Wasatch Weather Weenies

It ended up being a pretty good weekend for Utah storm chasers with two tornadoes reported yesterday in the state, one at Strawberry Reservoir, the other near Snowville. There were a number of good videos of the Strawberry Reservoir tornado, including the one below. WATCH: Weak Tornado touches down at Strawberry Reservoir. No damage. No injuries. @abc4utah @StormHour @WeatherNation @UtahIsAwesome #utwx 📸: Carlena Zitting Garzarelli pic.twitter.com/rbrkvQWsQh — Alana Brophy (@AlanaBrophyNews) May 28, 2018 If desired, you could call this a waterspout, which is a tornado that forms over water or moves from land to water.  It would probably rate as an EF0 on the Enhanced Fujita Scale, with winds of 65-85 mph. I haven't seen any video of the Snowville tornado, but the NWS reported that pictures to broadcast media suggested a brief touchdown with no damage or injuries. The most impressive storm of the weekend was a mesocyclone that was observed by radar near Elko, ...

I often think that one way to alleviate pressure on the Cottonwood Canyons is to better promote the recreation opportunities that exist in other areas around Salt Lake City. With the holiday weekend upon us, we opted to hike this morning up Lookout Peak, which sits at the head of upper City Creek Canyon and is most easily accessed from Affleck Park along State Route 65. In a previous life, I had mountain biked down the hiking route after circling into it from Big Mountain Pass.  Those were the good old days, pre-Bonneville Shoreline Trail and extensive mountain biking in the Park City area, which necessitated riding all sorts of narrow trails and avoiding face plants as we descended with hard-tail bikes with about 2 inches of front-fork travel. Today we found ideal hiking conditions, with plenty of wildflowers. It's about 4 miles and 2700 vertical feet to the summit, depending on where you start.  The views today were fantastic and include vistas of Little Black Mou...

Mass exodus from northern Utah begins shortly with the annual pilgrimage to southern Utah and other environs for Memorial Day weekend.  I'm not traveling this weekend, but am taking a keen interest in the staycation forecast.  Today looks to be a hot, dry one, but a closed low lurks over California.  This closed low will drift eastward and be located over Nevada tomorrow.  Thus, tomorrow is a transition day for Utah, with cooler air spreading in from the east.  The southeast part of the state will continue with dry, warm, windy conditions, but the western half of the state should be cooler tomorrow afternoon.  Northern Utah has a slight chance of a late day shower or thunderstorm.  NAM 700-mb temperature (color contours), 500-mb geopotential height (black contours), 700-mb wind (barbs) and 3-hour accumulated precipitation (color fill) forecast valid 0000 UTC 27 May (1800 MDT 26 May) 2018. The closed low drifts slowly eastward through the Memor...

Pretty disturbing late May snowpack numbers from around the state as a super majority of SNOTEL stations are now reporting zero or near zero snowpack water equivalents. Source: NRCS In the central Wasatch, only Snowbird is reporting what I'll call "above the noise" snowpack water equivalent values with 6.2 inches.  The freefall over the past month is quite obvious if you follow the blue trace below.   Source: NRCS That gives us about a "weekish" of snow cover duration left at that site. In the western Uintas, the Trial Lake SNOTEL has maybe a day or two left with 1.0" of water equivalent on the pillow. Source: NRCS Bald Mountain Pass, which is a bit higher, looks like it still has about a footish of snow on the ground.  With effort, there's probably some skiing to be had up there, but this is a pretty meager snowpack for the approaching Memorial Day weekend.   Whose got the most? The Doc Daniel site in the Bear River Range...

See  http://www.nws.noaa.gov/os/notification/pns18-15gfs-upgrade.htm .

I'm on a short road trip to La Jolla, California where I'm visiting the Center for Western Weather and Water Extremes at the Scripps Institution of Oceanography.  There's a lot of great research happening here, so the trip has been quite invigorating.  Morning walks on the beach have been nice as well, although San Diego has been draped in "May Gray" since I got here.  Flying out of Salt Lake City late Sunday revealed some curiosities about terrain shading in Little Cottonwood Canyon.  In particular, note how the high terrain north of the canyon is casting a shadow on the north facing sidewall.  This can happen at our latitude between the spring and fall equinoxes when the sun sets north of west and is most pronounced at the summer solstice (late June).

My son and I have thought about skiing Kings Peak all season.  We figured we'd wait until the road was melted out and then give it a shot.  Then, work, weather, and other factors conspired to prevent us from doing it, until yesterday. Our plan was to do it as an overnighter, skiing in, setting up camp at about 11,000 feet, summiting, spending the night, and then skiing out on frozen snow the next morning. There were, however, two major problems with this plan.  First, there was very little snow.  Second, it was exceptionally warm. The trailhead sits at 9400 feet.  Bone dry.  That was somewhat expected since the road was open, and we naively thought we would hit snow shortly up the trail, but alas, that wasn't to be.  Instead it was 3 or 4 miles of hauling overnight packs with an additional 12-14 pounds of AT gear up the trail.  In addition, the Kings Peak trail is nearly pan flat.  So you don't get an abrupt transition from no...

It is well known that the US is lagging other forecasting centers, such as the European Center for Medium Range Weather Forecasting and the UK Meteorological Office, in global model forecast skill.  In testing now is an entirely new dynamical core for the US Global Forecast System, developed by the Geophysical Fluid Dynamics Laboratory (GFDL) and known as the Finite Volume Cubed-Sphere Dynamical Core, or FV3 for short.  See  https://www.gfdl.noaa.gov/fv3/ for gory details.  Source: https://www.gfdl.noaa.gov/fv3/ Experimental "FV3GFS" runs are now being produced by NCEP and I've started to download them to weather.utah.edu .  Look for FV3-13km (experimental) in the left hand nav bar.  For now, I'm only downloading wind and precipitation forecasts.  These should be at near-native resolution and hopefully my post-processing of the data is calculating the 3-hour precipitation correctly.  If you see anything odd, let me know. In additio...

Modern technology is disrupting many industries, including news.  Today (Monday), the Salt Lake Tribune announced it was eliminating 34 of its 90 newsroom staff .  This isn't the first time they have downsized.  It ma not be the last.  I love reading a print newspaper in the morning, but I'm one of the few diehards left in the valley.  Advertising revenue for the Trib is down 40% in two years and circulation has dropped from 85,000 to 31,000 in four years. I've witnessed massive change in regional and local science reporting during my career.  When I began as a professor 23 years ago, most reporters I interacted with were science specialists or reporters.  This was true for television as well as print.  Television suffered first.  Instead of science specialists, I mostly interact today with general reporters or camera people, the latter with a list of questions handed to them by a supervisor.  Science is complicated.  Reporting sc...

You just have to love a rainy day like this when we reach May.  Anything from here on out is a blessing and loved by all the vegetation. Not willing to give up on the ski season, however, we had a Cascadian experience in Little Cottonwood Canyon this morning.  The drive up the canyon was entertaining enough.  There are probably only a couple of days each spring where everything is green and cloud base is near the canyon mouth to give you views like those below in the lower canyon.  The Alta web cams suggested that we might break out and be in only occasional murk above 8500 feet and indeed we broke out, temporarily, at the base of Snowbird. The view from the parking lot was beautiful when we arrived, although the clouds were in and out during our tour.  Sadly, Superior is quickly losing it's white coat this spring.  As I've mentioned several times this year, the key to a good ski day is low expectations.  Ours were pretty much rock ...

It's never over until it is over.  At 1200 UTC (0600 MDT) this morning, and upper-level trough was centered just northwest of northern Utah.  Local radar shows precipitation filling in across the northern half of the state.  Most of this precipitation is still light and scattered, but there is a band of heavier precipitation across the northern Great Salt Lake and a few stronger showers scattered about. If you think it feels humid and sticky out there, that's because it is (by Utah standards).  Dewpoints at the airport this morning were near 50ºF.  Turning out attention to the mountains, it's balmy up there, with a 700-mb temperature of about +3˚C. Current surface temperatures include 39˚F at Alta Base, 36˚F at Alta-Collins, and 32˚F at the summit of Mt. Baldy (thank you Alta Ski Patrol for keeping the observations going in the off season).  That gives us a freezing level of about 11,000 feet and a snow level of perhaps 10,000 feet. The m...

If you haven't been out for a hike, run, or bike in the Avenues foothills or along the east bench, stop what you are doing and go now.  May is by far the best month for lowland adventures in northern Utah as the hills green up, but snow lingers on the mountains.  I nearly had to pinch myself yesterday when I was out for a ride on the Bonneville Shoreline Trail with a carpet of grass and wildflowers covering the lowlands and a coating of snow in the mountains (see above). How quickly the hills turn brown (or if you prefer, "golden") depends on whether or not we can continue to get the occasional storm as we approach the dog days of summer.  Let's hope the trough that will affect our weather later this week and weekend can deliver. 

If you were skiing early in the morning this past weekend, you may have noticed that the snow surface was frozen despite temperatures being above 32˚F.  Conversely, there are times when the snow surface is melting but temperatures are below 32˚F.  How can this happen? The reason is that there are several energy sources and sinks for the snowpack besides the direct exchange of heat with the atmosphere.  The direct exchange of heat with the atmosphere is known as sensible heat flux .  When the atmosphere is warmer than the snow surface, the sensible heat flux is typically positive, which by itself would yield either a warming snow surface or melting snow if the snow surface was at 32˚F, but there are other sources and sinks that can also play a role, as depicted below. Latent heat flux is produced by the exchange of moisture with the atmosphere.  If the air is dry, and ice is sublimating (or water evaporating if the snow surface consists of both water and...