Originally Posted by
slim_slag
Yep, PROB10 isn't allowed, only 30 or 40.
Weather is all probablilty. Normally you show the most probable forecast (with significant changes within the period). If there are two PROBs the same, which would you show?
This forecaster chose to detail both. PROB 10 is not 'not allowed'; it's not ICAO SARP, but an ICAO-contracted State could file a difference.