Wednesday, March 22, 2017

A Juicy Late March Airmass

Well, it's a juicy one out there this morning.  The meteogram from the Salt Lake City airport shows and abrupt 5ºF drop in temperature and 9ºF rise in dewpoint just before midnight MDT as the flow shifted to NW-N with the passage of a modest cold front.

Source: MesoWest
Source: MesoWest
Dewpoints increased further to the high 40s by about 6 AM and as I write this are lingering around 45ºF.  For the most part, a dewpoint in the high 40s doesn't get much attention, but for us, they are the highest observed in the past 30 days (see blue line below) and possibly much longer than that (MesoWest only provides point-and-click access to the past 30 days).

Source: MesoWest
Thus, my skin and lungs greatly appreciated the pulse of moisture I felt when I went out for the paper at 6 AM.

Although we've cooled off some, temperatures remain above average for a morning in March in both the valleys and the mountains.  In the case of the latter, at 7 AM it was 36ºF at the base of Alta and 33ºF at Alta-Collins (9700 feet).  Alta-Collins picked up 4" of snow last night with 0.81" of water.  It may have started out as rain at that elevation, but I suspect most of the 0.81" fell as snow, so we're talking thick, creamy stuff.  It's tough to say from the web cams, but it appears most of the precipitation below about 9000 feet fell in the form of rain overnight.  What a waste of water!

On my way to the bus at about 7 AM, I saw a number of flashes of lightning over the Wasatch.  Indeed, flashes were detected this morning around the Bear River Migratory Bird Refuge, the south Salt Lake Valley, the Cottonwoods, and Parley's Canyon (see filled circles below).

What you see is what you get and for the rest of the day today, scattered showers and thunderstorms are on tap.  Snow levels will remain high and probably around 8000-9000 feet, but may temporarily drop in heavier precipitation.  

Right now it looks like a pretty good deluge tonight and tomorrow as the main trough comes through, with snow levels mercifully lowering tonight and reaching near bench level by about 8 am tomorrow morning.  This sounds crazy, but the skiing might actually be good tomorrow at upper elevations.  The average water content of the snow will be high, but that will help bury the spring snow, and it should be right-side up.  


  1. FYI, the SPC has a marginal risk of severe storms for Utah today.