Here is my new weekly weather quiz question. What is “Zonal Flow ?”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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An upper level low (Shaded “U” shape with blue arrows) continues an increased onshore flow that has cooled us down considerably. Weak high pressure (Shaded “Arch” shape with blue arrows) tries to take over, but low pressure quickly moves in. The weather will be near-perfect for the Lane County Fair today, but just a slight chance of showers Friday night through Sunday evening as the Fair continues.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 20 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 12 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 20 in the Good category measuring Ozone.

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

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Advisories: None at this time.

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

• AM clouds, a mix of clouds and sun this afternoon, mostly clear tonight,
• Mostly sunny Friday AM, partly cloudy in the afternoon, mostly cloudy with a slight (20%) chance of showers late Friday night and Saturday AM, partly cloudy to mostly cloudy and a bit cooler in the afternoon, mostly cloudy with a slight (20%) chance of showers Saturday night.
• highs 82-79 lows 54-58 cooling to 55 Saturday night.
• Mostly cloudy with a slight (20%) chance of showers Sunday AM, a (30%) chance of showers in the afternoon and evening, partly cloudy with a slight (20%) chance of showers Sunday evening, just partly cloudy late Sunday night,
• Partly cloudy Monday AM, then mostly sunny and warmer Monday afternoon, Tuesday and Wednesday, mostly clear each night.
• highs 80-90 lows near 54. (seasonal averages high 84 low 52)

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Forecast for the Umpqua Basin including Roseburg:

• Mostly cloudy this AM, sunny and a bit warmer this afternoon and Friday, mostly clear tonight, mostly clear in the evening and partly cloudy Friday night,
• Partly cloudy with a slight (20%) chance of light rain or drizzle Saturday AM, a slight (20%) chance of light rain or sprinkles in the afternoon, then just partly cloudy Saturday night.
• highs 83-88 lows 56-59.
• Partly cloudy  a bit cooler and with a slight (20%) chance of showers Sunday and in the evening, partly cloudy late Sunday night,
•  Mostly sunny and warmer Monday, mostly clear Monday night,
• Then sunny and a bit warmer Tuesday and Wednesday, clear Tuesday night.
• highs 83-94 lows 57-60. (seasonal averages high 86 low 57)

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

• Mostly cloudy this AM, sunny this afternoon, mostly clear this evening, partly cloudy with patchy coastal fog late tonight,
• Mostly cloudy with patchy coastal fog Friday AM and partly cloudy in the afternoon while sunny inland, partly cloudy in the evening, mostly cloudy  Friday night with a slight (20%) chance of light rain and drizzle late Friday night,
• Mostly cloudy with a slight (20%) chance of AM rain and drizzle Saturday, partly cloudy in the afternoon evening, mostly cloudy with a slight (20%) chance of showers Saturday night.
• highs near 68 lows near 56.
• Mostly cloudy with a slight (20%) chance of showers Sunday and in the evening, just partly cloudy Sunday night,
• Mostly sunny Monday, mostly clear at night,
• Sunny Tuesday and Wednesday, clear Tuesday night.
• highs near 68 lows near 56. (seasonal averages high 65 low 53)

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Forecast for the Cascades in Lane County:

• A mix of clouds and sun this AM, mostly sunny this afternoon, mostly clear tonight,
• Mostly sunny Friday, clouds increasing too mostly cloudy with a slight (20%) chance of showers late Friday night and Saturday AM, partly cloudy and a bit cooler Saturday afternoon, then a slight (20%) chance of showers late Saturday night.
• free air freezing level 11,000 ft. today, 12,000 ft. tonight and Friday, snow level above 8,000 ft. Friday through Saturday night.
• highs 70-73 cooling near 65 Saturday lows near 45.
• A mix of clouds and sun with a slight (20%) chance of showers and a bit cooler Sunday, mostly cloudy with a slight (20%) chance of showers Sunday evening, just partly cloudy late at night and Monday AM, mostly sunny and warmer Monday afternoon, Tuesday and Wednesday, mostly clear each night.
• snow level above 8,000 ft. Sunday and Sunday night, 10,000 ft. Monday, 11,000 ft. Monday night and Tuesday, 12,000 ft. Tuesday night, then 14,000 ft. Wednesday.
• highs 62-78 lows 42-45.

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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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