By Ann Baskerville Meteorologists and support staff at the National Weather Service Chicago's Station in Romeoville, Illinois monitor weather conditions 24 hours a day, 7 days a week to inform more than 10 million citizens in 23 counties of severe weather threats. Matt Friedlein, Lead Forecaster for NWS Chicago, said that while technological advances have allowed for greater radar precision and more methods of relaying warning information since the Romeoville station opened in December 1991, the NWS Chicago's core mission remains the same: spreading the message of weather awareness and informing the public of severe weather threats. Friedlein said weather awareness begins with citizens remaining aware of weather conditions capable of producing strong storms and tornadoes. Using advanced computer models to analyze weather data, meteorologists can recognize the potential for severe weather in a region days in advance . For example, five days prior to the November 17, 20