NOUS41 KWBC 291418



Technical Implementation Notice 14-19

National Weather Service Headquarters Washington DC

1020 AM EDT Tue Apr 29 2014


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:  Hurricane Weather and Research Forecast

          (HWRF) Model Changes: Effective June 3, 2014


Effective on or about Tuesday, June 3, 2014, 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 vertical resolution of the HWRF atmospheric model

from 43 to 61 levels and raise the model top from 50 hPa to 

2 hPa, expand the size of the 9km domain by 20 percent (from

10 degrees x10 degrees  to 12 degrees x 12 degrees) and 3km domain

by 10 percent (from 6.5 degrees x 6.5 degrees to 7.1 degrees

x 7.1 degrees).


-Upgrade the nest movement algorithm to generate storm total

rain and wind swath products directly from the model output.

-Upgrade WRF NMM core to WRF community version V3.5.1.

-Upgrade the ocean model (POM) to 1/12 degrees MPI POM with unified

trans-Atlantic basin, and for the first time, 3D ocean for

Eastern Pacific basin. 


-Make further improvements to HWRF vortex initialization scheme

including cycling the invests to prevent cold start for a

named/numbered storm

-Improve HWRF Data Assimilation System through upgrade of one-

way hybrid EnKF-3DVAR GSI to community version V3.3, data

assimilation to include all conventional and satellite radiance

data and aircraft Tail Doppler Radar (TDR)/Dropsonde data in the

9km domain; only conventional, TDR and Dropsonde data in the 3km


-Add operational forecast products from HWRF to include tornado

probability forecasts and new variables for  downstream

applications (hurricane wave model)

-Fix bugs and enhancements for the GFDL vortex tracker


The 2014 HWRF model configuration has been extensively tested

with a combination of all the upgrades listed above for a 6-year

sample of cases (2008-2013) and the results showed that for

Atlantic basin track and intensity, the 2014 HWRF showed about

10 percent improvement compared to the current operational HWRF. 


Product Changes:


-ASCII files of storm total wind and rain swath will have twice

the resolution (0.05o) than the current operational products


-HWRF tracker output (ATCF) will now include hourly data for the

first 9 hours and 3-hourly for rest of the forecast period.

-The auxiliary history files for wave model in binary format

(out4wave_d01, out4wave_d02 and out4wave_d03) will be replaced

by new files in netCDF format (wrfdiag_d01, wrfdiag_d02 and



Additional products and their contents:


-3D fields in all GRIB2 files will now have 6 additional levels

(30, 20, 10, 7, 5 and 2 hPa)

-The following fields will be added to the GRIB2 files:


    CIN (Convective Inhibition)

    Storm Relative Helicity

    19GHz simulated brightness temperature from SSMI/S F17 (both

        vertical and horizontal polarizations)

    Rime factor on pressure surface

-The auxiliary history files (wrfdiag_d01, wrfdiag_d02 and

wrfdiag_d03) will include the following additional fields:

    Incoming/Outgoing Radiation

    SST, fluxes for sensible heat, latent heat and momentum

    Lowest model level temperature and height

    Tornado genesis


More details about the HWRF-MPIPOM are available at:


The HWRF GRIB2 products are disseminated via the NCEP FTP server

and are not available on NOAAPORT or AWIPS.


These changes will result in up to a 12-minute delay in product

dissemination time. A change in delivery time was proposed in an

NWS Public Information Statement issued March 25, 2014. Based on

the responses received, NWS will move forward with this change

in dissemination time of the HWRF products.


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

  College Park, Maryland, 20740. 



NWS National Technical Implementation Notices are online at: