NOUS41 KWBC 131915 AAC

PNSWSH

 

Technical Implementation Notice 16-41 Updated

National Weather Service Headquarters Silver Spring, MD

315 PM EDT Mon Mar 13 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: Upgrade to the North American Mesoscale (NAM)   

          Forecast System and Discontinuation of Downscaled GFS

          by NAM Extension (DGEX) Forecast System Effective

          March 21, 2017

 

Updated to change the implementation date from March 15, 2017,

to March 21, 2017, due to critical weather declaration

 

Effective on or about March 21, 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.

 

* Discontinue all DGEX model output

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

* Make resolution changes for NAM nests

* Implement major changes to NAM Data Assimilation System (NDAS)

* Implement model changes: convection, microphysics, land-

surface upgrades; frequency of physics calls increased

 

- FORECAST MODEL CHANGES

 

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

(from 6 to 3 km), and CONUS fire weather (from 1.333 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) Updated Ferrier-Aligo microphysics to improve stratiform

precipitation, better anvil reflectivity, reduce areas of

light/noisy reflectivity over oceans

6) Improved effect of frozen soil on transpiration and soil

evaporation, leads 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 tropical 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) The output grid for nests will change:

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

HRRR (see link below for difference)

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

   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) All NAM nests grids will be output 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) Added 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) Ceiling height (HGT) in the NAMv4 is changed from height

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

files

 

6) The NAM 12km CONUS grid #218 file will be renamed

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

 

7) The 0.108 deg lat/lon Caribbean grid will be renamed

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

 

8) The 0.108 deg lat/lon Hawaii grid will be renamed

  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. In NAMv4 it is being renamed and

will 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,

this contains mostly surface fields that will not be in the new

awak3d file:

  nam.tCCz.awp242FF.tm00.grib2

 

10) The GRIB2 labeling for 0-6 km integrated vertical u- and v-

components of the wind shear is changing from "6000-0 m above

ground" to "0-6000 m above ground"), this field is output in the

following grids:

  nam.tCCz.awak3dFF.tm00.grib2

  nam.tCCz.awip3dFF.tm00.grib2

  nam.tCCz.awipakFF.tm00.grib2

  nam.tCCz.awphysFF.tm00.grib2

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

ib2

 

11) The GRIB2 sigma value label for 0.33-0.67 sigma RH and 0.67-

1.00 sigma RH will change to 0.33-0.66 sigma RH and 0.66-1.00

sigma RH in the following grids:

  nam.tCCz.awipakFF.tm00.grib2

  nam.tCCz.grbgrdFF.tm00.grib2

 

12) The GRIB2 sigma level label for 0.7848 sigma temperature and

0.8967 sigma temperature will change to 0.78483 sigma

temperature and 0.89671 sigma temperature for the following

grids:

  nam.tCCz.awip32FF.tm00.grib2

  nam.tCCz.awipakFF.tm00.grib2

  nam.tCCz.grbgrdFF.tm00.grib2

 

13)  With the NAM Alaska nest horizontal grid resolution

changing from 6 km to 3 km, it will no longer run with

convective parameterization. Therefore the following convective-

type fields will no longer be output for the Alaska nest:

  Accumulated convective precipitation

  Convective precipitation rate

  Convective cloud top/bottom pressure

  Deep convective cloud top/bottom pressure

  Shallow convective cloud top/bottom pressure

  Total convective cloud cover

  Deep convective heating rate

 

14) The total snow water equivalent on the ground will be added

to the file:

  nam.tCCz.awip20FF.tm00.grib2

 

15) The GRIB2 processing for the NAM nests has been streamlined

so that all 6 NAM nests will output the same variables. Thus,

the following fields that are now only available from the NAM

CONUS nest will also be output from the Alaska, Hawaii, Puerto

Rico, and Fire weather nests:

  80 meter above ground pressure, specific humidity,

temperature, and wind

  0-6 km integrated vertical u- and v-components of the wind

shear

  Vertically-integrated liquid water

As part of the streamlining of the GRIB2 processing for the NAM

nests, the following variables will be removed from the output

grid for the NAM Fire Weather nest:

  Dew point temperature on pressure levels except for 300, 400,

500, 700, 850, 925, and 1000mb

  Dew point temperature at the 1st and 2nd model levels above

ground

  Absolute vorticity at 200 and 300mb levels

  Vertical velocity, relative humidity, and specific humidity at

2, 5, 7, 70mb levels

  Turbulent kinetic energy at 2, 5, 7, 10, 20mb levels

  Cloud ice, cloud water, rain, and snow mixing ratio and rime

factor at 2, 5, 10, 20, 70mb levels, and on the 2nd model level

above ground

  Grid-point latitude and longitude

  PBL Regime

  1-h average non-convective cloud cover

  Equivalent radar reflectivity factor for snow and rain

  1-h average total cloud cover

  Height, pressure, temperature, and reflectivity on the 2nd

model level above ground

 

16) NAMv4 output files on the NCEP/NWS web servers will be

written as GRIB2 format from the post-processing, instead of

first being written out in GRIB1 format and converted to GRIB2.

The GRIB2 compression type for each NAM domain will be as

follows:

  JPEG2000: Hawaii, Puerto Rico and Fire Weather nests

  Complex packing with 2nd order spatial differencing: CONUS

nest, Alaska nest and all output from 12km NAM parent domain

 

Variables in those grids created with GRIB2 complex compression

may occasionally contain invalid negative numbers.

 

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

 

17) The number of days archived on the NCEP web services will be

changed from 28 days to 7 days.

 

18) Based on feedback from PNS 16-43, remove NAM-driven Great

Lakes Wave (GLW) model, on this date the following products will

be removed from /com/wave/prod/glw.YYYYMMDD/:

  glw.tCCz.spec_tar.gz

  glw.grlc_2p5km.tCCz.grib2

  glw.wstp.grlc_2p5km.tCCz.grib2

  Several bulletins provided within glw.tCCz.bull_tar

  Several bulletins provided within glw.tCCz.cbull_tar

  Several bulletins provided within glw.tCCz.csbull_tar

  Several bulletins provided within directory bulls.tCCz

Where CC is cycle at 00, 06, 12 and 18Z

 

- PRODUCT REMOVALS FROM WEB SERVICES

 

NCEP solicited public feedback through the 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 removed from the NWS servers and can

instead by found on the NCEP 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

  fh.00FF_tl.press_gr.awip12

  fh.00FF_tl.press_gr.awipak

  fh.00FF_tl.press_gr.grbgrd

  fh.00FF_tl.press_gr.icwf20

  fh.00FF_tl.press_gr.icwf3d 

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

servers as direct grib output or by using NOMADS grib filter and

are encouraged to transition to the NCEP servers at any time.

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.grib2

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 GRIB1 NAM grid 215 products under directory

"PT.grid_DF.bb/" on the NWS web servers.

 

- NOAAPORT PRODUCT TERMINATIONS

NCEP solicited public feedback through the 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) All 00z and 12z cycle NAM FAX charts will be removed

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

UPA                            PYMA[357]0 KWBC

UPA                            PYMA[28]5 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.shtml

 

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

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

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

3) 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,

please 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

 

NNNN