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.

________________

An upper level low pressure trough (Shaded “U” shape with blue arrows) is returning our rain chances. A frontal system moves in today 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.

________________

Air Quality Index:

Eugene-Springfield: The Air Quality Index is 13 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 13 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 23 in the Good category measuring Particulate Matter.

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

________________

Advisories: None At This Time.

________________

Eugene-Springfield Pollen Count:

Grass………. Low (0)

Trees………. High (358)

Last Counted: 3/24/16

Data Courtesy of Oregon Allergy Associates.

________________

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

• Mostly cloudy and a bit cooler with some sun breaks and a good (50%) chance of showers this afternoon (under 0.10 in. of rain possible), rain this evening, showers late tonight (0.25 in. of rain possible),
• Mostly cloudy and a bit cooler with showers and a slight (20%) chance of thunderstorms Easter Sunday afternoon (0.10 in. of rain possible, small hail possible), showers likely (70%) and a slight (20%) chance of thunderstorms and small hail possible in the evening, a good (50%) of showers late Sunday night (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, then just partly cloudy late Monday night.
• highs 55-53 lows 44-37.
• Mostly sunny and a bit warmer Tuesday and Wednesday, mostly clear both nights,
• Sunny and a bit warmer Thursday, mostly clear at night,
• Then mostly sunny and a bit warmer Friday.
• highs 56-69 lows 36-38. (seasonal averages high 58 low 38).

_____

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).

___________________

Forecast for Roseburg:

• Mostly cloudy with rain likely (70%) and a bit warmer this afternoon and evening (under 0.10 in. of rain possible), showers likely (70%) late tonight (0.15 in. of rain possible),
• Mostly cloudy with a good (50%) chance of AM showers, showers likely (70%) with a slight (20%) chance of thunderstorms and a bit cooler Easter Sunday afternoon (0.10 in. of rain possible, snow level 3,000 ft.) and in the evening, rain and snow showers with a slight (20%) chance of thunderstorms late Sunday night (0.10 in. of rain possible, snow level 2,500 ft. late at night),
• Mostly cloudy with rain and snow showers likely (60%) Monday (snow level 2,000 ft. rising to 2,500 ft. in the afternoon), then a slight (20%) chance of showers Monday night.
• highs 58-55 lows 42-38 warming back to 42 Monday night.
• Partly cloudy in the AM, sunny and a bit warmer Tuesday, mostly clear at night,
• Mostly sunny and a bit warmer Wednesday, mostly clear Wednesday night,
• Then sunny Thursday and Friday, clear Thursday night.
• highs 60-66 lows 39-43. (seasonal averages high 59 low 40).

________________

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

• Cloudy and a bit warmer with rain likely (70%) this afternoon and evening, a good (50%) chance of coastal showers late tonight while inland showers likely (70%) late tonight (0.25 in. of rain possible),
• Mostly cloudy with AM showers likely (70%), showers likely (70%) with a slight (20%) chance of thunderstorms and a bit cooler Easter Sunday afternoon and at night (0.20 in. of rain possible, more in storms),
• Mostly cloudy with showers likely (70%) and a bit warmer Monday, then partly cloudy with a slight (20%) chance of showers at night,
• highs 57-52 warming to 54 Monday lows 46-42.
• Partly cloudy in the AM, sunny and a bit warmer Tuesday afternoon, mostly clear at night,
• Mostly sunny and a bit warmer Wednesday, mostly clear Wednesday night,
• Then sunny Thursday and Friday, clear Thursday night.
• highs 57-62 lows 43-47. (seasonal averages high 54 low 42).

________________

Forecast for the Cascades in Lane County:

• Mostly cloudy with a good (50%) chance of rain and a bit cooler this afternoon (0.10 in. of rain possible), rain this evening, rain and snow showers late tonight (0.50 in. of rain possible),
• Mostly cloudy and cooler with rain and snow showers Easter Sunday (0.25 in. of rain possible, 2-4 in. of snow possible), rain and snow showers with possible hail late Sunday night,
• Mostly cloudy with rain and snow showers likely (60%) and a bit warmer Monday, a (30%) chance of rain and snow showers in the evening, then partly cloudy with a slight (20%) chance of rain and snow showers late Monday night.
• snow level 6,000 ft. this afternoon, 7,000 ft. falling to 6,000 ft. late tonight, 4,000 ft. Sunday, 3,000 ft.  Sunday night, then 3,000 ft. Monday and Monday night.
• highs 40-34 warming to 36 Monday lows 28-24.
• A mix of clouds and sun and warmer Tuesday, just partly cloudy Tuesday night,
• Then mostly sunny and a bit warmer Wednesday, Thursday, and Friday, mostly clear each night.
• snow level 4,000 ft. Tuesday, 5,500 ft. Tuesday night, 6,500 ft. Wednesday, 7,500 ft. Wednesday night and Thursday, then 9,000 ft. Thursday night and Friday..
• highs 43-53 lows 25-28.

________________

**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.

________________

Get your local Eugene-Springfield and Lane County news on-line at eugenedailynews.com.

________________