Here is my new weekly weather quiz question. What is “Rayleigh Scattering?” 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 high (Shaded “Arch” shape with blue arrows) is going to weaken and a trough of low pressure (Shaded “U” shape with blue arrows) will slowly take over sending a cold front to the Pacific Northwest.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 42 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 28 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 49 in the Good category measuring Ozone.

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

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Advisories:

• A HEALTH ADVISORY CONTINUES FOR SUNSET BAY STATE PARK BEACH LOCATED IN COOS COUNTY FOR HIGHER-THAN-NORMAL FECAL BACTERIA WHICH CAN RESULT IN DIARRHEA, STOMACH CRAMPS, SKIN RASHES, UPPER RESPIRATORY INFECTIONS AND OTHER ILLNESSES. DIRECT CONTACT WITH THE WATER – ESPECIALLY BY CHILDREN AND THE ELDERLY, WHO MAY BE VULNERABLE TO WATERBORNE BACTERIA – SHOULD BE AVOIDED IN THIS AREA UNTIL THE ADVISORY IS LIFTED. VISITORS SHOULD AVOID WADING IN NEARBY CREEKS, POOLS OF WATER ON THE BEACH, OR IN DISCOLORED WATER AND STAY CLEAR OF WATER RUNOFF FLOWING INTO THE OCEAN.
• A HEALTH ADVISORY CONTINUES FOR UPPER KLAMATH LAKE AND AGENCY LAKE DOWN TO KENO DAM, LOCATED JUST NORTH OF KLAMATH FALLS ALONG HIGHWAY 97 IN KLAMATH COUNTY. WATER MONITORING BY THE USGS HAS CONFIRMED THE PRESENCE OF BLUE-GREEN ALGAE TOXINS WHICH CAN BE HARMFUL TO HUMANS AND ANIMALS. SWALLOWING, INHALING OR SKIN CONTACT WITH WATER DROPLETS SHOULD BE AVOIDED.

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

• Mostly clear tonight,
• Mostly sunny and a bit cooler Saturday, partly cloudy Saturday night through Sunday AM, mostly sunny and cooler in the afternoon, mostly clear in the evening, mostly cloudy late Sunday night,
• A mix of clouds and sun Monday AM, then increasing clouds to mostly cloudy and cooler with a slight (20%) chance of showers in the afternoon and at night.
• lows 56-50 highs 88-72.
• A mix of clouds and sun and a bit cooler with a slight (20%) chance of showers Tuesday AM, a slight (20%) chance of afternoon rain, mostly cloudy with a slight (20%) chance of evening rain, rain likely (70%) Tuesday night through Wednesday evening, showers likely (70%) late Wednesday night,
• Mostly cloudy with AM showers likely (70%), a good (50%) chance of showers Thursday afternoon, a slight (20%) chance of showers at night,
• Then a mix of clouds and sun and warmer with a slight (20%) chance of showers Friday.
• highs 73-68 warming back to 74 Friday lows 49-53. (seasonal averages high 79 low 48)

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Your Saturday College Football Forecasts:

Ducks vs Michigan State at Spartan Stadium, East Lansing, MI- Kickoff 5 PM PDT- (8 PM EDT): Partly cloudy 56 and cooling to 50 by the end of the game, Wind- NNE 5 mph.

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Beavers vs Michigan at Michigan Stadium, Ann Arbor, MI -Kickoff 9 AM PDT (12 PM EDT): Mostly cloudy 60 warming to 65 by the end of the game, Wind- N 10-15 mph.

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Forecast for the Umpqua Basin including Roseburg:

• Mostly clear tonight,
• Sunny and cooler Saturday, mostly clear at night,
• Partly cloudy Sunday AM, sunny in the afternoon, clear in the evening, partly cloudy late Sunday night and Monday AM, increasing clouds to mostly cloudy and cooler with a (30%) chance of rain in the afternoon, a slight (20%) chance of showers in the evening, then a slight (20%) chance of rain late Monday night.
• lows 60-47 highs 93-74.
• Mostly cloudy with a slight (20%) chance of rain and cooler Tuesday and in the evening,  rain likely (60%) late Tuesday night,
• Mostly cloudy and a bit cooler with rain Wednesday through Thursday, a good (50%) chance of showers Thursday night,
• Mostly cloudy Friday with a slight (20%) chance of AM showers, then just partly cloudy and a bit warmer Friday afternoon,
• highs 72-80 lows 54-52. (seasonal averages high 80 low 52)

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

• Partly cloudy this evening with patchy coastal fog while patchy inland fog late tonight,
• Mostly cloudy with patchy AM fog, partly cloudy Saturday afternoon and in the evening, mostly cloudy at night,
• Partly cloudy in the AM, sunny Sunday afternoon, mostly clear in the evening, partly cloudy Sunday night,
• Mostly cloudy with a (40%) chance of rain Monday afternoon, cloudy with a (30%) chance of evening rain, a (40%) chance of rain late Monday night.
• lows 56-52 highs near 66.
• Mostly cloudy and a bit cooler with a slight (20%) chance of rain Tuesday afternoon, rain and breezy Tuesday night through Wednesday night,
• Mostly cloudy with AM rain likely (70%) Thursday, a good (50%) chance of showers and a bit warmer in the afternoon, a (40%) chance of showers Thursday night,
• Mostly cloudy with a slight (20%) chance of showers Friday AM, then just partly cloudy Friday afternoon.
• highs 65-63 warming back to 65 Friday lows near 55. (seasonal averages high 65 low 51).

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Forecast for the Cascades in Lane County:

• Mostly clear tonight,
• Mostly sunny Saturday AM, partly cloudy and a bit cooler Saturday afternoon and at night,
• Mostly sunny, but cooler Sunday, partly cloudy Sunday night,
• Mostly cloudy and a bit cooler with a (30%) chance of showers Monday afternoon, mostly cloudy with a (30%) chance of evening showers, then partly cloudy with a slight (20%) chance of showers late Monday night.
• free air freezing level 15,000 ft. tonight through Sunday, 14,000 ft. Sunday night, 13,000 ft. Monday AM, snow level above 8,000 ft. Monday afternoon and Monday night.
• lows 52-37 highs 83-63.
• A mix of clouds and sun and cooler Tuesday with a slight (20%) chance of AM showers, a slight (20%) chance rain in the afternoon and evening, a good (50%) chance of rain late Tuesday night,
• Mostly cloudy and cooler with a good (50%) chance of rain Wednesday AM, rain and a bit warmer in the afternoon and evening, showers likely (70%) late Wednesday night,
• A mix of clouds and sun Thursday with AM showers likely (70%), a good (50%) chance of showers and a bit cooler in the afternoon, a (40%) chance of evening showers, a slight (20%) chance of showers late Thursday night,
• Then a mix of clouds and sun and a bit warmer with a slight (20%) chance of showers Friday.
• snow level 6,500 ft. Tuesday and Tuesday night, 7,500 ft. Wednesday, then above 8,000 ft. Wednesday night through Friday.
• highs 53-62 lows 38-43.

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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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