Here is my weekly weather quiz question for the last time. What is “Isentropic Analysis?  Here is the correct answer. Isentropic Analysis is a way the forecaster can look at the atmosphere in 3-dimensions instead of looking at constant pressure surfaces (such as the 850 mb, 700 mb, 500 mb, etc.) which are in 2-dimensions. In this analysis method, the forecaster looks at constant potential temperature (the temperature that it would take if we compressed or expanded it adiabatically to the pressure of 1000 mb) surfaces. Air parcels move up and down these surfaces; therefore, the forecaster can see where the moisture is located and how much moisture is available.

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An Upper Level Low Pressure Trough (“U” shape) is approaching the Pacific Northwest. The graphics for days 1-3 show the frontal system approaching the coast Sunday and then moving in. The graphics for days 3-7 show an increase in complex frontal systems moving our way Tuesday through next Saturday continuing the rain chances.

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Air Quality Index:

Eugene/Springfield: The Air Quality Index is 43 in the Good category measuring Particulate Matter.

Oakridge: The Air Quality Index is 20 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 20 in the Good category measuring Particulate Matter.

Data courtesy of Lane Regional Air Protection Agency (LRAPA)

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ADVISORIES:

• NONE AT THIS TIME.

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

• Mostly cloudy tonight,
• Mostly cloudy with a (40%) chance of AM rain, showers and cooler Sunday afternoon (0.25 in. of rain possible), showers Sunday night (0,25 in. of rain possible),
• Mostly cloudy and a bit cooler with showers Monday, a slight (20%) chance of evening showers , becoming partly cloudy late at night,
• A mix of clouds and sun and a bit warmer Tuesday, partly cloudy with a slight (20%) chance of evening showers, then partly cloudy late Tuesday night.
• lows 44-32 warming to 34 Tuesday night highs 54-49 warming to 53 Tuesday.
• Clouds and sun with a slight (20%) chance of AM showers, a mix of clouds and sun with a good (50%) of showers and a bit warmer Wednesday afternoon, mostly cloudy with a good (50%) chance of showers Wednesday night,
• Mostly cloudy with rain and a bit cooler Thursday and at night,
• Mostly cloudy with AM showers and snow showers, showers and a bit cooler Friday afternoon (snow level 1,500 ft.), evening showers likely (70%), partly cloudy with a good (50%) chance of rain and snow showers Friday night (snow level 1,000 ft.),
• Clouds and sun with a good (50%) chance of AM snow showers, a mix of clouds and sun and a bit warmer with a good (50%) chance of showers Saturday afternoon (snow level 1,500 ft.).
• highs 55-47 warming to 50 Saturday lows 38-32. (seasonal averages high 57 low 38)

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Home Wood Heating Advisory:

Posted Daily

Eugene-Springfield: GREEN– Burning is Allowed.

Oakridge: GREEN– Burning is Allowed.

*Note: Pellet stoves may be used anytime if they produce no visible emissions.

Data courtesy of Lane Regional Air Protection Agency (LRAPA

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Eugene-Springfield Pollen Count:

Forecast for the Umpqua Valley including Roseburg:

• Mostly cloudy with a (40%) chance of evening showers, showers late tonight (under 0.10 in. of rain possible),
• Mostly cloudy with showers and cooler Sunday (0.10 in. of rain possible) and Sunday night (0.10 in. of rain possible, snow level 3,000 ft.),
• Mostly cloudy with AM rain and snow showers, a bit cooler with a good (50%) chance of rain and snow showers Monday afternoon (0.10 in. of rain possible), a slight (20%) chance of evening rain and snow showers, just mostly cloudy late at night,
• Mostly cloudy start, partly cloudy with a slight (20%) chance of showers and a bit warmer Tuesday afternoon, partly cloudy with a slight (20%) of evening showers, then mostly cloudy with a slight (20%) chance of showers Tuesday night.
• lows 42-33 warming to 37 Tuesday night highs 55- 52 warming to 56 Tuesday.
• Mostly cloudy with a slight (20%) chance of AM rain and snow showers, a bit cooler with a (30%) chance of showers Wednesday afternoon and evening, a (30%) chance of rain and snow showers late Wednesday night,
• Mostly cloudy with a good (50%) chance of AM rain and snow showers, showers likely (70%) and a bit cooler Thursday afternoon, rain and snow showers likely (70%) at night,
• Mostly cloudy and a bit cooler with rain and snow showers likely (70%) Friday, a good (50%) chance of rain and snow showers Friday night,
• Then mostly cloudy and a bit warmer with a good (50%) chance of rain and snow showers Saturday.
• highs 55-48 warming to 52 Saturday lows 40-33. (seasonal averages high 59 low 40)

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Forecast for The South Oregon Coast Including Coos Bay and North Bend:

• Mostly cloudy with a good (50%) chance of evening showers continuing  tonight (under 0.10 in. of rain possible),
• Mostly cloudy and a bit cooler with showers Sunday (0.50 in. of rain possible), showers Sunday night (0.25 in. of rain possible),
• Mostly cloudy with AM showers likely (70%), a bit cooler with a good (50%) chance of rain Monday afternoon (0.10 in. of rain possible), a slight (20%) chance of showers Monday night with patchy coastal frost late at night and areas of inland frost late Monday night,
• Mostly cloudy with a slight (20%) chance of showers and a bit warmer Tuesday and at night.
• lows 42-33 highs 57-50.
• Mostly cloudy and a bit cooler with a (40%) chance of rain Wednesday, a (30%) chance of rain at night,
• Mostly cloudy with a good (50%) chance of AM showers, showers likely (70%) and a bit cooler Thursday afternoon and evening, rain and snow showers likely (70%) late at night,
• Mostly cloudy with AM rain and snow showers likely (70%), showers likely (70%) and a bit cooler Friday afternoon, a good (50%) chance of rain and snow showers Friday night,
• Then mostly cloudy with a good (50%) chance of rain and snow showers Saturday.
• highs 54-48 lows near 35. (seasonal averages high 55 low 42)

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Forecast for the Northern Oregon Cascades including the Cascades in Lane County:

• Mostly cloudy with a slight (20%) chance of rain tonight,
• Mostly cloudy with a (40%) chance of AM rain and snow, showers and a bit cooler Sunday afternoon (0.25 in. of rain possible, 1 in. of snow possible), rain and snow showers Sunday night (0.50 in. of rain possible, 2-5 in. of snow possible),
• Mostly cloudy a bit cooler with rain showers and snow showers Monday (no snow accumulation expected), a good (50%) chance of evening showers, and good (50%) chance of snow showers late at night,
• Clouds and sun with a slight (20%) chance of AM snow showers, a mix of clouds and sun and a bit warmer with a (40%) chance of rain and snow showers Tuesday afternoon, partly cloudy with a good (50%) chance of evening showers and snow showers, then a slight (20%) chance of snow showers late Tuesday night.
• snow level 5,000 ft. tonight and Sunday, 5,000 ft. falling to 3,500 ft. late Sunday night, 3,000 ft. Monday, 2,000 ft. Monday night, 3,000 ft. Tuesday, then 3,500 ft. Tuesday night.
• lows 32-19 highs 46-34.
• Mostly cloudy with a good (50%) chance of AM snow showers, snow and rain showers likely (70%) and a bit cooler Wednesday afternoon, evening snow and rain showers likely (70%), a good (50%) chance of snow showers late Wednesday night,
• Mostly cloudy with a good (50%) chance of AM snow, snow and rain and a bit cooler Thursday afternoon, evening snow and rain, snow late at night,
• Mostly cloudy and a bit cooler with snow showers Friday (afternoon snow possibly heavy at times), evening snow showers likely (70%), a good (50%) chance of snow showers Friday night,
• Then a mix of clouds and sun and a bit warmer with a good (50%) chance of snow showers Saturday.
• snow level  3,000 ft, Wednesday through Thursday, 2,000 ft. Thursday night, at the surface Friday and Friday night, then 1,500 ft. Saturday.
• highs 36-30 lows 23-20.

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For all of your Eugene-Springfield and Lane County News, Weather, and Sports go to: EugeneDailyNews.com

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