When out spotting severe weather, it may become neccessary to record wind speed and report it to either your net control or MPX. In order to accurately measure the wind you need an anemometer.
These tools can be very expensive if you don't watch yourself.
http://www.inspeed.com makes a mag mount mobile anemometer that sells for about $90. This is the model I use, but if you don't have $90 to throw around for a wind gauge, then might I suggest a $35 hand held model from the Sportsmans Guide Warehouse (in St. Paul) You can view it here :Handheld Anemometer
These are just a few suggestions if you are looking to find tools that help you accurately measure and report the wind speed.