wxgeek's weather-Precip in the ext forecast-Update Jan 27

Update Sun Jan 27

Surprised to see that we actually got an inch of snow yesterday, but thankful for the moisture. Southwest mountains got up to 16 inches of snow yesterday, with central mountains around 3-7 inches.

Today will be mostly sunny with a few flurries across the mountains west of the Divide. Attention then turns to next upstream system. Snow will move back into western CO tonight and become heavy west of the Divide by Monday morning. NWS has issued Winter Storm Warnings and Winter Weather Advisories for most mountain areas west of the Divide. Southwest mountains will again be the snow winners with 1-2 feet of snow expected. 8-16 inches expected across the central and northern mountains from tonight through Tuesday morning. Snow will move east during the day on Monday with snow reaching the foothills by Monday late afternoon/evening. Strong westerly winds will accompany snow in the mountains creating very difficult driving conditions on Monday into Tuesday morning. I would expect possible road closures in the usual places. Snow level will initially be 6000-7000 ft then lower to Plains level Monday night. Latest models runs develop a surface low a bit farther north Monday, so this may limit the amount of snow for our foothills and Plains. If the surface low develops north of the Palmer Divide, we don't get the upslope flow needed to enhance snow in the foothills, as the surface winds retain a westerly component that dries the air out. If the surface low develops south of the Palmer Divide, then we get the better upslope flow. Trusting the latest models, I think our snow totals will be a bit lower now. Looking at 1-4 inches for the foothills, and 1/2 to 2 inches for the Plains. Best chances for snow in the foothills looks to be Monday evening and night. Models suggest we could see another band of snow Tuesday afternoon/evening, but any additional accumulation would likely be less than an inch or two. Strong west to northwest winds will exist Tuesday into Wednesday across eastern CO, so blustry with the potential for blowing and drifting of snow.

Snow likely to continue across the northern and central mountains Wednesday and Thursday under brisk northwest flow aloft, while the foothills and Plains will remain dry. All of CO will dry out anmd warm up Friday into next weekend. Longer rangfe models debating if any precip will show up the following week. Models vascilating with precip early the following week, but fairly consistent in bringing precip into CO late the following week.
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"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 Fri Jan 25

Pleasant day across the state today. Sub-Tropical upper trough currently off the Baja coast is bringing rain to SoCal, and precip will spread into AZ later today and tonight, and into southwest CO late tonight into Saturday. Some heavy rain expected across AZ, that may cause some flash flooding potential on Saturday. For CO, precip moves into southwest mountains tonight and early Saturday, and spreads to all of western CO during the day on Saturday. Snow level expected to be 8000-9000 ft tonight and Saturday, lowering to 7000-8000 ft Saturday night. Currently a winter storm warning for the southwest mountains for 8-16 ibches of snow, and a winter weather advisory for the central mountains for 5-10 inches of snow. These run from 5 am Saturday through 5 pm Sunday. Snow will be more spring like, i.e. wet and heavy. Models bring some light precip east to the foothills and adjacent Plains Saturday afternoon/evening, but not sure how much of this will reach the ground with low levels east of the Divide very dry still. We could see some light precip or showers, with snow level 8500-9500 ft, but no accumulation expected east of the Divide. Travel across higher passes west of the Divide on Saturday could become difficult.

We will see a break on Sunday, with only some lingering mountain flurries west of the Divide with snow level 7000-8000 ft.

Then on to the next system. Models in better agreement today, although still some differences, but that is to be expected. General trend is for the upper trough to move into the Great Basin on Monday then across the Rockies on Tuesday. Still not sure how much upslope flow will develop across eastern CO, but for now will assume some. Hence, snow should move into western CO Sunday night into Monday. Snow level should remain in the 6000-7000 ft level during this time. Some heavy snow is possible Monday across the southwest and central mountains. Snow will move east Monday night into Tuesday across all of eastern CO, with snow level down to plains level. Snow should end by Wednesday morning across eastern CO, but some flurries may linger through the remainder of next week west of the Divide under a moist northwest flow aloft.

For snow amounts, looks like big amounts in the mountains, with 10-20 inches possible acros the southwest and central mountains, and 8-16 inches for the northern mountains from Sunday night into Wednesday. For eastern CO, latest model output has 3-6 inches possible for the foothills and 1-4 inches for the plains from Monday night into Wednesday morning. Models still evolving on this system, so forecast likely to still change. If the system develops a stronger surface low to our south, more upslope and potential for higher snow amounts. If the low develops to our north, then lighter amounts.

Either way, expect colder temps all of next week with the chance for snow in our foothills Monday through Wednesday, which we desperately need.
_________________
"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 Thu Jan 24

Weak system moving across CO today. Precip will be confined to areas west of the Divide where a few inches of snow may fall across west facing slopes. Precip should dissipate this evening. For the foothills and Plains today, dry and windy at times creating increased fire danger as RH values below 10% many areas, hence Red Flag Warning was issued by NWS for the foothills between 6000-9000 ft through 5 pm Thursday.

For Friday, the day will start off nice, but we will see mid and high clouds associated with a sub-tropical upper low increase during the day. Pretty mild temps across the state expected. Precip from this system will move into southwest CO Friday afternoon and night. Snow level will remain high with this system due to the sub-tropical incluence, so expect snow level to be in the 8000-9000 ft range Friday into Saturday. Precip will spread across all of western CO Saturday and presist into Saturday night. Currently expect nearly all precip to remain west of the Divide, with only very isolated showers possible in the foothills Saturday. Some precip is possible across southern CO south of US 50 on Saturday as well. Southwest mountains above 9000 ft could see 5-10 inches of snow from this system, with 2-5 inches possible elsewhere west of the Divide above 9000 ft.

Then we discuss the next system. Models appear to be completely baffled by this next system, with drastic run to run differences, and the GFS and Euro now in vast disagreement. Latest Euro run forms a cutoff low over CA and brings no precip to CO, while the GFS has remained a little more consistent in bringing an upper trough through CO next Monday/Tuesday. Despite the Euro being the better medium range model, will go with the GFS solution for now as it has been overall more consistent and it is in line with other models such as the NAM, Canadian and UK Met Office. However, even latest runs of the GFS limit the amount of snow we can expect east of the Divide, as the surface low is now forecast to form over northeast CO versus southeast CO, so very little upslope. The mountains west of the Divide still look posed to receive a fair amount of snow, with snow levels lower. Based on the GFS, current forecast would have precip moving into western CO Sunday with snow level initially 7000-8000 ft. SNow expected to become heavier Sunday night into Monday with snow level lowering to valley floors over western CO. Cold front will move through the foothills Monday afternoon, so some light snow is possible as front moves trhough and right after. Snow likely to persist into Tuesday across western CO with some flurries possible east of the Divide. For the mountains west of the Divide, looks like another 6-12 inches possible with this system, with higher amounts possible. For the foothills, currently looks like somewhere between 1/2 inch and 2 inches, with most areas seeing amounts closer to the lower end of this range.

Since models are struggling so much with this system, forecast confidence is pretty low, and I expect forecast will change between now and this weekend.

Longer range forecast looks like temps cool down closer to seasonal norms for most of next week, with some mountain snow possible under brisk northwest flow aloft.
_________________
"Climatology is what you expect, Weather is what you get".

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

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Mountain Wave clouds limiting sunshine to much of the Front Range today, so temps not as warm in cloudy areas as expected. Temps still well above seasonal norms, but records probably not in danger.

Cold front still expected to cool temps for Thursday, and bring some light snow to the mountains west of the Divide, and mostly north of I-70, with maybe 1-2 inches possible.

A cutoff low that has formed off the Baja coast is forecast by models to move across CO Friday into Saturday. This will bring an influx of sub-tropical clouds into CO on Friday, and bring a chance for precipitation by Friday afternoon across western CO. Snow level will be quite high for this time of year due to the sub-tropical influence, with initial snow level 8000-9000 ft on Friday. Clouds and precip move east on Saturday, although precip remains mostly west of the Divide with snow level 7500-8500 ft. Southwest mountains should get the brunt of this system, with maybe 4-8 inches possible, and 2-5 inches possible for other mountain areas. Some showers will be possible Saturday east of the Divide, mostly across the foothills, with snow level 8500-9500 ft, and no accumulation expected.

Attention then turns to our next stronger system. Models in decent agreement that an upper trough will move across the west coast Sunday, into the Great Basin on Monday, and across the central and southern Rockies on Tuesday. Precip expected to move into western CO on Sunday, with snow level 6500-7500 ft. Precip moves east to about the foothills on Monday afternoon with snow level lowering to 5000-6000 ft. Models disagree somewhat on the upslope component available from Monday afternoon into Tuesday evening. GFS has the strongest upslope and hence the most snow for eastern CO, while the Euro has less upslope and snow. At this time I would go for good chances for snow for the foothills and Plains Monday night into Tuesday afternoon, but fairly light amounts, say maybe 1-3 inches at this time. Mountains could see a foot or more of snow from this system. If the system develops a good upslope flow like the GFS contends, we could see substantially more snow in the foothills, but will have to wait and see future model runs to determine that. The trough could also take most of the energy north of us and we could see very little snow in the foothills. It will definitely be colder early next week as compared to this week.

Longer range models then build an upper ridge back across the western US next week and beyond, so looks like February will start off dry and mild across CO.
_________________
"Climatology is what you expect, Weather is what you get".

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

Bump for Jan 24 update

Bump for Jan 25 update

Bump for Sunday Jan 27 Update