Below is the 0600 GFS forecast of 500-mb heights from this 1200 UTC this morning through 0000 UTC 22 June (1800 MDT Tuesday). Pretty much a worst-case scneario for us as the ridge over central North America builds westward across the U.S. Southwest and then northward into the Intermountain West.
The forecast for Tuesday afternoon shows a core of 700-mb temperatures at or above 20ºC across southern Utah, with Salt Lake City around 18ºC.
|GFS 500-mb height and 700-mb temperature forecast valid 0000 UTC 22 June (1800 MDT Tuesday)
Such temperatures would be a record for that date and time (based on the Salt Lake City area upper-air sounding record) and near the all-time record for the month of June of 19.0ºC.
Based on what I'm seeing in the extended model forecasts, I think we have a solid shot at the hottest June on record at Salt Lake City. Although temperatures have been a bit more reasonable for the last several days, the average temperature for the first 16 days of June ranks as the 5th warmest compared to the average temperatures for all of June in the past.
|Source: NOAA Regional Climate Centers