Wasatch Weather Weenies

It was a very cold morning on the Wasatch Back.  How about a -24ºF at Kimball Junction, a -13ºF at the base of Park City, and a -17ºF in Thaynes Canyon 24-hour minimum temperatures for period ending at 1636 UTC 31 December 2014. Source: MesoWest. I did an interview with PCTV this morning and had quite an experience driving over Parley's Canyon just before sunrise, very near the time of minimum temperatures above.  The "always trustworthy" car thermometer showed a temperature fall of about 12ºF from Parleys Summit to the base of the Canyons as I decended into the cold pool resident within Snyderville Basin. What was most amazing were the variations in temperature at Park City Mountain Resort.  All of the observations in the plot below were collected at 1615 UTC (0915 AM MST).   At that time, skiing down the King Con trail from the top of the King Con chair to the bottom of Silverlode involved a temperature change of 28ºF from 14ºF at the top to -14ºF at the ...

One of the most dramatic temperature contrasts that I can remember exists across the central Wasatch today. Observations at sites between 9000 and 10000 feet on the Park City side include -8F at Condor (Canyons), -11 at 9990 (Canyons), -10 at Daybreak (Canyons), -9 at Summit (Park City), and -8F at Ontario (Deer Valley).  A "warm" outlier is Jupiter (Park City), which is at 10,000 ft and at -4F.  More on this in a minute. Contrast that to Little Cottonwood where Alta-Collins is 0F and Top Cecret is 0F.  In Big Cottonwood, Solitude-Apex, at an elevation of about 9000 feet, its 6ºF.  Even at the top of the Snowbird tram at 11,000 feet its -5F, warmer than the aformentioned sites at 9000 to 10000 feet on the Park City side. It would be fascinating to do a ski tour across the Park City Ridgeline today as there appears to be a fairly large temperature contrast across it.  Near as I can tell, the top of the coldest air is very near the ridgeline (~10,000 ft), w...

I am reminded this morning of the Norwegian saying, " there's no such thing as bad weather, only inappropriate dress ."  Peak gusts this morning of 77 mph in Farmington (Site AP611 @ 7:52 AM), 68 mph in Centerville (CEN @ 7:00 AM), and 60 mph at the University of Utah (WBB @ 4:35 AM).  Temperatures along much of the Wasatch Front are in the low teens or single digits.  There's great skiing to be had in the central Wasatch, but check out the temperatures in the latest MesoWest plot below.  Sub zero at nearly all locations.  The contrast between the east side and west side is most impressive.  Below -10ºF at most mid-mountain observing sites from Deer Valley to the Canyons.  In contrast, it's balmy in Little Cottonwood where temperatures are only in the minus single digits. Surface winds (barbs) and temperatures (digits) at 15:56 UTC (08:56 AM MST).  Source: MesoWest One thing you will notice in the plot above is that the winds in the central ...

Cold air pushed across the Wasatch Mountains this afternoon, initiating the development of easterly downslope winds at the University of Utah.  Temperatures have declined steadily since just after 11 am and you can see the arrival of the airmass from the east in the meteogram below as there is a sharp drop in dewpoint (green line) and increase in easterly winds.  Temperatures are now in the low 20s with winds gusting into to 28 mph.  BRRRR!!!! It looks like I'll have a long, cold wait for the bus this afternoon!

Remember a couple of weeks ago when we were skiing on manmade snow at the resorts and searching for anything we could find in the backcountry?  Well those days are officially OVER! First we had the Base-Building Concrete Deluge thanks to that juicy atmospheric river, followed by the Christmas Miracle Storm.  Then, beginning yesterday, the Return of the Greatest Snow on Earth. If I'm adding up the automated observations from Alta-Collins correctly, the storm that began yesterday morning and continues today has now laid down 20 inches of snow with an average water content of 4.2%. The skiing yesterday in the Wasatch backcountry was pretty much as good as it gets.  Low-water content snow usually looks good in pictures, but sometimes doesn't ski as well as you might think, especially if it falls on a relative hard base.  That wasn't the case yesterday as it was falling on settled snow from the Christmas Miracle Storm and it skied fantastic.  A few photos below...

This post has been updated to reflect the fact that 1917, not 1916 as originally written, was the warmest December on record. - JS Here's a meteorological oddity for you.  The day after Christmas was the first this month with a below average minimum temperature at the Salt Lake City airport.  It was also the first day this month with a below average maximum temperature. So far this month we've been on pace for back-to-back Novembers rather than a November and a December.  Indeed, the average temperature for December so far (40.7ºF) is pretty close to the long-term (30-year) average for November (40ºF).  Incredibly, December 1916  1917 was even warmer, with a month-long average of 41.9ºF. 1916  1917 will be able to sleep well knowing its record is safe.  The next few days will feel very much like December and will pull the average for the this December down considerably.

The Christmas storm was yet another where the rich (i.e., Little Cottonwood) just keep getting richer.  What kind of a Ponzi scheme is Mother Nature running this year? As summarized by the National Weather Service, here are the snow totals for the storm so far showing very nicely the contrast from Little Cottonwood to Park City: Snowbird: 24" (through 6 AM Friday) Alta-Collins: 19" (4 AM Friday) Alta UDOT: 15" (3 AM Friday) Big Cottonwood Spruces: 12" (5 AM Friday) Solitude: 9" (5 AM Friday) Brighton Crest: 13" (7 AM Friday) Canyons, 8800 ft: 12" (7 AM Friday) Park City Summit: 6" (7 AM Friday) Some of these numbers are real headscratchers for me.  Only 9" at Solitude and 6" at Park City Summit, but 12" at Canyons and 13" at Brighton?  I wish I planned on skiing today just to walk around the Park City Ridgeline to see what the heck is going on and whether or not these numbers are real or just an artifa...

I'm not one for superstition and wives' tales, but I did see a good "snow sun" with a faint halo while skinny skiing at North Fork Park this morning.   Surely that's a good omen for our Christmas Miracle storm?  The NWS has hoisted the Winter Storm Warning for the Wasatch Front and Mountains and is calling for 3-6 inches on the valley floors, 5-10 inches on the benches, and 10-20 inches in the mountains (see http://www.wrh.noaa.gov/slc/ for specifics and updates).  Hopefully tomorrow things will look like this. Photo: Tyler Cruickshank. Merry Christmas from the Wasatch Weather Weenies!

After considerable negotiations, I've been able to convince Mother Nature to allow the Snow Miser to bring snow to Salt Lake City for Christmas. Source: RankinBass Snow Miser's magic is already apparent in the latest model forecasts (surely you've heard about them already).  Below is the latest NAM bringing the Christmas miracle front across northern Utah late on Christmas eve, just in time for Santa to have a very-late-night landing on snowy roofs across the valley.  Don't let your kids get up too early. Oh, and there's a special treat for the skiers.  This is a real Utah storm that will bring a right-side-up snowfall for the entire Wasatch.  The Cottonwoods will probably come out on top as usual, especially in the later post-frontal storm stages, but even you poor, deprived souls on the Park City side should be happy with your gifts on Christmas Day.  No coal for you.  Santa has removed you from the Naughty List! And I've arranged for Santa...

Near as I can tell, nearly all the Wasatch Resorts are struggling today.  Many lifts are closed either due to wind or avalanche danger.  The Utah Avalanche Center reports some tree blowdown.  Things will be better tomorrow and the snow will still be there. We're fortunate that many of the ski areas send us observations from their weather stations.  This allows us to put events like this into perspective and it helps a lot with forecasting.  The highest reported wind gust today at the top of Snowbird was 105 mph at 9 am. That's out there in outlier territory.  My friends at MesoWest tell me that it's the highest gust they can find in their archives for Hidden Peak, although they note that there are lots of periods when we don't get data and their record goes back only to 1997.  utahweather.org reports that Hidden Peak had a 124 mph gust on November 8, 1986 .  Thus, it can blow harder, but 105 is quite a gust for this location.

There was a moment yesterday morning when snow levels were still near 7000 feet, snow was falling with a water content of 10% or so, and pictures were rolling in on my twitter feed showing some decent turns that I thought perhaps this storm won't be as bad as I thought. And then Mother Nature invoked Marshawn Lynch and went into Beast Mode . Ridge top winds started to gust over 90 miles per hour (see above), mid-elevation temperatures climbed, snow levels rose, and the snow or whatever the hell was falling at that point became thicker than Cascade Concrete.  I would call it the Nightmare Before Christmas except for one thing. I LIVE FOR THIS STUFF. Wow, what a storm.  We are currently up to a storm total of almost 3.5 inches of water at both Alta-Collins and our new observing system in upper Albion Basin.  Precipitation observations in snow are notoriously bad when it is windy, so frankly I find it quite remarkable how close these two are and that they seem fai...

As anticipated for the last few days, atmospheric river conditions have pushed into northern Utah and are bringing widespread precipitation (valley rain, mountain snow) to the northern half of the state. The large scale pattern is illustrated nicely by the 12-hour GFS forecast valid at 1200 UTC (0600 MST) this morning (sorry to use a forecast, but I have a narrow window to write this).  An upper-level ridge is parked off the U.S. West Coast with strong water vapor transport (color scale) extending inland into Utah. Source: NWS If you want to get strong water vapor transport into northern Utah, this is one of two ideal scenarios, the other being an atmospheric river that extends across Baja California and over the lower Colorado River Valley.  In both instances, the atmospheric river avoids interaction with the high, broad Sierra Nevada. Patterns like this are often called dirty ridges by meteorologists since clouds and precipitation extend well downstream of the ridg...

Although we all love beautiful, pristine snowflakes, the reality is that most snowflakes in winter storms have been abused in some way, shape, or form. If you were out today, you probably saw a few pristine snowflakes, but also plenty of defective ones.  Here are a few examples to illustrate the flake diversity.  All of these were taken with my el cheapo point-and-click camera over a period of just a few minutes.   First we have two somewhat pristine stellar dendrites.  These are Mother Nature's favorite sons as they have experienced little riming and have landed on my thigh without mechanical fracturing.   The next is lightly rimed.  You can tell it was a 6 armed snowflake at one time, but as the flake fell, it collected supercooled cloud droplets (i.e., cloud droplets that are colder than 0ºC but haven't yet frozen), which froze on contact and coated the flake to some degree.   Here's another that's moderately rimed.  The s...

The semester is over, Google Calendar tells me I have no events scheduled for today, and therefore I have some "personal matters" to attend to today (wink wink).  Thus I am providing an educational video for you that should help you to understand the highly variable nature of wintertime weather in Utah. I often tell my students that everything you need to know about weather and climate is in The Year Without a Santa Claus , from which that video is excerpted.  Yup, you get a diverse meteorological education at the University of Utah.  Models continue to look on track for a Sunday–Monday storm as discussed in the previous post.  Keep your fingers crossed.

Over the past couple of days, the medium-range forecast models have been hinting at the potential for an inland penetrating atmospheric river (AR) and a significant precipitation event for the mountains of northern Utah beginning on Sunday. We begin yesterday in the western Pacific where strong moisture convergence along a cold front east of Japan contributed to the formation of the AR, which was characterized by high integrated water vapor values (contours, with warmer colors indicating higher values). Those of you longing for powder might take a gander at the satellite image above and see numerous cloud bands extending from the coast of Asia to Japan where it has been puking powder for the better part of the past week or two.  My facebook feed from Hakuba has simultaneously invoked joy and jealousy as it's been day after day of photos like the ones below. Source: https://www.facebook.com/hakuba1 But I digress.  The loop below shows the observed and forecast...

Smog over the Salt Lake Valley this morning as viewed from the Avenues So far this year, the air quality in the Salt Lake Valley has been far better than the previous two years.  Although it is on the upper east bench and thus is a cleaner observing site compared to those on the valley floor, air quality sensors at our mountain meteorology lab near Red Butte Canyon show that PM2.5 concentrations over the past month have only briefly exceeded 30 ug/m3. Source: MesoWest Differences in the severity, frequency, and persistence of poor cool-season air quality episodes over the Salt Lake Valley aren't the result of changes in emissions, but instead meteorology.  Although we've had another dry start to the inversion season this year, we haven't had a big cold intrusion since mid November to establish a cold pool over the valley.  In addition, we've had enough weak systems come through to stir things up from time to time.  But, perhaps most importantly, we haven...

US Air Force Colonel Steve DeSordi made my day today when he sent me a photo of him reading Secrets of the Greatest Snow on Earth at the Qatari Minister of Defense's beach house on the Persian Gulf.

The world 24-hour snowfall record is 76 inches at Silver Lake, Colorado on April 14–15, 1921.  I've always been interested in this record for a few reasons.  One is that it's HUGE.  Another is that if I had a time machine, it would be one of the events I would surely target to experience, both to see the crazy snowfall records, but also to see if the record truly "holds water." Silver Lake is just east of the Continental Divide and due west of Boulder, Colorado, at an elevation of a bit over 10,000 feet (see the P thumbnail below). As is the case with many old snowfall records, the Silver Lake record has its quirks.  The veracity of the record was first examined  in a paper by J. L. H. Paulhus of the U.S. Weather Bureau (now the National Weather Service) that appeared in Monthly Weather Review in 1953 .  It turns out that the 24-hour total of 76 inches is an estimate based on the proration of a 27.5 hour accumulation of 87 inches. Source Paulhus ...

It was great to see the return today of the unofficial state bird of Utah, the stellar dendrite. They were plentiful on the landscape. Looks like a storm total of 11 inches now on the Alta–Collins stake.  However, we need more. Then again, as Dave Hanscom and Alexis Kelner say in Wasatch Tours Volume 2 , true cross-country touring is, after all, a character developing and strengthening form of recreation.

It's been a while since I took a broader look at the state of the snow across the west so I thought I'd have a look today. Based on snowpack snow-water equivalent, things are fairly grim across much of the west including Colorado, Utah, Nevada, Oregon, and Washington.  The northwest interior fares a bit better, with some mountain basins sitting closer to average.  Relative to average, the healthiest snowpacks are in western Wyoming.  The "beefiest" snowpack relative to climatology is in the Albion Mountains of southeast Idaho.  Pomerelle ski area is there, but even at 145% of average, they are only reporting a 27-33" base. Source NRCS Another perspective is provided by automated snow-depth sensors.  If you are looking for 3 feet or greater, look for upright green, blue, or purple triangles (see scale at lower left).  If you look hard, you can find a few of the green ones (37–48 inches) in the North Cascades and Northern Rockies.  There looks to...

Yesterday was one of the more frustrating days I can remember as a meteorologist.  Temperatures at the Salt Lake Airport simply refused to budge.  The meteogram below shows how the day went.  We were 55º before 11 am, and still could only top out at 57ºF.  Granted, that's still 19ºF above average, but it fell well short of my expectations. Source: MesoWest The development of fairly thick cloud cover didn't help any, but I'm still amazed that the strong flow couldn't scour out the shallow stable layer and lens of cool air that was camped over the Salt Lake Valley.  You can see both the strong flow and the shallow stable layer in the afternoon sounding below.  If we had scoured out that layer, we would have likely had a record high for the day. Source: SPC So, let's do this again today.  Once again we have everything in place.  Strong winds aloft (even stronger than yesterday is likely), a warm airmass, and an existing maximum temperatur...