WELCOME, ISABEL ... NOW GO AWAY! As you can imagine, the next 24 hours will be very difficult from a commuting standpoint, as Hurricane Isabel - or the remnants thereof - strike Philadelphia. As of 6:00pm, the R5 Paoli-Thorndale and R6 Cynwyd lines are already impacted. The R5 is running with nearly 1 hour delays due to a downed tree near Merion. The R6 is not running at all, with passengers being forced to transfer to shuttle buses at Overbrook.
On another weather related note, the 104 and 119 were also running with delays, due to an accident on West Chester Pike at PA 352 in Westtown. 4232 block, which normally runs short-turns between 69 St and Newtown Square was forced to cover missing West Chester runs, with 4231 block catching up to it at West Chester. The 119 that normally arrives in West Chester at 5:35pm was running about 10 minutes late, which is highly unusual for that section of the line.
It would not be a surprise if SEPTA ran Regional Rail (or at least the lines they can safely operate) on a Saturday or Sunday schedule (at least on the Paoli-Thorndale line, it better be a Saturday schedule, otherwise there'd be no service between Malvern and Thorndale) tomorrow. SEPTA reports that shuttle buses would be deployed as required on major rail lines, so it's also possible that transit service could end up operating on a Saturday or Sunday schedule as well.
The only advice that I can offer is to listen to as many news outlets as possible tomorrow (as sometimes, information tends to vary from station to station).