More Snow Chances This Week
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Author:  wxgeek [ Feb 11, 2018 3:56 pm ]
Post subject:  More Snow Chances This Week

Pretty nice day across the state today in the wake of our first measurable snow in a while. Temps close to seasonal norms today.

On Monday, upper level trough will dig south into the Great Basin from the Gulf of Alaska and create a diffluent southwest flow aloft over CO. Precip will move into western o Monday morning and move eats to about the Front Range Crest during the afternoon, with snow level near 6000 ft. Foothills may see some brief light snow Monday afternoon, but not much beyond a dusting to a half inch is currently expected. Mountain areas could see 5-10 inches of snow, with a foot or more over the southwest mountains through Tuesday morning. Precip should diminish Monday night across the state and end by Tuesday morning.

Tuesday and Wednesday look mostly dry and mild statewide. Some clouds may begin to move into the state by Wednesday afternoon as temps should be above average each day.

Latest models have a new twist to our forecast later in the week. Upper level low still expected to form off the central CA coast Tuesday, but latest models now have another system moving down from the Pacific Northwest on Wednesday, that will "pick up" the upper low off the CA coast and a combined upper level trough will move across CO on Thursday. Precip is now forecast to move into western CO Wednesday night with snow level near 6000 ft, and then a cold front will push south across CO during the day on Thursday and precip will spread across eastern CO during the day on Thursday into Friday morning. Current models suggest foothill areas could see 3-7 inches of snow from this system, with an additional 6-12 in the mountains, and 2-5 inches for the Urban Corridor and plains. Because this is a recent development, not very high confidence as models could change their handling of this situation in coming days.

Upcoming weekend weather currently looks nice, mostly sunny with temps near average. For next week, models handle things very differently, so not a good consensus at this time. GFS brings upper level trough to our north early next week with cooler temps and some snow Monday into Tuesday. ECMWF meanwhile digs the upper trough down the West Coast keeping the majority of energy far to our west, so only some light snow across western CO Monday and Tuesday, but potentially more snow when the system ejects across CO later in the week. Hard to tell which solution is correct at this time, but as usual I prefer the ECMWF for this time range.

Author:  wxgeek [ Feb 12, 2018 2:38 pm ]
Post subject:  Re: More Snow Chances This Week

Cloudy and cool day across the state today. Low clouds and fog across eastern CO with snow moving into western CO along and west of the Divide with snow level near 6000 ft. Snow will intensify this afternoon into tonight from the Front Range crest westward and finally diminish Tuesday morning as snow level lowers to near 4000 ft by Tuesday morning. For our foothills, we may see a dusting to a half inch from this afternoon through Tuesday morning, but not much more expected. Farther west, mountains will see substantial snow. Central and Northern mountains will see 6-12 inches, while southwest mountains could see 8-16 inches. Just a few lingering flurries in the mountains on Tuesday, while eastern Co will see mostly sunny skies and temps that will rise above average. Wednesday looks dry statewide with temps a tad above average.

Next system will move into CO Wednesday night into Thursday morning along and west of the Divide with snow level 5000-6000 ft. Models differ on snow amounts with this system, with the American models much drier than the European model which phases the northern and southern systems better and advects a lot of sub-tropical moisture up into CO. Will have to see how they evolve as the GFS would bring less than an inch of snow into our foothills Thursday while the ECMWF brings 3-7 inches. Mountains again will receive 5-10 inches of snow from Wednesday night into Thursday evening.

Friday and Saturday look dry statewide. Temps Friday will be on the cool side of average while rising above average on Saturday.

Models maintain some big difference son next system from the Gulf of Alaska for early next week. GFS keeps a faster track and more inland, while the ECMWF is slower and keeps the system farther west. GFS would bring snow into much of CO by Sunday afternoon and would persist snow and cold temps through Tuesday morning. ECMWF would bring snow into western CO Monday morning and would keep snow going through Wednesday morning. Either way this evolves, expect much cooler temps and some snow early next week, just a matter of how much. Mountains look to receive substantial snow, while eastern CO may see some snow with GFS being snowier than the ECMWF. Models hopefully begin to converge later this week.

Wednesday looks mostly dry next week, then GFS brings another system from the Gulf of Alaska into CO with more snow and cold temps to Thursday into Friday next week, while the ECMWF is dry for CO late next week.

Author:  wxgeek [ Feb 14, 2018 1:14 pm ]
Post subject:  Re: More Snow Chances This Week

Story today for much of CO will be the strong southwest winds, especially over the mountains and foothills along with warm temps due to katabatic winds. As two upper level troughs approach the state today, southwest winds will increase with speeds of 30-60 mph and higher gusts which will persist into Thursday morning. Aloft, upper level trough will kick out from off the SoCal coast and upper level trough racing down from the Pacific Northwest will combine over CO tonight into Thursday evening. First wave of precip will move into western CO this evening into tonight and remain mostly along and west of the Divide with snow level near 7000-8000 ft. Precip will intensify Thursday morning as northern upper trough gets closer and brings snow lvele down to 5000-6000 ft as precip will remain along and west of the Front Range Crest during the day on Thursday. During this time mountains will receive significant snowfall combined with 30-60 mph winds to create whiteout conditions and make travel through the mountains difficult to impossible. For our foothills, winds will remain strong during the day on Thursday, and snow will be confined to western sections with mostly blow off snow. It will not be until Thursday afternoon/evening until cold front moves south across eastern CO that foothills will see any accumulating snow. From about 4 pm through 10 pm foothills and eastern CO may see a trace to 2 inches of snow as snow level lowers below 4000 ft. Areas like the Palmer Divide may see heaviest snow as winds turn to northwesterly. In the mountains, Winter Storm Warning will be in effect from this evening through Thursday evening for 6-18 inches of new snow. Snow should finally wind down Thursday night with clearing by Friday morning.

Friday should be mostly sunny with temps near average statewide. Weekend weather also looks dry statewide with temps near to slightly above average.

Models beginning to come into better agreement on weather for next week. Deep upper level trough will move down from the Gulf Of Alaska to the Pacific Northwest on Sunday and into the Great Basin on Monday and across CO on Tuesday. Snow will move into western CO Sunday night into Monday morning and spread into eastern CO Monday evening into Tuesday night. This system will contain cold air so an all snow event that could produce significant amounts in the mountains and portions of eastern CO including our foothills. Snow should end Tuesday night with clearing on Wednesday. Current models suggest mountains could see an additional 6-18 inches, with 6-12 inches in the foothills, and 3-8 inches over the Urban Corridor and plains. Temps will be well below average Monday and Tuesday.

The period Wednesday through Saturday looks dry next week statewide as temps remain below average. Precip chances return next Saturday, and then again early the following week as upper level pattern change remains in effect with upper ridge much farther west in the Pacific, which allows storms to move down into the Western U.S. and across CO.

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