This presentation will quickly summarize the history of the HRRR and then focus on the testing (already underway as of Aug 2011) of the 2012 version of the HRRR. Two new strategies have emerged for improved assimilation and retention of radar reflectivity, by modulating reflectivity-related latent heating by local stability conditions, and by applying reflectivity in four consecutive 15-min periods at 3-km resolution. Both strategies will likely be applied for 2012.
Improved design for assimilation of near-surface observations, including an impact on soil moisture fields, is also now moving toward testing. This area of changes will address a moist bias in initial HRRR fields that have contributed to overforecasting of convection in summer 2011, despite the overall progress for the HRRR in 2011 compared to 2010.
The testing of the version expected for 2012 will be summarized in this paper, including changes both in the HRRR configuration of the WRF model, including revised boundary-layer, cloud microphysics, and land-surface schemes. It will also include modifications in the assimilation with components in both the 13km Rapid Refresh and in the 3km HRRR.