  The Geostationary Operational Environmental Satellite R (GOES-R) series of
four satellites are the next generation NOAA GOES satellites. Once on orbit and
commissioned, they are renamed GOES 16-19, making critical terrestrial and
space weather measurements through 2035. GOES 16 and 17 are currently on orbit,
having been launched in 2016 and 2018, respectively. The GOES-R satellites
include the EUV and X-ray Irradiance Sensors (EXIS) instrument suite, which
measures calibrated solar irradiance in 8 lines or bands between 25 and 285 nm
with the Extreme Ultraviolet Sensors (EUVS) instrument. EXIS also includes the
X-Ray Sensor (XRS) instrument, which measures solar soft X-ray irradiance at
the legacy GOES bands. The EUVS measurements are used as inputs to the EUVS
Model, a solar spectral irradiance model for space weather operations that
predicts irradiance in twenty-two 5 nm wide intervals from 5 nm to 115 nm, and
one 10 nm wide interval from 117 to 127 nm at 30 second cadence. Once fully
operational, NOAA will distribute the EUVS Model irradiance with 1 minute
latency as a primary space weather data product, ushering in a new era of rapid
dissemination and measurement continuity of EUV irradiance spectra. This paper
describes the EUVS Model algorithms, data sources, calibration methods and
associated uncertainties. Typical model (relative) uncertainties are less than
$\sim$5\% for variability at time-scales longer than 6 hours, and are
$\sim$25\% for solar flare induced variability. The absolute uncertainties,
originating from the instruments used to calibrate the EUVS Model, are
$\sim$10\%. Examples of model results are presented at both sub-daily and
multi-year timescales to demonstrate the model's capabilities and limitations.
Example solar flare irradiances are also modeled.
