Tuesday, January 22, 2013

Stirred, Not Shaken?

The big question on everyone's mind is when will we get rid of this inversion and the pollution (especially in Utah county where PM2.5 levels this morning are at 120 ug/m3, nearly 3.5 times the National Ambient Air Quality Standard).  There is a much advertised trough coming in on Thursday and it may help, but I'm not sure if it will give us complete relief.

The problem is that the trough, at least as forecast, is not very strong and brushes by to the north.  We get the tail end of the system, which brings our 700-mb (near-crest-level) temperatures down to about -6ºC and gives us some precipitation, but that's about it.

To fully mix out the cold pools that are present over most of the valleys and basins of northern Utah likely requires colder temperatures aloft and/or stronger winds.  Thus, this may be a case where the inversion is stirred, but not shaken.  We will probably see a drop in PM2.5 levels (precipitation will help with this too), but not a complete mix out.  Thanks to the precipitation, there's a chance we could get fogged in.    

Of course, inversion mixout is extremely difficult to forecast, so maybe we will do better than I expect.  If not, my advice is that you prepare a vodka martini, 3 measures of Gordon's gin, 1 measure of vodka, 1/2 measure of Kina Lillet vermouth, shake it very well until it's ice cold, pour it into a deep champagne glass, and garnish with a slice of lemon peel.


  1. Nice that you touched on this today. I greatly struggled with my 7-day this morning- went out on a limb with the thinking that some mixing would occur. Of course, mix-out would affect all the days following the event, so it makes my 7-day look drastically different. Events in the past show that with 700mb between 30-40 kt for a duration over 12hours, we usually get at least a partial clean-out in SL valley- Not so sure about the low-lands near the lake- but possible. -Grant Weyman

  2. Do you think the Sunday one will be enough to kick out inversion?

  3. Love that you've got KSL has you on speed dial Jim! Kudos to Mr Weyman for signing his name.