[CANUFNET] Trees and wind

[Ian Wilson]

Hi all,
 
I've been approached by a meteorologist who is looking at trying to link
wind speeds to thresholds, or a range of thresholds, where tree damage
is commonly seen.  I passed on a good review article by Dr. Kim Coder on
the subject,
http://www.urbanforestrysouth.org/resources/library/storm-wind-loads-on-
trees/at_download/file_name
but he's also looking for input from other foresters or arborists.
 
If you have some observations or data on the subject, please pass them
on to me, and I will forward them.  Below is some more information on
what he is looking for.
 
thanks, 
 
Ian Wilson
City of Kelowna
 
--------------------------------------------------------------
 
     Currently I am working on a project that is trying to link impacts
to wind speeds. Specifically the Meteorological Service of Canada is
trying to come  up with some impact statements to go along with the
meteorological numbers that we use in our worded forecasts and warnings.
This recognizes that fact that forecasts that give the wind speed in
km/h are not easily translated by members of the public into the impacts
that the wind may have.  Since wind has a big impact on the City of
Kelowna Parks dept' I wonder if you could help us out by letting us know
that the impacts are for various wind speeds.  What type of damage would
you associate with a 50-70 km/h wind, a 70-80 km/h/ wind, a 90-100 km/h
wind and winds greater than 100 km/h (gusts included). Do you have any
sense of this or have you ever tried to quantify it?  Perhaps you have
an idea based on the number of crews that have to be called in to clear
fallen trees and debris.  Perhaps it is not just wind speed that is
important, but considerations such as wind direction, how wet it has
been, whether trees are in leaf or not etc. 

    To use an example we have heard from municipal parks people that
tree branches start to break off with winds gusting to 70 km/h.  The
storm of November 12th 2007 produced wind of 90 km/h in Penticton
uprooting mature trees and causing widespread power outages and the
evacuation of some neighbourhoods. Any information that you have along
on the impacts that certain speeds of wind have would be greatly
appreciated.

  If you have any questions or please do not hesitate to give me a call.



Gabor Fricska 
Sector Development Meteorologist 
Environment Canada 
National Services Office - Natural Resources 

3140 University Way 
Kelowna BC 
Tel  (250) 491-1517 
Fax (250) 491-1506 

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