nickd: There was a little comment in the last discussion about the model shift. Some of it seems to be just becuase the models had more data to injest.

From the discussion:
LARGE-
SCALE MODELS...AIDED BY DATA FROM THE NOAA GULFSTREAM JET MISSION
LAST EVENING...INDICATE THAT THIS RIDGE SHOULD PERSIST THROUGH 72
HR EVEN THOUGH A DEEP-LAYER TROUGH SHOULD APPROACH THE WESTERN
GULF COAST BY 72 HR. THIS PATTERN SHOULD ALLOW ISIDORE TO MOVE
GENERALLY NORTHWESTWARD FOR 48-72 HR...AND THIS IS SUPPORTED BY
ALL TRACK GUIDANCE. THE OFFICIAL FORECAST IS SLIGHTLY TO THE LEFT
OF THE PREVIOUS PACKAGE...AND IS ALONG THE RIGHT SIDE OF THE
GUIDANCE ENVELOPE.