Here is my weekly weather quiz question for the last time. What is a “Thalweg?” Here is the correct answer. A Thalweg: In hydrologic terms, the line of maximum depth in a stream. The thalweg is the part that has the maximum velocity and causes cutbanks and channel migration. I’ll have a new weekly weather quiz question for you 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. Good luck.

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An upper level low (Shaded “U” Shape with blue arrows) will be moving West to East north of us giving us some cooler weather. It looks like a frontal system will be heading our way Wednesday with very little or no effect on our weather except to keep us a bit cooler. A high pressure ridge (“Arch” shape with blue arrows) Takes over to bring more sunshine and warmer temperatures again.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 41 in the Good category measuring Ozone.

Oakridge: The Air Quality Index is 26 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 40 in the Good category measuring Ozone.

Data courtesy of Lane Regional Air Protection Agency (LRAPA).

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Advisories:

• A RED FLAG WARNING FOR GUSTY WINDS AND LOW RELATIVE HUMIDITY IS IN EFFECT UNTIL 10 PM TONIGHT FOR THE EAST SLOPES OF THE NORTHERN OREGON CASCADES AND THE LOWER COLUMBIA BASIN OF OREGON.
• A RED FLAG WARNING FOR ABUNDANT LIGHTNING ON DRY FUELS IS IN EFFECT UNTIL 8 PM THIS EVENING FOR THE WESTERN KLAMATH NATIONAL FOREST.
• A Blue-Green Algae health advisory in effect for Odell Lake in Lane County has been lifted. Water testing has confirmed the presence of blue-green algae and the toxins they produce. People should avoid swallowing water while swimming or inhaling water droplets as a result of high-speed water activities, such as water skiing or power boating, in areas where blooms are identified. Although toxins are not absorbed through the skin, people who have skin sensitivities may experience a puffy, red rash at the affected area.
• A Blue-Green Algae health advisory remains in effect for Howard Bay (sometimes called Howards Bay or Howard’s Bay) in Upper Klamath Lake ONLY. People should avoid swallowing water while swimming or inhaling water droplets as a result of high-speed water activities, such as water skiing or power boating, in areas where blooms are identified. Although toxins are not absorbed through the skin, people who have skin sensitivities may experience a puffy, red rash at the affected area.

 

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Forecast for the Southern and lower Mid Willamette Valley including Eugene-Springfield and Albany-Corvallis:

• Mostly clear tonight,
•  Sunny and a bit cooler Monday, clear at night,
• Partly cloudy in the AM, sunny and a bit warmer Tuesday afternoon and Wednesday (a bit cooler), clear both nights.
• lows near 55 highs 87-89 cooling back to 87 Wednesday.
• Sunny and warmer Thursday and Friday, clear both nights,
• Sunny and a bit cooler Saturday and Sunday, clear Saturday night.
• highs 94-97 cooling to 90 Sunday lows near 56. (seasonal averages high 83 low 51)

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Eugene-Springfield Pollen Count:

Grass………. Low (3)

Trees………. Low (0)

Last Counted: 8/11/16

Data Courtesy of Oregon Allergy Associates.

The Grass and Tree Pollen season is officially over now.

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Forecast for Roseburg:

• Mostly clear tonight,
• Partly cloudy in the AM, sunny and a bit cooler Monday afternoon, mostly clear at night,
• Partly cloudy Tuesday AM, sunny and a bit cooler in the afternoon, mostly clear Tuesday night,
• Then sunny and a bit warmer Wednesday, clear at night.
• lows near 58 highs near 92.
• Then sunny and a bit warmer Thursday, Friday, (a bit cooler) Saturday and Sunday, clear each night.
• highs 90-96 lows 63-59. (seasonal averages high 85 low 56)

 

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Forecast for The South Oregon Coast Including Coos Bay and North Bend:

• Partly cloudy this evening, mostly cloudy patchy coastal fog and a slight (20%) chance of drizzle late tonight and Monday AM, sunny Monday afternoon, mostly clear in the evening and cloudy with patchy coastal fog late Monday night while mostly clear inland in the evening and cloudy late at night,
• Then just partly cloudy Wednesday and Wednesday night.
• lows near 54 highs near 65.
• Mostly cloudy Thursday AM, sunny and a bit warmer in the afternoon, mostly clear Thursday night,
• Mostly sunny and a bit warmer Friday, then partly cloudy and a bit coler Friday night through Sunday.
• highs 69-73 cooling to 65 Sunday lows 55-53. (seasonal averages high 65 low 53)

 

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Forecast for the Cascades in Lane County:

• Mostly clear tonight with a slight (20%) chance of showers and thunderstorms this evening,
• Then sunny Monday, Tuesday and Wednesday, clear each night,
• snow level above 5,000 ft. tonight, free air freezing level 15,000 ft. Monday through Wednesday night.
• lows 48-52 cooling back to 48 Wednesday night highs near 80.
• Then sunny and a bit warmer Thursday, Friday, (a bit cooler Saturday and Sunday, clear each night.
• free air freezing level 15,000 ft. Thursday, 16,000 ft. Thursday night through Friday night, then 15,000 ft. Saturday and Sunday night.
• highs 84-78 lows 52-50.

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**Because weather forecasting is a combination of science, intuition, and timing there can be no absolute guarantees that individual forecasts will be 100% accurate. Nature is in a constant state of flux and sudden unexpected weather events can happen.

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Get your local Eugene-Springfield and Lane County news on-line at eugenedailynews.com.

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