Thursday, June 7, 2018

Cool Change This Weekend

Cool change is an Australian term for cold frontal passages in which hot, dry, northerly flow is replaced by cooler southwesterly flow from the Southern Ocean.  Those long in the tooth may remember the hit song Cool Change, by the Melbourne-based Little River Band, written by Glenn Shorrock, which was released in 1979 and is considered one of the top 30 Australian songs of all time by the Australasian Performing Right Association.

The stuff you can find on Wikipedia!

Utah will have it's own cool change this weekend as the hot, southerly to southwesterly from the American southwest are replaced by westerly to northwesterly flow originating over the Pacific Ocean.  I am counting the minutes!

The NWS forecast calls for above average temperatures to predominate through Saturday, with high temperatures for today, Friday, and Saturday, of 93˚F, 91˚F, and 97˚F, respectively.  The GFS forecast for 6 PM MDT Saturday (0000 UTC 10 June) shows hot, continental, southwesterly flow across Utah.  However, it also shows an approaching cold front over central and eastern Nevada, with a 22˚C 700-mb temperature contrast from central Utah to northern California.

By midnight MDT (0600 MDT 10 June), the cold front and the start of the cool change is forecast to be moving across northern Utah.

And, but noon MDT sunday (1800 UTC 10 June), we are solidly in the post-frontal airmass and 700-mb temperatures have dropped to just below 0˚C.  Splendid!

The GFS time height section shows the situation, with a very well defined cold front moving across the Salt Lake City International Airport just after 0600 UTC Sunday.  The front is predominantly dry and will probably produce no precipitation, but it could produce a few low clouds over the mountains.

There is some uncertainty in the precise timing of the front, but a weekend in which Saturday is a scorcher and Sunday is much cooler looks to be a lock.  Enjoy the cool change.

1 comment:

  1. Current forecast is min temp in Salt Lake of 48 on overnight Sunday June 10 into Monday June 11. Pulled the data back to 1874, there are 37 days w a min below 48 of 144 in the period, which is the 25 percentile. Interestingly, there is essentially no trend, 0.0076 degrees per year for the min on June 11. The lowest min is 40 in 1947 and 1929. We did get a 42 in 2008.

    Hopefully this will verify, I'm really dreading nuclear July w overnight lows above 80. Maybe this July will be a cool change.