Thursday, October 28, 2010

Chapstick day in the mountains

Todays is a great example of what I call a Chapstick day.  Dewpoints are so low in the mountains that you spend your whole day licking your lips and applying lip balm.  There is a strong connection between skiing and Chapstick, not just for obvious reasons.  Suzy Chaffee, a member of the US Ski Team during the 1968 Winter Olympics, was Chapstick's main spokesperson for many years, earning the name "Suzy Chapstick."

But I digress.  This morning's sounding pretty much tells the tale as we have a series of stable layers in the lower troposphere with extremely low dewpoints (<-40C) between 600 and 725 mb.

Typically such dry conditions indicate that the air has subsided from upper-levels, which is consistent with the upper-level ridge that is presently over the region.

The Alta-Mt. Baldy mesowest station clearly shows these dry conditions as well, with dewpoints since about 0330 MDT running bellow -23C.

This is not as low as the sounding, which could reflect instrumentation errors at such low dewpoints or the influence of sublimation from the snowpack.  The rapid drop in dewpoint at around 0330 MDT probably indicates when the subsidence advected the vertical moisture gradient below the elevation of the Mt. Baldy summit.

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