The National Blend of Models (NBM) is a nationally consistent and skillful suite of calibrated forecast guidance based on a blend of both NWS and non-NWS numerical weather prediction model data and post-processed model guidance. The goal of the NBM is to create a highly accurate, skillful and consistent starting point for the gridded forecast. This new way to produce NDFD grids will be helpful providing forecasters with a suite of information to use for their forecasts. The NBM is considered an important part of the efforts to evolve NWS capabilities to achieve a Weather-Ready Nation.
The first version of the NBM was released January 6, 2016 in CONUS AWIPS 16.1.1, after Congress mandated that the NWS develop a blended model approach following Hurricane Sandy in 2012. This first version used 3 models (GFS, GEFS mean, CMCE mean) and covered temperature, wind, and sky cover over the CONUS region two times a day. Version 2, released November 15, 2016 in CONUS and OCONUS AWIPS 16.2.2, added coverage over Alaska, Hawaii, and Puerto Rico.
Further versions aim to expand on the current NBM capabilities. Version 3 makes major changes to the blend capabilities. Over CONUS, V3.0 will run hourly from 0-36 hours. The number of models used in the blend has also been greatly increased, and now includes numerous mesoscale and short-range models in addition to global models used in previous versions. In addition to temperature and winds, the version 3.0 will produce precipitation forecasts, Ceiling height and Visibility, as well as supporting weather, snow, and ice forecasts. Additionally V3.0 will add precipitation to Alaska and Hawaii.