Shortsale day for Dow Jones Index

Tomorrow is shortsale day. I know that it is rallying from 11040 double bottom. But on a shortsale day, a nice shorting opportunity can be found, ususally 30-70 points for Dow. If there is an afternoon rally with just a mild decline in the earlier part, then this would be a sign of trend change. The immediate trend is to go higher. If the markets is ranging within 40 points for most of the time, then it is usually followed by a nice decline on the next day.