Question:
What is the lowest temperature at which a tornado can form?
Replies:
Nathan,
I do not think that we can specify a minimum temperature for tornado
formation, as a tornado can (and do) form in the wintertime,
particularly in the southern Plains states and the southeastern
part of the USA (although they can extend up through the midwestern states).
These tornado situations are typically associated with a thunderstorm
embedded in a winter cold front. In the winter there can be some dramatic
differences in temperature and humidity between the air mass preceding
the cold front (not much above freezing and humid) and the air behind
the cold front (well below freezing and dry), leading to
strong thunderstorm development and tornados.
Interestingly, there are usually more fatalities from winter tornados than
from Spring tornados, even though winter tornados tend to have
shorter tracks and are not as intense. This is because the areas
where they occur are more vulnerable; a much higher percentage of
the population in these areas live in mobile homes, which provide
little protection from tornados, and the tornados are more difficult to
detect since they are embedded in cold fronts with their associated
rain/snow (as opposed to Spring supercell tornados which people are
more alert to since they can more easily see the supercell approaching).
David R. Cook
Meteorologist
Climate Research Section
Environmental Science Division
Argonne National Laboratory
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