wxgeek's weather- weekend snow forecast

Well, the models are coming into better agreement regarding the track of our upcoming system, but the concensus is not a good thing if you were hoping for lots of snow this weekend in the foothills. System is currently along the western British Columbia coast and will move southeast today into the weekend. Models now suggest the energy will split, with the northern branch taking the majority of energy into the northern Plains and Midwest. A southern branch will dig into eastern UT and southwest CO on Sunday. This scenario will bring decent snow to the mountains of CO, but a limited amount to the foothills and Plains. Details are as follows....

Ahead of this system, strong westerly winds will slide south over CO tonight into Saturday morning. Strongest winds will be over the mountains and foothills, with wind speeds of 25-50 mph, and gusts to 65 mph possible. Westerly winds will die down after cold front passes Saturday afternoon/evening. Winds will be close to High Wind Warning criteria, so NWS may issue wind advisories later today for this event.

Cold front will push south from WY into CO Saturday. Cold front will make it south to about the I-70 corridor by 3 pm, then continue south through the state during the night. Winds behind the front will become northerly and gusty at times. Snow will move south behind front over the northern and central mountains Saturday. The problem with this system is that the strong westerly winds in advance will dry out the lower layers of the atmosphere east of the Divide. The northerly winds behind the cold front are now forecast to remain north, so not a very good upslope component, we need northeast winds for that. So the lower levels will have a hard time saturating, especially east of the foothills on Saturday night. Hence, the snow forecast now looks much less favorable. The GFS and Euro models are more favorable for snow, while the NAM and WRF are less favorable. These are pretty typical biases in the models, but it is much better to have all models onboard for snow events. All the models have some upslope in the lowest levels for eastern CO, but the depth of the upslope flow is fairly limited, up to 10,000 ft in the GFS and Euro, but only up to about 8000 ft in the NAM and WRF. The mountains will receive the brunt of this system, with snow extending east to about the foothills, then pretty dry east of there. So the farther west you go, the more snow that is likely. Snow looks to start in the foothills by late Saturday afternoon, then move south overnight and persist into Sunday late morning or early afternoon. Heaviest snow for the foothills looks to be south of I-70, and from about 10 pm Saturday to 8 am Sunday. Snow will move into south central CO on Sunday afternoon. Snow totals from Saturday afternoon into Sunday afternoon now look like this:

Northern and Central Mountains: 5-10 inches
Southwest Mountains: 3-7 inches
Foothills: 2-5 inches (heavier west and south)
Urban Corridor: 1/2 to 3 inches (heaviest west of I-25)
Eastern Plains: Trace to 2 inches

Temps will drop dramatically behind cold front passage on Saturday. Once front passes, temps will remain from 0 to 20 degrees F, with below zero reading possible Sunday night/Monday morning. Expect roads should be in decent shape Monday morning, although snow and ice definitely possible in sections with temps remaining so cold.

Extended range models keep storms moving into CO on a fairly regular basis. Next chance for snow will be Monday into Tuesday morning, although it appears nearly all of this precip will remain west of the Divide. Foothills may see a light dusting. We get a break with mostly dry conditions Tuesday and Wednesday, then a chance for more snow Thursday into Friday. This system has some potential to be a good snow maker for the foothills and Plains, but will have to wait and see how it evolves. Mountains will definitely get a good amount, but will have to wait and see how much may be possible for the foothills and Plains. Next system arrives Saturday night into Sunday, again definitely good amounts for the mountains and potential for snow in the foothills and Plains. More precip chances the following week as well. This pattern will bring regular snow to the mountains, and some snow to the foothills and Plains, with temps remaining at or below seasonal norms into the extended range. Good news for ski conditions and fire conditions across the state. Beyond December, we will have to wait and see what type of pattern sets up.
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