Update to previous chart linked below Looking at a moving average of the NYSE New highs minus new lows. My thoughts in the first chart were that observing the prevailing trend of the moving average would give clues to the health of the market.
If the prevailing trend of New High-New Lows holds, the current pull back may be short lived. A break here similar to Sept will likely lead to a more significant pull back.
This looks like a longer term problem. I zoomed out some on this, and while there are only a few instances I just can't see how a total break down in the New High-New Lows moving average is not a huge warning. The previous three times saw further breakdowns in the moving average once the prevailing trend was broke. The better scenario is a 2011 style correction, but even that lead to nearly a full year of no market gains.