v13.0.0- released 04/16/2020
Release Notes:  HWRF v13.0.0 (Major)

Summary

This version (HWRF v.13.0.0) is an upgraded version based on 2016 operational HWRF v11.0.7. The new release has been fully tested and compared with the forecast results with 2016 operational HWRF. It has shown significant skill improvement in intensity forecasts (10%) and neutral to positive impact on track forecasts in all global basins. The scientific and technique upgrades and changes are highlighted as follows:

Upgrade dynamic core from WRF3.8.1 to WRF3.9.1 (with bug fixes);
Model vertical resolution is increased from L61 (model top 2mb) to L75 (model top 10mb) for AL/EP/CP basins, and from L43 (model top 50mb) to L61 (model top 10mb) for WP/IO basins. The vertical resolution is also redistributed to better resolve upper hurricane outflow levels.
The sizes of the two nested domains are slightly reduced, d02 from (25°x25°) to (~24°x24°), and d03 from (8.3°x8.3°) to (~7.0°x7.0°);
Improved vortex initialization (new composite storm vortex)
Fully Cycled HWRF ensemble hybrid DA system for TDR and priority storms
GSI upgrades include new data sets for GSI (hourly AMV’s, clear-water-vapor AMV’s)
New tracker is implemented
Scale-aware SAS scheme upgrades
Ferrier-Aligo microphysics scheme upgrades
Adjust momentum and enthalpy exchange coefficients(Cd/Ch)
Partial cloudiness modification for RRTMG (DTC)
Turn on Data Assimilation for all storms in East Pacific Basin; 
Reducing coupling time step from 9min to 6 min for both ocean and wave coupling and adjusting vortex tracking time step accordingly
Increased vertical level for POM from 24 to 41 levels, and reducing internal time step from 270s to 180s
Waves boundary conditions from global wave model
HYCOM ocean coupling for WPAC, NIO

Description of Change

       The system change includes:
The new system will use more computer resources to run cycled DA system, in terms of both node usage and disk storage;
Increased vertical level for POM from 24 to 41 levels, and reducing internal time step from 270s to 180s;
Increased vertical resolution from 43 to 61 for WPAC and NIO storms;
Ocean coupling system (HYCOM) for WP/IO storms;
Waves boundary conditions from global wave model;
Run 8 storms for NHC responsible areas, compared to 7 current system;
Additional new products: MAG and AWIPS2; 

Benefit of Change

The upgraded system will provide improved track and intensity forecasts in all global basins, especially for Atlantic and Eastern-Pacific; 
With increased vertical resolution and model physics, the new system will provide improved storm structure forecasts and detailed smaller scale storm features;
Upgraded DA system assimilates more satellite observations, which will provide well-balanced initial conditions, eliminating initial shocks noted in previous version;
For priority storm (either when TDR obs is available or NHC top priority storm), the new HWRF DA system uses background error covariance calculated from the cycled HWRF-based ensemble, which will further improve storm track/intensity forecasts;
Adjust momentum and enthalpy exchange coefficients(Cd/Ch) provide improved and more realistic vertical wind profiles compared to the observations;
The new system will provide improved hurricane/tropical cyclone forecasts for all global basins;
The new system will provide additional model output for downstream application;

User Impact Statement

No user impact, the delivery time will be the same, i.e. around T+5:55

Technique Impact Statement

The new system requires more computer resources:

For one priority storm, the forecast job requires 1992 cores (83 nodes). The computer resource requirement for  the rest 7 storms  remain the same as 2016 HWRF, i.e. 1512 cores (63 nodes);;
The new forecast job runs 96min, similar run time to the current system;
The new system requires 120 nodes (3 nodes per storm),  compared to current 80 nodes,  and two hour runtime window to conduct 40-member, 6h forecasts for DA purpose;
The new system requires 162G disk space per cycle. 

Risk
       None

Proposed Implementation
June 15, 2018