NOUS41 KWBC 111918 AAA


Technical Implementation Notice 12-19, Amended

National Weather Service Headquarters Washington DC

318 PM EDT Fri May 11 2012


To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS Partners, Users and Employees


From:     Timothy McClung

          Science Plans Branch Chief

          Office of Science and Technology


Subject:  Amended: Hurricane Weather and Research Forecast

          (HWRF) Model Changes: Effective May 24, 2012


Amended to reschedule implementation for Thursday, May 24, 2012.  Also added clarification about nest product filename.


Effective on or about Thursday, May 24, 2012, beginning with the 1200 Coordinated Universal Time (UTC) run, the National Centers for Environmental Prediction (NCEP) will upgrade the HWRF - Princeton Ocean Model (POM) coupled system. The scientific enhancements include the following:


- Implement triple-nesting capability with a new centroid

  based nest movement algorithm

- Configure the inner-most grid at cloud-resolving 3 km

  horizontal resolution with explicit representation of

  convective processes

- Implementation of GFS Shallow Convection

- Modifications to SAS deep convection, GFS PBL, GFDL

  surface physics and Ferrier microphysics

  parameterizations suitable for higher resolution and

  based on observational findings

- Redesign of vortex initialization for 3 km resolution

  with improved interpolation algorithms and better

  representation of composite storm

- Improved POM initialization in the Atlantic domain and

  new 1-D ocean coupling for Eastern Pacific basin

- Upgrade the HWRF GSI to V3.5 and use of new Hybrid

  GSI/GFS for initial and boundary conditions once the

  Hybrid GSI/GFS has been implemented operationally

- Improvements to HWRF Unified Post Processor to generate new

  SSM/I simulated microwave satellite imagery products

- Very high-resolution (every 5 sec.) storm tracker output

  to support National Hurricane Center (NHC) operations


Test results from the combination of these upgrades showed significantly improved track, intensity and structure forecast skills and improved track, intensity and storm radius forecast biases in both Atlantic and Eastern North Pacific basins. 


Product Changes:


The following elements will be added to the HWRF model output GRIB files:


-simulated microwave satellite imagery products from SSM/I-S


Additional products and their contents:


- new intermediate grid output GRIB files (*hwrfprs_i.grb*

  and *hwrfsat_i.grb*) at a horizontal resolution of 0.1

  deg. lat/lon

- nest (innermost domain) GRIB files (*hwrfprs_n.grb* and

  *hwrfsat_n.grb*) will now be at highest resolution of 0.03

  deg. lat/lon (Note:  this change will result in a filename

  change on the NWS FTP server.  The current filename is

  ns.{stormname}.YYYYMMDDHH_fh.00##_tl.press_gr.0p1deg.  The

  filename will change from *press_gr.0p1deg to


- new merged grid (innermost + intermediate) output GRIB

  files (*hwrfprs_m.grb* and *hwrfsat_m.grb*) for selected

  variables at a horizontal resolution of 0.03 deg. lat/lon

- combined grid output GRIB files (*hwrfprs_c.grb* and

  *hwrfsat_c.grb*) will now be a combination of all three

  domains at highest resolution of 0.03 deg. lat/lon

- parent grid output GRIB files (*hwrfprs_p.grb* and

  *hwrfsat_p.grb*) remain unchanged and will be at the same

  0.25 deg. lat/lon resolution.


A new very high temporal frequency (5 sec) tracker output product (ascii text file) is added at the request of NHC.


There will be an increase of roughly 8GB in product size due to high resolution output and additional elements.


These changes will result in about a 20 minute delay in product dissemination time.  This change was proposed in an NWS Public Information Statement issued February 1, 2012.  Based on the responses received, NWS will move forward with this change in dissemination time of the HWRF products.


The HWRF GRIB products are disseminated via the NCEP FTP server and are not available on NOAAPORT or AWIPS.


More details about the HWRF-POM are available at:


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 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.


For questions regarding these model changes...please contact:


  Dr. Vijay Tallapragada

  NCEP/Environmental Modeling Center

  Hurricane Forecast Project

  Camp Springs, Maryland

  301-763-8000 x 7232


NWS National Technical Implementation Notices are online at: