Here is my new weekly weather quiz question. What is a “Back-building thunderstorm?” 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) continues to control our weather. Another frontal system (Position shown is Wednesday) will keep our temperatures cooler than normal and keep the chance for rain with us also.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 30 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 8 in the Good category measuring Particulate Matter.

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

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

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Advisories:

• AN AIR QUALITY ALERT HAS BEEN ISSUED UNTIL FURTHER NOTICE FOR CROOK, DESCHUTES, GILLIAM, GRANT, JEFFERSON, MONROE, SHERMAN, UMATILLA, UNION, WILLOWA, WASCO, WHEELER, BENTON AND COLUMBIA COUNTIES IN OREGON.
• 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:

• A mix of clouds and sun today, partly cloudy this evening, mostly cloudy late tonight,
• Mostly cloudy with a good (50%) chance of rain and a bit cooler Tuesday afternoon (under 0.10 in. of rain possible), cloudy with a good (50%) chance of showers Tuesday night (under 0.10 in. of rain possible),
•  A mix of clouds and sun with a good (50%) chance of showers Wednesday, then partly cloudy with a slight (20%) chance of showers late Wednesday night.
• highs 77-70 lows 55-48.
• A mix of clouds and sun with a slight (20%) chance of showers Thursday, mostly cloudy with a (30%) chance of showers in the evening, a (30%) chance of showers late Thursday night and Friday, partly cloudy with a slight (20%) chance of showers  in the evening, just partly cloudy late Friday night,
• AM clouds, then mostly sunny and and a bit warmer Saturday and Sunday, mostly clear Saturday night.
• highs 70-77 lows near 48. (seasonal averages high 81 low 50)

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Forecast for the Umpqua Basin including Roseburg:

• Sunny and a bit warmer today, mostly clear this evening, partly cloudy late tonight,
• Partly cloudy Tuesday, mostly cloudy with a (40%) chance of evening rain, a (40%) chance of showers late Tuesday night (under 0.10 in. of rain possible),
• Mostly cloudy with a slight (20%) chance of showers in the AM, partly cloudy and cooler with a slight (20%) chance of showers Wednesday afternoon, then partly cloudy late Wednesday night.
• highs 79-70 lows 55-57 cooling to 50 Wednesday night.
• Partly cloudy Thursday, partly cloudy with a slight (20%) chance of showers late Thursday night through Friday evening, just partly cloudy Friday night,
• Mostly sunny and  warmer Saturday, mostly clear at night,
• Then sunny and warmer Sunday.
• highs 72-80 lows near 50. (seasonal averages high 83 low 54)

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

• Partly cloudy this AM, sunny this afternoon, partly cloudy tonight,
• Mostly cloudy and a bit cooler with a slight (20%) chance of AM coastal rain  Tuesday while partly cloudy inland in the AM and mostly cloudy with a slight (20%) chance of inland showers in the afternoon (under 0.10 in. of rain possible), then partly cloudy with a (30%) chance of showers Tuesday night (under 0.10 in. of rain possible),
• Mostly cloudy with a slight (20%) chance of showers Wednesday AM, then partly cloudy and a bit cooler in the afternoon and Wednesday night.
• highs 68-64 lows 56-52.
• Partly cloudy Thursday, partly cloudy with a slight (20%) chance of showers Thursday night and Friday, partly cloudy Friday night,
• Then mostly sunny and a bit warmer Saturday and Sunday, mostly clear Saturday night.
• highs 65-70 lows 50-52. (seasonal averages high 66 low 52).

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Forecast for the Cascades in Lane County:

• Partly cloudy today and tonight,
• A mix of clouds and sun in the AM, becoming mostly cloudy with a slight (20%) chance of rain Tuesday afternoon, cloudy with a good (50%) chance of showers Tuesday night,
• A mix of clouds and sun and a bit cooler with a good (50%) chance of showers Wednesday, mostly cloudy with a slight (20%) chance of afternoon showers, then mostly cloudy with a slight (20%) chance of showers Wednesday night.
• free air freezing level 14,000 ft. today, 12,000 ft. tonight, snow level above 8,000 ft. Tuesday and Tuesday night, 7,500 ft. Wednesday and Wednesday night.
• highs 64-57 lows 42-44 cooling to 38 Wednesday.
• A mix of clouds and sun a bit cooler with a slight (20%) chance of showers Thursday afternoon, mostly cloudy with a slight (20%) chance of evening showers, partly cloudy with a slight (20%) chance of showers at night,
• Partly cloudy with a (40%) chance of showers and a bit warmer in the afternoon and evening, just partly cloudy Friday night,
• Partly cloudy Saturday AM, mostly sunny and a bit warmer in the afternoon, partly cloudy at night,
• Then mostly sunny and a bit warmer Sunday.
• snow level 6,500 ft. Thursday and Thursday night, 7,000 ft. Friday and Friday night, free air freezing level 9,000 ft. Saturday, then 11,000 ft. Saturday night and Sunday.
• highs 56-65 lows 38-40.

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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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