Tuesday, January 23, 2018

The More Things Change, The More They Stay The Same

"Pattern change" is currently on my list of banned words and phrases for good reason as it was being thrown around repeatedly for weeks despite the fact that nobody really knows what it means. 

As I've been watching the large-scale pattern for the last several weeks, there has certainly been variability.  Ridges and troughs have formed and dissipated.  There have been some major cyclogenesis events.  However, one thing has remained constant.  The large-scale pattern has been very high amplitude, meaning a wavy jet, especially from the Pacific Ocean to Europe. 

That situation looks to continue for the foreseeable future.  Below is the 10-day GFS forecast for the northern hemisphere dynamic tropopause.  The dynamic tropopause separates the troposphere, or the lower atmosphere in which we all live and reside, from the stratosphere and basically sits at jet-stream level.  Note in particular the high-amplitude, wavy nature of the pattern, with strong ridges and anticyclones (high-pressure systems) forming in several areas including over the Behring Sea and North Atlantic.  Basically, the large-scale flow is highly disrupted. 

This is essentially what we have seen now for weeks.  High amplitude patterns like this can be good for snow if you are in the right place (check out the Alps), but we haven't.  The tendency in Utah has been for us to be under the influence of high-amplitude ridging or just to the south of the storm track. 

So, the more things change, the more they stay the same.  We get the occasional storm, but a real storm cycle is hard to come by.  Unless the storm track shifts southward more than currently predicted, that looks to be the case over the next seven days.  Our best bet for snow, as indicated by the NAEFS forecast plume below is Thursday and maybe Thursday night, with maybe a bit here or there thereafter. 

The NAEFS plume above may even be a bit optimistic for Thursday and Thursday night as the water equivalents advertised by the NAM, GFS, and Euro fall in the low end.  Most members of our downscaled SREF are generating only .1 to .5 inches of water equivalent.  The optimistic Canadian model (CMCE members in the plot above) appears to be an outlier. 

As usual, keep expectations low and hope for the best.  A small storm will be appreciated, but recognize that I have yet to see the whites of the eyes of a real pattern change.  However, my crystal ball only sees out about 7 to 10 days.  Let's hope February is better. 

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