3-D Hurricane Tracking System Avoids Surprises

April 15, 2008 -- Hurricane forecasters are adopting a new system that lets them combine Doppler radar systems to watch a hurricane revving up in real time just before coming ashore.

The Vortex Objective Radar Tracking and Circulation (VOTRAC) system does what satellite imagery, aircraft and individual Doppler radars cannot by piecing together all the wind data on a storm every six minutes into a more complete and accurate picture of what as storm is doing.

This sort of data can provide critical warnings during storms -- such as last year's Hurricane Humberto -- in which the cyclones power up dangerously just before hitting land.

Because Doppler radars are regional and do not reach far out to sea, VORTRAC is perfectly suited to monitoring storms in the last hours before they strike land, say its developers at the National Center for Atmospheric Research (NCAR).

This also happens to be the point at which storm-tracking aircraft are less able to gather data, because they can't drop their instruments over land without endangering people on the ground.

"In general, they do not like to fly the reconnaissance aircraft over land," said Colin McAdie of the National Hurricane Center (NHC), where VORTRAC is being put to use to fill in that gap.

The definitive test of VORTRAC was when Humberto went from being a tropical storm to a hurricane in 19 hours and then came ashore near Port Arthur, Tex.