CHARLOTTE, N.C. -- The National Weather Service recommends that every home have a NOAA weather radio, designed to alert homeowners if a tornado is on its way.
But five years ago the NewsChannel 36 I-Team identified gaps in the radio coverage for NOAA weather radio transmitters in the Charlotte area including portions of Iredell, Cabarrus, Rowan and Mecklenburg counties.
Forecasters say there will always be some gaps in radio signal coverage.
The National Weather Service has since improved its broadcast coverage considerably by adding an additional transmitter on a tower near US Highway 21 south of Mooresville in southern Iredell County and by upgrading its old transmitter on Spencer Mountain near Gastonia.
But Terry Benthall, the Data Program Manager and the National Weather Service's Greenville-Spartanburg office, which serves the Charlotte area, says "There always will be gaps no matter how many transmitters you put up."
Benthall says mountains, trees and buildings can block radio signals and interfere with the alarm tones sent out to warn of tornadoes, floods and other severe weather.
Benthall also says television sets, computer monitors and even some fluorescent lights can interfere with radio signals.
Benthall suggests homeowners attach external antennae outside the home to avoid interference. The antennae do not require towers or elaborate construction but can be as simple as a wire run outside a window.
The NOAA weather radio is the quickest way to get a tornado alert from the National Weather Service. But Benthall is realistic about how often they are used.
"Being honest, how many people have NOAA weather radio?" he says.
The next generation of tornado and severe weather alerts may leapfrog over radio signals altogether and go straight to cell phones and smart phones.
WCNC-TV meteorologist Brad Panovich says programmers and developers are already at work on technology to deliver warnings to all cell phones in a given area, similar to a reverse 911 call warning homeowners with a so-called "land line" or hard wired phone. Only Panovich says new technology might not require homeowners to subscribe, but would call or text cell phones based on location. Panovich says such technology would not require GPS but rather depend on cell towers triangulating the locations of all cell users in the path of the storm.
There are however, a host of proprietary, privacy and political barriers to navigate before such a service would be put in place. Would consumers be charged for warnings under their data plans? Would the warnings include "Amber alerts" for missing children? Would telcom companies all have to cooperate to use the cell towers? Could consumers block the warnings if they chose to?
Those and many more technical questions will have to be worked out before the National Weather Service or private interests begin to use cell towers to transmit warnings.