Here is my weekly weather quiz question for the last time. What is  “Radar Reflectivity?” Here is the correct answer. Radar Reflectivity is the sum of all backscattering cross-sections (e.g., precipitation particles) in a pulse resolution volume divided by that volume. The radar reflectivity can be related to the radar reflectivity factor through the dielectric constant term |K|^2, and the radar wavelength. 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 pressure trough (Shaded “U” shape with blue arrows) is returning our rain chances. A frontal system moved in Saturday increasing the rain chance over Oregon. An upper level ridge of high pressure (Shaded “Arch” shape with blue arrows) takes over starting to clear us out late Monday and keeping the sunshine around for the rest of the workweek.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 12 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 58 in the Moderate 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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Eugene-Springfield Pollen Count:

Grass………. Low (0)

Trees………. High (358)

Last Counted: 3/24/16

Data Courtesy of Oregon Allergy Associates.

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

• Mostly cloudy with sun breaks and a bit cooler with showers and a slight (20%) chance of thunderstorms this afternoon, Easter Sunday, (0.10 in. of rain possible, small hail possible), showers likely (70%) and a slight (20%) chance of thunderstorms and small hail possible this evening, showers likely (70%) and colder late tonight (0.10 in. of rain possible, more in storms),
• Mostly cloudy with a good (50%) chance of showers Monday, partly cloudy with a slight (20%) chance of evening showers, just partly cloudy late Monday night.
• Mostly sunny and a bit warmer Tuesday, mostly clear at night,
• highs 53-56 lows 38-35.
• Sunny and a bit warmer Wednesday, Thursday, and Friday, clear each night,
• Then mostly sunny and a bit cooler Saturday.
• highs 60-69 cooling to 66 Friday lows 36-42. (seasonal averages high 58 low 38).

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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 Roseburg:

• Mostly cloudy with AM showers likely (70%), showers likely (70%) with a slight (20%) chance of thunderstorms and a bit cooler this afternoon, Easter Sunday, (0.10 in. of rain possible, snow level 3,500 ft. falling to 3,000 ft.) showers likely (70%) with a slight (20%) chance of thunderstorms this evening, rain and snow showers  late tonight (0.10 in. of rain possible, snow level 3,500 ft. falling to 3,000 ft. late at night),
• Mostly cloudy with rain and snow showers likely (60%) Monday AM, showers likely (70%) in the afternoon (snow level 2,500 ft. rising to 3,000 ft. in the afternoon), a slight (20%) chance of showers Monday night (evening snow level 3,500 ft.),
• Partly cloudy in the AM, sunny and a bit warmer Tuesday afternoon, then mostly clear at night.
• highs 53-60 lows 37-42 cooling to 36 Tuesday night.
• Mostly sunny and a bit warmer Wednesday, mostly clear Wednesday night,
• Sunny and a bit warmer Thursday and Friday, clear both nights,
• Then just partly cloudy and a bit cooler Saturday.
• highs 66-73 cooling to 69 Saturday lows near 43. (seasonal averages high 59 low 40).

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

• Mostly cloudy with AM showers likely (70%), showers with a slight (20%) chance of thunderstorms and a bit cooler this afternoon, Easter Sunday, and this evening, showers late tonight (0.20 in. of rain possible, more in storms),
• Mostly cloudy with showers likely (70%) and a bit warmer Monday, just partly cloudy at night and  Tuesday AM, sunny and a bit warmer Tuesday afternoon, then clear at night.
• highs 52-56 lows near 43.
• Mostly sunny and a bit warmer Wednesday, mostly clear Wednesday night,
• Sunny and warmer Thursday, sunny and cooler Friday, clear each night,
• Then partly cloudy Saturday.
• highs 62-69 cooling back to 62 Saturday lows near 46. (seasonal averages high 54 low 42).

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Forecast for the Cascades in Lane County:

• Mostly cloudy and cooler with rain and snow showers this afternoon, Easter Sunday, (0.25 in. of rain possible, 1-4 in. of snow possible), rain and snow showers with possible tonight (0.25 in. of rain possible, 2 in. of snow possible),
• Mostly cloudy with rain and snow showers likely (70%) and a bit warmer Monday, a (30%) chance of rain and snow showers in the evening, partly cloudy with a slight (20%) chance of rain and snow showers late Monday night,
• Then just partly cloudy and warmer Tuesday and Tuesday night.
• snow level 3,500 ft. Sunday, 3,000 ft.  Sunday night through Monday night, then 4,500 ft. Tuesday and Tuesday night.
• highs 34-43 lows near 24.
• Then mostly sunny and a bit warmer Wednesday, Thursday, and Friday, mostly clear each night,
• Then just partly cloudy Saturday.
• free air freezing level 6,000 ft. Wednesday, 8,000 ft. Wednesday night and Thursday, 9,000 ft. Thursday night, 10,000 ft. Friday, then 9,000 ft. Friday night and Saturday.
• highs 48-53 lows 25-33.

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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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