20/20 Rule May Be Invoked

I have this simple "rule" for recognizing when the atmosphere is going into big-time outlier mode over Salt Lake City and I call it the 20/20 rule.  Situations in which the 700-mb (roughly crest level) are less than –20ºC or more than +20ºC are rare and on the outer edge of the distribution of temperatures we observe over Salt Lake City.

The latest GFS forecast suggest that we will flirt with the +20 later this week, putting the +20 contour somewhere between Provo and Salt Lake on Friday afternoon.

The record high for that day is 102ºF and if this forecast holds up we may make a run at that, possibly exceeding it if the southerly flow can get going.  This is still a 5 1/2 day forecast, so no point in getting to excited (or depressed) yet, but it appears we may be in for a scorcher.