Here is my weekly weather quiz question for the last time. What is a “Back-building thunderstorm?”  Here is the correct answer. A Back-building Thunderstorm is a  thunderstorm in which new development takes place on the upwind side (usually the west or southwest side), such that the storm seems to remain stationary or propagate in a backward direction. 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 (Shaded “U” shape with blue arrows) that has been controlling our weather is being replaced by high pressure (Shaded “Arch” shape with blue arrows) and that means the rain goes away again. The low is moving eastward as the high pressure takes over for the long Labor Day Holiday Weekend. Weather will be good, but chilly for the Duck game this evening.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 27 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 12 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).

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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:

• Partly cloudy with patchy fog this AM, mostly sunny and warmer this afternoon, mostly clear tonight,
• A mix of clouds and sun Sunday, partly cloudy at night,
• Mostly sunny and a bit warmer Monday (Labor Day), then partly cloudy Monday night.
• highs 73-76 lows 46-50.
• Partly cloudy Tuesday AM, mostly sunny and a bit warmer in the afternoon, mostly clear at night,
• Then mostly sunny Wednesday, Thursday and Friday, mostly clear each night.
• highs 82-84 lows near 52. (seasonal averages high 80 low 49)

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Your College Football Weather Forecast:

Today- Ducks vs Eastern Washington – Autzen Stadium- Kickoff: 5 pm (PDT)

Forecast: Temperature near 70 and falling, mostly sunny late in the afternoon then mostly clear in the evening and at night, wind: W 5-10 mph shifting NW 5-10 mph at night. Remember, after the sun goes down it will get chilly. Dress appropriately.

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Forecast for the Umpqua Basin including Roseburg:

• Partly cloudy and warmer this afternoon, mostly clear tonight,
• Partly cloudy and warmer Sunday and in the evening, clear at night,
• Sunny and a bit warmer Monday (Labor Day), then clear Monday night.
• highs 73-82 lows 48-53 cooling to 50 Monday night.
• Mostly sunny and a bit warmer Tuesday, mostly clear at night,
• Sunny and a bit warmer Wednesday and Thursday, clear at night,
• Then sunny and a bit warmer Friday.
• highs 85-90 lows near 54. (seasonal averages high 82 low 53)

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

• Partly cloudy this AM, sunny this afternoon, mostly clear this evening, partly cloudy tonight through Sunday night,
• Sunny Monday (Labor Day), then clear at night.
• highs near 67 lows near 52.
• Mostly sunny Tuesday and Wednesday, mostly clear at night,
• Sunny and a bit warmer Thursday, mostly clear at night,
• Then mostly sunny Friday.
• highs near 68 lows 53-55. (seasonal averages high 66 low 52).

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Forecast for the Cascades in Lane County:

• A mix of clouds and sun today with a slight (20%) chance of AM showers, partly cloudy tonight,
• Mostly sunny Sunday AM, party cloudy in the afternoon and Sunday night,
• Mostly sunny and warmer Monday (Labor Day), then mostly clear at night.
• snow level 5,500 ft. today, free air freezing level 9,000 ft. tonight, 10,000 ft. Sunday, 11,000 ft. Sunday night, 9,000 ft. Monday, then 12,000 ft. Monday night.
• highs 58-65 lows 37-42.
• Mostly sunny and a bit warmer Tuesday, Wednesday and Thursday, mostly clear each night,
• Then sunny Friday.
• free air freezing level 12,000 ft. Tuesday, 13,000 ft. Tuesday night and Wednesday, 12,000 ft. Wednesday night, then 13,000 ft. Thursday through Friday.
• highs 70-74 cooling to 72 Friday lows 45-48 cooling back to 45 Thursday night.

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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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