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No winner this week. Here is my weekly weather quiz question for the last time. What is a “gust front?” Here is the answer. A gust front is the leading edge of cool air rushing down and out from a thunderstorm. There are two main reasons why the air flows out of some thunderstoms so rapidly. The primary reason is the presence of relatively dry (low humidity) air in the lower atmosphere. This dry air causes some of the rain falling through it to evaporate, which cools the air. Since cool air sinks (just as warm air rises), this causes a down-rush of air that spreads out at the ground. The edge of this rapidly spreading cool pool of air is the gust front. The second reason is that the falling precipitation produces a drag on the air, forcing it downward. If the wind following the gust front is intense and damaging, the windstorm is known as a downburst. I’ll have another weekly weather quiz question for you starting next 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.
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Advisories: A HIGH SURF ADVISORY IS IN EFFECT UNTIL 10 PM TONIGHT FOR THE NORTH AND CENTRAL OREGON COAST. A WINTER WEATHER ADVISORY IS IN EFFECT UNTIL 4 PM TODAY FOR THE NORTHERN OREGON CASCADE FOOTHILLS, AND THE CASCADE FOOTHILLS OF LANE COUNTY, THE NORTHERN OREGON CASCADES AND THE CASCADES OF LANE COUNTY. A WINTER WEATHER ADVISORY IS IN EFFECT UNTIL 4 PM TODAY ABOVE 1,500 FT. FOR THE SOUTH CENTRAL AND SOUTH OREGON COAST, CENTRAL DOUGLAS COUNTY, EASTERN CURRY COUNTY, JOSEPHINE COUNTY, THE EASTERN DOUGLAS COUNTY FOOTHILLS, JACKSON COUNTY, THE SOUTH CENTRAL AND SOUTH OREGON CASCADES, AND THE SISKIYOUS MOUNTAINS. A HIGH SURF ADVISORY IS IN EFFECT UNTIL 10 PM TONIGHT FOR THE SOUTH CENTRAL OREGON COAST.
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A high pressure ridge ( “Arch” shape on yellow line) was dominating our weather pattern giving us sunshine and mild weather. A trough of low pressure (“U” shape on the yellow line) is sliding up to the coast and a cold front has moved through bringing back the rain, dropping snow levels , and even dropping some light snow showers to the valley floor. Another frontal system (position shown is Sunday) will be sliding to the south bringing colder air and falling snow levels. There will be a chance of more snow falling even down to the valley floor.
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Here are your detailed forecasts.**
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Forecast for the Southern and lower Mid Willamette Valley including Eugene-Springfield and Albany-Corvallis: Mostly cloudy with rain or snow showers (snow level 1,000 ft., 0.25 in. of rain possible) this afternoon and evening, a good (50%) chance of scattered rain or snow showers (0.10 in. of rain possible) tonight, rain and snow showers (0.15 in. of rain possible) likely (60%) Sunday, mostly cloudy with a (40%) chance of rain and snow showers in the evening, a slight (20%) chance of rain and snow showers (under 0.10 in. of rain possible) late Sunday night, then partly cloudy Monday and Monday evening, then mostly cloudy Monday night highs 46-43 lows 32-27. Cloudy with a good (50%) chance of rain Tuesday (AM snow level 1,000 ft.), rain Tuesday night, showers likely (60%) Wednesday and Wednesday night, a good (50%) chance of showers Thursday, then mostly cloudy with a good (50%) chance of rain Thursday night and Friday highs 45-49 lows 36-33. (seasonal averages high 53 low 35)
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Forecast for the Umpqua Basin including Roseburg: Mostly cloudy with rain and snow showers likely (60%) today (snow level 2,000 ft., under 0.10 in. of rain possible), a (30%) chance of rain and snow showers tonight (snow level 1,500 ft. falling to 1,000 ft. late, under 0.10 in. of rain possible), mostly cloudy with a good (50%) chance of rain and snow showers (snow level 1,000 ft. rising to 1,500 ft.) Sunday, a (30%) chance of rain and snow showers Sunday night (snow level 1,500 ft.), mostly cloudy Monday AM, partly cloudy in the afternoon and evening, then mostly cloudy with a slight (20%) chance of rain and snow late Monday night highs 44-47 lows 33-28 warming to 33 Monday night. Mostly cloudy with a good (50%) chance of rain and snow Tuesday AM, rain and snow in the afternoon and breezy, evening rain, rain and snow late Tuesday night, mostly cloudy with rain and snow showers likely (60%) Wednesday through Thursday night, then mostly cloudy with rain likely (60%) Friday highs 48-40 warming to 52 Friday lows near 38. (seasonal averages high 55 low 38)
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Forecast for the South Oregon Coast including Coos Bay and North Bend: Mostly cloudy with coastal showers likely (60%) with a good (50%) chance of rain and snow showers in the afternoon (snow level 1,500 ft. , 0.10 in. of rain possible), a (40%) chance of coastal showers and a (40%) chance of rain and snow showers (snow level 1,500 ft. rising to 2,000 ft. late at night, under 0.10 in. of rain possible) inland tonight, a (40%) chance of coastal showers Sunday, a (40%) chance of inland rain and snow showers in the afternoon (under 0.10 in. of rain possible), mostly cloudy with a (40%) chance of coastal showers and inland rain and snow showers Sunday night, AM mostly cloudy, partly cloudy Monday afternoon, then mostly cloudy with a good (50%) chance of rain Monday night highs 46-48 lows 35-32 warming to 36 Monday night. Mostly cloudy with rain likely (60%) Tuesday AM, rain and windy in the afternoon, rain Tuesday night and breezy, showers likely (60%) Wednesday through Thursday, showers likely (60%) Thursday night, then mostly cloudy with rain likely (60%) Friday highs 48-52 lows 40-42. (seasonal averages high 53 low 41).
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Forecast for the Cascades of Lane County: Mostly cloudy with snow showers (3-7 in. of snow possible) today and windy (wind: W 20-30 mph gusts to 50 mph), snow showers (1-3 in. of snow possible) tonight, snow showers likely (60%), Sunday, a good (50%) chance of snow showers Sunday night, a mix of clouds and sun with a slight (20%) chance of snow showers Monday, then just partly cloudy Monday night snow level at the surface today through Monday, then free air freezing level at the surface Monday night highs 25-28 lows 17-14 warming to near 20 Monday night. Mostly cloudy with AM snow, a good (50%) chance of rain and snow Tuesday afternoon, rain and snow Tuesday night, snow showers likely (60%) Wednesday, rain and snow showers likely (60%) Wednesday night, a good (50%) chance of snow showers Thursday, then mostly cloudy with a good (50%) chance of snow Thursday night and Friday snow level 2,500 ft. Tuesday afternoon, 3,000 ft. Tuesday night, at the surface Wednesday, 2,500 ft. Wednesday night and Thursday, at the surface Thursday night, then 3,000 ft. Friday highs 29-24 warming to near 33 Thursday lows near 20.
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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 news on-line at Eugene Daily News.com.
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