An Update on Recent Development with the National Blend of Models

The National Blend of Models (NBM) is a nationally consistent and skillful suite of calibrated forecast guidance based on numerical weather prediction model data. The NBM is instrumental in the National Weather Service’s (NWS) efforts to provide decision support services to protect life and property by minimizing time spent on forecast-generation and maximizing time spent on communicating potential weather hazards and their associated uncertainties with customers and core partners. Deterministic forecasts from NBM are already used routinely within the NWS for forecasts for Day 3 and beyond.

NBM version 4.2 is scheduled for implementation in December 2023. Improvements include new hourly probability and percentile forecasts for wind speed and gusts and notable improvements to winter weather and precipitation forecasts. Probability and percentile forecasts from NBM often provide important uncertainty and probability information that can be used to enhance short-term forecasts and impact decision support services, even for some extreme events. In this presentation, we will demonstrate the tools used to verify NBM forecasts and the performance of those forecasts. We will also demonstrate how the percentile and probability forecasts generated by NBM, when combined with the expertise provided by local forecasters in the field, can be extremely useful in generating short-term forecasts and decision support services for customers across the weather enterprise.