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NAM vs GFS

 
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antoinebo



Joined: 30 Mar 2007
Posts: 121

PostPosted: Tue Feb 18, 2014 10:26 pm    Post subject: NAM vs GFS Reply with quote

Any one out there know the difference between NAM 12K and GFS 0.5 deg?

Yes they are both Models - But why are they so different in what they predict?
And more importantly, any history of which one may be more reliable for the cape?

Yes - Long, long winter....
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WaterKook



Joined: 10 Apr 2000
Posts: 1472
Location: The Dude abides!!!!!

PostPosted: Wed Feb 19, 2014 8:56 am    Post subject: Reply with quote

Found this on the web......
GFS model

GFS stands for the Global Forecast System. It is run by National Centers for Environmental Prediction (NCEP) which is a unit of NOAA (National Oceanic and Atmospheric Administration), NWS (National Weather Service), USA. The GFS is run four times per day (00 UTC, 06 UTC, 12 UTC, and 18 UTC) out to 384 hours. Since July 2010 it is run with resolution of 27 km out to 192 hours (previously 35 km) and then with lower resolution for up to hour 384. GFS datafiles that are currently available from NOAA have resolution of 0.5 degree (about 50 km) so this is the real resolution of products that you can see here or on other websites that use the same source. Windguru only uses 180 hours of forecast, because beyond this it's more "crystal gazing" then forecast I think . You see that the model resolution is not that great but it covers the whole Globe!

NAM model

The North American Mesoscale (NAM) is a regional mesoscale model using enhanced terrain and improved parameterization of surface and precipitation processes. It is also run by NCEP, formerly it's name was Eta, but in early 2005 it was renamed to NAM. Windguru uses 84 hour forecast data in 3 hour step which covers Northern America with average resolution of 0.11 degree (about 12 km). Updates four times per day. Much higher resolution than GFS should give more precise short term forecasts.


Laughing

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antoinebo



Joined: 30 Mar 2007
Posts: 121

PostPosted: Wed Feb 19, 2014 10:15 pm    Post subject: Reply with quote

Ok so far so good
Question is why so much discrepancy between the 2.
Look at Friday and Sat. The models dont agree on Wind strength and air temp

Iwindsurf shows Nam which looks way more conservative

In the end, I really dont care that much about these models....
It just happens that one says I am sailing on Friday and the other says I won't
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shreddbob



Joined: 31 Mar 1987
Posts: 279
Location: Massachusetts

PostPosted: Thu Feb 20, 2014 1:00 am    Post subject: Reply with quote

"Die Winter..Die!!" That's funny!

Tragically, I need to see grass in side yard before I think about sailing. Just shoveled all the snow off the roof…onto side yard Sad
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