NOUS41 KWBC 311335 AAA

PNSWSH

 

Service Change Notice 17-83 Updated

National Weather Service Headquarters Silver Spring MD

935 AM EDT Mon Jul 31 2017

 

To:      Subscribers: 

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network

          -NOAAPORT

          -Other NWS Partners, Users and Employees

 

From:     Dave Myrick

          NWS Office of Science and Technology Integration

 

Subject:  Updated: Implementation of the new Hurricanes in a

          Multi-scale Ocean-coupled Non-hydrostatic (HMON)

          Model Version 1.0.0: Effective August 15, 2017

          and request for comments

 

Updated to change implementation date from August 1, 2017, to

August 15, 2017

 

Effective on or about Tuesday, August 15, 2017, beginning with

the 1200 Coordinated Universal Time (UTC) run, the National

Centers for Environmental Prediction (NCEP) will implement the

HMON coupled modeling system.

 

This version, HMON v1.0.0, is the first version for the system.

The release has been fully tested and compared with the

discontinued Geophysical Fluid Dynamics Laboratory (GFDL)

Hurricane Model (GHM) results. It has shown significant skill

improvements in terms of storm track and intensity forecasts in

Northern Atlantic (NATL) Basin, Eastern Pacific Basin (EPAC) and

the Central Pacific (CPAC) Basin. HMON also provides a first

step for the NCEP Environmental Modeling Centers' (EMC) efforts

towards unification of operational models within the NOAA

Environmental Modeling System (NEMS) framework.

 

MODEL DESCRIPTION

 

The scientific and technique details are as follows:

 

- The dynamical core is a Non-hydrostatic Multi-scale Model on a

B grid (NMMB).

- There are 43 vertical levels, where the model top is at 50

hPa.

- It includes vortex relocation, but has no data assimilation.

- Two-way Coupling is with Ocean Model (HYCOM) for EPAC and CPAC

basins; uncoupled for NATL basin.

- The HMON system will provide improved track forecasts in NATL,

EPAC and CPAC basins. HMON also will provide improved intensity

forecasts for NATL, EPAC and CPAC basins. The coupled HMON

system will provide additional ocean products compared with GHM.

 

This model is considered the replacement for the Geophysical

Fluid Dynamics Laboratory (GFDL) Hurricane Model (GHM). Due to

differences in underlying physics, two variables present in the

GHM grib output will not be produced by HMON, and some others

are being replaced by similar but not identical output. These

differences are detailed in the Model Output section. For more

information on the removal of the GFDL model, please see the

following notices:

http://www.nws.noaa.gov/os/notification/pns17-07gfdl.htm

http://www.nws.noaa.gov/os/notification/scn17-45discontinue_gdflaaa.htm

 

The 2017 HMON system has been fully tested and compared with the

forecast results with 2016 operational GHM. HMON has shown

significant skill improvement in intensity and track forecasts

in NATL, EPAC and CPAC basins. A PowerPoint presentation

explaining the new HMON model and comparing its results to GHM

can be found here:

http://www.emc.ncep.noaa.gov/gc_wmb/vxt/LinZhu/HMON_stats/FY17_HMON_OD_brief_042817.pptx

 

MODEL OUTPUT INFORMATION

 

HMON output will be available beginning Aug 1, 2017, on the

following NCEP web services:

 

http://nomads.ncep.noaa.gov/pub/data/nccf/com/hur/prod/

http://www.ftp.ncep.noaa.gov/data/nccf/com/hur/prod/

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/hur/prod/

 

Parallel data will be available beginning June 28, 2017 on a

storm by storm basis here:

 

http://para.nomads.ncep.noaa.gov/pub/data/nccf/com/hur/para/

 

The directory structure will be:

  hmon.YYYYMMDD

  Where YYYY is year, MM is month, and DD is day

 

A) HMON GRIB files will be available for the following domain

resolutions:

  1. domain 01 = 75 deg x 75 deg grid, resolution 0.20 deg

    NAMEID.YYYYMMDDCC.hmonprs.d1.0p20.fFFF.grb2

      Where NAMEID is storm name and storm identification

number. CC is cycle output (00z, 06z, 12z, 18z). FFF is forecast

hour valid from 000-126 at 3 hourly intervals.

 

  2. d02 = 12 deg x 12 deg grid, resolution 0.06 deg

    NAMEID.YYYYMMDDCC.hmonprs.d2.0p06.fFFF.grb2

      Where NAMEID is storm name and storm identification

number. CC is cycle output (00z, 06z, 12z, 18z). FFF is forecast

hour valid from 000-126 at 3 hourly intervals.

 

  3. d03 = 8 deg x 8 deg, resolution 0.02 deg

    NAMEID.YYYYMMDDCC.hmonprs.d3.0p02.fFFF.grb2

      Where NAMEID is storm name and storm identification

number. CC is cycle output (00z, 06z, 12z, 18z). FFF is forecast

hour valid from 000-126 at 3 hourly intervals

 

NOTE: As stated above, HMON grib2 output will have most of the

same variables currently present in GFDL/GHM with these

differences:

 

   - Missing with no replacement due to differences in

underlying model physics

     * Graupel [kg/kg]

     * Temperature Tendency by All Physics [K/s]

 

   - Replaced

     * Geometric Height [m] - Replaced by Geopotential Height

     * Ice Water Mixing Ratio [kg/kg] - Replaced by Cloud Ice

     * U Component of Hourly Maximum 10m Wind Speed [m/s] -

Replaced by max wind U-Component of wind, saved in the grib

output as “max wind” level for U-wind

     * V Component of Hourly Maximum 10m Wind Speed [m/s] -

Replaced by max wind V-Component of wind, saved in the grib

output as “max wind” level for V-wind

     * Humidity Mixing Ratio [kg/kg] - Replaced by specific

humidity

 

B) Track file in atcf format

   NAMEID.YYYYMMDDCC.trak.hmon.atcfunix

    Where NAMEID is the storm name and identification, CC is the

cycle.

 

C) Swath text files at 0.03 deg resolution

   NAMEID.YYYYMMDDCC.precip.asci

    file maximum 10m wind: NAMEID.YYYYMMDDCC.sfcwind.asci

 

D) Intensity & track text files

   afos format: NAMEID.YYYYMMDDCC.afos

       variables:  hour, latitude, longitude, heading/speed

   stats format: NAMEID.YYYYMMDDCC.stats.tpc

       variables:  hour, latitude, longitude, minimum surface

pressure, maximum surface wind

   stats short format: NAMEID.YYYYMMDDCC.grib.stats.short

       variables: hour, longitude, latitude, minimum surface

pressure, maximum surface wind

 

More details about the HMON system are available at:

 

http://www.emc.ncep.noaa.gov/gc_wmb/vxt/HMON/index.php

 

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.

 

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

  Lead Physical Scientist

  NOAA/NCEP/Environmental Modeling Center

  National Centers for Weather and Climate Prediction

  College Park, Maryland, 20740. 

  Tel: 301-683-3746

  E-Mail: avichal.mehra@noaa.gov

 

For questions regarding the data flow aspects of these data

sets, please contact:

 

     Carissa Klemmer

     NCEP/NCO Dataflow Team Lead

     College Park, MD

     301-683-0567

     ncep.list.pmb-dataflow@noaa.gov

 

NWS Service Change Notices are online at:

 

  http://www.nws.noaa.gov/os/notif.htm

 

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