Thursday, February 2, 2017

Answers to Your Pressing Questions

Is Groundhog Day Stupid?


When Will This Inversion Crack?

I don't really know.  Cloud cover, precipitation, trough passages, increasing flow may all weaken it over the next couple of days, but none of these are a lead-pipe cinch to crack it once and for all.  The strength of the inversion and depth of the cold pool weakened further last night, but we're still left with smog over the valley and PM2.5 levels at unhealthy for sensitive groups level.  The coldest, densest air near the Great Salt Lake is likely to be especially stingy about departing.  It could be a long, slow process, but I go to bed each night hoping that I awake to clear air.

Do Masks Help?

My read of the literature is that it depends, so chose wisely unless you simply want to make a political statement.  Surgical masks are ineffective as they don't filter out the small 2.5 micron and smaller particles.  N95 masks are better and filter out about 95% of particles around 0.3 microns in size during testing.  They can, however, be tight fitting and pose a problem for people with some respiratory and cardiac issues.  More here.

What About the Skiing?

Our student dawn patrollers are still finding settled powder in the backcountry.  It's remarkable how long powder lasts on the northern half of the compass, even when temperatures are above 0ºC, when the humidity and sun angle are low.

That being said, we need snow, but similar to cracking the inversion, there is no lead-pipe cinch for a major dump in the mountains through the weekend.  Instead, we will see some periods of snow at times, although we're still seeing a wide range of forecasts being produced by the ensembles.  An example is the SREF, which is putting out anywhere from 0.3 to 1.4 inches of water at Alta through Sunday afternoon, with Friday night and Saturday morning offering up the highest probabilities of snow.

Let's hope we end up on the high end of those projections.  It will take a good dump at this stage to bury the crusts in sunny and wind-effected areas and cover the stiff tracks that exist elsewhere.  Professor Powder doesn't like to feel the bottom!


  1. I suggest going all the way and filtering vapors as well. What you're breathing in during the inversion isn't limited to particles. Plus, the pink helps make the political statement that much stronger.

  2. "Professor Powder doesn't like to feel the bottom" I love it! Me neither

  3. Love your blog and your book, thanks for writing. Yesterday's post included a PM2.5 chart from campus. This is interesting to me because I live near upper campus/research park. Is that data available to the public? And how do those numbers correlate with the information? Thanks!

    1. You'll have to fumble around with the graphical display option on the left hand side if you want a graph.

      The data, to my knowledge, is based on the sole real-time sensor at Hawthorne Elementary.