Hopefully everyone has enjoyed our latest summer weather during winter, but winter will make a big return beginning Monday. All models now in very good agrement on upper trough that will move down from the north and combine with western trough moving east from CA. Cold front will push south from WY on Monday morning, with snow to follow shortly after cold frontal passage with good upslope flow. Snow will begin between 6 am and 9 am most foothill areas, earlier farther north. Morning commute will begin to get slick later in the morning, but with recent warm temps, initail snow likely to melt and then create ice underneath later snow, so roads could be very slick later in the day on Monday. Snow to become heavier by Monday afternoon and evening causing Monday evening commute to be pretty bad. Snow amounts look like 4-8 inches for most foothill locations, up to 10 inches in favored areas, and 2-5 inches for the Plains. NWS has issued a Winter Weather Advisory for all of eastern CO. Snow should lighten by Monday night but continue into much of Tuesday with upslope flow, low clouds and fog. I do not expect much additional accumulation after midnight Monday through, only a half inch to an inch after that in cold arctic air.
The real impact with this system will be the arctic air mass that moves over CO late Monday through Wednesday. This is by far the coldest air of the season, and is the coldest air to affect CO in many years. Temps by Monday night will be at or below zero, and will likely remain below zero until Wednesday afternoon. Low temps Tuesday morning from -5 to -15 F, with high temps Tusday from -10 to 0. Low temps Wednesday morning from -10 to -20 with high temps Wednesday from 0 to 10. Temps finally moderate on Thursday with temps back in the 20's. Wind chill values from Monday night through Wednesday will be dangerous, with values in the -20 to -40 range, so any outside exposure will be dangerous at times. If pets are normally left outside, they may need inside shelter Tuesday and Wednesday.
Long range models indicate a more active weather pattern for us, as the upper ridge retrogrades westward into the eastern Pacific, allowing an upper trough to form over the western US and bring more storms into CO from British Columbia. Next chance for snow will be next weekend, with additional storms possibe the following week.
Too bad future generations aren't here to see all the great things we are spending their $$ on!!
