#55 Postby wjs3 » Wed Jun 07, 2006 8:42 pm
I know we're really talking about model handling of development, and not track so much, but the issue of consensus applies to track too.
And while consensus on tracks is "good..."
One of the worst sets of model performance I've seen in recent years has to be Ivan. As I recall, there was continuous model consensus that the storm was going to start a poleward move run after run, day after day as it croseed the Carribean...yet it did not.
From Stacy Stewart's analysis:
"Official track forecasts had, in general, a persistent right-of-track bias for the first 11 days of Ivan's existence as a tropical cyclone (Figure 5a). The official track forecasts relied heavily on the global model forecasts, which prematurely eroded the large and strong subtropical ridge to the north of Ivan that extended well westward across the Bahamas, Florida, and into the Gulf of Mexico. In fact, several of the GFS model forecast cycles consistently eroded the ridge across Bahamas and took Ivan well to the east of Florida, even as the hurricane was approaching Jamaica. The westward jog that Ivan made on 11 September appears to be, at least in part, the result of a mid- to upper-level cold low to the north of Hispaniola that moved slowly southwestward rather than weakening and lifting out to the northeast as some of the models had been forecasting"
So, consensus is good, but guidance is guidance, just that. Even if models agree, they can agree and be wrong.
WJS3
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