Thursday, June 20, 2013

A Lack of Moisture

My friends of Meteorological Solutions Inc. sent me some remarkable observations taken near Milford, Utah yesterday.  It is hard to imagine a lower atmosphere completely devoid of water vapor, but yesterday in Milford is probably as close as you can get.  The observations taken ~1700 MDT (2300 UTC) show an hourly average temperature of 82.6ºF/28.1ºC and a Relative Humidity of 0.427%, yielding a dewpoint of -42.3ºF/-41.3ºC and a dewpoint depression of 125ºF/69.4ºC.

That's the big 125 in Fahrenheit!  I don't have an encyclopedic memory, but good luck finding something bigger than that.  Maybe in the central Sahara, the Empty Quarter, or Death Valley?  Incredible.


  1. There is a SCAN soil moisture station at Milford that registered a 2 inch volumetric water content of 5% yesterday, which might be the minimum allowed for that particular soil (some water gets chemical bound to the soil grains). That is also the lowest it has been in at least the last year and a half (6% at end of last June). Looks like it has been steadily decreasing since the beginning of march from a peak of 37% after they got almost an inch of rain on 3/9/13. Very little precip since that event.

  2. I don't doubt it was extremely dry based on other observations in the area, but you are talking about a 0.1 g/kg water vapor mixing ratio. Are such dew point observations accurate to the tenths of a degree and RH observations to the thousandths of a percent?

  3. Probably not. Just reporting what was there, but granted, the suggested precision is misleading. It was, however, bone dry.