We are still on track for what should prove to be an historic surge of cold air into northern Utah as both the NAM and GFS are bringing in an airmass for Wednesday that would produce the coldest 700-mb temperatures observed in Utah since at least 1956. The NWS is now calling for a
maximum temperature at KSLC on Wednesday of 16F.
I did some quick Hysplit trajectories this morning. These can be flaky (not sure what is going on with that one from SoCal), but show we're dealing with air originating from the Arctic and interior British Columbia (these are 84 hour backwards trajectories from 12Z Wed).
The NAM is also producing some lake effect snow through Wednesday and Wednesday night. Also, with heights this low I believe the 700-mb level is around 9,000 feet, which means -25 C at 700 mb might keeps valley temps below 10 degrees F on Wednesday if models are right.
ReplyDeleteMight *keep* temps below 10 F... sorry for the typo
ReplyDeleteChecking with the NWS records, the lowest daily maximum on record for KSLC during the month of November is 14.8 (November 15, 1955) -- that looks to be in jeopardy this week.
ReplyDeleteThe daily record max will certainly fall, I agree with Jon that the monthly record could be busted too:
ReplyDeleteRecord low max for 11/24: 22.4 F (1931)
Record low max for November: 14.8 F (11/15/1955)
Record low min on 11/24: 0 F (1931)
Record low min for November: -13.6 F (11/16/1955)
Even dry-adiabatic, the NAM's -24.1 C at 700 mb at 5PM Wed only translates to 15 F at KSLC.
That record occurred the year prior to the start of the radiosonde data we've been examining. A quick look at the NCEP/NCAR GR suggests 700-mb temps were perhaps -24C (+/- 3C as I'm eyeballing) that afternoon.
ReplyDeleteAt least if we get a lake plume it might keep us from a sub-zero "surprise" on Thanksgiving morning. A little fresh snow cover and clearing skies, and some spots around the state could easily fall below -20 F Thursday morning I suspect.
ReplyDeleteYeah, bets on minimum temperatures in Peter Sinks and Rush Valley being taken...
ReplyDeleteIt makes you wonder what kind of airmass was involved when we bottomed out at -13.6. I find it interesting that it looks like it occurred right on the heels of the record low maximum.
ReplyDelete