A few notes on trend by Linda Raschke published in her great book Street Smarts: High Probability Short-Term Trading Strategies
Once a trend is established, it takes considerable power and time to turn it.
A major trend seldom reverses without warning, such as a pronounced loss of momentum followed by a period of accumulation or distribution, or a buying or selling climax.
In strong trends, reactions become shallower as the trend progresses.
The absence of any pattern or swing in the price implies a continuation of the prevailing trend. The strongest trending action tends to be accompanied by a decrease in volatility. This could be describes as a methodical eating away of overhead supply, or a slow, steady price deterioration in the case of a downtrend.
Trends tend to begin after the market has wound down to an equilibrium level. Just as volatility collapses in the middle part of a trend, price action can become more parabolic in the later stages of a trend. In some extreme cases, 75% of the gains can come in the last 20% of the move.