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NOUS41 KWBC 221450

Technical Implementation Notice 16-27
National Weather Service Headquarters Washington DC
1050 AM EDT Fri Jul 22 2016

To:  Subscribers:
 -NOAA Weather Wire Service
 -Emergency Managers Weather Information Network
 Other NWS Partners and Employees

From: Timothy McClung
 Portfolio Manager
 Office of Science and Technology Integration

Subject: RTMA, URMA, NAM DNG and SREF Upgrade:
 Effective August 23, 2016

Effective on or about Tuesday, August 23, 2016, beginning with
the 1200 Universal Coordinated Time (UTC) cycle (15Z cycle for
the SREF), the National Centers for Environmental Prediction
(NCEP) will upgrade the Real-Time Mesoscale Analysis (RTMA), Un-
Restricted Mesoscale Analysis (URMA), and North American Model
(NAM) Downscaled Numerical Guidance (DNG) and make minor product
modifications to the Short-Range Ensemble Forecast (SREF)
System.  The changes include some scientific changes and product
changes. They are outlined below for each modeling system.


- Replace the current terrain and land/sea mask used in the
system with the new EMC/GFE consensus terrain and land/sea mask
in the 2.5km CONUS domain. The use of the common terrain and
land/sea mask will eliminate the need for NWS forecasters to
reduce the RTMA and URMA analyses to their local GFE terrain.

- Improve the CONUS and Alaska grids of wind speed by analyzing
wind speed directly as a scalar, as opposed to deriving it from
the control variables of stream function and velocity potential.

- Produce new URMA output for Hawaii and Puerto Rico on 2.5km
grids.These new URMA systems will provide "truth analyses" for
the National Blend of Models Project. The output will contain
analysis and analysis uncertainty for the following parameters:
Surface pressure, 2m-temperature, 2m-dewpoint, 2m-specific
Humidity, 10-m u-wind component, 10m-v wind component, 10-m wind
speed, 10-m wind direction, 10-m gust, and surface visibility.
At this time these products will only be available on the NCEP
ftp server at: and

in subdirectories hiurma.YYYYMMDD and prurma.YYYYMMDD.The
filenames will be:


where 2dvarges is background/first guess, 2dvaranl is analysis
and 2dvarerr is analysis uncertainty, YYYYMMDD is year, month,
day and CC is cycle from 00-23.

- Add GRIB2 files for Cloud Ceiling Height (CEIL) analysis (anl)
and Cloud Ceiling Height analysis uncertainty (err) for RTMA and
URMA for the 2.5km CONUS grids only.  At this time these
products will only be available on the NCEP ftp server at: and

The filenames will be:


where 2dvaranl is analysis and 2dvarerr is analysis uncertainty,
CC is cycle from 00-23, and ndfd and nwrfc denote which CONUS
grid is used.

GRIB2 files for CEIL should be considered experimental at this
time.  After sufficient evaluation, if these fields are promoted
to operational, we will put these fields into the larger
RTMA/URMA output files and no longer have them in separate

- Add URMA-CONUS grids of maximum temperature (TMAX) and minimum
temperature (TMIN) to NDGD at:

   file name - ds.maxt.bin  MAX temperature
   file name -  MIN temperature

and to NOAAPORT with the following WMO headers:

    LTQA98 KWBR URMA TMAX or TMIN Analysis
    LTQA98 KWBR URMA TMAX or TMIN Analysis Uncertainty

The MAX temperature grid is only available from the 08Z cycle
run and the MIN temperature from the 20Z cycle run.

NAM DNG Changes

- Replace the current terrain and land/sea mask used in the
system with the new EMC/GFE consensus terrain and land/sea mask
for the 2.5km CONUS domain.

- Modify the wind gust calculation at intermediate hours
(1,2,4,5, etc) to use the maximum of the NAM nest wind gust and
downscaled wind speed.This calculation is already done at the
0,3,6, etc forecast hours and this change will make it
consistent across all forecast hours.

- Add new variables Cloud Ceiling height [gpm], and Mean Sea
Level Pressure (Eta model reduction) [Pa] to the 2.5km CONUS,
3km Alaska, Puerto Rico and Hawaii NAM DNG files on the NCEP ftp

- Add hourly output of Total Cloud Cover field for all NAM DNG
domains.  It was previously available only every 3 hours.
- Remove the 5km CONUS and 6km AK NAM DNG GRIB files from the
NCEP servers. These products have been replaced by the 2.5km
CONUS and 3km Alaska products.

Removed: nam.YYYYMMDD/nam.tCCz.smartconusFF.tm00.grib2
Replacement: nam.YYYYMMDD/nam.tCCz.smartconus2p5FF.tm00.grib2

Where CC is cycle and FF is forecast hour

- Modify the GRIB encoding for the Haines Index fields to use
the value 9.9 x 10^10 for the missing value.

SREF Changes
- Update the SREF ensemble mean, probability and spread products
on NOAAPORT to add the 0-3h accumulated precipitation parameter,
which is erroneously being skipped.

- Add the following fields to all of the SREF output grids
(grids 132, 212, 216, 221 and 243) on the NCEP ftp server at:

Water Equivalent of Snow Depth (both instantaneous and 3-hourly
Snow Depth

- Increase the forecast hours available in the probability files
available on the NCEP ftp server for grid 132 from 72 hours to
87. The filename is sref.tCCz.pgrb132.prob_3hrly.grib2

Real-time sample parallel data for the RTMA/URMA and NAM is
available via the following URLs:

More information about the RTMA and URMA update is available at:

Parallel RTMA:

Parallel URMA:

Operational RTMA:

Operational URMA:

Parallel vs. Ops RTMA:

Parallel vs. Ops URMA:

For questions regarding these changes, please contact:

   Geoff DiMego (
   NCEP/EMC Mesoscale Modeling Branch
   College Park, Maryland

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

   Carissa Klemmer
   NCEP/NCO Dataflow Team
   College Park, Maryland

NWS National Technical Implementation Notices are online at: is the U.S. government's official web portal to all federal, state and local government web resources and services.