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) will keep us warmer than normal for one more day Monday then upper level low pressure (Shaded “U” shape on previous graphic) starts taking over. A frontal system (shown out to the Northwest over the Pacific Ocean) will return the chance of showers by late Monday into Tuesday. By next Sunday another frontal system will be moving into the Pacific Northwest.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 23 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 4 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 18 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,
• Mostly sunny Monday AM, becoming partly cloudy with a slight (20%) chance of showers and thunderstorms in the afternoon, partly cloudy in the evening, mostly cloudy with a slight (20%) chance of  showers and thunderstorms late Monday night,
• Mostly cloudy with a slight (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 good (50%) chance of showers and a slight (20%) chance of thunderstorms in the evening, a slight (20%) chance of showers late at night,
• Then cloudy and a bit cooler with showers likely (70%) Wednesday and Wednesday night.
• lows 50-48 highs 78-63.
• Cloudy with a (40%) chance of showers Thursday, mostly cloudy with a (30%) chance of evening showers,  just mostly cloudy at night,
• A mix of clouds and sun and a bit warmer Friday, partly cloudy Friday night through Saturday night,
• Then mostly sunny Sunday AM and partly cloudy and a bit cooler Sunday afternoon.
• highs 63-73 cooling to 70 Sunday lows 44-48. (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,
• 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, a good (50%) chance of showers late Tuesday night,
• Then mostly cloudy with showers likely (60%) Wednesday and Wednesday night.
• lows 50-48 highs 85-62.
• Cloudy with a good (50%) chance of showers 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 through Sunday.
• highs 63-76 cooling to 73 Sunday lows 45-48. (seasonal averages high 67 low 45).

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

• Mostly clear tonight,
• Sunny in the AM, more clouds to partly cloudy and cooler Monday afternoon and evening with a slight (20%) chance of inland thunderstorms, a slight (20%) chance of showers late Monday night,
• Mostly cloudy and a bit cooler with a (30%) chance of showers Tuesday, cloudy with a (40%) chance of showers Tuesday night,
• Mostly cloudy with showers likely (60%) and a bit cooler Wednesday, then cloudy with a (40%) chance of showers Wednesday night.
• lows 52-48 highs 70-57.
• Cloudy with a (40%) chance of showers Thursday, mostly cloudy with a slight (20%) chance of showers Thursday night and Friday, then partly cloudy with a slight (20%) chance of showers Friday night through Sunday.
• highs 57-63 cooling to 60 Sunday lows 47-50. (seasonal averages high 57 low 45)

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Forecast for the Cascades in Lane County:

• Mostly clear tonight,
• Mostly sunny Monday AM, partly cloudy with a (40%) chance of showers and thunderstorms in the afternoon and Monday night,
• Mostly cloudy and a bit cooler with a slight (20%) chance of showers and thunderstorms Tuesday, cloudy with showers likely (60%) and a slight (20%) chance of thunderstorms in the evening, a good (50%) chance of showers late Tuesday night,
• AM showers likely (70%), mostly cloudy and a bit cooler with showers and a slight (20%) chance of thunderstorms Wednesday afternoon, cloudy with showers likely (70%) and a slight (20%) chance of scattered thunderstorms in the evening, then a good (50%) chance of showers late at night.
• free air freezing level 11,000 ft. falling to 10,000 ft. late tonight, snow level above 8,000 ft. Monday through Tuesday, 8,000 ft. Tuesday night and Wednesday, then 7,500 ft. Wednesday night.
• lows 40-35 highs 70-54.
• Mostly cloudy with a (40%) chance of showers and a bit cooler Thursday and in the evening, a slight (20%) chance of showers late Thursday night,
• A mix of clouds and sun and a bit warmer with a slight (20%) chance of showers Friday, partly cloudy with a slight (20%) chance of showers at night,
• A mix of clouds and sun and a bit warmer with a slight (20%) chance of showers Saturday, partly cloudy with a slight (20%) chance of evening showers, just partly cloudy late Saturday night,
• Then partly cloudy and a bit cooler with a slight (20%) chance of showers Sunday.
• snow level 6,000 ft. Thursday, 6,000 ft. Thursday night, 6,500 ft. rising to above 8,000 ft. Friday, above 8,000 ft. Friday night through Saturday evening, free air freezing level 11,000 ft. late Saturday night and Sunday AM, then snow level above 8,000 ft. Sunday afternoon.
• highs 52-60 cooling to 58 Sunday lows 35-42.

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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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