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 19 in the Good category measuring Ozone.

Oakridge: The Air Quality Index is 13 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 19 in the Good category measuring Ozone.

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

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Advisories:

• A RED FLAG WARNING IS IN EFFECT FOR THUNDERSTORMS PRODUCING ABUNDANT LIGHTNING FROM NOON MONDAY UNTIL 11 PM TUESDAY FOR THE NORTH OREGON CASCADE FOOTHILLS, THE CENTRAL OREGON CASCADE FOOTHILLS, THE MT. HOOD NATIONAL FOREST WEST OF CASCADE CREST AND THE WILLAMETTE NATIONAL FOREST.
• A RED FLAG WARNING IS IN EFFECT 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, THE SOUTHERN BLUE AND STRAWBERRY MOUNTAINS, THE NORTHERN BLUE MOUNTAINS OF OREGON AND THE CENTRAL BLUE 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:

• Partly cloudy tonight,
• Partly cloudy Monday with a slight (20%) chance of showers and thunderstorms in the afternoon, becoming mostly cloudy with a (30%) chance showers and thunderstorms at night,
• A mix of clouds and sun Tuesday, mostly cloudy with a slight (20%) chance of evening showers and thunderstorms, a slight (20%) chance of showers late Tuesday night,
• Mostly cloudy Wednesday AM, partly cloudy in the afternoon and Wednesday night with a slight (20%) chance of evening showers
• lows 57-60 cooling to 54 Wednesday night highs near 85.
• A mix of clouds and sun and just a bit cooler Thursday with a (30%) chance of afternoon showers and thunderstorms, partly cloudy with a (30%) chance of showers and a slight (20%) chance of thunderstorms in the evening, mostly cloudy with a slight (20%) chance of showers late Thursday night,
• Mostly cloudy with a slight (20%) chance of AM showers, partly cloudy with a slight (20%) chance of showers Friday afternoon and evening, just partly cloudy late Friday night,
• Mostly sunny and a bit warmer Saturday and Sunday, mostly clear Saturday night.
• highs 78-84 lows near 55. (seasonal averages high 84 low 52)

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Forecast for the Umpqua Basin including Roseburg:

• Partly cloudy and hazy with more patchy smoke tonight,
• Partly cloudy with AM haze, patchy smoke and a slight (20%) chance of thunderstorms Monday afternoon, mostly cloudy with patchy smoke and a slight (20%) chance of thunderstorms, a (30%) chance of thunderstorms late Monday night,
• Mostly cloudy with a slight (20%) chance of showers Tuesday AM, partly cloudy with a slight (20%) chance of showers thunderstorms in the afternoon and evening, mostly cloudy with a slight (20%) chance of showers late Tuesday night,
• Partly cloudy and a bit cooler with a slight (20%) chance of thunderstorms Wednesday and and at night.
• lows near 60 highs 86-88.
• Mostly cloudy and cooler with a (30%) chance of showers and a slight (20%) chance of thunderstorms Thursday and Thursday night.
• Mostly cloudy Friday AM, sunny and a bit warmer in the afternoon, mostly clear at night,
• Mostly sunny Saturday, mostly clear Saturday night,
• Then sunny and warmer Sunday.
• 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:

• Partly cloudy this evening, mostly cloudy tonight,
• Mostly cloudy with a slight (20%) chance of coastal showers Monday afternoon, a slight (20%) chance of evening inland thunderstorms, a (30%) chance of showers and a slight (20%) chance of thunderstorms late Monday night,
• Mostly cloudy with a slight (20%) chance of coastal showers Tuesday while mostly cloudy with a slight (20%) chance of inland AM showers and partly cloudy with a slight (20%) chance of afternoon thunderstorms, mostly cloudy with a slight (20%) chance of coastal showers at night while a slight (20%) chance of evening inland thunderstorms and a slight (20%) chance of showers late Tuesday night,
• Then mostly cloudy with a slight (20%) chance of showers Wednesday and Wednesday night.
• lows near 58 highs near 66.
• Mostly cloudy with a slight (20%) chance of showers Thursday and in the evening, just mostly cloudy late Thursday night and Friday AM, sunny in the afternoon, mostly clear at night,
• Then mostly sunny and a bit warmer Saturday and Sunday, mostly clear at night.
• 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:

• Partly cloudy with a slight (20%) chance of showers and thunderstorms this evening, just partly cloudy late tonight and Monday AM, mostly cloudy with a (30%) chance of showers and thunderstorms in the afternoon (under 0.10 in. of rain possible, more in storms), mostly cloudy with a (40%) chance of showers and thunderstorms Monday night (under 0.10 in of rain possible, more in storms),
• A mix of clouds and sun Tuesday with a slight (20%) chance of AM showers, a slight (20%) chance of showers and thunderstorms and a bit warmer in the afternoon, mostly cloudy with a slight (20%) chance of showers and thunderstorms in the evening, partly cloudy with a slight (20%) chance of showers late Tuesday night,
• 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, then a slight (20%) chance of showers late Wednesday night.
• snow level above 8,000 ft. tonight through Wednesday night.
• lows near 48 highs near 76.
• 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 thunderstorms in the afternoon, partly cloudy with a (30%) chance of showers and thunderstorms in the evening,  mostly cloudy with  a slight (20%) chance of showers and thunderstorms late Thursday night,
• Mostly cloudy with a slight (20%) chance of showers and thunderstorms Friday AM, partly cloudy in the afternoon and at night,
• Partly cloudy Saturday AM, mostly sunny and warmer in the afternoon, mostly clear Saturday night,
• Then mostly sunny Sunday.
• snow level above 8,000 ft. Thursday through Friday, free air freezing level 11,000 ft. Friday night, then 13,000 ft. Saturday through Sunday.
• highs 65-72 lows 43-47.

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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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