Here is my weekly weather quiz question for the last time. What is a “Roll Cloud?” Here is the correct answer. A  Roll Cloud is a low, horizontal tube-shaped arcus cloud associated with a thunderstorm gust front (or sometimes with a cold front). Roll clouds are relatively rare; they are completely detached from the thunderstorm base or other cloud features, thus differentiating them from the more familiar shelf clouds. Roll clouds usually appear to be “rolling” about a horizontal axis, but should not be confused with funnel clouds. 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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Another upper level high pressure ridge (Shaded “Arch” shape with blue arrows) strengthens and moves over us for more sunshine for the weekend through early next when upper level low pressure (Shaded “U” shape on previous graphic) starts taking over. By Tuesday morning a frontal system is preparing to bring more rain.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 19 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 8 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 17 in the Good category measuring Particulate Matter.

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

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Advisories: None At This Time.

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Home Wood Heating Advisory:

Eugene-Springfield: GREEN – Burning is Allowed.

Oakridge: GREEN – Burning is Allowed.

*Note: Pellet stoves may be used anytime if they produce no visible emissions.

Advisory Courtesy of Lane Regional Air Protection Agency (LRAPA).

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

• Clear tonight,
• Sunny and much warmer Sunday, clear Sunday night,
• Mostly sunny and a bit cooler Monday, a slight (20%) chance of evening thunderstorms otherwise a slight (20%) chance of showers Monday night,
• Mostly cloudy and cooler with a (40%) chance of showers Tuesday, then cloudy with a (40%) chance of showers at night.
• lows 43-50 highs 80-70.
• Cloudy and a bit cooler with a good (50%) chance of showers Wednesday AM, a bit cooler with a good (50%) chance of showers and a slight (20%) chance of thunderstorms in the afternoon and evening, a good (50%) chance of showers late Wednesday night,
• Mostly cloudy with a (40%) chance of showers Thursday, a slight (20%) chance of showers  at night,
• Then a mix of clouds and sun Friday with a slight (20%) chance of AM showers, mostly cloudy in the evening, partly cloudy with a slight (20%) chance of showers late Friday night and Saturday AM, then just partly cloudy and a bit warmer Saturday afternoon.
• highs 65-68 lows near 46. (seasonal averages high 64 low 41).

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Eugene-Springfield Pollen Count:

Grass………. Moderate (6)

Trees………. Moderate (38)

Last Counted: 4/26/16

Data Courtesy of Oregon Allergy Associates.

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Forecast for Roseburg:

• Mostly clear tonight,
• Sunny and much warmer Sunday, mostly clear at night,
• AM sun, partly cloudy with a slight (20%) chance of thunderstorms Monday afternoon, mostly cloudy with a slight (20%) chance of thunderstorms in the evening, a slight (20%) chance of showers late Monday night,
• Mostly cloudy with a (20%) chance of AM showers, a bit cooler with a (30%) chance of showers and a slight (20%) chance of thunderstorms Tuesday afternoon, cloudy with a (30%) chance of showers and a slight (20%) chance of thunderstorms in the evening, then a (40%) chance of showers late Tuesday night.
• lows 44-50 highs 85-75.
• Mostly cloudy with AM showers likely (60%), showers likely (70%) and a slight (20%) chance of thunderstorms and a bit cooler Wednesday afternoon, cloudy with a good (50%) chance of showers and a slight (20%) chance of thunderstorms in the evening, a good (50%) chance of showers late at night and Thursday, mostly cloudy with a (30%) chance of showers Thursday night,
• Mostly cloudy and a bit warmer with a slight (20%) chance of showers Friday and Friday night,
• Then partly cloudy with a slight (20%) chance of showers and a bit warmer Saturday.
• highs 64-70 lows near 48. (seasonal averages high 66 low 45).

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

• Mostly clear tonight,
• Sunny and much warmer Sunday, clear Sunday night,
• Sunny in the AM, more clouds to partly cloudy and cooler Monday afternoon, mostly cloudy with a slight (20%) chance of showers at night,
• Mostly cloudy and a bit cooler with a (30%) chance of showers Tuesday, then cloudy with a (40%) chance of showers Tuesday night.
• lows 48-53 cooling to 50 Monday night and Tuesday night highs 79-63.
• Mostly cloudy with showers likely (70%) and a bit cooler Wednesday, cloudy with a (40%) chance of showers Wednesday night and Thursday, mostly cloudy with a slight (20%) chance of showers Thursday night,
• Just mostly cloudy and a bit warmer Friday, then partly cloudy Friday night and Saturday.
• highs 59-62 lows near 50. (seasonal averages high 57 low 45)

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Forecast for the Cascades in Lane County:

• Mostly clear tonight,
• Sunny and a bit warmer Sunday, clear Sunday night,
• Mostly sunny Monday AM, partly cloudy with a slight (20%) chance of showers and thunderstorms in the afternoon, a (40%) chance of showers and a slight (20%) chance of thunderstorms in the evening, a slight (20%) chance of showers late Monday night,
• A mix of clouds and sun with a slight (20%) chance of AM showers, a bit cooler with a (40%) chance of showers and a slight (20%) chance of thunderstorms in the afternoon and evening, then mostly cloudy a good (50%) chance of showers late Tuesday night.
• free air freezing level 9,000 ft. tonight, 9,000 ft. rising to 10,000 ft. Sunday afternoon and Sunday night, then snow level above 8,000 ft. Monday through Tuesday night.
• lows 35-43 cooling to 39 Tuesday night highs 63-65 cooling to 60 Tuesday.
• Mostly cloudy and a bit cooler with a good (50%) chance of showers and a slight (20%) chance of thunderstorms Wednesday, showers likely (70%) with a slight (20%) chance of scattered thunderstorms in the evening, a good (50%) chance of showers late at night,
• Cloudy with a (40%) chance of showers and a bit cooler Thursday, mostly cloudy with a (30%) chance of evening showers, a slight (20%) chance of showers late Thursday night,
• A mix of clouds and sun with a slight (20%) chance of showers Friday, partly cloudy with a slight (20%) chance of evening showers, mostly cloudy with a slight (20%) chance of showers late at night,
• Then a mix of clouds and sun and a bit warmer with a slight (20%) chance of showers Saturday.
• snow level  7,500 ft. Wednesday, 7,000 ft. Wednesday night, then 6,000 ft. Thursday and Thursday night, 5,500 ft. Friday, then snow level above 8,000 ft. Friday night and Saturday.
• highs 54-50 warming back to 54 Saturday lows 35-38.

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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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