As I understand it, the GRIB files are just an unreviewd computer model FORECAST for winds based on synoptic conditions. They are not a report of observed conditions. And the computer models don't necessarily predict short lived strong winds that come with a frontal passage.

Not sure I wold have been scared out of he GS by this forecast. But I might have timed it or changed course to avoid he GS during the front. Travelling with a rally may set up a herd mentality where skippers no longer make individual decisions based on the capabilities of their own boat.