BA is also warning of poor weather at LHR and the likelihood of cancellations tomorrow. Given that there are issues at both ends, they are very likely to cancel some BA flights to AMS too, if they have not already done so. BA cancelled several flights to AMS for the last such storm 2 weeks ago. As such, there may not be any space for KL to rebook you onto BA, even if BA gets some flights into AMS tomorrow morning.

https://www.britishairways.com/trave...l?p_faqid=6284

At the moment, the first two flights of the morning from LHR are cancelled. No cancellations yet from LCY or LGW