wxgeek's weather-More wind and snow-update Feb 29

Wed Feb 29

Happy Leap Day to everyone. Apparently my bbq cover celebrated last night and lept to another county. A mini break from snow and wind across the state today, but it won't last long. Upper trough currently along the west coast will move east across CO Thursday and Friday. there will be 2 distinct impulses rotating through the broad upper trough. First impulse will bring snow to western CO beginning tonight, mostly affecting northern and central mountains west of the Divide. Snow will continue into Thursday and become heavy at times over the mountains. Winter Storm Warning will be in effect from 5 pm this evening through 9 am Friday for central and northern mountains. Expect 8-16 inches of additional snow from this system which will make travel across CO difficult from tonight through Friday. Second impulse will move across CO Thursday night into Friday, and this impulse will focus activity over the southwest mountains where a Winter Storm Watch is in efefct from 9 am Thursday through 5 pm Friday for 10-20 icnhes of new snow.

For the foothills, breezy tonight in advance of upcoming system. Clouds increase Thursday morning leading to a chance for snow Thursday afternoon. Best chances will be for western foothill areas. Snow will spread slowly east into the Urban Corridor by Thursday evening and persist Thursday night. As always, snow amounts are the toughest part of the forecast. Based on recent systems, will favor the more generous model output for snow, so I think 1-4 inches will fall from Thursday afternoon into Friday morning. Snow could cause Thursday evening commute to be a little slick at higher foothill elevations, and will likely cause the Friday morning commute to be slower and slick. Second surge will bring additional snow to the foothills and Urban Corridor and Palmer Divide during the day on Friday. I currenhtly expect 2-5 inches of additional accumulation on Friday, so Friday evening commute could be slow as well. Snow should end by Friday evening. Some models are predicting little if any accumulation for the entire period, but feel this is a fairly strong system and a surface low is forecats to develop near the TX panhandle region so we should see some decent upslope flow from these systems to promote higher snow amounts.

As system moves east, another high wind event looks like a good bet Friday night into Saturday morning with wind speeds of 30-60 mph possible. This will be another Bora wind event. A Bora wind event is strong westerly winds behind a cold front. Chinoook winds are strong westerly winds ahead of a cold front, so they are drier and warmer than Bora winds, but they both feel like strong westerly winds, Bora wind events tend to have a more northwesterly flow, while Chinook winds tend to be more westerly to southwesterly.

The weekend currently looks fabulous, except for some breezy westerly winds Saturday morning til around noon. Expect mostly dry and mild temps across the state this weekend. For skiers, awesome snow conditions, but brisk westerly winds Saturday. Also, very high avalanche danger. Sunday looks to be sunny and mild. Fair weather should continue into early next week before another upper trough will bring more snow chances by Tuesday night into Wednesday, mostly for the northern and central mountains west of the Divide.

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Tue Feb 28

Well, there seems to be a trend this year. Given any chance to snow, it does, regardless of what the models think. Last year, when models thought it would snow, it didn't. More proof that Mother Nature does what she wants, and we really don't have a clue at times. Band of snow associated with cold front came through this morning and front held together much stronger than models predicted, once again. Front is now east of I-25 so any flurries should be ending soon across the foothills and Urban Corridor. Some snow will continue across the far northeast Plains into this afternoon.

Attention now turns to high winds tonight. High Wind Warning is in effect for the foothills from 9 pm tonight through 9 am Wednesday. West to northwest winds of 30-60 mph likely, with some gusts in the 60-75 mph range possible, with strongest winds north of I-70 in Boulder and Gilpin Counties. Winds should die down by late Wednesday morning, but will remain breezy the remainder of the day. Mostly dry across the state on Wednesday.

Next system from the Pacific Northwest will move into CO on Wednesday night bringing yet more snow to the northern and central mountains. Additional winter highlights will likely be issued for this next round of snow in the mountains. As the upper trough moves across CO on Thursday, a surface low is forecast to develop near the CO/OK border, which would promote a decent upslope flow for eastern CO, especially for the foothills and Palmer Divide. Currently looks like snow will become likely in the foothills and Palmer Divide by Thursday afternoon and persist into Friday morning, with flurries possible trhough Friday evening. Snow also looks likely across all of eastern CO Thursday night into Friday mroning. Right now I would guess 3-6 inches for favored foothill and Palmer Divide areas, and maybe 2-4 inches for the Urban Corridor, Plains and Banana Belt. These amounts may be adjusted from subsequent model runs on Wednesday.

It also looks like a good possibility of another Bora High Wind Event Friday night into Saturday morning. The remainder of the weekend should be mild and dry acros sthe state and into Monday. Long range models call for another system late Tuesday into Wednesday next week.
_________________
"Climatology is what you expect, Weather is what you get".

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

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Mon Feb 27

System digging along the west coast has slowed down some, so timing for incoming system to CO has slowed a bit, but track is consistent with previous forecasts. Upper level trough now along the CA coast will move into northern UT by Tuesday morning and off into western NE/SD by Tuesday evening. Surface low now over southern NV will move into northwest CO by Tuesday morning and into western NE by Tuesday evening. For today, strong southerly winds will exist over eastern CO with speeds of 20-45 mph. Winds will turn to a more southwesterly direction this afternoon and overnight but speeds will remain in the 20-45 mph range. Snow will move into the southwest mountains by this evening and across all mountains west of the Divide tonight. Southwest mountains will be favored by this system due to southwest flow aloft. Winter Storm Warning out for nearly all mountain areas west of the Divide. Southwest mountains expecting 12-24 inches between Monday evening and Tuesday evening, and 8-16 inches possible over the central and northern mountains. Snow will become heavy Monday night into Tuesday afternoon, so a difficult travel period across CO with road delays and closures possible, along with extreme avalanche danger. Cold front will move east across CO on Tuesday and may bring a chance for a brief period of light snow or flurries to the foothills and eastern Plains Tuesday afternoon into evening. Best chances actually appear to be across the far northeast Plains where 1-2 icnhes of snow possible. For the foothills, flow aloft remains westerly, so anywhere from a dusting to an inch possible, with many areas not receiving any accumulation.

As system moves east on Tuesday night, looks like we will have a good Bora Wind Event, which means strong westerly winds after a cold frontal passage. Chinook winds are pre-frontal. Currently looks like westerly winds in the 30-60 mph range Tuesday night into Wednesday morning with gusts to 70 mph possible. Strong winds will also exist across the Plains Tuesday night, but strongest winds will be along the foothills.

Wednesday still on tap for a break across the state, with winds diminishing and warmer temps.

Next Pacific system to move down from the Pacific Northwest into CO from Wednesday night into Friday. Two disctinct waves will move across CO. The first impulse will affect the northwest mountains Wednesday night and bring snow to all mountains west of the Divide on Thursday. This system will favor the northern and central mountains with another 5-10 inches of snow. This system brings a good chance for accumulating snow to the foothills and Plains Thursday evening into Friday morning. Second impulse will move across CO on Friday and reinforce snow across the mountains, foothills and Plains during the day on Friday. Currently looks like foothill areas could see 2-6 inches of snow Thursday and Friday, although still pretty early to pin down amounts. Snow should end by Friday evening, and another Bora Wind event may occur Friday night into Saturday morning.

Good news is that models are predicting a dry and mild weekend, and continue that pattern into early next week before another system if forecast to arrive by the middle of next week.
_________________
"Climatology is what you expect, Weather is what you get".

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

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Sun Feb 26

Sunny and crisp day on tap today across the state. Only a few light flurries across higher terrain of the northern mountains. Brisk winds this morning will die down this afternoon.

On Monday winds turn to a southerly direction. Southeast across the Plains and southwest in the foothills ahead of next Pacifc system. Upper trough will dig along the west coast today to near the CA/NV border area Monday morning, then track into northern UT Monday evening and into western NE by Tuesday morning. This track is consistent across most models, so good confidence in this track which will keep the surface low tracking across the CO/WY border. Snow develops in the southwest mountains Monday afternoon and becomes heavy across all mountains west of the Divide Monday night. Winter advisories and warnings will likely be in place from Monday evening through Tuesday evening for 10-24 inches in the southwest mountains, and 8-16 inches for the central and northern mountains. Travel will become very difficult across western CO Monday night into Tuesday afternoon. For the foothills, this system will be another high wind event with wind speeds in the 25-50 mph range with gusts to 60 mph Monday afternoon into Tuesday afternoon. Snow will move east to about the Front Range Crest Monday night, but I only expect to see some blow off snow or flurries across the foothills Monday night into Tuesday morning, with lmaybe a dusting to an inch or so, although many areas may not see any accumulation.

Snow continues in the mountains west of the Divide on Tuesday as upper flow turns to a more favorable northwest direction for the central and northern mountains. Just cooler and more wind for the foothills and Plains. The potential for an enhanced mountain wave on Tuesday night exists, so we could see high wind warning criteria winds Tuesday night into Wednesday morning.

Wednesday looks like a break day across the state with sunny skies and dry conditions. Next system takes aim at CO Thrusday into Friday. Upper trough will move from the Pacific Northwest across CO and bring additional snow to the central and northern mountains, and a better chance for accumulating snow to the foothills and Plains from Thursday afternoon into Friday afternoon.

Long range models then brings an upper ridge across CO next weekend with mild temps and dry conditions across 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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Tough week to be a forecaster in Colorado, at least we got the High Wind Event right. When I bust a forecast I find it interesting to look back and see where the forecast went wrong. In this case, models accurately depicted keeping the flow aloft from the northwest, which normally severely limits the amount of snow in the foothills and adjacent Plains. However, the dynamics associated with the cold front and jetstream aloft outweighed the drying northwest flow and created a situation where the Conditional Symetric Instability (CSI) created banded snowfall, mostly between the foothills and I-25 and the Palmer Divide where 4-10 inches of snow fell. Good to put these lessons in the memory bank for future reference. As my former college Synoptic Meteorology professor would tell us, "If you can be wrong and not like it, that's a good trait. If you can't handle being wrong, find a different profession". And, "all forecasts aren't necessarily bad, the timing was just off". I also try to put busted forecasts into perspective. Today, the bad forecast caused some inconvenience and maybe caused some people to have a bad day, but humans adapt well and can wake up, see more snow, and adjust. I have a friend who was a forecaster in the Special Forces, and his bad forecast cost 6 elite military personnel their lives quite a few years ago, and he still struggles with that. So as the weather never rests, time for the next forecast....

Some lingering flurries today but most activity will end by later this afternoon, and skies will clear by tonight. The foothills may see some gusty westerly winds tonight with speeds in the 20-45 mph range, so nothing like the insane winds of the past 2 days. However, with fresh snow on the ground, we could see some blowing and drifting of snow across roads tonight into early Friday morning. Friday should be a glorious day across the state with lots of sunshine and temps back to near seasonal norms. Strong winds should die down after about noon and be relatively calm.

The next Pacific system is on tap to move into CO Saturday. Clouds will increase during the day as well as strong west to southwest winds. Snow will move into the central and northern mountains late Saturday afternoon into Saturday night with an additional 3-7 inches expected. All snow should remain west of the Divide. For the foothills, winds will increase with speeds in the 25-60 mph range from Saturday afternoon into Sunday morning. Things quit down on Sunday, with winds decreasing by afternoon. Only some lingering flurries expected in the northern mountains on Sunday.

Extended range models then indicate a developing upper trough will move across CO on Monday into Tuesday. Snow will develop west of the Divide Monday and spread east during the day, with snow possible in the foothills by Monday evening. A surface low is forecast to develop near the TX panhandle, so eastern CO has the potential to see a decent upslope snow event from late Monday through Tuesday, so a system to keep an eye on. Models then bring yet another system across CO late next week with more snow possible for the mountains, foothills and Plains.
_________________
"Climatology is what you expect, Weather is what you get".

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

Bump for Feb 26 update

Bump for Monday Feb 28 update

Bump for Feb 28th update

Bump for Feb 29 update