NOUS41 KWBC 272000 AAA



Service Change Notice 17-17 Updated

National Weather Service Headquarters Silver Spring, MD

400 PM EDT Mon Mar 27 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: Updated:  RTMA and URMA Upgrade: Effective May 2, 2017


Updated to change implementation date to Tuesday, May 2, 2017


Effective on or about Tuesday, May 2, 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:


- Changes to model components

- Addition of new product fields, including onto NOAAPORT

- Product output changes


1) Model Changes


A. The following changes are made for RTMA-CONUS and URMA-CONUS

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

 b) Change the background field for the cloud ceiling height

analysis from downscaled RAP forecast to downscaled 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 NAM forecast to a downscaled 1-hour RAP forecast.


The expansion of the CONUS domain is in response to a request

from the Ocean Prediction Center. It also benefits the western

WFOs and the National Blend Project. It should be noted that

products for the smaller NDFD CONUS grid and Northwest River

Forecast Center grid will continue to be disseminated as before.

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 also makes the RAP the primary background model used to

generate the background field over Alaska for all variables.


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

 a) NCEP is adding Alaska (AK) and Puerto Rico (PR) QPE's 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 River Forecast

Centers' 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 (i.e. 168hr33mn)

after validation time.


Note 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 Northwest River Forecast Center (NWRFC) and

Missouri Basin River Forecast Center (MBRFC, falling back to 6h

QPE when an 24h QPE is unavailable), 6h QPE from CB and CN RFCs,

and 1h QPE from the other 8 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 re-made 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 is in support of the NWS AHPS -

the 24h mosaic will serve as precipitation source for


2) Changes on web services


The following web sites 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.


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/SBN

Total precipitation over Alaska and Puerto Rico will be added

where the 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. We will

review any feedback and decide whether to proceed.


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: