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Re: [OM] OT: Weather Forecasting

Subject: Re: [OM] OT: Weather Forecasting
From: Chris Trask <christrask@xxxxxxxxxxxxx>
Date: Tue, 28 Oct 2014 11:38:03 -0700 (GMT-07:00)
>
>  That's interesting, Chris. What strikes me, in this age of mini/micro/
>soon to be nano computers, is that we are reading about a computer weighing
>in at over a hundred tons. And that is just to obtain accurate forecasts of
>five days or so. What must it take to forecast out a month, three months?
>Can it even be done?
>

     They are going to be able to provide running updates at one-hour intervals 
in place of the present 3-hour interval.  In the American (GFS, NAM, RAP) 
system, we have a 6-hour cycle for GFS and NAM and a 1-hour cycle for RAP.  GFS 
is reliable out to seven days, preliminary at eight days, and questionable 
beyond that.  NAM goes out to 84 hours, and RAP to 18 hours.

     A system such as the one under way at the Met office would render 
GFS/NAM/RAP obsolete overnight.  Keep in mind that the present British system 
accurately forecast the path of TS Sandy while the American forecasters said it 
was going to go to the north, then NNE, then NE.  It wasn't until 2-3 days 
before landfall that they realised what was going to happen.  I was looking at 
the GFS 500mB VT charts and saw it 5-6 days prior to landfall.  The significant 
factor in the difference was the regional high pressure sitting over Nova 
Scotia and far southern Greenland which provided the final steering winds.

     With the increasing volatility of the weather patterns in the northern 
hemisphere, even five days is sometimes a stretch.

     An interesting piece of similar weather forecasting history is the 
category 5 hurricane that destroyed Galveston in 1900, resulting in an 
estimated 10,000 deaths.  The Cuban forecasters had more experience than the 
Americans with forecasting hurricanes, but the American forecasters dismissed 
them out of cultural predjudice.  The book "Isaac's Storm" by Erik Larson 
provides a pretty good history of what happened.


Chris

When the going gets weird, the weird turn pro 
     - Hunter S. Thompson
-- 
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