Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Hurricane Wind Speeds

[Subject Prev][Subject Next][Thread Prev][Thread Next]
David,

When it comes to hurricanes, weather stations (even NWS) report what is reported to them from the National Hurricane Center. The National Hurricane Center reports wind velocities predicated on "sustained winds". The standards were developed by Saffir and Simpson. I talked to Herb Saffir. Herb Saffir is a friend of mine, and you are no.... (forgive me I lapsed into politics).

Herb explained to me that a "sustained wind" was a one minute wind. All the velocities listed in the Saffir-Simpson Scale are are one minute winds. When winds are reported by weather stations, they just report readings from various anemometers. Anemometers are set up everywhere. Some are set up correctly, most are not. Even the properly set up anemometers must have the reported wind velocities from calibrated anemometers normalized to 3 second gust. That takes a bit of time, and they are generally off the air by the time that data is ready.

I have run into this many times. Even the US Air Force report only crude readings from anemometers some at the edge of escarpments. The escarpment effect and the duration must be normalized to develop a 3 second gust. I have seen this done more often incorrectly than correctly.

I learnt all this stuff from wind gurus like Herb Saffir, Dr. Fujita, Jon Peterka and Emil Simu.

Regards,
Harold Sprague





From: "M. David Finley, P.E." <pec(--nospam--at)isgroup.net>
Reply-To: <seaint(--nospam--at)seaint.org>
To: <seaint(--nospam--at)seaint.org>
Subject: Hurricane Wind Speeds
Date: Wed, 1 Sep 2004 16:48:13 -0400

What criteria is used for the hurricane wind speeds that are reported by the National Weather Service? Are they 3-second gust? fastest-mile? something else?

I'm just trying to correlate the wind speeds that are being reported to what we design for per the ASCE 7 code.

David Finley


_________________________________________________________________
On the road to retirement? Check out MSN Life Events for advice on how to get there! http://lifeevents.msn.com/category.aspx?cid=Retirement


******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* * This email was sent to you via Structural Engineers * Association of Southern California (SEAOSC) server. To * subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
* Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you * send to the list is public domain and may be re-posted * without your permission. Make sure you visit our web * site at: http://www.seaint.org ******* ****** ****** ****** ******* ****** ****** ********