Dear all, 

I want to call your attention to the dynamic between hurricanes, forecasters, 
and populations that is going on right now, in the US.  .  Two dangerous 
tropical storms are approaching the East,  and the forecasters are starting to 
do that dance that they do when the situation is REALLY dicey.  There is a 
illicit (?) principle in forecasting (I have had it confessed to me) called the 
"least regret forecast".  The LRF is something like, "be reluctant to change 
your forecast for fear that you will have to change it BACK."  There is 
probably good reason for this because the members of the public hear forecasts 
with different time delays and it is very easy to hear simultaneously that the 
storm is going to hit to the LEFT of where it was last forecast and that it is 
going to hit to the RIGHT of where it was last forecast.  In such a situation, 
large numbers of the public are likely to just stop listening, altogether.   
Also, with the right delay, the LRF can produce the same amplifications  of 
publilc behavior that delayed feedback produces in the auditory pathways.  

If anybody else is interested in this dynamic, you can follow it live at 
www.wundground.com  (The Weather Underground).   One personal response to the 
LRF is to extrapolate from the trend in forecasts.  So for instance, if the 
first forecast is that the storm is going to hit New Orleans and the next 
forecast is that it is going to hit at the LA-TX boundary, start evacuating 
Galveston! This rule of thumb seems to work  until just before landfall, when 
the final track is likely to be back toward the original forecast track from 
the last pre-landfall forecast.  

I am probably wrong about all of this,  so let me fall back on my basic claim, 
which is that the dynamic is interesting. and worthy of your attention.   

Hope others will keep an eye on it and comment. 

Nick    



Nicholas S. Thompson
Emeritus Professor of Psychology and Ethology, 
Clark University ([EMAIL PROTECTED])
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