Monday, July 17, 2023

NOAA launches new hurricane forecast model

The Hurricane Analysis and Forecast System (HAFS) “moving nest" Model.
Global map showcasing land mass in green and water in black, clouds in white and tropical storms outlined in a green boxes representing the moving nest model.
The HAFS model is now operational.
Compared to NOAA’s existing hurricane models, the experimental version of HAFS 2019-2022 showed a 10-15% improvement in track predictions, did about the same for intensity, did better at rapid intensification.
(Image credit: NOAA)

From Meteorological Technology Int by Dan Symonds

NOAA’s National Hurricane Center, a division of the US National Weather Service, has a new model to help produce hurricane forecasts this season.
The Hurricane Analysis and Forecast System (HAFS) will run alongside existing models for the 2023 season before replacing them as NOAA’s premier hurricane forecasting model.

Rick Spinrad, NOAA Administrator, said, “The quick deployment of HAFS marks a milestone in NOAA’s commitment to advancing our hurricane forecasting capabilities and ensuring continued improvement of services to the American public.
Development, testing and evaluations were jointly carried out between scientists at NOAA Research and the National Weather Service, marking a seamless transition from development to operations.”
Hurricane Florence, from space.
courtesy of Alexander Gerst / Flickr

Running the experimental version of HAFS from 2019 to 2022 showed a 10-15% improvement in track predictions compared with NOAA’s existing hurricane models.
HAFS is expected to continue increasing forecast accuracy, thereby reducing the impact of storms on lives and property.

HAFS is as good as NOAA’s existing hurricane models when forecasting storm intensity and is better at predicting rapid intensification.
HAFS was the first model last year to accurately predict that Hurricane Ian would undergo secondary rapid intensification as the storm moved off the coast of Cuba and barreled toward southwest Florida.

Over the next four years, HAFS will undergo several major upgrades, ultimately increasing the accuracy of forecasts, warnings and life-saving information.
By 2027, the NOAA Hurricane Forecast Improvement Program (HFIP) aims to reduce all model forecast errors by nearly half compared with 2017.

An example of the Hurricane Analysis and Forecast System or HAFS
running for Hurricane Ian in 2022.
An example of the Hurricane Analysis and Forecast System or HAFS
running for Hurricane Ian in 2022.

HAFS provides more accurate, higher-resolution forecast information over land and ocean and is comprised of five major components: a high-resolution moving nest; high-resolution physics; multi-scale data assimilation that allows for vortex initialization and vortex cycling; 3D ocean coupling; and improved assimilation techniques that allow for the assimilation of novel observations.
The foundational component is the moving nest, which allows the model to zoom in with a resolution of 1.9km on areas of a hurricane that are key to improving forecasts of wind intensity and rain.

Ken Graham, director of NOAA’s National Weather Service, said, “With the introduction of the HAFS forecast model into our suite of tropical forecasting tools, our forecasters are better equipped than ever to safeguard lives and property with enhanced accuracy and timely warnings.
HAFS is the result of strong collaborative efforts throughout the science community and marks significant progress in hurricane prediction.”

HAFS, the first regional coupled model to go into operation under the Unified Forecast System (UFS), was developed through community-based collaboration and the streamlining of the operational transition process.
As HAFS uses the FV3 — the same dynamic core as the US Global Forecast System — it will have a unified starting point when initiated for hurricane prediction and will also integrate with ocean and wave models as underlying inputs.
The current standalone regional hurricane models – HWRF and HMON – each have their own starting point for modeling the atmosphere.
Leveraging the FV3 in HAFS reduces overlapping efforts, making the NOAA modeling portfolio more consistent and efficient.

HAFS is the first new major forecast model implementation using NOAA’s updated weather and climate supercomputers, which were installed last summer.
HAFS would not be possible without the speed and power of these new supercomputers, called the Weather and Climate Operational Supercomputing System 2 (WCOSS2).

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