NOUS41 KWBC 211130



Service Change Notice 17-17

National Weather Service Headquarters Silver Spring, MD

730 AM EST Tue Feb 21 2017


To:       Subscribers:

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS Partners and Employees


From:     Dave Myrick

          NWS Office of Science and Technology Integration


Subject:  RTMA and URMA Upgrade: Effective March 28, 2017


Effective on or about Tuesday, March 28, 2017, beginning with

the 1500 Universal Coordinated Time (UTC) cycle, the National

Centers for Environmental Prediction (NCEP) will upgrade the

Real-Time Mesoscale Analysis (RTMA) and the Unrestricted

Mesoscale Analysis (URMA) as follows:


- Change model components

- Add new product fields, including on NOAAPORT

- Make product output changes


1) Model Changes


A. The following changes are made for RTMA-Continental U.S.


 a) Expand the domain westward by 200 columns (about 500 km)

 b) Change the background field for the cloud ceiling height

analysis from downscaled Rapid Refresh (RAP) forecast to

downscaled High-Resolution Rapid Refresh (HRRR) forecast. The

downscaled RAP is only retained along the edges of the domain

which are not covered by the HRRR. 

 c) Update the accept list for the wind direction-based

observation quality control

 d) Change the background field for visibility in Alaska from a

downscaled North American Mesoscale (NAM) forecast to a

downscaled 1-hour RAP forecast.

Expanding the CONUS domain is in response to a request from the

Ocean Prediction Center. The change also benefits western NWS

Weather Forecast Offices and the National Blend of Models

project. NCEP will continue to disseminate products for the

smaller National Digital Forecast Database (NDFD) CONUS grid and

Northwest River Forecast Center (RFC) grid. The use of the 3-km

HRRR model to provide the background for cloud ceiling

represents an upgrade over the use of the coarser 13-km RAP

model. The updated wind direction-based observation accept list

reflects the most recent wind statistics from the HRRR model

used to provide the background for the wind analysis. Using the

RAP (rather than NAM) forecast to generate the background for

visibility for Alaska allows the use of a shorter-term forecast:

1 hour with RAP, up to 6 hours with NAM. This change also makes

the RAP the primary background model used to generate the

background field over Alaska for all variables.

B. The following changes will be made for the NCEP Stage IV:

 a) NCEP is adding Alaska (AK) and Puerto Rico (PR) Quantitative

Precipitation Estimates (QPE) to the Stage IV/URMA. The AK Stage

IV is 6h/24h; the PR Stage IV is 1h/6h/24h. The 6-hourly AK and

PR Stage IV files are made into precipitation URMA by mapping

them from the RFC's local 4.7km polarstereographic grids to the

AK NDFD grid (3km polarstereographic) and the PR NDFD grid

(2.5km Mercator). The AK/PR Stage IV/URMAs are made/remade

within an hour (at xxhr:33mn hourly run time) of QPE

transmission from RFCs to NCEP, and a final re-run is made 

7 days (e.g., 168hr33mn) after validation time.


On AK Stage IV/URMA: due to the severe lack of reliable

precipitation observations in Alaska, especially in winter, this

QPE is considered qualitative and should be used with caution. 


 b) The CONUS Stage IV 24h (12Z-12Z) will be mosaiced directly

from 24h QPEs from the Northwest RFC and Missouri Basin RFC

(MBRFC falling back to 6h QPE when an 24h QPE is unavailable),

6h QPE from Colorado Basin and California-Nevada RFCs, and 1h

QPE from the other eight central/eastern RFCs. The 24h mosaic

will be made/remade hourly at each run cycle from 12:33 to

23:33Z after the day's validation time (12Z), then remade at

1/3/5/7-days after validation time (at the 12:33Z run).

Currently, the 24h Stage IV is a simple sum of the 6h Stage IV

made at 15:33/21:33/23:33Z after the ending 12Z, then remade at

12:33Z 1/3/5/7 days later.  This change supports the NWS

Advanced Hydrologic Prediction Service. The 24h mosaic will

serve as precipitation source for


2) Changes on web services


The following websites host data:


 a) All precipitation analysis data will be moving from its

current location of

hourly/prod/nam_pcpn_anal.YYYYMMDD -->


   Where YYYY=4 digit year, MM=2 digit month, DD=2 digit day


 b) New precipitation analysis files for Alaska and Puerto Rico

will be available under the new location:


  - Stage IV precipitation analysis output


  - Gif images of the Stage IV precipitation analysis output


  - Precipitation URMA files, mapped from Stage IV to NDFD grids


    Where XX=[01|06|24] for PR, [06|24] for AK, and HH=2 digit


    These files will be available as follows:

-     01h every hour

-     06h when HH=00, 06, 12, and 18

-     24h when HH=12


 c) The following cloud ceiling files will be removed and their

contents combined into existing files as noted below.


From pub/data/nccf/com/rtma/prod/rtma2p5.YYYYMMDD remove:


and its contents, cloud ceiling (CEIL), will move into:



From pub/data/nccf/com/urma/prod/urma.YYYYMMDD remove:


and its contents, cloud ceiling (CEIL), will move into:



3) Additional URMA products over NOAAPORT/Satellite Broadcast

Network. Total precipitation over Alaska and Puerto Rico will be

added; WMO header information will be as follows:


T1T2A1A2ii cccc

  - cccc is KWBR 

  where R is Real Time Mesoscale Analysis / Analysis of Error

  - T1 = L for forecast hours: A=00                    

  - T2 specifies parameter as follows:

      E - Total Precipitation

  - A1 specifies the grid ID as follows:

      C  - grid 195 URMA 2.5 km  (Puerto Rico)

      K  - grid  91 URMA 3.0 km (Alaska)

  - A2 specifies the forecast hour as follows:

      A=00  (Analysis)

  - ii specifies level as follows:

      98 = Surface


The WMO headers for Alaska and Puerto Rico are:

  Alaska is         LEKA98   KWBR

  Puerto Rico is    LECA98   KWBR


4) Product output changes

 a) As noted above, cloud ceiling (CEIL) will be added to the

following files:

 - rtma2p5.tHHz.[2dvaranl|2dvarerr]_[ndfd|nwrfc].grb2

 - urma2p5.tHHz.[2dvaranl|2dvarerr]_[ndfd|nwrfc].grb2


Real-time sample parallel data for the RTMA/URMA is available

via the following URLs:


Real-time sample parallel data for the precipitation analysis is

available here:


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:


Any questions, comments or requests regarding this

implementation should be directed to the contacts below.


For questions regarding these changes, please contact:

      John Derber

      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 Service Change Notices are online at: