NOUS41 KWBC 091525



Technical Implementation Notice 16-18

National Weather Service Headquarters Washington DC

1125 AM EDT Thu Jun 9 2016


To:       Subscribers: 

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS Partners, Users and Employees


From:     Timothy McClung

          Portfolio Manager

          NWS Office of Science and Technology Integration


Subject:  Hurricane Weather and Research Forecast

          (HWRF) Model Changes: Effective July 12, 2016


Effective on or about Tuesday, July 12, 2016, 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 and technical enhancements include the following:


-Upgrade dynamic core from WRF3.6a to WRF3.7.1a (with bug fixes)

and reduce time step (dt=30 s vs. 38 4/7 s) for improved track

and intensity forecasts in all global basins, especially for

Atlantic and Eastern-Pacific(EPAC)

-Increase nested domain size, d02 from (12 degrees x12 degrees)

to (25 degrees x 25 degrees), and d03 from (6.5 degrees x7.0

degrees) to (8.3 degrees x8.3 degrees) and upgrade to new scale-

aware SAS convection scheme for all domains. This change allows

the new system to better handle large storms and provide

improved storm structure forecasts with detailed smaller scale

storm features


 -Upgrade GSI, assimilating more satellite observation data in

GSI (CrIS, SSMI/S, METOP-B changes) and turn on Data

Assimilation (DA) for all storms in East Pacific Basin. The

upgraded DA system provides well-balanced initial conditions,

eliminating initial shocks (spin up and spin down)noted in

previous version

-Physics upgrades include:

 a) implementation of new GFS PBL (2015 version)

 b) updated momentum and enthalpy exchange coefficients(Cd/Ch)

 c) improved vertical wind profile in the surface and boundary

    layer. These upgrades provide more realistic vertical wind

    profiles compared to the observations

-Use Real Time Ocean Forecast System (ROTFS) data to initialize

POM model for EPAC storms to have more realistic oceanic Initial

Conditions (IC) and improved Rapid Intensification (RI)

forecasts this coming season

-Extend Ocean coupling for all Northern Hemisphere basins

including Central North Pacific (CPAC), Western North pacific

(WPAC) and North Indian Ocean (NIO) for enhanced tropical

cyclone track and intensity forecast skill;

-Add one-way coupling to wave model (Hurricane Wave Model) for

North Atlantic and East Pacific storms, which would allow us to

replace Hurricane Wave model in FY17


The 2016 HWRF model configuration has been extensively tested

individually and with a combination of all the upgrades listed

above for a 3-year period (2013-2015). The results showed

further improvements in tropical cyclone track and intensity

forecasts in all global oceanic basins compared to the current

operational HWRF. 


Product Changes:

- Changes to output products include filename changes, domain

increases for some output grids, resolution changes for some

output grids, and the removal of some obsolete products. 

Details are provided below.


The file naming convention in the 2015 version of HWRF is

changed to include domain and resolution information in the file


2015 HWRF        2016 HWRF                Change

parent domain:

*hwrfXX.d1.0p20*   *hwrfXX.synoptic.0p125* resolution increase

                                           from .2 to 0.125 deg

global domain:

*hwrfXX.d123.0p25* **    filename change

outer-nested domain:

*hwrfXX.d2.0p06*   *hwrfXX.storm.0p02*    domain increase to 

                                          25x25, resolution            

                                          increase to 0.02 deg

inner-nested domain:

*hwrfXX.d3.0p02*   *hwrfXX.core.0p02*    domain increase to



The following grids are being removed due to resolution

increases or the information being duplicative of the products

listed above:

*hwrfXX.d123.0p06*        global domain at lower resolution

*hwrfprs.d123.0p06*        combination of 18/6/2 km grids

*hwrfsat.d12.0p06*         combination of 18/6/2 km grids

*hwrfXX.d23.0p02*          combination of 6/2 km grids

In the above examples hwrfXX is either hwrfprs (pressure level

output of atmospheric variables including surface variables) or

hwrfsat (synthetic satellite brightness temperatures).

Additional products and their contents:

Additional simulated synthetic imagery from different satellite

sensors will be included in *hwrfsat* output files in order to

provide global coverage for all oceanic basins, including:


GOES-13 for North Atlantic;

GOES-15 for East, Central Pacific;

SEVERI for South, East Atlantic, and Indian Ocean;

HIMIWARI (MTSAT-2 in 2015 version) for West, Central Pacific;

DMSP/F17 SSMI/S for All basins;

InSat-3D/Kalpana for Indian Ocean.


The variables in the non-satellite output files (*hwrfprs*) will

remain the same as 2015 HWRF.


The HWRF GRIB2 products are disseminated via the NWS and NCEP

FTP servers and NOMADS and are not available on NOAAPORT or



More details about the HWRF-MPIPOM are available at:


NCEP Central Operations has supplied a set of sample output for

a recent storm so that users can examine the new filenames and

output formats.  Data is available at


in the directories hwrf.YYYYMMDDCC, where YYYYMMDDCC is the

year, month, day and cycle.


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. Avichal Mehra or Dr. Vijay Tallapragada

  NOAA/NCEP/Environmental Modeling Center

  Hurricane Forecast Project

  National Centers for Weather and Climate Prediction

  College Park, Maryland, 20740 

  Tel: 301-683-3746 (Avichal) 301-683-3672 (Vijay)



For questions regarding the data flow aspects of these data

sets, please contact:


  Carissa Klemmer

  NCEP/NCO Dataflow Team Lead

  College Park, MD



NWS National Technical Implementation Notices are online at: