Thursday, May 18, 2017

Record Cold Temperatures Aloft

Official temperature records are kept for the surface, but let's give some love today to the atmosphere aloft.

The cold upper-level trough that moving through our area is a record setter.  Soundings collected 0000 UTC (1800 MDT) yesterday afternoon and 1200 UTC (0600 MDT) this morning broke records for the coldest temperature observed at that date and time at 700 mb (about 10,000 ft/3,000 m) and 500 mb (about 18,000 ft/5,500 m).
700 mb
00z 18 May 2017: -9.1˚C
Prior Record: -9.0˚C

12z 18 May 2017: -9.5˚C
Prior Record: -9.2˚C

500 mb
00z 18 May: -28.7˚C
Prior Record: -27.8˚C

12z 18 May: -27.7ÂșC
Prior Record: -25.1˚C
Prior records are based on soundings collected at Ogden and Salt Lake City from 1948-2014, although there are gaps in which no data is available.  Thus, these upper-air records are perhaps not as impressive as a record at the surface where there is a much longer history available.  Still, it provides some illustration that this is an unusually cold airmass for mid May in northern Utah.

So, is global warming over?  Sorry, but no.  We can see that our extreme cold is regional in nature using the great Climate Reanalyzer site from the University of Maine.  The plot below is the departure of today's daily mean GFS forecast surface temperature from the 1979–2000 average.  The interior western US is a local cold spot, as is parts of interior Asia.  There is also extreme warmth in other areas, especially the northeast United States.  For the globe as a whole, the average surface temperature is 0.45˚C above the 1979–2000 average.

Source: Climate Reanalyzer
Thus, our cold weather is a nice illustration of how one region can still get unusually cold even as the planet warms.

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