Wasatch Weather Weenies

Global temperatures have been remarkably warm over the past 12 months or so.  April numbers are not quite out yet from the National Centers for Environmental Information, so the analysis below is based on the 12-month period ending in March.  Average temperatures were 1.26°C (2.27°F) above the 20th century mean, easily the warmest such period on record.   Source: NCEI Locally, the airport also saw its warmest April–March on record with an average temperature of 56.8°F. Source: https://xmacis.rcc-acis.org/ It was a pretty good ski season, but a lot depended on elevation.  At the Salt Lake City Airport, total snowfall from November to April was only 28.3", 14th lowest since 1876 (lowest on record is 14.3" in 1934).  Mean November to April temperatures were 42.4°F, 4th highest on record (highest on record is 43.6°F in...you guessed it...1934).  It was a dream winter in many respects meteorologically.  Not a lot of snow to shovel in the valley an...

Yesterday, two skiers died tragically in an avalanche somewhere near Big Willow Cirque on Lone Peak (details still forthcoming).  This after a storm cycle in which Alta Ski Area reported 42" of snow and even the benches received substantial accumulations in some areas.  How unusual is such May snow? This is a hard question to answer concretely mainly because the available records at bench and upper elevations are spotty, inconsistent, and limited.  For bench level, I will fall back to my usual standby, the Bountiful Bench cooperative observer site, which is at an elevation of 4950 feet.  This is a bit lower than perhaps one would like, but it has continuous records back to 1975 with no missing data. First lets look at snowfall during May. This station has observed 1" or more of snow in 20 out of the 50 Mays on record, with a mximum of 27.9" in May 1975.  Impressive!  Second is 1983 with 15.6", followed by this May with 10.2", although it should be noted tha...

 It didn't take long yesterday after the front went through for precipitation to change to snow at my place (5,000 ft elevation).  The photo below was taken at 1:52 PM in the afternoon when lots of big aggregates (combinations of two or more ice crystals) were falling. Aggregates are common in warm storms because ice is "stickier" at temperatures near 0°C.   By evening the grass was covered, and by morning it looked like proper winter.  Fortunately, the roads are warm and driving to the office this morning wasn't too difficult despite the snow covered roads.   As I write this, the radar looks quite active, so I anticipate we will see snow continue along the east bench for at least a couple more hours before the valley precipitation becomes more scattered.   Meanwhile in the mountains, Alta is closed to uphill skiing. The automatic snow interval sensor at Alta-Collins has been a bit erratic for this storm period, but if I blink and throw out w...

This is a blog post that deserves all caps.  The models continue to advertise a major May storm cycle that will bring substantial snowfall to the mountains of northern Utah.  As I write this on Sunday morning, the south winds are blowing and temperatures in the Salt Lake Valley are in the 60s.   But everything is about to change.  A look at the latest observations shows northwesterly flow and colder air to our west.  Along I-80 at at Knolls it's 43°F.   The front will likely push through the Salt Lake Valley from about 9–11 AM this morning.  Precipitation will also spread across the area.  The coldest of the cold air arrives tonight.  The GFS shows unstable, northwesterly flow tomorrow morning with 700-mb tempeatures around -8°C.  In January, that would probably mean wet snow on the valley floor.  In May, it's probably down to near bench level.  Don't be surprised to see flakes late today or tomorrow.   For ...

Forecasts for late Sunday and early next week are, how shall I put it, interesting.  Both the GFS (below) and the Euro are bringing a deep upper-level trough and strong cold front into northern Utah on Sunday afternoon.   Then, in the wake of that system, there's a prolonged period of moist, northwesterly flow with a couple of weak disturbances thrown in to help juice things up.  Below is the forecast for 1500 UTC (9 AM MDT) Monday showing heavy orographic snow showers over the Wasatch.   The forecast 700-mb temperatures at that time are also about -7°C, which could drop snow levels to near the benches.   For upper Little Cottonwood, the latest GFS is going off and produces 3" of water and 35" of snow for Alta-Collins from around 11 AM Sunday through noon Tuesday.   That is, however, an upper-end forecast, topped by only a few members of the downscaled NAEFS.  the NAEFS mean is closer to 2" of water and a bit over 20" of snow. ...