NOUS41 KWBC 111930



Technical Implementation Notice 15-25

National Weather Service Headquarters Washington DC

320 PM EDT Mon May 11 2015


To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS Partners, Users and Employees


From:     Timothy McClung

          Chief Operating Officer

          NWS Office of Science and Technology Integration


Subject:  Hurricane Weather and Research Forecast

          (HWRF) Model Changes Effective June 9, 2015


Effective on or about Tuesday, June 9, 2015, 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:


- Increase the horizontal resolution of all three domains of the

HWRF atmospheric model from 27km/9km/3km to 18km/6km/2km and

upgrade the WRF Nonhydrostatic Mesoscale Model (NMM) core to

community version V3.6.1

- Upgrade and improve HWRF vortex initialization scheme and pre-

processing system in response to increased resolution of both the

Global Forecast System (GFS) and the HWRF models

- Improve HWRF Data Assimilation System through upgrade of one-

way hybrid Ensemble Kalman Filter-Three Dimensional Variational

(EnKF-3DVAR) Gridpoint Statistical Interpolation (GSI) to

Environmental Modeling Center (EMC) GSI v5.0.0. Inner core data

assimilation in the 6km and 3km domains will include all

conventional data, NOAA P3 Tail Doppler Radar (TDR) data, and

dropsonde data from NOAA P3, GIV, Air Force Hurricane Hunters and

NOAA/NASA Unmanned Aircraft Systems (Global Hawk) when available.

- Implement new GFS EnKF driven 40-member high-resolution (2km)

HWRF ensembles for TDR data assimilation

- Upgrade and tune HWRF physics to accommodate model resolution

increase: replace Ferrier microphysics with Ferrier-Aligo scheme;

replace Geophysical Fluid Dynamics Laboratory (GFDL) radiation

with Rapid Radiative Transfer Model (RRTMG) and introduce sub-

grid scale cloudiness parameterization in RRTMG; modify

specification of drag coefficient for momentum (Cd) in the

parameterization of surface physics and air-sea interactions;

improve GFS Planetary Boundary Layer (PBL) with specification of

wind-speed dependent vertical mixing; and replace GFDL slab model

to more advanced NOAH Land Surface Model

- Add simulated brightness temperatures for new satellite sensors

in all global basins as an additional operational forecast


- For the first time, expand operational HWRF capabilities by

increasing the maximum number of model runs at any given time

from 5 to 7 and to run year-long, providing forecast guidance for

all global tropical cyclones including in the Western North

Pacific, Southern Pacific, North and South Indian Oceans.  HWRF

model will run uncoupled in all basins except North Atlantic and

Eastern North Pacific.

- Implement operational HWRF workflow using complete Python based

scripts for more efficient and unified system that runs in all



The 2015 HWRF model configuration has been extensively tested

individually and with a combination of all the upgrades listed

above for a 4-year period (2011-2014). The results showed further

improvements in Atlantic Hurricane intensity forecasts by about

10 percent compared to the current operational HWRF. 


Product Changes:

- File name Changes.

The file naming convention in the 2015 version of HWRF has

changed to include domain and resolution information and to

include a 3-digit forecast hour for all hours in the file name.


    2014 HWRF                 2015 HWRF


*.hwrfprs_p.grb2f* ---> *.hwrfprs.d1.0p20.fhhh.grb2

*.hwrfsat_p.grb2f* ---> *.hwrfsat.d1.0p20.fhhh.grb2


*.hwrfprs_n.grb2f* ---> *.hwrfprs.d3.0p02.fhhh.grb2

*.hwrfsat_n.grb2f* ---> *.hwrfsat.d3.0p02.fhhh.grb2


*.hwrfprs_i.grb2f* ---> *.hwrfprs.d2.0p06.fhhh.grb2

*.hwrfsat_i.grb2f* ---> *.hwrfsat.d2.0p06.fhhh.grb2


*.hwrfprs_m.grb2f* ---> *.hwrfprs.d23.0p02.fhhh.grb2

*.hwrfsat_m.grb2f* ---> *.hwrfsat.d23.0p02.fhhh.grb2


*.hwrfprs_c.grb2f* ---> *.hwrfprs.d123.0p20.fhhh.grb2

*.hwrfsat_c.grb2f* ---> *.hwrfsat.d123.0p20.fhhh.grb2


- New output files.


*.hwrfprs.d123.0p25.fhhh.grb2: similar to *.hwrfprs_c.grb2f* but

in GFS global domain (NCEP GRID 193, 1440x721 lon/lat, 0.25 deg)


*.hwrfsat.d123.0p25.fhhh.grb2: similar to *.hwrfsat_c.grb2f* but

in GFS global domain (NCEP GRID 193, 1440x721 lon/lat, 0.25 deg)


where hwrfprs is pressure level output of atmospheric variables

including surface variables, hwrfsat is synthetic satellite

brightness temperatures, and hhh is the 3-digit forecast hour

(000, 003, 006, ... , 012, 015, 018, ... , 120, 123, 126).  All

the output files will be in GRIB2 format; 0p02, 0p06, 0p20, and

0p25 indicate domain resolutions in lat/lon grid.

- 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;

MTSAT-2 for West, Central Pacific;

DMSP/F17 SSMI/S for All basins;

InSat-3D/Kalpana for Indian Ocean.


The content of non-satellite output files (*hwrfprs*) will remain

the same as 2014 HWRF.


The HWRF GRIB2 products are disseminated via the NCEP FTP server

and are not available on NOAAPORT or AWIPS.


More details about the HWRF-MPIPOM 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

  NOAA/NCEP/Environmental Modeling Center

  Hurricane Forecast Project

  National Centers for Weather and Climate Prediction

  College Park, Maryland, 20740. 

  Tel: 301-683-3672



NWS National Technical Implementation Notices are online at: