Here is my weekly weather quiz question for the last time. What is “Zonal Flow ?” Here is the correct answer. Zonal Flow is large-scale atmospheric flow in which the east-west component (i.e., latitudinal) is dominant. The accompanying meridional (north-south) component often is weaker than normal. Compare with meridional flow. 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. 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) will continue to slide through the Pacific Northwest. An upper level high pressure ridge will take over bringing back the sunshine Monday and warming us up for the rest of the week.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 24 in the Good category measuring Ozone.

Oakridge: The Air Quality Index is 6 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 25 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:

• Partly cloudy with a (40%) chance of showers this evening, a slight (20%) chance of showers late tonight (under 0.10 in. of rain possible),
• Partly cloudy Monday and in the evening, clear late Monday night,
• Partly cloudy and warmer Tuesday and in the evening, mostly clear at night,
• Sunny and hot Wednesday, then clear at night.
• lows 54-59 highs 80-98.
• Sunny and hot Thursday, mostly clear at night,
• Mostly sunny and bit cooler but still hot Friday, clear Friday night,
• Then mostly sunny and a bit cooler Saturday and Sunday, mostly clear Saturday night.
• highs 100-92 lows 63-65. (seasonal averages high 84 low 52)

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Eugene/Springfield Pollen Count:

Trees: Low- 2

Grass: High- 53

Reading as of: 7/24/15

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Forecast for the Umpqua Basin including Roseburg:

• Partly cloudy with a slight (20%) chance of showers this evening (under 0.10 in. of rain possible), just partly cloudy late tonight and Monday AM, sunny and warmer Monday afternoon, Tuesday and Wednesday, clear nights,
• lows 56-67 highs 83-105.
• Mostly sunny and hot Thursday with a slight (20%) chance of afternoon and evening thunderstorms, mostly clear with a slight (20%) chance of thunderstorms Thursday night,
• Mostly sunny with a slight (20%) chance of thunderstorms Friday and Saturday, mostly clear with a slight (20%) chance of thunderstorms Friday night, a slight (20%) chance of thunderstorms Saturday evening, just partly cloudy late Saturday night,
• Then partly cloudy with a slight (20%) chance of thunderstorms and a bit cooler Sunday.
• highs 106-96 lows near 66. (seasonal averages high 86 low 57)

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

• Partly cloudy with a slight (20%) chance of showers this evening, partly cloudy late tonight and Monday AM, sunny and a bit warmer in the afternoon, clear Monday night,
• Sunny and a bit warmer Tuesday and Wednesday, clear both nights.
• lows 56-63 highs 67-78.
• Sunny and a bit cooler Thursday, mostly clear Thursday night,
• Mostly cloudy Friday and Saturday, mostly clear Friday night, then partly cloudy Saturday night and Sunday.
• highs 70-73 cooling to 68 Sunday lows near 58. (seasonal averages high 65 low 53)

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Forecast for the Cascades in Lane County:

• Partly cloudy with a good (50%) chance of scattered showers and a slight (20%) chance of thunderstorms this evening, a slight (20%) chance of showers late tonight,
• Partly cloudy Monday AM, mostly sunny and warmer in the afternoon, mostly clear at night,
• Sunny and warmer Tuesday and Wednesday, clear both nights.
• snow level above 8,000 ft. tonight, free air freezing level 10,000 ft. Monday, 12,000 ft. Monday night, 13,000 ft. Tuesday, 14,000 ft. Tuesday night, then 15,000 ft. Wednesday and Wednesday night.
• lows 42-57 highs 64-83.
• Mostly sunny Thursday and Friday, mostly clear both nights,
• Then mostly sunny and a bit cooler with a slight (20%) chance of showers and thunderstorms Saturday and Sunday, mostly clear with a slight (20%) chance of thunderstorms Saturday evening.
• free air freezing level 15,000 ft. Thursday through Friday night, then snow level above 8,000 ft. Saturday through Sunday.
• highs 85-80 lows near 62.

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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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