snow will be light, and overnight into Sunday. This will be associated with a cold front, so the temps by Sunday will be back in the low 40s.
The meteorological winter has begun, it is defined as the three coldest months of the year in the northern hemisphere, December, January, and February. This is the period of time where meteorologist determine records and averages for the region as it is set time period each season. The astronomical winter is defined by the relationship between the Earth and the Sun. The winter solstice begins this year on Dec. 21st at 1:19 am local time. The direct rays of the sun will be over the Tropic of Cancer and we will experience the shortest number of daylight hours. Winter ends on the day of the vernal equinox, when the direct rays of the Sun are over the equator, which is on March 20th at 2:01am local time next year.
Please stay safe.
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