Here is my weekly weather quiz question for the last time. What is the “dew point?”  Here is the correct answer.The Dew Point (Abbrev. DWPT) – A measure of atmospheric moisture. It is the temperature to which air must be cooled in order to reach saturation (assuming air pressure and moisture content are constant). A higher dew point indicates more moisture present in the air. It is sometimes referred to as Dew Point Temperature, and sometimes written as one word (Dewpoint). 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 pressure trough (Shaded “U” shape with blue arrows) is moving in behind the high pressure ridge (Shaded “Arch” shape with blue arrows) that is leaving us. A frontal system will push in (position shown is Wednesday) bringing more clouds, slightly cooler temperatures and a continued chance of precipitation.

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Air Quality Index:

Eugene-Springfield: The Air Quality Index is 10 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 10 in the Good category measuring Particulate Matter.

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

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Advisories:

• A RED FLAG WARNING IS IN EFFECT FROM 11 AM TODAY UNTIL 11 PM TUESDAY FOR THUNDERSTORMS WITH ABUNDANT LIGHTNING FOR THE EAST SLOPES OF THE CENTRAL OREGON CASCADES, THE DESCHUTES NATIONAL FOREST, MINUS SISTERS RANGER DISTRICT, THE EAST SLOPES OF THE NORTHERN OREGON CASCADES, THE CENTRAL MOUNTAINS OF OREGON, THE LOWER COLUMBIA BASIN OF OREGON, AND THE SOUTHERN BLUE AND STRAWBERRY MOUNTAINS.
• A HEALTH ADVISORY HAS BEEN ISSUED FOR UPPER KLAMATH LAKE AND AGENCY LAKE DOWN TO KENO DAM TO THE CALIFORNIA BORDER, 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 cloudy this AM, partly cloudy this afternoon and evening, mostly cloudy late tonight,
• A mix of clouds and sun with a slight (20%) chance of showers and thunderstorms Monday afternoon, mostly cloudy with a slight (20%) chance of evening showers and thunderstorms, a slight (20%) chance of showers late at night,
• A mix of clouds and sun with a slight (20%) chance of showers and a bit warmer Tuesday, partly cloudy with a slight (20%) chance of evening showers, then mostly cloudy with a slight (20%) chance of showers late Tuesday night.
• highs 85-88 lows 58-60 cooling back to 58 Tuesday night.
• Mostly cloudy Wednesday AM, partly cloudy in the afternoon and Wednesday night,
• A mix of clouds and sun and just a bit cooler Thursday with a (30%) chance of afternoon thunderstorms, mostly cloudy with a (30%) chance of showers and a slight (20%) chance of thunderstorms in the evening, a slight (20%) chance of showers late Thursday night,
• Mostly cloudy with a slight (20%) chance of AM showers, just partly cloudy and a bit warmer Friday and Friday night,
• Then partly cloudy in the AM and mostly sunny and warmer Saturday afternoon.
• highs 84-77 warming to 84 Saturday lows 56-53. (seasonal averages high 84 low 52)

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Forecast for the Umpqua Basin including Roseburg:

• Mostly cloudy with patchy smoke today and a slight (20%) chance of AM showers, partly cloudy and hazy with more patchy smoke this afternoon and  tonight,
• Partly cloudy with patchy smoke and a slight (20%) chance of thunderstorms Monday afternoon, mostly cloudy with patchy smoke and a slight (20%) chance of showers Monday night,
• Mostly cloudy and a bit warmer with a slight (20%) chance of showers Tuesday, partly cloudy with a slight (20%) chance of showers Tuesday night.
• highs 86-88 lows near 60.
• Partly cloudy and a bit cooler with a slight (20%) chance of showers Wednesday and in the evening, then mostly cloudy with a slight (20%) chance of showers late at night,
• Mostly cloudy with a slight (20%) chance of showers and a bit cooler Thursday and in the evening, just partly cloudy late Thursday night and Friday AM, then sunny and a bit warmer Friday afternoon, mostly clear at night,
• Then sunny Saturday.
• highs 88-78 warming to 86 Friday and Saturday lows 59-57. (seasonal averages high 86 low 56)

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

• Mostly cloudy with a slight (20%) chance of showers this AM, just mostly cloudy this afternoon, partly cloudy this evening, mostly cloudy with a slight (20%) chance of coastal showers late tonight,
• Mostly cloudy with a slight (20%) chance of coastal showers Monday while a slight (20%) chance of inland showers in the afternoon, a slight (20%) chance of showers Monday night,
• Mostly cloudy with a slight (20%) chance of showers Tuesday and at night.
• highs near 66 lows near 58.
• Mostly cloudy with a slight (20%) chance of showers Wednesday through Thursday, partly cloudy with a slight (20%) chance of showers Thursday evening, just partly cloudy late Thursday night and Friday AM, sunny in the afternoon, mostly clear at night,
• Then mostly sunny and a bit warmer Saturday.
• highs 70-66 warming back to 70 Friday lows near 56. (seasonal averages high 65 low 53)

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Forecast for the Cascades in Lane County:

• A mix of clouds and sun today with a slight (20%) chance of showers and thunderstorms this afternoon, mostly cloudy with a slight (20%) chance evening showers and thunderstorms, mostly cloudy with a (20%) chance of showers late tonight,
• A mix of clouds and sun and a bit warmer Monday with a (30%) chance of showers and thunderstorms in the afternoon, mostly cloudy with a slight (20%) chance of showers and thunderstorms in the evening, a slight (20%) chance of showers late Monday night and Tuesday AM, a slight (20%) chance of showers and thunderstorms and a bit warmer in the afternoon, partly cloudy with a slight (20%) chance of showers and thunderstorms in the evening, then a slight (20%) chance of showers late Tuesday night.
• snow level above 8,000 ft. today through Tuesday night.
• highs 72-78 lows near 49.
• Partly cloudy with a slight (20%) chance of showers Wednesday AM, a slight (20%) chance of showers and thunderstorms and a bit cooler in the afternoon and evening,  a slight (20%) chance of showers late Wednesday night,
• A mix of clouds and sun and just a bit cooler Thursday with a slight (20%) chance of AM showers, just a bit warmer with a (30%) chance of showers and a slight (20%) chance of thunderstorms in the afternoon, partly cloudy with a (30%) chance of evening showers and a slight (20%) chance of thunderstorms, a slight (20%) chance of showers late Thursday night and Friday AM, partly cloudy and a bit warmer in the afternoon, mostly clear at night,
• Then mostly sunny and warmer Saturday.
• snow level above 8,000 ft. Wednesday through Friday, then free air freezing level above 8,000 ft.
• highs 74-63 warming to 72 Saturday lows near 45.

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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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