NOUS41 KWBC 121120

PNSWSH

 

Technical Implementation Notice 16-41

National Weather Service Headquarters Washington DC

720 AM EST Mon Dec 12 2016

 

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:  Upgrade to the North American Mesoscale (NAM) Forecast

          System and Discontinuation of Downscaled GFS by NAM

          Extension (DGEX) Forecast System Effective 

          February 1, 2017

 

Effective on or about February 1, 2017, beginning with the 

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

for Environmental Prediction (NCEP) is proposing to implement

Version 4 of North American Mesoscale (NAM) and discontinue the

Downscaled GFS by NAM Extension (DGEX) Forecast System. Changed

include the following:

 

- Discontinue all DGEX model output

- Remove legacy NAM products on NOAAPORT and NCEP/NWS servers

- Make resolution changes for NAM nests

- Make major changes to the NAM Data Assimilation System (NDAS)

- Make model changes to convection, microphysics, land-surface

upgrades; frequency of physics calls increased

 

FORECAST MODEL CHANGES

 

1) Resolution changes to the CONUS (from 4 km to 3 km), Alaska

(from 6 km to 3 km), and CONUS fire weather (from 1.333 km to 

1.5 km) nests

2) More frequent calls of physics (now every 2nd time step for

all domains); change frequency of radiation updates for the NAM

12 km parent domain from hourly to every 20 minutes

3) Advect specific humidity every dynamics time step

4) Changes to Betts-Miller-Janjic convective scheme to improve

12 km parent QPF bias, especially during the cool season

5) Update Ferrier-Aligo microphysics to improve stratiform

precipitation, better anvil reflectivity, reduce areas of

light/noisy reflectivity over oceans

6) Improve effect of frozen soil on transpiration and soil

evaporation, leading to reduced cold/moist bias during cool

season

7) Radiation/microphysics changes to reduce incoming surface

shortwave radiation; reduced warm-season 2-m temperature bias

 

 

DATA ASSIMILATION / ANALYSIS CHANGES

 

1) Replace 12-h NAM Data Assimilation System (NDAS) with 

3-h analysis updates for the 12 km parent domain with a 6-h data

assimilation cycle with hourly analysis updates for the 12 km

parent and the 3 km CONUS/Alaska nests. The Hawaii/Puerto

Rico/Fire weather nests will be initialized from the 12-km first

guess at the end of 6-h assimilation cycle.

2) Use of lightning data (from NLDN and ENL networks) and radar

reflectivity-derived temperature tendencies in the diabatic

digital filter initialization.

3) Add execution of the diabatic digital filter initialization

prior to the NAM forecast (was only run during NDAS in current

ops NAM version 3).

4) Assimilate new observation types:

  - Aircraft data: Aeromexico, ADS-C, Air-Wisconsin

  - New satellite radiance data: NOAA NPP (ATMS, CRIS),

    METEOSAT-10 SEVIRI, DMSP-F17 SSMIS; METOP-B AMSUA, MHS,

    IASI

  - New GPS Radio Occultation data: METOP-B 3 (subtype)

  - New satellite winds: Himawari-B, METEOSAT-7, 10 Imager WV

AMV, 

    NOAA-15, 18, 19 AVHRR IR AMV, METOP-A, B AVHRR AMV

 

 

OTHER SCIENCE CHANGES

 

1) Reinstate use of 557th Weather Wing (formerly AFWA) 23 km

snow depth analysis using envelope adjustment.

2) Use a new climatology of fresh water lake temperatures

(FLAKE) for inland water bodies not resolved by the 1/12th

degree RTG_SST_HR analysis in the CONUS, Alaska and Fire weather

nests

3) Reduce terrain smoothing in all NAM nest domains

3) Use NESDIS burned area data (30-day and 2-day average) in the

fire weather nest; greenness fraction and albedo are adjusted

based on the 30-day average, top-layer soil moisture based on

the 2-day average

4) Perform rropical cyclone relocation for the 12 km parent

domain at the start of the 6-h catchup cycle and for the NAM

forecast first guess.

 

 

OUTPUT CHANGES TO WEB SERVICES

 

Files below can be found on the following NCEP services:

  nomads.ncep.noaa.gov/pub/data/nccf/com/nam

  www.ftp.ncep.noaa.gov/data/nccf/com/nam

  ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/nam

 

1) Change output grid for nests:

CONUS nest: change from grid #227 to the same output grid as the

HRRR (see

http://www.emc.ncep.noaa.gov/mmb/namgrids/conusoutgrid.jpg” for

difference)

  nam.tCCz.conusnest.hiresfFF.tm00.grib2

      Where CC is cycle and FF is forecast hour 00-60

Alaska nest: change from the 6 km NDFD grid to the 3 km NDFD

grid

  nam.tCCz.alaskanest.hiresfFF.tm00.grib2

     

2) Output all NAM nests grids hourly from 0-60 hour; in the

current ops NAMv3 they were output hourly from 0-36h and 

3-h from 39-60 hour.

 

3) Add 1-h maximum precipitation rate (PRATE) and frozen

precipitation rate (SRWEQ) to the following grids:

  nam.tCCz.awip32FF.tm00.grib2

  nam.tCCz.awip12FF.tm00.grib2

  nam.tCCz.awak3dFF.tm00.grib2

  nam.tCCz.##nest.hiresfFF.tm00.grib2

    Where CC is cycle and FF is forecast hour and ## is either:

alaska, conus, prico, hawaii, firewx

 

4) Add a new visibility field based on the GSD algorithm to the

following output grids (this field is labeled with vertical

level=cloud top (VIS)

  nam.tCCz.awip3dFF.tm00.grib2           

  nam.tCCz.awipakFF.tm00.grib2     

  nam.tCCz.awip12FF.tm00.grib2

  nam.tCCz.awphysFF.tm00.grib2

  nam.tCCz.awip32FF.tm00.grib2

  nam.tCCz.awak3dFF.tm00.grib2

  nam.tCCz.awiphiFF.tm00.grib2

 

 

nam.tCCz.(alaska|conus|prico|hawaii|firewx)nest.hiresfFF.tm00.gr

ib2

  Where CC is the cycle time and FF is the forecast hour

 

5) Change ceiling height (HGT) in the NAMv4 from height above

ground level to height above mean sea level for all output files

 

6) Rename the NAM 12km CONUS grid #218 file:

  nam.tCCz.awphysFF.grb2.tm00 -> nam.tCCz.awphysFF.tm00.grib2

 

7) Rename the 0.108 deg lat/lon Caribbean grid: 

  nam.tCCz.afwacaFF.grb2.tm00 -> nam.tCCz.afwacaFF.tm00.grib2

 

8) Rename the 0.108 deg lat/lon Hawaii grid:

  nam.tCCz.afwahiFF.grb2.tm00 -> nam.tCCz.afwahiFF.tm00.grib2

 

9) The current NAM 12km Alaska grid #242 file contains both

surface and upper level data. Rename NAMv4 and change it to 

contain mostly pressure level data:

  nam.tCCz.awak3dFF.grb2.tm00 -> nam.tCCz.awak3dFF.tm00.grib2

 

A second grid #242 file called is being added to the server 

containing mostly surface fields that will not be in the new

awak3d file:

  nam.tCCz.awp242FF.tm00.grib2

 

10) Write NAMv4 output files on the NCEP/NWS web servers as

GRIB2 format from the post-processing, instead of first being

written out in GRIB1 format and converted to GRIB2. Users may

see some differences with the encoding and are encouraged to

upgrade their software to handle this. Please see the links

below for upgraded code:

  http://www.nco.ncep.noaa.gov/pmb/codes/GRIB2

  http://www.cpc.ncep.noaa.gov/products/wesley/wgrib2

  ftp://ftp.cpc.ncep.noaa.gov/wd51we/wgrib

 

11) Change the number of days archived on the NCEP web services

from 28 days to 7 days.

 

 

PRODUCT REMOVALS FROM WEB SERVICES

 

NCEP solicited public feedback through PNS 16-34 NAM Removals.

After balancing user comments with the code management of the

production suite the following changes will be made:

 

http://www.nws.noaa.gov/om/notification/pns16-34nam_removalaaa.htm

 

Files below can be found on the following

NCEP servers via

  nomads.ncep.noaa.gov/pub/data/nccf/com/nam

  www.ftp.ncep.noaa.gov/data/nccf/com/nam

  ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/nam

 

Or NWS servers via

  http://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.nam_CY.CC

  ftp://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/MT.nam_CY.CC

 

1) NAM Products listed will be discontinued from all NCEP web

services

  nam.tCCz.awip12FF.tm00.10m.uv.grib2

  nam.tCCz.awp217FF.tm00_icwf.grib2

  nam.tCCz.awipakFF.tm00_icwf.grib2

  nam.tCCz.awip218tiles_fFF.grib2.tar.gz

  nam.tCCz.awip32tiles_fFF.grib2.tar.gz

  tiles.tCCz directory

    NOTE: Users who wish to obtain a subset of NAM grids can

generate then directly using the grid sub setting option on the

NCEP NOMADS server at http://nomads.ncep.noaa.gov (click on

“grib filter” option)

  nam.tCCz.grb5fmFF.tm00.grib2

  nam.tCCz.grb_fmFF.tm00.grib2

    NOTE: Users can replace these with the 90 km North American

polar stereographic grid #104:  nam.tCCz.grbgrdFF.tm00.grib2

  nam.tCCz.smartconusFF.tm00.grib2

  nam.tCCz.smartakFF.tm00.grib2

    NOTE:  Users should instead be using the higher resolution

2.5/3km NAM DNG products

 

2) The following will be discontinued from the NWS servers:

  fh.00FF_tl.press_gr.awp218

  fh.00FF_pa.sw10m_tl.press_gr.awip12

  fh.00FF_tl.press_gr.awip20

  fh.00FF_tl.press_gr.awip3d

  fh.00FF_tl.press_gr.awp211

    NOTE: Users can access these data sets on the NCEP servers

as direct grib output or by using NOMADS grib filter. Please

reference this page for file name changes:

  http://www.nco.ncep.noaa.gov/pmb/products/nam/

 

3) The ndas.YYYYMMDD directories on the NCEP servers will be

discontinued. All grids and BUFR observation files from the

NAMv4 6-h assimilation cycle will be written into the

nam.YYYYMMDD directory. Since the 12-h NDAS will be replaced by

a 6-h data assimilation cycle with hourly analyses, the grid

#212 files from the current NDAS, for example:

./ndas.YYYYMMDD/ndas.tCCz.awip3d(00|01|02|03).tm12|09|06|03.grib

2 will be replaced by:

./nam.YYYYMMDD/nam.tCCz.awip3d(00|01).tm06|05|04|03|02|01.grib2

where YYYYMMDD is the cycle date, CC the cycle time

 

4) All DGEX model output from the NCEP servers under

dgex/prod/dgex.YYYYMMDD will be discontinued. The DGEX model

will no longer be run within the NCEP model suite.

  Where YYYYMMDD is year, month, day

 

5) Remove the NAM grid 215 products under directory

“PT.grid_DF.bb/” on the NWS web servers.

 

NOAAPORT PRODUCT TERMINATIONS

 

NCEP solicited public feedback through PNS 16-34 NAM Removals.

After balancing user comments with the code management of the

production suite the following changes will be made:

 

http://www.nws.noaa.gov/om/notification/pns16-34nam_removalaaa.htm

 

1) 00z and 12z cycle FAX charts

Description                 WMO Headers

00 Hour 200MB Isobar/Temp     QHUA17 KWBC

00 Hour 500MB Isobar/Temp     QHTA11 KWBC

00 Hour 700MB Isobar/Temp     QHTA07 KWBC

00 Hour 850MB Isobar/Temp     QHUA04 KWBC

Analysis 300MB Isobar         QHUA15 KWBC

This legacy code can no longer be supported on the next

generation supercomputer. If users are interested in the code to

create the charts, please contact EMC below. NCEP will also

investigate the possibility of the MAG creating replica charts.

 

Please see the link below for the exact WMO headers for 

items 2-4:

http://www.nco.ncep.noaa.gov/pmb/changes/nam_TIN_AWIPS_grids.sht

ml

 

2) Removal of the lower resolution only for: NAM NDFD 5km CONUS

(grid 197) and 6km Alaska grids (grid 198)

3) Removal of grid 217, 22 km Alaska region Polar Stereographic

4) Removal of grid 215, 20km Regional CONUS

4) Removal of all DGEX products

 

PARALLEL DATA:

 

A consistent parallel feed of data is available on the NCEP

server via the following URLs:

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

http://para.nomads.ncep.noaa.gov/pub/data/nccf/noaaport/nam

 

For more general information about the NAM, please see:

 

http://www.emc.ncep.noaa.gov/?branch=NAM

 

NCEP urges all users to ensure their decoders can handle changes

in content order, changes in the scaling factor component within

the product definition section (PDS) of the GRIB files, and

volume changes. These elements may change with future NCEP model

implementations. NCEP will make every attempt to alert users to

these changes before implementation.

 

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 the science aspects, please contact:

Eric Rogers

NCEP/EMC/Mesoscale Modeling Branch

College Park, MD

301-683-3682

eric.rogers@noaa.gov

 

For questions regarding the data flow aspects of these datasets, contact:

Carissa Klemmer

NCEP/NCO Dataflow Team Lead

College Park, Maryland 20746

301-683-0567

ncep.list.pmb-dataflow@noaa.gov

 

NWS National Technical Implementation Notices are online at:

 

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

 

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