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Service Change Notice 24-64
National Weather Service Headquarters Silver Spring MD
1100 AM EDT Thu Jun 13 2024

To: Subscribers:
 -NOAA Weather Wire Service
 -Emergency Managers Weather Information Network
 -NOAAPort
 Other NWS Partners, Users and Employees

From: Mike Farrar, Director
 National Centers for Environmental Prediction

Subject: Upgrade to Hurricane Analysis and Forecast System
(HAFS): Effective July 16, 2024

Effective on or about Tuesday, July 16, 2024 with the 1200
Coordinated Universal Time (UTC) cycle, the National Centers for
Environmental Prediction (NCEP) Central Operations (NCO) will be
implementing a new upgrade of Hurricane Analysis and Forecast
System version 2 (HAFSv2) replacing the existing HAFSv1 with both
HFSA and HFSB configurations be updated.

The scientific and technical enhancements include the following:

System and Infrastructure Upgrades:
- Latest version of ufs-weather-model, HAFSv2 final scientific
configuration freeze on February 8, 2024
- Increase moving nesting horizontal resolution from 6-2 km to
5.4-1.8 km (HFSA only)
- Reduce model time step from 90 to 72s (HFSB only)
- Updated horizontal advection options
- Improved model stability and runtime efficiency

Vortex Initialization Improvements:
- Enhance vortex initialization to cycle hydrometeor variables
and vertical velocity (HFSA only)
- Update composite vortex and reduce warm-cycling Vmax threshold
from 50 to 40 kt (HFSA only)

Data Assimilation Improvements:
- Ingest new high-resolution GOES-R mesoscale AMVs
- Scale-Dependent Localization for innercore DA
- Refine GPS RO (Radio Occultation) DA

Model Physics Advancement:
- Upgrade Thompson MP with bug fixes
- Thompson Microphysics for NATL basin, GFDL Microphysics for
EPAC/CPAC and JTWC basins (HFSA only)
- Update TKE EDMF PBL and SASAS CP schemes with vertical wind
shear impacts
- Change the radiation calling time step from 720s to 900s (HFSA
only)
- Reduce radiation time step from 1800 to 720s (HFSB only)
- Update CO2 fix files

Ocean/Wave Coupling:
- MOM6 ocean model coupling (HFSA only)
- CMEPS with inline-CDEPS coupling (HFSA only)

Post-processing:
- Upgrade GFDL Tracker

The HASFv2.0.0 system has been fully tested and compared with the
forecast skill of 2023 operational HAFSv1.0, demonstrating
overall improved tropical cyclone track and intensity forecast
guidance in all global oceanic basins.

Product Timing Changes:
There will be no changes on the HAFS product delivery time for
Users of public data on the NOAA Operational Model Archive and
Distribution
Service (NOMADS).

Data files for the HAFS remain at their current location on
NOMADS/FTPPRD web services at:

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/hafs/prod
https://nomads.ncep.noaa.gov/pub/data/nccf/com/hafs/prod
https://www.ftp.ncep.noaa.gov/pub/data/nccf/com/hafs/prod

An event driven parallel feed of HAFSv2.0.0 data is available on
the NCEP sites at the following URLs:

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/hafs/para
https://nomads.ncep.noaa.gov/pub/data/nccf/com/hafs/para
https://www.ftp.ncep.noaa.gov/pub/data/nccf/com/hafs/para

Sample HAFS products from HAFSv2.0 are available at:

https://www.emc.ncep.noaa.gov/gc_wmb/vxt/zack/HAFSv2_Sample_Files
/

NCEP encourages users to ensure their decoders are flexible and
are able to adequately handle changes in content order, changes
in the scaling factor component within the product definition
section (PDS) of the Gridded Binary (GRIB) files, and any volume
changes which may be forthcoming.  These elements may change with
future NCEP model implementations.  NCEP will make every attempt
to alert users to these changes prior to any implementations.

Any questions, comments or requests regarding this implementation
should be directed to the contacts below.  We will review any
feedback and decide whether to proceed.

For questions regarding these model changes, please contact:

Dr. Avichal Mehra
Chief, Dynamics and Coupled Modeling Group
NOAA/NCEP/Environmental Modeling Center
National Centers for Weather and Climate Prediction
College Park, MD
301-683-3746
avichal.mehra@noaa.gov

For questions regarding the data flow aspects of these datasets,
contact:

Margaret Curtis - HPC Dataflow Team Lead
NCEP/NCO Implementation and Data Services Branch
College Park, MD
301-683-0567
ncep.pmb.dataflow@noaa.gov

National Service Change Notices are online at:

https://www.weather.gov/notification