Monday, January 1, 2018

Parade of "Synoptic Debris" Continues into 2018

The past two months have produced remarkable weather in Utah and many portions of the southwest United States. 

Remarkably bad that is, if you are a skier.

Often meteorologists use averaging to illustrate slowly evolving aspects of the upper-level pattern over long periods.  If we do this for November, one sees just a hint of a broad upper-level (500-mb) ridge over the southwest US, with westerly flow strongest just to our north across the US Pacific Northwest. 

This was a pattern in which there was an active storm track just to our north, resulting in above average precipitation in many high-elevation areas of the Pacific Northwest, but below average precipitation for northern Utah and much of the southwest. 

December's pattern was more "high amplitude" with strong ridging along the Pacific coast and deep troughing over eastern North America.
Source: ESRL
This resulted in drier conditions shifting northward into the Pacific Northwest, but "roll over" precipitation helped in portions of the Northwest interior. 

The use of average conditions often obscures important aspects of the day-to day variability.  Thus, I put together a long loop of daily dynamic tropopause (jet level) analyses covering November and December.  The one thing to take away from this is how high amplitude (i.e., "wavy") the jet-stream pattern has been across the entire Northern Hemisphere.  We see some troughs moving across the western U.S., but they are often cut-off or strung out.  I call these troughs "synoptic debris."  Sometimes they can produce some snow for us, but this is a pattern that by and large is not one favoring frequent heavy snowfalls in northern Utah.  

Which brings us to the forecast.  Basically, more synoptic debris for western North America during the first 10 days of 2018, as advertised by the GFS. 

The next four days look dry in northern Utah, and then a piece of that synoptic debris, flirts with the area.  Some ensemble members give us some precipitation in the central Wasatch (Alta-Collins depicted below), although there are some members that keep snowfall totals to a minimum. 

Basically, this is business as usual for this winter.  Keep expectations low and hope for the best.  I'm debating whether or not to bring my rock skis in for a much needed tuneup, or save the money and just keep beating the hell out of them.  


  1. I really like the northern hemisphere animations, but I have a suggestion. Most computer screens are wider than tall, but the animation including the legends on top and bottom is taller than wide. If you moved the legend, particularly the date and time, to the left side, we could enlarge the whole thing to get a better view and still have it fit on a computer screen.
    Thanks, Alan Watson (Winthrop, WA)

  2. 1976-77 was the record breaking (up to that time) snow year in Wrn NY, culminating with the late January 1977 Buffalo blizzard.

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