] [Thread] [Date] [Author]

["Javier Encinas" <asdip(--nospam--at)adelphia.net>]

Harold:

Is the Saffir-Simpson scale compatible with the 3-sec-gust velocities of the
code? In other words, a category 4 hurricane (130-155 mph) is categorized
using the fastest-mile or the 3-sec-gust approach? Regards,

Javier Encinas, MSCE, PE
----- Original Message ----- 
From: "Harold Sprague" <spraguehope(--nospam--at)hotmail.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Monday, September 19, 2005 2:40 PM
Subject: RE: Wind velocity


> There are conversion algebraic "approximations" only.  You can be off by
> quite a margin depending on the velocity that is considered.
>
> Exact solutions from fastes mile to 3 second gusts are an iterative
process
> using the Durst Curve which is contained in the ASCE 7-02 page 296.  The
> iteration closes fairly quickly (about 3 or 4 cycles).  I developed a
> MathCAD template for conversions some years ago.  I had Jon Peterka of CPP
> Labs verify my technique.
>
> From that template I developed a series of tables for my own personal use
> some years ago that converts various winds to 3 second gusts.  I have
> converted Fujita Scale, Saffir Simpson Scale, Australian Cyclonic Scale.
> Beaufort Scale, World Meteorological Organization velocities, and Fastest
> Mile winds to 3 Second Gusts.
>
> It is important to get the velocities correct because the pressures vary
as
> a ratio of the velocities squared.  A little mistake in velocity can be a
> huge mistake in pressure.
> Example:
> A Cat 3 hurricane is 1.5 times greater in velocity than a Cat 1.  But a
Cat
> 3 pressure is 2.25 times greater than a Cat 1.
>
> Regards,
> Harold Sprague
>
>
>
>
>
> >From: "Javier Encinas" <jencinas(--nospam--at)coqui.net>
> >Reply-To: <seaint(--nospam--at)seaint.org>
> >To: <seaint(--nospam--at)seaint.org>
> >Subject: Wind velocity
> >Date: Mon, 19 Sep 2005 13:08:31 -0400
> >
> >What is the correlation between the "fastest mile" wind velocity and the
> >"3-sec gust" wind velocity. For example, what is the equivalent of a 110
> >MPH fastest mile velocity using the 3-sec gust approach? Regards,
> >
> >Javier Encinas, MSCE, PE
>
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