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RE: old wind speeds vs. new vs. weather station's

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The National Weather Service reports "3 second" gust wind velocities.  The
readings of the anemometers for your local weather reporter is generally the
correct height, but they generally just report peaks without normalizing the
reading to a "3 second" gust.  Another factor is to normalize the data to
filter out local, or terrain effects to produce a true base line free field
reading.  That is why most "official" NWS anemometers are located at
airports.  Many reporters give the "official" wind velocities, and also
local wind velocities.  They are not comparing similar values.

The old standard of a "one mile" wind was never widely accepted.  I believe
that there were only about 10 stations to ever report extreme winds in
fastest mile.  

In Colorado, locals report anemometer readings that can be very large.  But
they are generally anemometers attached to the side of houses, and the local
effects are huge.  The velocities can be quite large, but not a true measure
of free field wind velocity.

The other standards used for measuring extreme wind velocity are "sustained"
(which is a one minute wind) used for hurricanes, and the World
Meteorological Society's "10 minute mean".   There is also the "1/4 mile
wind" which was used by Dr. Fujita for tornadic winds.

Harold O. Sprague

> -----Original Message-----
> From:	Ken Peoples [SMTP:kspeoples(--nospam--at)]
> Sent:	Monday, October 07, 2002 9:58 AM
> To:	Seaint
> Subject:	old wind speeds vs. new vs. weather station's
> I understand that the current wind speeds are the 3-second gust speeds and
> that is why our area here in PA has changed from 70 mph to 90 mph.  What I
> am curious about is how either of these speeds relate to the speeds
> reported by the weather folks when they are talking about 90 mph winds.
> Would this weatherperson's 90 mph be compared to our old 70 mph or our new
> 90 mph or neither?  Just curious.
> Ken
> Kenneth S. Peoples, P. E.
> Lehigh Valley Technical Associates
> 1584 Weaversville Road
> Northampton, PA 18067-9039
> Phone: (610) 262-6345
> Fax: (610) 262-8188
> e-mail: kpeoples(--nospam--at) <mailto:kpeoples(--nospam--at)>

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