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  10 PM SUNDAY 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 DENSE FOG ADVISORY IS IN EFFECT FROM 10 PM TONIGHT UNTIL 10 AM SUNDAY FOR CENTRAL DOUGLAS COUNTY.
• A FREEZING FOG ADVISORY IS IN EFFECT FROM 10 PM TONIGHT UNTIL 10 AM SUNDAY 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 Thursday allowing a disturbance to bring us the chance of some light precipitation. In the meantime the ridge will regain strength and continue the dry weather through New Year’s Day.

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Air Quality Index:

Eugene-Springfield: The Pollution Index is 33 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 52 in the Moderate 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 this evening, partly cloudy with patchy fog late tonight and Sunday AM, mostly sunny in the afternoon,  mostly clear in the evening, partly cloudy with areas of fog late Sunday night,
• Areas of AM fog, partly cloudy with patchy fog Monday afternoon, mostly cloudy with patchy fog Monday night.
• Mostly cloudy with patchy fog and a slight (20%) chance of showers Tuesday, mostly cloudy with patchy fog Tuesday night (New Year’s Eve).
• lows 34-39 highs 55-50.
• Mostly cloudy with patchy fog Wednesday (New Year’s Day) and Wednesday night,
• Just mostly cloudy Thursday, mostly cloudy with a slight (20%) chance of showers with patchy fog late Thursday night,
• Mostly cloudy with a (30%) chance of rain Friday, then mostly cloudy with a slight (20%) chance of rain Friday night and Saturday.
• 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:

• Mostly clear tonight,
• Mostly sunny Sunday, partly cloudy Sunday night,
• A mix of clouds and sun Monday and Tuesday, mostly cloudy at night.
• free air freezing level 7,500 ft. tonight, 9,000 ft. Sunday, 10,000 ft. Sunday night, 10,000 ft. falling to 9,000 ft. Monday afternoon, 7,500 ft. Monday night, then 7,000 ft. Tuesday and Tuesday night.
• lows 27-30 highs 45-40.
• A mix of clouds and sun Wednesday (New Year’s Day), partly cloudy Wednesday night,
• Mostly cloudy Thursday and Thursday night,
• Mostly cloudy with a (30%) chance of rain Friday, then mostly cloudy with a slight (20%) chance of rain and snow Friday night and Saturday.
• free air freezing level 9,000 ft. Wednesday, 8,000 ft. Wednesday night through Thursday night, snow level 7,000 ft. Friday, 5,000 ft. Friday night, then 4,500 ft. Saturday.
• highs 43-45 cooling to near 40 Saturday lows 33-24.