How do you convert 0.85 atm to mmhg

1 atm = 760 mm Hg

so, (0.85atm)*(760mmHg/1atm) = 646mmHg

Observational data collected by doppler radar, radiosondes, weather satellites, buoys and other instruments are fed into computerized NWS numerical forecast models. The models use equations, along with new and past weather data, to provide forecast guidance to our meteorologists