Sorry, but no winner this week. Here is my weekly weather quiz question for the last time. What is a “Thermal Low.” Here is the correct answer. A Thermal Low is an area of low pressure that is shallow in vertical extent and produced primarily by warm surface temperatures. I’ll have another weekly weather quiz question starting Monday. Please remember to post your answer as a comment by clicking on “no comments /comments” in the upper right hand portion of this page under the caption, then add your comment. The first person to post the correct answer will win a week of free personalized weather forecasts tailored to your needs. The answer has to be a comment to win. An email answer will not count. Good luck.

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Advisories:

• AN AIR STAGNATION ADVISORY IS IN EFFECT UNTIL  NOON MONDAY FOR  THE GREATER PORTLAND AREA AND THE GREATER VANCOUVER AREA, THE CENTRAL WILLAMETTE VALLEY, AND THE SOUTH WILLAMETTE VALLEY.
• AN AIR STAGNATION ADVISORY IS IN EFFECT  THROUGH 10 AM WEDNESDAY FOR CENTRAL DOUGLAS COUNTY, EASTERN CURRY COUNTY, JOSEPHINE COUNTY, THE EASTERN DOUGLAS COUNTY FOOTHILLS, JACKSON COUNTY, NORTHERN AND EASTERN KLAMATH COUNTY, THE KLAMATH BASIN, WESTERN, CENTRAL, AND EASTERN LAKE COUNTY.
• A FREEZING FOG ADVISORY IS IN EFFECT FROM 10 PM TONIGHT UNTIL 10 AM MONDAY FOR EASTERN CURRY COUNTY, JOSEPHINE COUNTY, AND JACKSON COUNTY.
• A Blue-Green Algae warning  remains in effect for Lost Creek Lake, and Willow Creek Reservoir (NE Oregon). Water monitoring has confirmed the presence of blue-green algae that can produce toxins, state public health officials said. The algae levels are likely associated with dangerous cya, notoxin concentrations in the water that can be harmful to humans and animals. Swallowing or inhaling water droplets, as well as skin contact with water, should be avoided according to the authorities.

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An upper level high pressure ridge ( Shaded “arch” shape) is strengthening again. It will weaken a bit Monday into Tuesday allowing a weak disturbance to slip through for possible sprinkles. The ridge will regain strength and continue the dry weather through New Year’s Day, then a frontal system will bring another chance of precipitation between Thursday and Friday.

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Air Quality Index:

Eugene-Springfield: The Pollution Index is 34 in the Good category measuring Particulate Matter at HWY 99, Eugene. Data courtesy of Lane Regional Air Protection Agency (LRAPA)

Oakridge: The Pollution Index is 49 in the Good category measuring Particulate Matter at Willamette Activity Center, Oakridge.  Data courtesy of Lane Regional Air Protection Agency (LRAPA)

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Home Wood Heating Advisory:

Eugene/Springfield: (YELLOW) Burning Cautioned Against.

Oakridge: (YELLOW) Burning Cautioned Against.

The use of Pellet stoves is always allowed.

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Forecast for the South Oregon Coast including Coos Bay and North Bend:

• Mostly clear in the evening, partly cloudy with areas of fog late tonight,
• Mostly cloudy with areas of AM fog, patchy fog Monday afternoon, patchy evening coastal fog areas of fog late while patchy inland fog late Monday night,
• Mostly cloudy with patchy fog and a slight (20%) chance of AM coastal and inland rain, partly cloudy with patchy fog Tuesday afternoon, mostly cloudy with patchy fog Tuesday night (New Year’s Eve).
• Mostly cloudy with patchy fog Wednesday (New Year’s Day) and Wednesday night.
• lows near 38 highs 55-50.
• Mostly cloudy with patchy fog Thursday, a (30%) chance of rain with patchy fog late Thursday night,
• Mostly cloudy with a (30%) chance of rain Friday, mostly cloudy with a slight (20%) chance of rain Friday night and Saturday, a (%) chance of rain Saturday night,
• Then mostly cloudy with a slight (20%) chance of rain Sunday.
• highs 50-57 cooling to near 50 Friday and Saturday lows 37-40 cooling to 35 Friday night. (seasonal averages high 51 low 40)

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Forecast for the Cascades of Lane County:

• Partly cloudy tonight,
• A mix of clouds and sun Monday, mostly cloudy at night,
• Mostly cloudy with a slight (20%) chance of rain Tuesday afternoon, mostly cloudy at night (New Year’s Eve), A mix of clouds and sun Wednesday (New Year’s Day), then partly cloudy Wednesday night.
• free air freezing level 11,000 ft. falling to 10,000 ft. late tonight, 10,000 ft. falling to 9,000 ft. Monday afternoon, 8,000 ft. Monday night, snow level 6,000 ft. Tuesday, free air freezing level 7,000 ft. Tuesday night, 9,000 ft. Wednesday, then 7,500 ft. Wednesday night.
• lows 27-25 highs near 39.
• A mix of clouds and sun Thursday, mostly cloudy with a slight (20%) chance of rain at night,
• Mostly cloudy with a (40%) chance of rain Friday, a slight (20%) chance of rain and snow Friday night,
• A mix of clouds and sun with a slight (20%) chance of rain and snow Saturday, mostly cloudy with a good chance of rain and snow at night,
• Then mostly cloudy with a (40%) chance of rain and snow Sunday.
• snow level 7,000 ft. Thursday, 7,000 ft. at night, 6,000 ft. Friday, 4,000 ft. Friday night through Saturday night, then 4,500 ft. Sunday.
• highs 43-45 cooling to near 40 Saturday lows 33-24.