The HRRR and RAP Models were both upgraded today. Many changes to the internal physics where introduced which should improve the forecast accuracy of both models.
More details can be found here in a technical notice from NCEP.
http://www.nws.noaa.gov/om/notification/tin16-26rap_hrrrr.htm
The HRRR model was increased to 18 hours on the Wright-Weather site.
The RAP model will be increased to 21 hours from 18 hours later this week.
http://hrrr.wright-weather.com/hrrr.php
