wxgeek's weather-More cold and snow on the way-Update 12/29

Update Mon Dec 29

Arctic air firmly in place across most of CO today. Light snow also persists across much of the state, with heaviest snow currently along and west of the Divide and across the eastern plains. Snow amounts so far in the Urban Corridor and foothills generally in the 1-3 inch range, with a report of 5 inches in the Boulder foothills. NWS has issued a Winter Weather Advisory for much of eastern CO, mostly south of I-70 through 11 am Tuesday. NWS forecast has 5-9 inches of snow possible for our foothills, but I am not in agreement with that much snow. Currently have 2 inches on Conifer Mountain, and remaining snow through Tuesday evening is expected to be very light, so another 1/2 to 2 inches possible IMO. Mostly an arctic event, which tends to produce light snow amounts for most of eastern CO. Upper level trough currently over the northern Rockies with a small mid level circulation over southwest CO. Models forecast the upper trough to become a closed upper low and move over the Great Basin on Tuesday, then into southern NV Wednesday and over northern AZ on Thursday and into northern NM by Friday.This track is farther north than previous tracks, so now believe western CO will see some snow on Thursday, mostly south of I-70 and southern mountains likely to see snow Thursday afternoon and night. Only a few inches will be possible. Southern foothills could see some light snow Thursday, but no accumulation expected.

Temps expected to drop well below zero tonight, with lows of -5F to -15F possible in the foothills. Temps expected to remain below zero on Tuesday as light snow continues. Models begin to bring some warmer air aloft over CO by Tuesday night, so believe temps Tuesday night will not be as cold as Monday night, except in valleys where cold air drainage will keep temps very cold. Areas at higher elevations and along ridges will see slightly warmer temps Tuesday night.

By Wednesday, mostly sunny skies statewide and temps climbing back to near seasonal norms. As mentioned earlier, some snow possible Thursday south of I-70, but dry north. For the period Friday through Sunday, we should see dry conditions statewide with temps near seasonal norms.

Models now keep arctic air north of CO next week, so current forecast would be for dry conditions next Monday through Thursday, with temps climbing above seasonal norms by mid to late next week. Next chance for precip looks to be next Friday through Sunday.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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Update Sun Dec 28

Enjoy the sun and warmth today. Snow will move into the High Country today, mostly along and west of the Divide in the northern and central mountains. For the foothills, partly cloudy with breezy westerly winds at times, but otherwise a pretty nice day for late December.

Arctic front will push south through CO Monday morning. High temps for the day will be early morning, then fall steadily during the day. Upslope flow and snow will follow arctic frontal passage, with some moderate snow at times during the day on Monday. Snow will continue in the mountains and extend to most areas statewide. Winter Storm Warning in effect through 6 pm Monday for the Northern Mountains for 10-16 inches, while a Winter Weather Advisory is in effect for the central mountains through 6 pm Monday for 4-8 inches of snow. For the foothills, still thinking total snow amounts of 2-6 inches possible from Monday morning through Tuesday night. Most snow will fall Monday with 1-4 inches possible from 6 am Monday to 6 pm Monday, then light snow will persist through Tuesday night, so only another 1-2 inches from Monday night through Tuesday night. Snow and fog in the foothills will create winter driving conditions with snow and ice packed roads Monday through Wednesday morning. Travel through the mountains will also be difficult. For temps, we will start out the day Monday in the teens, but will drop below zero by Monday evening with overnight lows in the -5F to -15F range, High temps Tuesday expected to be in the -10F to 0F range, then overnight lows Tuesday night in the -15F to -5F range again. Normally outside animals may need shelter with this cold.

Temps will finally moderate Wednesday climbing back closer to seaosnal norms but still below average with mostly sunny skies. Temps expected to remain below freezing through most of the coming week, so limited melting with low sun angle. Most of CO will be dry Wednesday through Friday, with some snow across southern CO south of US 50, with best chances across the southwest mountains. Saturday also looks dry with temps near seasonal norms statewide.

By next Sunday, some snow will be possible in the mountains, and models suggest another arctic surge will move into CO Sunday night bringing snow and cold temps for the start of the work week on Monday. Longer range models suggest more snow possible towards the middle of next week with warmer temps as Pacific air begins to move into the state.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

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Sunny but cool day statewide with temps remaining well below seasonal norms. Flow aloft turns westerly and strengthens this evening into Sunday in advance of next system. Foothills and South Park could see gusty westerly winds of 15-35 mph this evening into Sunday afternoon, which may cause some blowing and drifting of recent snow.

Next system will move down from western Canada and begin to bring snow to western CO Sunday afternoon. NWS has issued a Winter Storm Warning for the northern mountains from 6 am Sunday through 6 pm Monday for 10-16 inches of snow. Winter Storm Watch has been issued for the central mountains, and this will likely become a warning as well for the same time period and similar snow amounts. For eastern CO, arctic front will push south Monday morning and bring cold temps, upslope flow and snow. Snow could become moderate at times during the day on Monday and cause roads to become slick. Snow is likely to persist across all of CO Monday and through Tuesday evening. Snow will likely become very light by Monday night, so additional accumulations on Tuesday will be very light. For the foothills, currently looks like 1-4 inches of snow possible, with majority falling between 6 am Monday and 6 pm Monday. GFS is more robust with snow, but given arctic nature, will side with the NAM and WRF that have lesser amounts. If the GFS is coorect, foothills could see higher amounts. Urban Corridor and plains likely to see from 1/2 to 3 inches of snow. Biggest impact from Monday afternoon through Wednesday morning will be cold temps. Temps in the foothills could be in the -5F to -15F range Monday night and Tuesday night. Highs expected to remain below zero. Plains will be slightly warmer, but not much, and mountains will be as cold, so not a typical arctic air mass that only affects eastern CO. Upper level system will remain west of CO, so cold air will be in place across all of CO. Monday and Tuesday will be a day to keep pets and some livestock sheltered due to extreme cold.

By Wednesday, most of CO will see warming temps and dry conditions, except for southwest CO where more snow will be possible through Thursday as upper level system tracks across AZ and NM. Only areas south of US 50 should see any snow Wednesday and Thursday.

Friday through Sunday should see dry conditions statewide as well as temps rise back near seasonal norms. Models debating about another arctic surge the following Monday, so we could see more snow and cold temps, but this is not a certainty yet. Beyond that, models have indicated a break through of Pacific mositure as upper ridge builds into Alaska. If this happens, CO could see warmer temps but significant snow, especially along and west of the Divide, which could create avalanche issues with wet Pacific snow atop dry snow. But we will have to wait and see how this unfolds.

_________________
"Climatology is what you expect, Weather is what you get".

"It is better to be roughly right than precisely wrong".

Bump for 12/28 update

Bump for 12/29 update