"Hotter than Hell"

I heard a Catholic priest say in downtown Salt Lake City this weekend that the weather is "Hotter than Hell."  Who am I to argue with a man of the cloth?

That said, let's take a quick look at the data and forecast as we approach the end of July.

The month actually started out with four days with minimum temperatures between 62 and 66 at the Salt Lake City International Airport.  And believe it or not on July 22nd, we actually had a maximum of only 87°F.  Other than thoat, it's been hot.  Since July 4th, every day but one has had a minimum temperature at or above 70°F and there have been nine days with a maximum temperature at or above 100°F, including the all-time record high of 109°F on July 12th.  

For the first 25 days of the month, the mean temperature at the Salt Lake City International Airport was 85.3°F.  This is not a record, but it is 4th all-time in the Salt Lake City area and 4.2°F higher than any equivalent period in the 20th century.  If you are wondering, the 20th century record is 81.1°F in 1985.  

The period also rates as the 4th warmest at the Bountiful Bench observing site with a mean temperature of 81.4°F, which is 3.1°F higher than any equivalent period in the 20th century.  There the 20th century record is 78.3°F in 1988.  

July is a month with less weather variability in Utah than we see in winter. On average, as shown in the mean 500-mb height analysis below, there is a mean 500-mb ridge to our east, with the axis centered over Colorado and Wyoming.  This results in the mid-latitude storm track being to our north.  Sometimes a midlatitude system can sneak in here, but it happens less frequently than in winter.  Instead, our weather is controlled more by variations in the strength and position of the ridge, which is a component of what is known as the North American Monsoon System. 

Source: https://psl.noaa.gov/cgi-bin/data/composites/printpage.pl

The forecast for the evolution of that ridge over the next several days does look hell like.  Below is the GFS forecast valid this afternoon [0000 UTC 28 January (1800 MST Tuesday)].  The 500-mb ridge (upper left panel) is centered to our east in northeast New Mexico.  Over northern Utah, the 700-mb temperatures (lower left panel), which are roughly at 10,000 feet or crest level, are around 18°C, which is quite high, but not record setting. 

That ridge though is expected to move slowly westward over the next few days and by 0000 UTC 2 August (1800 MDT Saturday) it is forecast to be parked over Utah.  The 500-mb heights are above 6000 meters, which is a value that typically draws the attention of meteorologists.  Forecast 700-mb temperature are exceptionally high and over 22°C in northern Utah.  In fact, at 6 PM on Saturday they are forecast to be 21.6°C, which would be more than 1°C higher than observed in the upper-air sounding record from the airport. 

The ridge in the ECMWF HRES is also parked over Utah, but not quite as strong.  That said, the 700-mb temperatures are also over 20°C in northern Utah and 22°C in portions of southern and central Utah. 

So, there is no rest for the wicked controlling the weather this week.  Lows at the airport will remain in the mid 70s or higher.  Maximum temperatures will be near or above 100.  If we're lucky, we'll get a thunderstorm, although the likelihood of that will be declining later in the week as the ridge moves overhead.  Temperatures will climb later in the week.  It's too soon to say if we might make a run for 105+, perhaps on Saturday, but it's in the cards. 

Hotter than Hell indeed.

Source: https://chatgpt.com/