Here is my 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.

________________

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 southward through Oregon bringing the chance of showers and thunderstorms yet this evening then the high pressure takes over for the long Labor Day Holiday Weekend. Weather will be good, but chilly for the Duck game Saturday evening.

________________

Air Quality Index:

Eugene-Springfield: The Air Quality Index is 25 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 5 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 24 in the Good category measuring Ozone.

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

________________

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.

________________

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

• Partly cloudy with a (40%) chance of showers and a slight (20%) chance of thunderstorms this evening, a (30%) chance of showers through late evening, partly cloudy with patchy fog late tonight and Saturday AM, mostly sunny and warmer in the afternoon, mostly clear Saturday night,
• 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.
• lows 45-50 highs 73-76.
• 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)

_____

Your College Football Weather Forecast:

Saturday- 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.

________________

Forecast for the Umpqua Basin including Roseburg:

• Mostly cloudy with a slight (20%) chance of thunderstorms this evening, mostly cloudy with a slight (20%) chance of isolated showers late tonight,
• Partly cloudy and warmer Saturday afternoon, mostly clear Saturday night,
• Partly cloudy and warmer Sunday and in the evening, clear at night,
• Sunny and a bit warmer Monday (Labor Day), then clear Monday night.
• lows 47-53 cooling to 50 Monday night highs 73-82.
• 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)

________________

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

• Partly cloudy tonight with a slight (20%) chance of inland evening showers,
• Partly cloudy Saturday AM, sunny in the afternoon, mostly clear in the evening, partly cloudy Saturday night through Sunday night,
• Sunny Monday (Labor Day), then clear at night.
• lows near 52 highs near 67.
• 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).

________________

Forecast for the Cascades in Lane County:

• Mostly cloudy with showers likely (70%) and a slight (20%) chance of thunderstorms this evening, partly cloudy with a good (50%) chance of showers late tonight,
• A mix of clouds and sun Saturday with a slight (20%) chance of AM showers, partly cloudy Saturday night,
• 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 6,000 ft. tonight, 5,500 ft. Saturday, free air freezing level 9,000 ft. Saturday night, 10,000 ft. Sunday, 11,000 ft. Sunday night, 9,000 ft. Monday, then 12,000 ft. Monday night.
• lows 37-42 highs 58-65.
• 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.

_______________

**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.

________________