GRIB Model

NBM Conus (National Blend of Models)

Provider:National Weather Service, NOAA (USA)
Model scope:North America
Update frequency:every hour
Resolution:1.3nm, 2.5km
Model duration:51 forecasts starting at 0 hr, ending at 11 days
Parameters:wind, wind gust, rain
GRIB model date:Tue Sep 25 06:00:00 2018 UTC
Download date:Tue Sep 25 07:04:15 2018 UTC
Download delay:1hr 04min

About the National Blend of Models

The National Blend of Models (NBM) is an interesting suite of models, well worth considering as you evaluate weather systems.

The following is from an online description of the NBM:

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 NBM model is currently at version 3.0, with a v3.1 upgrade expected in Sept 2018.

The quoted text above mentiones that both NWS and non-NWS models are blended into the NBM.

The list of model inputs, for version 3.0 of NBM, is:

(This list of inputs will expand in the planned v3.1 upgrade.)

The blending process

The word blend in NBM represents the key feature of this model. A wide variety of models are blended into the NBM final result. This blending process has been shown to improve the skill level present in the individual models.

Cliff Mass, an Atmospheric Science professor at the University of Washington, has published a presentation describing the blending process, referred to as MOS. The presentation is an interesting read, if you want to understand some of the techniques that may be present in the NBM blending process.

The blend in the NBM is different from an ensemble model in two major ways.

  1. first, the blending in the NBM does not use simple averaging, and Prof. Mass’s paper talkes about how this may work, in some detail. The blending in NBM is much more sophisticated than a simple average, and it is able to improve the skill of the result as well as retain detail in the data.

  2. secondly, the input models to the blend are from a wide variety of sources, both from NOAA and from outside of NOAA. For example, models from both Canada and the US Navy are included as elements of the blend. Both high resolution regional models and global models are considered. In a way, the NBM is a meta-ensemble, an advanced blending of other ensemble (and non-ensemble) models

NBM Conus

A brief comparison of the NBM Conus domain to the NDFD Conus domain is useful. Where the NDFD Conus data is restricted only to the USA, the NBM data covers the entire grid, including the portions of Canada and Mexico that the NDFD data omits.

The NBM Conus domain is also slightly larger, extending further west and north compared to the NDFD domain.

Additional Information

For additional information, see:

Global Models

North America




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