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Here is this week’s weather quiz question. What is a “Radiosonde” used for in weather forecasting? Extra credit points if you can tell me what new technology is replacing radiosondes. Please post your answer as a comment after the forecasts on this page. The first person to post the correct answer will win a week of free personalized weather forecasts tailored to your needs. Good luck.

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The upper air flow (yellow jet stream and dark colors for winds) shows a  trough of low pressure swinging down from the Gulf of Alaska (“U” shape offshore) which is pushing a new frontal system our way.  More storms will be coming at us including this frontal system that will come in for Christmas Day. Not much of a chance of a “White Christmas” in the valleys because it will be too warm. Our best chance of valley snows usually comes in January and February.

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Advisories: A WINTER WEATHER ADVISORY IS IN EFFECT UNTIL NOON TODAY FOR THE WESTERN COLUMBIA RIVER GORGE.

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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 likely (60%) this AM, scattered afternoon showers (0.10 in. of rain possible), partly cloudy this evening, mostly cloudy with a slight (20%) chance of rain tonight,  a (40%) chance of rain Thursday AM, a slight (20%) chance of rain Thursday afternoon (0.10 in. of rain possible) and Thursday night  highs 45-47 lows 33-39. Mostly cloudy with a  good (50%) chance of rain Friday (Christmas Eve), rain likely (60%) Friday night, rain Saturday (Christmas Day), then rain Saturday night through Tuesday highs 48-44 lows 37-40. (seasonal averages highs 45 low 33)

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Forecast for the Umpqua Basin including, Roseburg:  Mostly cloudy with rain likely (60%) this  AM, a (30%) chance of rain this afternoon (snow level 2,500 ft. rising to 3,000 ft,), a slight (20%) chance of showers tonight, cloudy with a  good (50%) chance of rain and snow showers Thursday AM, cloudy with a good (50%) chance of showers in the afternoon (snow level 2,000 ft. rising to 3,500 ft.), a slight (20%) chance of showers Thursday night (snow level 3,500 ft.) highs 47-50 lows 35-39. Cloudy with a good (50%) chance of showers Friday, rain likely (60%) Friday night (Christmas Eve), rain Saturday (Christmas Day), then rain Saturday night through Sunday evening, rain and snow showers Sunday night, then rain and snow showers likely (60%) Monday through Tuesday highs 50-45 lows 42-35. (seasonal averages high 48 low 34)

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Forecast for the South Oregon Coast including Coos Bay and North Bend: Mostly cloudy with with AM rain likely (60%), a good (50%) chance of showers this afternoon, cloudy with a  (40%) chance of showers tonight, a good (50%) chance of showers Thursday and breezy (wind: S 20-30 mph at the shore and S 10-20 mph inland, gusts to 40 mph increasing to 50 mph in the afternoon), a (40%) chance of showers Thursday night and  breezy (winds: S 20-30 at the shore and S 15-20 mph inland, gusts 50 mph decreasing to 40 mph late at night) highs 49-55 lows 39-45. Showers likely (60%) Friday and breezy, rain Friday night (Christmas Eve), rain Saturday (Christmas Day), rain and breezy Saturday night and Sunday, evening rain then showers late Sunday night and breezy, showers likely (60%) and breezy Monday, then showers likely (60%) Monday night and Tuesday highs 55-49 lows 46-39. (seasonal averages high 52 lows 39).

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Forecast for the Cascades of Lane County: Mostly cloudy with snow likely (60%) this  AM, rain and snow showers in the afternoon (1-3 in. of snow possible), mostly cloudy with a (30%) chance of rain and snow tonight, a (40%) chance of rain and snow Thursday and Thursday night snow 3,000 ft. today through Thursday, and 4,500 ft. to 3,500 ft. Thursday night highs 35-32 lows 24-28. Mostly cloudy with a good (50%) chance of rain or snow Friday and rain likely (60%) Friday night (Christmas Eve), rain likely (60%) Saturday (Christmas Day), rain and snow Saturday night and Sunday, then snow Sunday night through Tuesday snow level 5,000 ft. Friday, 6,500 ft. Friday night, 5,500 ft. Saturday and Saturday night, 4,000 ft. Sunday and 3,000 ft. Sunday night,  and 2,500 ft. Monday highs 38-30 lows between 29-23.

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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.