As an ISEE watcher, I would say yesterday's number is likely indicating short term weakness. I might consider it on par with the 242 on Oct 24th and the 237 on Oct 3rd. Both readings were followed by a small drop over the respective next couple of days.
As an indicator of more long term market change, the ISEE has been very quiet for a while...really since last Dec's prolonged extreme readings. I track a few derivatives of the ISEE including the running cumulative change, which I consider an indicator of a build up of buying or selling pressure. If the 12-day MA of this cumulative reading hits either +50 (top) or -50 (bottom), that's extreme. The cumulative has been flatlining around 0 for a while now.
For a chart of the ISEE and my derivatives, check here: