wxgeek's weather-Holiday Weather Outlook-Update 12/26

Update Fri Dec 26

Snow diminishing in most areas of CO, with just lingering flurries and light snow as upper trough moves across the state today. Temps will remain well below seasonal norms and skies will begin to clear this evening.

Saturday should be mostly sunny with temps remaining slightly below seaosnal norms. On Sunday, next system approaches CO. Snow will move into western CO, mostly northern mountains druing the day on Sunday with clouds increasing elsewhere. By Sunday night, arctic front and snow will move into eastern CO with upslope conditions. The bigger question with this system is how much snow fall, as arctic systems usually do not produce much snow, but this system has better upper level dynamics so has the potential for greater snowfall amounts. Snow and arctic air persists Monday across all of eastern CO with some snow into the mountains as well associated with upper level trough to the west. Models suggest snow and cold temps will persist into Tuesday evening before conditions begin to clear. Models keep atmosphere saturated up to 20,000 ft or so, thus not a typical arctic front and air mass. Heaviest snow will likely be Sunday night into Monday afternoon, with only light snow after that. Amounts at this time look to be in the 2-5 inch range for the foothills, with 1-3 inches for the Urban Corridor and plains. Mountrains may see from 2-6 inches. Temps by Monday will be single digits most areas east of the Divide with temps dropping below zero Monday night into Tuesday, so some very cold air. Temps begin to moderate some on Wednesday but will remain well below seasonal norms.

Thursday into Friday, upper level system cuts off over AZ and then moves across NM. Southern portions of CO could see some light snow or flurries, mostly south of US 50, although southern foothills could see a brief flurry, but no accumulations expected.

Next system for CO looks to be next Sunday into Monday, with another cold system bringing arctic temps and light snow. After that, models suggest upper ridge will form over Alaska, allowing Pacific air to undercut and move into the western U.S., so warmer temps with snow into western CO, but of course that could change.

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

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

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WS has issued a Winter Storm Warning for the foothills from 3 pm Thursday through Noon Friday including the Palmer Divide, with 6-14 inches of snow possible. I am not as convinced as the NWS in snow amounts for this system. WRF model has much less precip, and amounts from NAM and GFS ro me seem more in the 5-10 inch range, but the end result is that most of CO will experience a white xmas this year. Snow moves into western CO Thursday morning, and spreads into eastern CO Thursday afternoon and evening. Thinking snow starts in the foothills between 2 pm and 6 pm Thursday. Snow will persist and become moderate to heavy Thursday night, becoming light snow Friday morning but persisting most of the day Friday into Friday evening. Mountain snow amounts of 6-18 inches posisble, so difficult driving conditions across CO Thursday. Snow amounts of 4-9 inches seem likely for the foothills and Palmer Divide, with the potential for up to 12-14 inches in favored locations. For the Urban Corridor, snow amounts of 2-6 inches likely, lesser amounts farther east.

Breezy conditions will exist in the foothills tonight into Thursday morning before cold front moves south and upslope flow develops and much cooler temps. Friday will have cold temps and snow with snow ending Friday night. Could be some tough trvel conditions in the foothills and Urban Corridor by Thursday night through Friday afternoon.

Weekend looks mostly dry with temps remaining below seasonal norms and some flurries in the mountains. By Monday, next system will bring more snow to CO and some very cold arctic air. Snow amounts should be less than upcoming system, but add to snow already on the ground, maybe another 2-5 inches for mountains and 1-3 inches for the foothills. Wednesday through Friday looks mostly dry with temps near seasonal norms to begin the new year. Chance for some snow towards next weekend.

Time to go enjoy our family tradition of Dunguness Crab on xmas eve, some good wine and open presents with family. I hope everyone else enjoys time with family or friends in whatever way is enjoyable for you. The weather should not impact our travel back to CO Thursday, so all is well. Elswehere, very rainy day across mpost of the eastern U.S. today, which may impact travel in some areas.

_________________
"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 Tue Dec 23

Breezy and cool day across CO today. Strong northerly winds persist east of I-25 with winds of 25-50 mph as High Wind Warning expires at 5 pm this evening. Strong winds will diminish some in the mountains and foothills tonight.


Wednesday will be partly cloudy with temps warming back to near seasonal norms. Some gusty westerly winds will develop Wednesday afternoon east of the Divide as lee trough develops across eastern CO. Westerly winds will remain gusty into Wednesday night.

Next system will move in from the west on xmas day. Models now in good agreement that upper trough will approach CO Thursday and bring snow to western CO during the day with snow level 5000-6000 ft initially. Snow will spread east into eastern CO by Thursday afternoon and evening. Snow level lowers to plains level by Thursday afternoon. Snow likely to persist across all of CO Thursday night into Friday morning. Snow will begin to diminish by Friday afternoon. Winter Storm Watch has been issued for the High Country, likely to be upgraded to a warning. Snow amounts of 6-18 inches will be possible along and west of the Divide, so travel xmas day will be difficult across CO. Snow amounts in the foothills and Palmer Divide should be in the 2-6 inch range, with heaviest snow Thursday evening and night. For the Urban Corridor and plains, expect 1-3 inches of snow.

Weekend now looks to be mostly dry, with some light snow possible in the mountains. Temps should be near seasonal norms. These conditions should persist into Monday as well.

Next system to impact CO looks to be next week Tuesday into Wednesday as system moves down from the northwest. Very cold temps will be possible next Wednesday and New Years Day as arctic air mass moves into eastern CO.

_________________
"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 21

Happy Winter Solstice from CA to everyone. Certainly enjoying fresh seafood and time by the ocean out here with family and friends.

For CO, wintry weather will be in place from the Front Range Crest westward next 48 hours. Winter Storm Warning is in place for 1-2 feet of snow, along with west to northwest winds of 25-50 mph with gusts to 75 mph, which will create difficult to impossible travel conditions through the mountains through Tuesday morning. Snow level 7000-8000 ft today, lowering to plains level by tonight. For the foothills, mostly windy conditions with winds of 25-50 mph and gusts to 65 mph possible through Tuesday morning. For snow, only 1/2 to 2 inches expected in the foothills, with higher amounts possible in western areas. Conditions improve by Tuesday afternoon with snow diminishing and winds decreasing. Temps expected to remain below seasonal norms Tuesday, but will warm back to seasonal norms under mostly sunny skies Wednesday.

Next system has all but fizzled. Some snow possible xmas day west of the Divide, but no snow now expected for the foothills or plains. Friday and Saturday look mostly sunny statewide with temps near seasonal norms.

Next system would be Sunday into Monday as system moves down from western Canada. Models suggest we could see see several inches of snow, but not ready to bank on this yet, will see how things evolve. Longer range, models suggest upper ridge builds into the eastern Gulf of Alaska keeping Co under a cool northerly flow, with temps possible very cold next week and some periods of snow possible into New Years Day.

_________________
"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 Wed Dec 17

Mostly cloudy and cool day across the state today as upper trough brings moisture from Pacific systems into CO today and tomorrow. Models less robust with precip today, which seems more likely. Snow has developed mostly south of I-70 from the mountains into the foothills and plains this morning, and models suggest light snow will spread to most areas south of I-70 this afternoon and evening. Heaviest snow will be over the southwest and central mountains today where 3-7 inches will be possible. For the foothills, now looks like 1/2 to 2 inches possible from this afternoon into tonight, with a dusting to an inch over the plains. Snow level will be from 5000-6000 ft this afternoon, lowering to plains level by this evening. Snow should diminish after midnight, except for the mountains where snow will persist. On Thursday, partly cloudy and cool most areas, except the mountains where light snow will persist into Thursday evening. Some flurries will be possible in the foothills Thursday afternoon, but little if any accumulation expected.

For Friday and Saturday, temps should warm to near seasonal norms or slightly above under mostly sunny skies. A few flurries possible in the mountains, but no accumulation expected.

Models continue to suggest a big pattern change starting on Sunday. Upper level ridge builds off the West Coast, and a strong and moist northwest flow aloft will carry Pacific moisture into CO. Under this pattern, it is usually the northern and central mountains that are the beneficiaries of robust snowfall. Models suggest northern and central mountains will begin to see snow during the day on Sunday with snow level 7000-8000 ft. East of the Divide, strong northwest winds will buffet the foothills and plains with wind speeds in the 20-45 mph range, with gusts to 60 mph possible. Strongest winds will likely be north of I-70. Snow and wind look to persist Sunday night into Monday morning. On Monday, models suggest a cold front will push through eastern CO, which will allow snow to move east into the foothills and plains with snow level lowering to 5000-6000 ft and snow persisting into Monday night. Snowfall diminishes on Tuesday and retreats west of the Divide but temps remain cool in wake of cold front and winds diminish some. Another burst of snow from the mountains to the plains will be possible Tuesday night into Wednesday afternoon. Mountains could receive 8-18 inches from Sunday into Wednesday, with foothills receiving 1-4 inches and plains 1/2 to 2 inches for the same period.

Models have continued the trend of bringing a much more significant system into CO on xmas day. Latest runs bring an upper trough from western Canada into the northern Rockies during the day on Thursday, and move it slowly down through CO by Saturday morning. At the surface, snow would move across CO from north to south during the day on Thursday with moderate to heavy snow possible at times. Snow would persist Thursday night and all day Friday, diminishing by Saturday morning. If this system progresses as models suggest, it would be a major snow event for all of CO. Snowfall would be measured in feet. But, before anyone gets too excited (too late for me), this is still a long way in the future and models will likely change the forecast a few times between now and then. The good news is that models have been consistent with this feature for a few days now, and the GFS and ECMWF are in excellent agreement at this point, which is unusual. So the event is looking more probable, it then will depend on track and timing to determine how much snow and where it will fall. If upper trough tracks farther east, it would skirt CO and limit snowfall. Too far west and snow falls farther west. Track today would be optimum for a CO snowstorm. The bad news is that this could severely impact travel across CO and flights during a very busy travel period. Will just have to wait and see how things evolve.

Some very cold temps would filter in behind this system next Saturday and Sunday as well. Models then suggest dry and mild conditions Monday through Wednesday the following week, with next chance for precip on Thursday into Friday to start the new year.

My wife and I will be heading to CA to spend some time with family and friends for the Holidays, so I may be limited on posts through xmas, but since we will have a vested interest in returning to CO, I will be tracking the potential storm for xmas and post when possible.

_________________
"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 Tue Dec 16

Mostly cloudy and cool day across the state, with some snow showers moving across the mountains today. Snow level around 6000 ft, but only light accumulations expected today across higher terrain.

On Wednesday and Thursday, latest models a bit more bullish with precip. Pacific system will begin to bring precip to western CO Wednesday morning with snow level 5500-6500 ft. heaviest snow will be in the southwest mountains initially. Precip spreads east during the day bringing a chance for snow to the foothills and plains by Wednesday afternoon into Wednesday night. Snow level lowers to plains level by Wednesday evening. Snow begins to dissipate Thursday morning, except it will persist in the mountains. Another lesser chance for snow to move into the foothills Thursday afternoon and evening. Latest models suggest mountains could get an additional 5-12 inches of snow from Wednesday morning through Thursday night. For the foothills and Palmer Divide, models suggest snow amounts of 1-3 inches likely, with the potential for up to 5 inches in favored areas from Wednesday afternoon into Thursday morning. Urban Corridor and plains look to receive 1/2 to 2 inches. Any additional amounts on Thursday look to be light, so less than 1 inch for the foothills.

By Friday, a few lingering flurries in the mountains, dry elsewhere with temps remaining below seasonal norms. System over the weekend has fizzled, perhaps a few flurries across the High Country, but dry elsewhere with temps near seasonal norms.

Models continue to strongly suggest a major pattern change for next week. Large upper ridge is forecast to build off the CA coast, which will push Pacific storms into the Pacific Northwest, then upper trough develops in the central U.S. This puts CO under a moist northwest flow aloft as systems move from the Pacific Northwest into the central U.S. The change will begin to appear late Sunday across CO, as temps will warm and westerly winds increase with snow developing in the mountains. Snow level rises to 7000-8000 ft. This pattern will persist for Monday through Wednesday next week, with 1-3 inches of snow each day for the northern and central mountains, dry elsewhere with strong westerly winds in the foothills and temps above seasonal norms. Models then persist in bringing a strong system into CO late Wednesday night into Friday morning. Chances look pretty good for most of CO to awake to a white xmas day and temps becoming very cold by Thursday afternoon. Currently looks like this could be a significant snow event, but still too early for much confidence in this.

Models then suggest dry and cool weather next Friday into Sunday. beyond that, models have been very inconsistent, so will wait to see how things evolve.

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

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

---

Improving weather conditions across the state today. Still some lingering flurries in the mountains and wrap around snow across northeast CO moving east. Some gusty north to northwest winds across areas of CO east of the Divide should diminish through the day into tonight.

On Tuesday, clouds will increase as Pacific system impacting CA today will move east into the Great Basin and CO. Some precip west of the Divide will be possible Tuesday with snow level 6000-7000 ft. Perhaps 1-3 inches possible across higher west facing slopes, with snow ending by Tuesday evening.

Next system from the Pacific is forecast to move into the Desert Southwest Wednesday into Thursday. Areas of precip will be possible west of the Divide Wednesday with snow level 5000-6000 ft. Precip will spread east Wednesday evening to include a chance for the foothills, although amounts would remain on the light side in the foothills. Mountains could receive an additional 1-4 inches Wednesday. By Thursday morning, heavier snow will be possible over southwest CO and the central mountains with 4-10 inches possible, but again light snow will be possible Thursday afternoon and night over the foothills and adjacent plains. Snow amounts again expected to be light, with perhaps 1/2 to 2 inches possible in the foothills. Some flurries will be possible Friday in the mountains, but dry elsewhere. Temps the entire week expected to remain at or below seasonal norms.

For the weekend, GFS and Euro have some differences. GFS now moves upper trough across CO quickly with little precip. Euro takes a slower route and would bring some precip to CO, especially the mountains. My preference is the Euro solution with a few inches of snow possible in the mountains, and some light snow also possible in the foothills on Sunday.

Next week continues to look very interesting. Both models build upper ridge along the West Coast, which would allow Pacific systems to move up into the Pacific Northwest and BC then dive down across CO. Long wave upper trough position is forecast to move into the central U.S. next week, which would keep CO cold and snowy. Models bring snow across CO in a series of systems. First system brings snow next Monday into Tuesday morning, then a much stronger system moves across CO Wednesday into Thursday night. If models are accurate, which is a stretch this far out, this could provide a record snowfall for xmas day for Denver. Current record of 7.8 inches was set in 2007. There was of course the xmas eve blizzard of 1982 that deposited 24 inches of snow in Denver. The potential system would also bring some very cold temps to CO next week. Models suggest this pattern would remain in place through the end of December, so additional snow and cold temps would be likely through New Years.

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

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

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