Wasatch Weather Weenies

It's looking like the last week of February and the first two days of March will largely be snowfree in the central Wasatch.  We have a weak cold front moving through today, but it's a dry one.  If it wasn't for the wind and the lower temperatures this afternoon, you probably wouldn't have noticed it. The Utah Snow Ensemble is flatlined until 2 March when a couple plucky members produce a little snow.  Most hold off until 0000 UTC 3 March or later.  After that, the various ensemble members are throwing spaghetti on the wall.  Some do nothing, others up to 40" of snow.  The spread in the runs is pretty consistent from 0 to 40.  Your guess is as good as mine for what's going to happen.   The reason for that spread is the highly split flow forecast to pervade over the west.  The latest Euro forecast valid 0000 UTC Monday 3 March shows the pronounced split over the eastern Pacific with one branch of the jet moving northward through Canada an...

Our recent storm cycle has pushed the mountain snowpack to about as close to median as you can get in northern Utah.  Per the latest SNOTEL observations, northern Utah basins are sitting anywhere from 90 to 107% of median snowpack water equivalent.  Source: NRCS The situation becomes grimmer over central and southern Utah, but I have cut that off in the plot above because who wants bad news these days.  We should add a bit more to the northern Utah mountain snowpack over the next few days as we're in what I'll call a "scrappy" west to northwest flow through Tuesday, meaning the mountains will squeeze out a bit of snow from time to time, and then another storm system rolls in later in the week.  As is often the case, the US GEFS ensemble is a bit wetter than the European Ensemble (ENS), but through 0000 UTC 22 February (5 PM Friday), the middle 50% of the Utah Snow Ensemble is generating 1.04–1.66" of water and 14-24" of snow for Alta-Collins.  Spread is grea...

Forecasts remain very much on track with the expectations from a couple of days ago (see An Exciting Forecast ).  For the central Wasatch and Alta-Collins specifically, the models are calling for snowfall to being today in southwesterly flow ahead of the approaching trough and continuing for the most part through Saturday afternoon when we are in the colder, post-frontal storm phase.   I wouldn't be surprised to see a break or two in the snowfall at times in there, but totals look to be impressive.  Through 11 PM MST Saturday, the GFS is coming in with 1.90" of water and 24" of snow.  The HRRR doesn't go out that far, but just through 11 PM MST Friday it's at 2.4" of water and 24" of snow, so it's quite excited about the warmer part of the storm.   Most members of the 82-member Utah Snow Ensemble are in the 1.5–3" of water and 20–40" of snow range through 0600 UTC 16 Feb (11 PM MST Saturday).   This is also a statewide storm, not some local...

I'm pretty excited about the latest forecasts as it looks like we are going to see a bonafide frontal system moving through Utah, spreading the goods around statewide.   But before jumping ahead to the storm, it's worth talking about what is going to be happening today and tomorrow.  During the day today, a cold trough will be dropping down out of the northwest and through Utah.  It will generate a little snow, mainly in the mountains and drop temperatures at all elevations.  Below is the GFS forecast valid 0000 UTC 12 February (5 PM MST Tuesday) showing the cold northwesterly flow with 700-mb temperatures of as low as -20ºC grazing the Utah-Idaho border.  My 20/20 rule is something I use to remember what the outlier 700-mb temperatures are in Salt Lake City and the northern Wasatch.  Anything above 20°C is unusually warm or below -20°C is unusually cold.  As shown in the sounding climatology below, 20ºC has historically been an upper-limit for 70...

Yesterday evening's weak disturbance tried to get us to Steenburgh Winter this season, but alas, like the Rams in Super Bowl XXXIV, we came up just short.  The obs from Alta-Collins show 5 quick inches falling, bringing the total snow depth to 99" for three hours.   Close, but not close enough. The rules of Steenburgh Winter are quite clear and strictly enforced.  If the plane of the goal line is not broken, there is no touchdown.  If there is no 100" by Feb 10, there is no Steenburgh Winter.  

Hell of a storm yesterday in Little Cottonwood Canyon with copious amounts of graupel.  Observations from the Alta-Collins site showed a storm total of 19" of snow and 2.70" of water which fell over a period of 18 hours.  Water equivalent rates remained above 0.2" per hour from 9 AM to 3 PM, above 0.37" per hour from 11 AM to 2 PM, and peaked at 0.41" from 12 to 1 PM.  The frontal structure during this event was complex, but I'd say the heaviest precipitation period was prior to and possibly during the frontal passage.   Watching the radar, it appeared that the Alpine Ridge between Little Cottwonwood Canyon was the locus for heavy precipitation development and that is confirmed by the MRMS Radar only precipitation estimate below which showed an elongated area of more than 1.25" of water and a maximum of up to 1.50" from just west of the American Fork Twin above Snowbird to Sunset Peak just east of Alta.  Source: https://mrms.nssl.noaa.gov/qvs/prod...

Below is a transcript of the letter that I sent to Utah Senator John Curtis concerning the cuts being proposed for NOAA and the National Weather Service by President Trump and DOGE.  A slightly modified version was sent to Representative Blake Moore and submitted to the Salt Lake Tribune for consideration as Public Commentary.  If enacted, these cuts will put the safety of Utahn's at risk.  Media reports suggest that the cuts being considered are 30% to the budget and 50% to personnel. There is no private sector company today ready to take on the enormous responsibility of protecting life and property in Utah from high-impact weather and cuts to the National Weather Service will weaken their ability to provide critical decisions support services to emergency managers.  If you agree (or even if you disagree and want to share an alternative opinion), please consider writing your legislative leaders.  Dear Senator Curtis: I am a Professor of Atmospheric Scienc...