View Single Post
  #31  
Old 03-07-2016, 09:41 PM
Phil Hart's Avatar
Phil Hart
Registered User

Phil Hart is offline
 
Join Date: Jan 2007
Location: Mount Glasgow (central Vic)
Posts: 1,091
Quote:
Originally Posted by strongmanmike View Post
Yes excellent indeed

How should one interpret the predictions when the two lines (GFS & ACCESS) on the Meteogram diverge and completely disagree...?

Mike
Sorry I didn't reply to this earlier but important to note this.. the Meteograms are a very quick and convenient way to grab a cloud forecast but you really must look at the maps if you want to understand the forecast and the differences.

One model (or just one model run) might have an area of low cloud stopping 10km short of your location, and another might have it directly over you. Such small differences are just random fluctuations (noise) in the model output and rarely indicative of real weather, but they will show as a big divergence when viewed as a point forecast via the Meteogram.

A quick look at the map over a few time steps will help separate model signal from noise . The actual weather that arrives might be something different again.

But yes, if the map shows a big and consistent difference between GFS and ACCESS in the 1-3 day forecast, then it's maybe 70-30 odds for ACCESS better (wild indicative guess). Once you're looking 3-5 days ahead, then it's 50-50 either way.

Phil
Reply With Quote