Jan-soon

January 26, 2015 Matt Lammers

Couple of fun things to discuss today that only involve moderate amounts of precipitation/snowfall. Firstly, because of the oddball southeasterly flow that the Wasatch is currently sitting under, the snow at some of the resorts has been melting for essentially the last 24-48 hours. This is pretty atypical for January, but lows at places like the top of Sunnyside in Alta and Empire Peak in Deer Valley stayed well above freezing overnight last night, and high temperatures today have since risen into the mid-50s at many locations around 7-8,000 feet.

Now, as for the system coming through tomorrow through Wednesday - this is why the title is "Jan-soon." Typically, we see our winter systems coming in as troughs from the northwest, with decent southerly winds prior to the front, and cold temperatures/northwest flow afterwards. In this case, the moisture and closed-low forcing are coming directly up from the south, passing over Arizona and the Mojave Desert before driving through Nevada, and then being dragged eastward through Wyoming.

So what does this mean for us? Well, we can expect some clouds and scattered snow showers during the day on Tuesday, total snowfall during the day maxing out at just a couple of inches. Tuesday night into Wednesday mornign is when the maximum forcing and moisture appear to be sliding through, with snowfall totals overnight in the 2-4" range, although the latest models have tended to back off this. All in all, we're looking at 4-6" total in most areas, with the Bear Rivers and Cottonwoods looking to benefit the most, and Sundance and Park City likely on the low side of things. If you're interested in a nice drive, the Tetons look to be getting the brunt of this system (as they have been with most storms this year), so head up there for a better chance of fresh pow.

After this, it looks like another Jan-soon system is projected to cruise on through Thursday night into Friday, with most of the forcing and moisture remaining well to our south (Taos and Durango areas are highlighted in this system, although Brian Head might benefit a decent amount as well). The models remain highly divergent on this system, with some offering totals in the 4-8" range, while others leave us high and dry, so we have pretty low confidence even with it only being a few days out. Long term the GFS and ECMWF diverge almost entirely (with the EC looking better on the snowfall side, and GFS more on the dry side), so that's all I'll comment about that.

A note to those who might happen to use the weather.utah.edu resources for their own forecasting (we do - there are some treasures in those GRADS-generated model figures) - we recently got a hookup for some sweet Upper Cottonwood BUFR data from the new 13-km GFS, so for those of you using the meteograms from the GFS and are wondering how the accumulated precip totals got so bonkers...there's your answer. It's no longer the Uintah-satch at 37 kilometers, there is actual resolving of terrain in the GFS...take it for what it is!

Record Heat

January 25, 2015 Jeff Massey

Tomorrow won't just be warm, it will be hot.  The atmosphere will be as hot as it normally is around the middle of June!  Unfortunately most valley locations will not realize this heat since we have an inverted atmopshere right now, but the mountains will bake.  I am not sure high north will hang on to dry snow or not after this, but tomorrow your best bet for good skiing will be on sunny aspects that might even corn up.

Longing for powder?  Head east.  Ski areas in southern New England could end up with 2+ feet of blower powder by Wednesday morning.

Utah will get some snow on Tuesday, as Peter mentioned, but I am not too excited about the amonts.  I am thinking 2-5 inches for places above 6500 feet.  This precip will stream in from the south in a monsoonal surge of moisture.  Yes monsoon, that is how weird this January has been.  We will take the snow, but it might not even be enough to cover up the crusts that wll form in tomorrow's heat.

Another storm is possible Thursday night into Friday, and the big question is how far north moisture from this system gets.  Recent model runs have been trending further north, giving the cottonwoods and Park City resorts some light snow, but I will need to see a few more model cycles before I jump on board with this.  Looks like southern Utah will likely get some decent snow out of it though

Still waiting for a definitive pattern change in the long range that will snap this ugly dry spell, but not much to report yet.  Models continue to show ridging through the frist week of Feburary.  Let's hope the storms this week over produce and improve our conditions!

A Storm on the Way

January 24, 2015 Peter Veals

Alright! I am pleased to see that the models have been in reasonable agreement for a while now, so I can put some faith in what I'm seeing as far as a (modest) storm coming our way this week.

First, a brief mention of today's conditions. I got out for a great tour today in Big Cottonwood, and found pretty variable conditions...wind board in places, a sun crust on the sunnier aspects, and some recrystalized powder in the shady spots up high. Not amazing, but it was still great to be out on the big peaks though. The temps have been great for comfortable skiing lately.

As far as the forecast is concerned, I have some bad news for tomorrow before we can talk about the upcoming storm. In short, we're all going to get baked tomorrow and Monday...and I'm not talking about any products from Colorado. It's going to get really warm in the Wasatch. Near record temps in the mountains on Monday. Normally, a January warm spell like this, due to the low sun angle and radiational cooling at the snowpack surface, will not destroy the high north-facing snow. However I am worried about what looks to be a continuation of today's ridgetop clouds for tomorrow. This would very effectively radiate the atmospheric warmth down to the snowpack (a process known as "greenhousing"). I also worry that this isn't your typical January warm spell...we'll be near record territory on Monday. So, I guess we'll have a crust to deal with in most spots as we hopefully break this dry spell.

Now on to the good stuff. Tuesday evening will see some precip beginning to work into our area, and it should last through late Wednesday. It's a little early, but I'm thinking 3-7" for the upper Cottonwoods would be  reasonable, and snow levels look to be somewhere around 6,500ft for most of the event. I'll be curious to see what Jeff goes for tomorrow though, as he has thus-far outforecasted me this season.

Looking our further, the models have another storm affecting us late-week, although more precip will likely fall the further south you go from the Wasatch. Still looks like we'll get something though, and it bears watching. We'll keep you updated.

Low Confidence

January 22, 2015 Ian Glenn

Well we've had a post from Matt about our high confidence in ridiculously warm temperatures this weekend, and let me re-iterate, ridiculously warm! So now let's talk about something exciting but that we have low confidence in. The last few runs of the GFS as well as the ECMWF have included the possibility that next week there could be snow as a cut-off low to our south moves north bringing a lot of moisture to the region west of the Rockies. This is the sort of storm pattern you might expect to see in Fall or Spring, but we'll take it even though it's supposed to be the middle of winter!

On Tuesday night into mid-day Wednesday of next week, if the surge of moisture is aligned properly, it could bring up to 8" of fresh albiet warm powder to the Wasatch mountains! If it is not aligned properly, southern Utah might still get some, but it could go too far west and hit Nevada instead. I looked at an ensemble of 12 GFS runs each made with slightly different initial conditions and only one of them produced a direct hit for northern Utah. Many to most of them produce at least a little bit of precipitation. So I'm saying there's about an 8% chance right now we'll get a powder day for next Wednesday. Talk about low confidence! But there's a good chance for at least some snow so we'll update you as the direction the surge will take becomes more clear!

High Confidence

January 20, 2015 Matt Lammers

It's rare that we have really high confidence in a forecast, but we feel pretty good in thinking that there will be essentially zero precipitation in the next week. None of the models suggest anything measurable, as Northern Utah will remain under the influence of what will initially be a dry northerly flow pattern (keeping things initially cold through midweek), followed by a brief cloudy interlude on Friday, and then sun and warming through early next week underneath a beefy ridge. Sunday through Tuesday should provide ideal tanning conditions for those interested in skiing topless, or simply enjoying a post-groomer adult beverage on one of the myriad base lodge decks throughout the Wasatch.

This is what we are very confident about...so on to the more speculative, post-ridge period on the periphery of reliable forecasting. The models diverge around 7 days out, with the GFS sending a closed low up from the Baja coast through central California, dragging a swath of warm moist air up through Utah, providing the potential for a few inches of snowfall at higher elevations (>8,000 feet, maybe lower if intensity is high), and rain lower down (looking at you, Snowbasin and Sundance).

On the other hand, there's the ECMWF, which sends the same closed low farther west, off the California coast, bringing precip to the Sierras and the southern Cascades, but taking a path that does little for Utah, as the moisture tap would be blocked by the High Sierras.

Either way, this is on the limits of predictability, and the eventual result could be either a sizeable system or continued high pressure after 7 days. For now, enjoy some sweet groomers/lingering backcountry freshies! Storms will be here again!

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