Wasatch Weather Weenies

Yesterday afternoon my twitter feed became populated with claims of everything from great powder to free refills in the Wasatch.  Is this really what it has come to? I know things have been really really hard this January, but buck up.  This is Utah not Colorado!  We don't get excited about snow until we hit English measurement double digits , meaning 10 inches or more.  We thumb our noses at metric measurement double digits , meaning 10 cm (4 inches), something that nobody even reached yesterday.  I'm sure the 2–3 inches of snow that fell on the Park City side improved the skiing, but you are snow snobs.  Don't stoop to such levels! A few more ensemble members and the GFS have recently shifted to pulling the storm track further south and giving us some action Tuesday and Wednesday.  Keep your fingers crossed that the low probability outcome discussed in the post from Thursday verifies.  Sometimes Mother Nature does roll snake eyes.

"And then depression set in" - John Winger, Stripes If you are trying to avoid Seasonal Affective Disorder (SAD), today's weather is not for you.  It's about as grey and drab as it can get.  Our camera peering at the Wasatch Range from the University of Utah upper campus shows thick cirrostratus clouds, but further adding to the darkness is the valley smog/haze, evident on the right side of the photo.   Source: MesoWest Here's a view looking at the Wasatch Range from the west showing the nicely layered atmosphere with the valley smog and cirrostratus deck separated by a clear layer aloft.  I guess the place to be today is somewhere in that clear layer.   Source: MesoWest

If the forecast from the 0600 UTC GFS verifies, the central Wasatch will remain sandwiched between storms to our south or storms to our north over the next week, getting just what we can from brush-by precipitation events. First we have the system moving into the southwest today and giving them precipitation through Saturday.  We are expected to be on the northern edge of this system.   Once that system moves downstream, the we get brushed by systems to our north.  Again, we're right on the edge of the action.   In situations like this, a slight shift in storm position can make a difference and I like to consult forecast ensembles to get an idea of range of possibilities.  Let's start with the Short Range Ensemble Forecast System (SREF), from which we can examine the potential for precipitation as the system affecting the southwest brushes by us the next couple of days.  There are 22 members of this ensemble, of which only 9 produce any ...

The highest elevations of Arizona, New Mexico, southern Utah, and southern Colorado will be getting some late Thursday through Saturday thanks to moisture streaming into the region from the south and east as shown in the integrated water vapor and 850-mb wind forecast for 0600 UTC 30 Jan (late Thursday). This leads to the development of wide-spread precipitation across the region. as illustrated by the forecast below for 1800 UTC (1100 MST) Friday 30 January. The northern Utah mountains are skunked in the forecast for that time and that is largely the case through the weekend, although we may see a few lingering snow showers today and then perhaps a stray snow shower or two through Friday.  Although a few inches fell in the northern Wasatch last night (the central Wasatch go the shaft), it appears we will make it through January with only one major storm.  What a pity. Those of you considering a southern road trip should keep an eye on the forecasts.  It's a com...

Yesterday afternoon's sounding from the Salt Lake City International Airport recorded a 700-mb (~10,000 ft) temperature of 7.8ºC.   This is the highest 700 mb temperature ever recorded between December 17 and March 21 and in line with what we typically observe in mid June .  I've annotated the observation on the sounding climatology below to show how anomalous the temperature is for January.  The red trace represents the highest 700-mb temperatures at each of the twice-daily sounding times during the year. Source: SPC Perhaps not surprisingly, Alta set a record high for the day of 58ºF.  This beat their previous record of 43ºF for the date by 15ºF! Source: NWS That's a huge trouncing, but the previous 43ºF record for yesterday was the lowest maximum temperature record during January (tied with Jan 3rd).  The record for the entire month of January remains 59ªF, set on January 12, 1996 and January 20, 2005 (the latter noted above).  Thus, the max ...

Consider yourself transported to a Bizzaro world, one in which the upper-level flow is from the east and you can ski in short sleeves in January. Here's the view of the Bizzaro world this morning.  The upper-level flow is what we call highly amplified, with a ridge over western North America and a deep trough over the eastern United States (Northeast skiers rejoice, dumpage is coming your way!).  There is also a closed upper-level low off of Baja California that will provide us with more Bizzaro weather in the near future. Here's this morning's sounding from the Salt Lake City airport.  Note the deep easterly flow from 800–550 mb.  It will be an unusually short flight if you are coming to Salt Lake City from Chicago today.  Temperatures increase from 0ºC at the surface to 7.2ºC at 775 mb.  At 700 mb, roughly 10,000 feet, the free atmosphere temperature was 5.2ºC. Source: University of Wyoming That's quite steamy for late January.  The grap...

Here are your four weekend updates from the Wasatch Range. 1. State of the Snow Much of the snow in the Wasatch has been affected by wind, sun, or humans, but incredibly there is some good settled powder to be had in sheltered areas on the north side of the compass despite it being almost 2 weeks since the last storm. This time of year you can really see the power of the sun as the south aspects are baking and in some cases have lost their snow, whereas you can find powder on the north aspects. 2. Warmth I noted a couple of days ago about the building ridge and the potential for very warm temperatures at 700-mb (10,000 feet) today (Sunday) and Monday.  Well, the great warmup is underway and the GFS forecast 700-mb temperature is 3.5ºC for 5 PM this afternoon and 5.8ºC for 2 PM Monday afternoon. You can kiss more of that south aspect snow goodbye. 3. The January "Monsoon Surge" Tropical moisture will be streaming into northern Utah and giving us some precipita...

There is much to be learned about future climate change by looking at the present or the past and that certainly is the case for the current water year, which began on October 1st. So far, it has been an unusually warm water year with an average temperature of 43.1ºF at the Salt Lake City airport through January 20.  Only four similar periods in the instrumented period have been warmer. One way to isolate the influence of temperature on the mountain snowpack is to examine the fraction of water year precipitation that is retained in the snowpack.  This fraction will be near 100% if most of the precipitation falls as snow and there is little loss of snow on the ground to either melting or evaporation and it will be less than 100% (possibly far less) if some of the precipitation falls as rain and is not retained in the snowpack (for example, rain that falls before snow is on the ground or falls on a snowpack that is water saturated) or if there is melting or evaporation. ...

A remarkably high amplitude upper-level pattern is setting up over the western United States, one that will bring record or near record temperatures aloft and then the possibility of an almost monsoon-like surge of tropical moisture into the southwest and eventually Utah.  Yup, we are heading into outlier mode .   The loop below shows the latest forecast from the GFS and some of the key large-scale circulation features at play.  Over the next couple of days, a high amplitude upper-level ridge develops along the west coast and progresses eastward.  Nearly concurrently, a closed low forms off the coast of the Gulf of California.  This is a result of what meteorologists call anticyclonic wave breaking and it results in a high-over-low block (a.k.a., Rex block) over the western United States.  Subsequently, the closed low draws tropical moisture northward over the Gulf of California and into the southwest U.S. in a manner that is reminiscent of monsoon surg...

Yesterday was remarkably clear and beautiful and I had the good fortune of traveling to Utah Valley University on the Frontrunner train to give a talk.  This was my first time taking the Frontrunner south from Salt Lake Station and it is a great ride, especially when you can sit there gaping at big, white mountains the entire way.  It has to be the most scenic commuter rail ride in America. Many people asked me where the inversion was.  It's such a shame that when we get a clear day this time of year we're surprised, but that's the way it is. So where was the inversion yesterday?  Too high to cause a major increase in pollution and smog.  Yesterday afternoon's sounding shows the inversion (red shaded area) way the heck up there above 700 mb and generally above all but the highest peaks.  Below the inversion, the atmosphere was fairly well mixed, so our pollution was dispersing nicely.  In addition, we had some light northwesterly flow to help ca...

If you want to ski fresh snow, you'd better call in sick and head up ASAP to enjoy the angry inch that fell in some locations last night.  After that, the odds favor a mainly dry 7-day period as illustrated by the NAEFS forecasts below which show yesterday evening's brief flurry followed mainly by flatline forecasts (i.e., no precipitation). The Canadian ensemble (CMCE) always seems to have at least one optimistic member, so you can always pin your hopes on that outlier (although I wouldn't). I recently extended the GFS forecasts graphics on weather.utah.edu from 180 to 240 hours, so in situations like this you can look even farther into the future for a powder hit.  Yeah, predictability is low at those long time horizons, but you can look anyway even though I call it "dream-prog land."  Last night's forecasts show an almost monsoon-like pattern at 186 hours out with a warm surge of moisture pushing northward into the state.  Perhaps it won't stay dr...

Model forecasts for the next 10 days are discouraging for powderhounds to say the least.  Other than the potential for dribs and drabs generated by weak systems, there's pretty much nothing in the way of potential storms for northern Utah.  Further, during the next week, a high-amplitude blocking ridge takes hold along the west coast.  It's even in the ECMWF forecast!  Source: ECMWF To illustrate how grim things are, the forecasts below are for the next week and have been derived from the North American Ensemble Forecast System (NAEFS) and downscaled for local terrain effects.  The average of the members we are using calls for under 3 inches of snow over the next week.    And the corresponding model traces for Alta shows only one member getting to 6 inches and most with no more than two inches.   Yup, the situation is nearly hopeless.  However, these are extended-range forecasts, so perhaps we can hope that we get a surpris...

I often tell people that a bad year in the Cottonwoods is better than a good year in Colorado.  There are a couple of reasons for this.  First, a bad year in the Cottonwoods is still probably 300-400" of snow (depending on location) which is more than average for much of Colorado.  Second, Colorado is a beautiful state and has a lot going for it, but it's still fun to poke fun at them from time to time!   I was thinking today as I was ski touring on a gorgeous bluebird day that this really hasn't been a great ski season by Cottonwood standards, but we still have it good compared to many other regions.  I've had some pretty good days this season and, even today, several days after the last big dump, there's still good snow to be found out there.   An old-school Wasatch ski tourer enjoys great powder and has the good sense to spoon his partner's track and conserve the hill for others that follow.  Such powder conservation is especially impor...

As discussed in an earlier post (see http://wasatchweatherweenies.blogspot.com/2015/01/upgrade-of-gfs.html), the GFS underwent a substantial upgrade on Wednesday of this week, including an increase in resolution to an effective grid spacing of about 13 km, very similar to the NAM. In addition, for the first time, NCEP is kindly providing high-resolution vertical profiles and time series from the GFS for Alta (in what is known as BUFR format). With help from Trevor Alcott, we've upgraded several of our products to take advantage of these improvements.  For example, the Little Cottonwood guidance tables, GFS time-height sections for Alta, and GFS meteograms for Alta at weather.utah.edu are now based on the high-resolution BUFR output. If you have been adjusting the old GFS precipitation forecasts to estimate precipitation at Alta (or other locations), you are probably going to need to tweak your approach some.  At least at Alta and other mountain locations, you're pr...

Source: NCDC The National Climatic Data Center released their end-of-year global analysis today concluding that 2014 was the warmest year in the instrumented record, with a globally averaged temperature 1.24ºF above the 20th century average and 0.07ºF warmer than the previous front runners 2005 and 2010 (see graph above).  You can access their full summary here .   I look at these year-to-year records or non-records as a bit of distraction as ultimately it is the long-term trend that really matters and it is clearly upward.  This upward trend is even more apparent when one takes a holistic view of the Earth's climate system (see Global Warming Hasn't Stopped ).  2014 shouldn't get too excited about this record as it won't have it for very long.  

The loop below shows how Mother Nature is putting the squeeze on us.  In the previous post we discussed how you can warm the air through subsidence or sinking motion and you can see that very well in the evolution of upper-level sounding profiles below which shows a strengthening and lowering of the inversion over the previous two days. Yesterday afternoon low clouds covered much of the Salt Lake Valley and many of the other valleys and basins of northern Utah.  Below shows the view from our mountain meteorology lab. Although dismal and grey, I was actually hoping that those clouds would hang on.  There is often a layer with good mixing beneath stratus and stratocumulus clouds of that type that is much deeper than we see during our typical inversion events.  Indeed that was the case yesterday and infact there was a deep surface based mixed layer that extended to the clouds, enabling our pollution to mix through a layer that was about 3000 feet deep.  T...

Many people think that inversions form because air in the valley cools, and this can be a mechanism for inversion formation or strengthening at night, but the primary mechanism for the formation of the persistent inversions that plague us during the winter is the warming of air aloft following an incursion of cold air at low levels.  This isolates a pool of cold air within the valley that is too dense to mix efficiently with the lower density air aloft.  Given the limited heating by the sun from November to February, we're stuck with a cold airmass that gets increasingly polluted with time. There are two major mechanisms that can contribute to the warming aloft.  The first is the horizontal transport of warm air, something that meteorologists call horizontal temperature advection . The second mechanism, which can be very important but is often under appreciated, is the sinking of air aloft.   As air sinks, its pressure increases and it is warmed by compression at...

Alta, Monday Afternoon.  Photo: Jake Hutchinson On Monday, it was almost as if Mother Nature had stored up two weeks of snow and decided to see if she could puke it out in just a few hours.  Snowfall rates were high and sustained throughout the central Wasatch.  I felt like a kid in a candy shop watching the automated snow depth sensors (about the best I can do when I can't be there).  It was quite an event, and it exceeded all meteorological expectations. I had the good fortune of not making a forecast for this event and I can tell you if I did I never would have gone for 16 inches (and 1.28" of water) in 10  8 hours (from 9 am to 5 pm) as was observed at Alta-Collins.  Official forecasts called for a 70% chance of 3-6" in the 5 am to 5 pm period, and a 30% chance of 7-9".  Note that they were calling for more after 5 PM, so overall, this was expected to be a pretty big event, but the early onset and intensity of the snowfall on Monday were n...

I don't know what kind of voodoo you people have been doing, but boy it sure looks to be working. Here's the 84-hour GFS forecast valid for 5 PM this afternoon.  The upper-level tough is overs southern Nevada and California and the northern Wasatch misses out on most of the action. Here's the 12-hour GFS forecast valid for 5 PM this afternoon.  The trough is instead along the Idaho-Nevada boarder and we are getting walloped! It's already deluging in the valley and nuking in the mountains.  Our automated sensor in Albion Basin has recorded 0.38 inches of water equivalent and about five inches of snow in the past two hours, including an increase of about four inches from 9 to 10 AM. With the start of the semester today, I'm unable to put together a proper forecast, but it looks like we're finally going to get our first big dump since Christmas week.  Check out utahskiweather.com for the gory details. And, as far as the pollution is concerned, GOOD...