From the JTWC:

MODEL DISCUSSION: NUMERICAL MODEL GUIDANCE IS IN GOOD AGREEMENT
THROUGH TAU 72 WITH APPROXIMATELY 125 NM SPREAD IN SOLUTIONS AT
THAT TIME. AFTER TAU 72, HOWEVER, DETERMINISTIC GUIDANCE DIVERGES AND
IS IN POOR AGREEMENT. ALL THE MODELS INDICATE THE SYSTEM WILL SLOW
AND BECOME QUASI-STATIONARY BUT DISAGREE ON WHERE THE SYSTEM WILL
WILL TRACK ONCE FORWARD MOTION RESUMES. ENSEMBLE GUIDANCE FAVORS A
SOLUTION THAT TURNS TYPHOON 12W BACK TO THE NORTH LEADING TO AN
EVENTUAL RE-CURVATURE SCENARIO. A SECONDARY GROUPING CONSISTING
PRIMARILY OF UKMET OFFICE-BASED MODEL GUIDANCE TRACKS HINNAMNOR
WESTWARD TOWARDS TAIWAN.

In human language: They don't know WTF this thing is going to do.