Here is my weekly weather quiz question for the last time. What is a “Nocturnal Inversion?” Here is the correct answer. A Nocturnal Inversion: Used interchangably with Radiational Inversion; a temperature inversion that develops during the night as a result of radiational cooling of the surface. Because the immediate surface (lower Boundary Layer) cools much more rapidly during radiational cooling conditions than the air just above (upper Boundary Layer), a temperature inversion can be created overnight, but typically erodes quickly after sunrise. ( Note: Inversion means the reverse of normal. Instead warm air is above cooler air.) 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.

________________

An upper level low (Shaded “U” shape with blue arrows) is still sending moisture our way. A frontal system approaches the coast Wednesday for even more precipitation. Here comes yet another frontal system approaching the coast and then pushing in by Friday.

________________

Air Quality Index:

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

Oakridge: The Air Quality Index is 18 in the Good category measuring Particulate Matter.

Cottage Grove: The Air Quality Index is 35 in the Good category measuring Particulate Matter.

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

________________

Advisories:

• A FROST ADVISORY IS IN EFFECT FROM 2 AM UNTIL 8 AM MONDAY FOR THE SOUTH CENTRAL OREGON COAST AND THE CURRY COUNTY COAST.

________________

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

• Mostly cloudy with a good (50%) chance of showers this evening tapering off by late tonight (under 0.10 in. of rain possible),
• AM clouds with a slight (20%) chance of showers, a mix of clouds and sun and a bit cooler with a slight (20%) chance of showers Monday and in the evening, just mostly cloudy  Monday night (under 0.10 in. of rain possible),
• Mostly cloudy with a (40%) chance of showers Tuesday (under 0.10 in. of rain possible), mostly cloudy Tuesday night,
• Cloudy with a good (50%) chance of AM rain, a bit warmer with rain increasing Wednesday afternoon, then rain rain at night.
• lows 33-38 highs 45-50.
•  Mostly cloudy with showers likely (60%) and a bit cooler Thursday, a slight (20%) chance of showers Thursday night,
• A mix of clouds and sun and just a bit warmer Friday, mostly cloudy with a good (50%) chance of rain Friday night,
• Mostly cloudy and a bit cooler with a (40%) chance of showers Saturday, partly cloudy with a slight (20%) chance of showers at night,
• Then a mix of clouds and sun Sunday.
• highs 48-53 cooling to near 50 Saturday and Sunday lows 38-40 cooling to 36 Saturday night. (seasonal averages high 49 low 35)

_____

Home Wood Heating Advisory:

Eugene-Springfield: GREEN – Burning is allowed.

Oakridge: YELLOW – Caution is Advised.

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

Advisory Courtesy of Lane Regional Air Protection Agency (LRAPA).

___________________

Forecast for Roseburg:

• Cloudy with evening rain and snow showers likely (60%), a good (50%) chance of rain and snow showers late tonight (0.10 in. of rain possible, 1 in. of snow possible, snow level 2,000 ft. falling to 1,500 ft. late tonight),
• Mostly cloudy with a (30%) chance of rain and snow showers Monday (under 0.10 in. of rain possible, snow level 1,500 ft.) a slight (20%) chance of rain and snow late Monday night (under 0.10 in. of rain possible, snow level 2,500 ft. at night),
• Mostly cloudy and a bit warmer with a (40%) chance of rain and snow Tuesday AM, a (40%) chance of rain and snow showers in the afternoon (under 0.10 in. of rain possible, snow level 2,000 ft.), just mostly cloudy Tuesday night,
• Mostly cloudy with a slight (20%) chance of AM rain and snow, rain and a bit warmer with a slight (20%) chance of rain Wednesday afternoon, then showers likely (70%) Wednesday night.
• lows 33-39 highs 46-53.
• Cloudy with a (40%) chance of showers and a bit warmer Thursday, mostly cloudy with a slight (20%) chance of showers Thursday night,
• Just mostly cloudy and a bit warmer Friday, mostly cloudy with a (40%) chance of rain Friday night,
• Mostly cloudy with a (40%) chance of showers Saturday, partly cloudy at night,.
• Then sunny and a bit cooler Sunday.
• highs 52-55 cooling back to 52 Sunday lows near 40. (seasonal averages high 52 low 37)

________________

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

• Cloudy with coastal showers likely (70%) and a slight (20%) chance of thunderstorms this evening and coastal showers likely (70%) late tonight while a (30%) chance of inland showers and a slight (20%) chance of thunderstorms this evening and a good (50%) chance of inland showers late tonight (0.15 in. of rain possible, snow level 2,000 ft.),
• Mostly cloudy with a (40%) chance of showers Monday while partly cloudy with a (40%) chance of inland AM showers and mostly cloudy with a slight (20%) chance of inland rain and snow showers in the afternoon (0.10 in. of rain possible, snow level 2,000 ft.), a slight (20%) chance of rain late Monday night (0.15 in. of rain possible),
• Mostly cloudy with a (40%) chance of AM rain (0.10 in. of rain possible, snow level snow level 2,000 ft.), a (40%) chance of showers Tuesday afternoon, a slight (20%) chance evening coastal showers and a slight (20%) chance of rain late Tuesday night (under 0.10 in. of rain possible),
• Rain likely (70%) Wednesday AM, rain and a bit warmer in the afternoon and evening, then showers likely (70%) late Wednesday night and breezy.
• lows 35-46 highs 50-55.
• Cloudy with a good (50%) chance of showers and a bit cooler Thursday, mostly cloudy with a slight (20%) chance of evening rain, rain likely (70%) late Thursday night,
• Mostly cloudy and a bit warmer Friday, a slight (20%) chance of evening rain, rain likely (70%) late Friday night,
• Mostly cloudy with a (30%) chance of showers and a bit cooler Saturday, partly cloudy at night,
• Then sunny and a bit warmer Sunday.
• highs 53-57 cooling back to 53 Saturday warming to 55 Sunday lows 47-40. (seasonal averages high 52 low 40).

________________

Forecast for the Cascades in Lane County:

• Mostly cloudy with a good (50%) chance of snow showers tonight and Monday, a slight (20%) chance of snow showers Monday night,
• A mix of clouds and sun with a good (50%) chance of snow showers and a bit warmer Tuesday, more clouds to mostly cloudy with  a slight (20%) chance of snow showers Tuesday night,
• Mostly cloudy and a bit warmer Wednesday with a slight (20%) chance of AM rain or snow, rain or snow in the afternoon, then rain or snow Wednesday night.
• snow level at the surface today through Tuesday, then 3,000 ft. Tuesday night.
• lows 17-28 highs 22-36.
• Mostly cloudy and a bit cooler with showers likely (60%) Thursday, a (40%) chance of showers Thursday night,
• A mix of clouds and sun and a bit warmer Friday, becoming mostly cloudy with a slight (20%) chance of rain at night,
• Then mostly cloudy with a (40%)  chance of rain and snow Saturday, partly cloudy with a slight (20%) chance of showers Saturday night,
• Then a mix of clouds and sun Sunday.
• snow level 3,500 ft. Thursday, 4,000 ft. Thursday night, free air freezing level 6,500 ft. Friday, snow level 4,500 ft. Friday, 5,500 ft. Friday night, 4,500 ft.  Saturday, 4,000 ft. Saturday night, then 4,500 ft. Sunday.
• highs 34-38 lows near 26.

________________

**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.

________________