Rapid Refresh

Rapid Refresh
Name	Rapid Refresh
Developer	National Oceanic and Atmospheric Administration
Type	Numerical weather prediction
Released	2012
Website	https://rapidrefresh.noaa.gov/

Rapid Refresh. The Rapid Refresh is a high-frequency, rapidly updating atmospheric prediction system operated by the National Oceanic and Atmospheric Administration (NOAA). It is a key component of the operational forecasting suite at the National Centers for Environmental Prediction (NCEP), designed to provide detailed short-term guidance for severe weather events and aviation. The system assimilates a vast array of observational data to produce updated forecasts every hour, focusing on the contiguous United States and surrounding regions.

Overview

The primary objective of this system is to generate highly current analyses and short-term forecasts to support critical decision-making. It is particularly vital for forecasting phenomena like thunderstorms, turbulence, and low-level wind shear that evolve on timescales shorter than traditional models. The framework is built upon the Weather Research and Forecasting (WRF) model and utilizes an advanced ensemble-based data assimilation technique known as the Gridpoint Statistical Interpolation (GSI) system. Operational guidance from this model is used extensively by forecasters at the Storm Prediction Center and the Aviation Weather Center.

Development and Implementation

Development was led by scientists at the Earth System Research Laboratory (ESRL), now part of NOAA's Oceanic and Atmospheric Research (OAR). The project aimed to replace the older Rapid Update Cycle (RUC) model, incorporating major advancements in data assimilation and model physics. Key figures in its creation included researchers from the Global Systems Laboratory and collaborators at the National Center for Atmospheric Research (NCAR). After extensive testing, it became fully operational at NCEP in 2012, following a period of parallel runs with the Rapid Update Cycle.

Technical Specifications

The operational configuration uses a hybrid ensemble-variational data assimilation method within the Gridpoint Statistical Interpolation framework. It ingests data from diverse sources including the Geostationary Operational Environmental Satellite (GOES), Automated Surface Observing System (ASOS) stations, NEXRAD radar, and commercial aircraft via the Aircraft Meteorological Data Relay (AMDAR). The model domain covers North America with a horizontal grid spacing of 13 kilometers and 50 vertical levels. It produces forecasts out to 18 hours, with a new cycle initialized every hour using the previous cycle's short-range forecast as a background.

Operational Use and Applications

Forecast products are fundamental for issuing Severe Thunderstorm Watch and Tornado Warning alerts by the National Weather Service. Meteorologists at the Weather Forecast Office in Norman, Oklahoma and other offices rely on its high-resolution output for nowcasting. The aviation industry utilizes its forecasts of icing conditions and ceiling and visibility for flight planning and safety. Furthermore, its data feeds into other specialized prediction systems like the High-Resolution Rapid Refresh (HRRR) model and supports renewable energy forecasting for wind farms across the Great Plains.

Comparison with Other Models

Compared to global models like the Global Forecast System (GFS), this system updates much more frequently and has a finer mesh over its regional domain, providing superior detail for mesoscale events. Its predecessor, the Rapid Update Cycle, had a coarser resolution and less sophisticated assimilation techniques. The High-Resolution Rapid Refresh model, a nested descendant, operates at a convective-allowing 3-kilometer grid, offering even finer detail for storm-scale prediction. Internationally, similar rapid-update systems include the Met Office's UKV model and Environment and Climate Change Canada's High Resolution Deterministic Prediction System (HRDPS).

Limitations and Future Directions

Current limitations include challenges in accurately initializing convective processes and representing complex terrain effects in regions like the Rocky Mountains. Future development, often referred to as the Rapid Refresh Forecast System (RRFS), aims to unify and expand the modeling suite with a broader domain and enhanced physics. This evolution is part of NOAA's broader Earth Prediction Innovation Center (EPIC) initiative to advance numerical weather prediction. Ongoing research focuses on improving the assimilation of Phased Array Radar data and satellite-derived atmospheric motion vectors to further increase forecast accuracy.

Category:Numerical climate and weather models Category:National Oceanic and Atmospheric Administration