A NOTE ON PRESSURE TENDENCY

Pressure tendency is a measure of how quickly atmospheric pressure is rising 
or falling.  This in turn can be correlated to wind speed, as generally 
the more rapid the pressure change, the stronger the winds (or potential). 
This is especially true for strong pressure rises, when the wind is essentially
"rushing in" to fill in for low pressure.   The graph of pressure tendency will
show the rate of pressure rises or falls in millibars per hour (mb/hr), and can 
give a general indication of wind strength in the near future as indicated by 
the following table..    

< 1 mb/hr... weak pressure change, generally light winds
1-2 mb/hr... moderate pressure change, moderate winds
> 2 mb/hr... strong pressure change, strong winds likely (especially with pressure rises)   

This is just a rough guide as local winds will also depend on a number of other 
factors such as local topography, airmass stability, snow cover, surface terrain, etc..
But it will give you a good indication of what kind of winds to expect in most 
situations.