The Leading Edge of Cooler Air Has Arrived

Northwesterly flow developed over the Salt Lake Valley this morning as the leading edge of cooler air began to penetrate into northern Utah.  Widespread northwesterly flow was apparent in the MesoWest surface plot just after noon.

Source: MesoWest

Sometimes cold air comes in with a bang, other times with a whimper.  This is a bit of a whimper as there wasn't a gangbuster frontal passage with a dramatic drop in temperature.  Nevertheless, the total change in temperature from yesterday to Monday is going to be quite large and around 25ºF for the valley.

By tomorrow morning, forecast 700-mb temperatures (10,000 ft) are expected to be near or below 0ºC across northern Utah.

The GFS (pictured above) is going for a 700-mb temperature of -1.3ºC for 6 am tomorrow morning at the Salt Lake City airport.  As discussed in the previous post, the lowest observed 700-mb temperature in the upper-air observing record for northern Utah in July is -1.4ºC, so we are going to be in rare territory.  It's going to be a cold night in the mountains and a refreshing night in the valley.