In (Pacific) Hurricane Darby's discussion this morning is the following:

THE TRACK FORECAST IS HEAVILY DEPENDENT ON THE EVOLUTION OF THE AREA
OF LOW PRESSURE CURRENTLY OVER THE WESTERN CARIBBEAN. NEARLY ALL
OF THE GLOBAL MODELS SHOW DEVELOPMENT OF THIS SYSTEM BY THE TIME IT
GETS TO THE WESTERN GULF OF MEXICO IN A FEW DAYS...AND THESE MODELS
STALL DARBY BY DAY 2 FOLLOWED BY A NORTHEASTWARD ACCELERATION ON
DAYS 4 AND 5...MOST NOTABLY INDICATED BY THE ECMWF AND UKMET. THE
OFFICIAL FORECAST FOLLOWS THIS GENERAL PATTERN...BUT DOES NOT
INDICATE A POSITION AS FAR TO THE EAST ON DAY 5 AS THE MODEL
CONSENSUS TVCN...WHICH IS BEING INFLUENCED BY THE ECMWF AND UKMET
OUTLIERS. ON ANOTHER NOTE...THE GFS SHOWS ALMOST NO DEVELOPMENT OF
THE CARIBBEAN LOW AND THEREFORE KEEPS DARBY ON THE WESTERN SIDE OF
THE RATHER HELTER-SKELTER GUIDANCE ENVELOPE. ESSENTIALLY...THE
STRONGER THE CARIBBEAN LOW GETS WHILE IN THE GULF OF MEXICO...THE
FARTHER TO THE EAST DARBY COULD BE LOCATED BY THE END OF THE
FORECAST PERIOD.