What is it about?

On 2 January 1999, a foehn wind produced a narrow band of temperatures up to 10 degrees Celsius (18 degrees Fahrenheit) warmer than the surrounding area in the central Great Tennessee Valley downwind of the Smoky Mountains. A relatively warm and nearly saturated air mass around the highest ridges of the Smoky Mountains was found to be the source of the adiabatically compressed air observed on the northwest side of the Smoky Mountains.

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Why is it important?

This particular event was interesting compared to other documented foehn wind events in that the dewpoint temperature rose substantially along with the actual temperature, resulting in little change in the observed surface relative humidity. Most other foehn wind events around the world experience air that dries significantly as it warms.


This warming event caught forecasters by surprise, and I was intrigued by the rise in dewpoint temperatures (which is different than other documented foehn wind events around the world).

David Morris Gaffin
National Weather Service

Read the Original

This page is a summary of: Unexpected Warming Induced by Foehn Winds in the Lee of the Smoky Mountains, Weather and Forecasting, August 2002, American Meteorological Society, DOI: 10.1175/1520-0434(2002)0172.0.co;2.
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