One knot equals 1.1 mph. The red flags indicate wind direction. For up-to-date maps of the jet stream (and other weather-related maps) visit the FNMOC Web site.

So what is the jet stream? And why is it there? Perhaps your image of the jet stream comes from maps broadcast during the weather portion of your local news. You know the kind: the ones where ...

a Newsweek map shows. The powerful 115 mph upper-level jet stream winds will heighten storm conditions from eastern Texas to western Mississippi. The National Weather Service (NWS) has issued an ...