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PNSWSH

 

Technical Implementation Notice 13-39, Amended

National Weather Service Headquarters Washington DC

725 AM EST Mon Dec 16 2013

 

To:       Subscribers:

          -Family of Services

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network

          -NOAAPORT

          Other NWS Partners, Users and Employees

 

From:     Tim McClung

          Chief, Science Plans Branch

          Office of Science and Technology

 

Subject:  Amended: Upgrade to RTMA and Initial Implementation

          of URMA:  Effective January 28, 2014

 

This notice was amended to reschedule implementation to 

January 28, 2014

 

Effective on or about Tuesday, January 28, 2014, with the 

1400 Universal Coordinated Time (UTC) cycle, the National Centers

for Environmental Prediction (NCEP) will upgrade the Real-Time

Mesoscale Analysis (RTMA) and introduce the Unrestricted

Mesoscale Analysis (URMA). The upgraded RTMA includes:

 

-Adding variables

-Changing resolution for Alaska

-Adding a new output grid

-Removing the 5km CONUS products except for those on NOAAPORT

 

URMA is an improved analysis created 6 hours after analysis time

(with the exception of precip, see URMA section below) to provide

a more complete set of observational data. There will also be a

change to the products available from the North American Model

(NAM) Downscaled Numerical Guidance (DNG) system. More specific

details of the changes are provided below.

 

Addition of New Fields:

 

Hourly grids of 10m wind gust and surface visibility will be

added to CONUS at 2.5km horizontal resolution, and Hawaii and

Puerto Rico at 2.5km. Similar grids, except 3-hourly, will be

added for Guam at 2.5km. These fields will be available in the

existing RTMA output files and will be disseminated over NOAAPORT

using the WMO headers listed in Table 1 below.

 

Change of Resolution for Alaska grid:

 

The current Alaska grid 6km resolution will be replaced with a

3km resolution grid (grid number 91). The output products will

contain hourly grids of 2m temperature, 2m dew point, 10m wind

speed, 10m wind direction, 10m u-wind component, 10m v-wind

component, 10m wind gust, surface pressure, surface visibility,

and model terrain height. The geographic coverage of the grid is

online at:

 

www.nco.ncep.noaa.gov/pmb/changes/docs/akrtma3p0_domain.png

 

The 3km products will be disseminated via the NCEP server, NOMADS

and NOAAPORT. In addition, the 6km grids currently available in

the National Digital Guidance Database (NDGD) at

 

ftp://tgftp.nws.noaa.gov/SL.us008001/ST.opnl/DF.gr2/DC.ndgd/GT.rtma/AR.alaska/

 

will be replaced by the new 3km grids. The 6km Alaska grids will

remain on NOAAPORT until such time as the Advanced Weather and

Information Processing System (AWIPS) can convert to using the

3km grids. The WMO headers for the 3km AK grids are listed below

in Table 2

 

Addition of new grids for NWRFC:

 

New output grids will be generated on a 2.5km grid that covers

the area of responsibility of the North West River Forecast

Center (NWRFC). The geographic coverage of the grid can be seen

at:

 

http://www.nco.ncep.noaa.gov/pmb/changes/docs/nwrfc_domain.png

 

The output products will contain hourly grids of 2m temperature,

2m dew point, 10m wind speed, 10m wind direction, 10m u-wind

component, 10m v-wind component, 10-m wind gust, surface

pressure, surface visibility, and model terrain height.  The

NWRFC products will be disseminated via the NCEP server and will

be available for http download on NOMADS.

 

Implementation of URMA:

 

Updated grids for the 2.5km CONUS and NWRFC domains, along with

the grids of 6-hour accumulated precipitation will be referred to

as the Unrestricted Mesoscale Analysis (URMA). URMA represents an

improved analysis more suited for verification since it adds

nearly all of the observations which are not used for the initial

analysis due to transmission latency issues. Grids of 2m

temperature, 2m dew point, 10m wind speed, 10m wind direction,

10m u-wind component, 10m v-wind component, 10-m wind gust,

surface pressure, and surface visibility will be made and

distributed 6 hours after the initial grids are made.

 

URMA will also include 6-hourly grids of accumulated

precipitation, remapped from the NCEP stage-IV precipitation. 

The 6-hourly precipitation accumulation fields covering a 24h

(12Z-12Z) period are available beginning at 15:35 UTC; the CONUS

mosaic is remade each hour as NCEPS receives new regional

analyses from RFCs. Complete CONUS coverage is generally achieved

by 21:35 UTC.

 

With the exception of the precipitation grids, each of the above

analysis grids will be accompanied by a grid of the corresponding

analysis uncertainty. The GRIB encoding for the URMA grids will

be the same as that for the RTMA grids for the same elements,

except that the generating model process number for URMA will be

118 (RTMA is 109). URMA will be available on the NCEP server,

NOMADS, NDGD, and will be sent over NOAAPORT with the WMO headers

listed in Table 2

 

Change in filenames and directory structure:

 

Previously, the grids for the analysis and the analysis error

were contained in the same output files. This file will be split

into an analysis-only file and an analysis error-only file.  On

NOMADS and the NCEP server, the following three filenames will be

available, with this example the 0000 UTC cycle for 2.5km CONUS:

 

  rtma2p5.t00z.2dvaranl_ndfd.grb2  -- analysis grids

  rtma2p5.t00z.2dvarerr_ndfd.grb2  -- analysis error

  rtma2p5.t00z.2dvarges_ndfd.grb2  -- first guess field

 

In addition, the directory structure under which the RTMA

products are available on the NCEP server will change. Today, the

files are available in directories:

 

 ../com/{model}/prod/{model}.YYYYMMDD

 

where {model} is akrtma, gurtma, hirtma, prrtma, rtma, and

rtma2p5, depending on geographic region.  With this upgrade, the

first {model} will be replaced with a generic "rtma" directory

name, and then the multiple geographic region names will follow

after the "prod" directory level.

 

Removal of 5km CONUS RTMA products:

 

In TIN 11-20, NCEP announced that the 2.5km CONUS RTMA products

were a replacement for the 5km grids.  The 5km products had to be

retained until such time as AWIPS could transition to the 2.5km

grids.  While the 5km grids will remain on NOAAPORT for a while

longer, NCEP will remove the 5km CONUS grids from NOMADS and the

NCEP ftp server with this upgrade.

 

Additional RTMA enhancements:

 

The old grids for CONUS at 5km and Alaska at 6km that will be

distributed only on NOAAPORT will henceforth be sampled from the

corresponding double-resolution grids, thus benefiting from the

more recent, improved science used to create the latter.

 

An hourly cross-validation will be added to CONUS RTMA at 2.5km

and URMA at 2.5km.

 

There will be improved quality of the grids of surface pressure

for Alaska, Hawaii and Puerto Rico thanks to the use of an

improved background field.

 

Associated change to the NAM DNG:

 

The NAM DNG is used as input to the RTMA.  To support some of the

changes to the RTMA system, more NAM DNG data is being made

available. Output will now be available hourly up to forecast

hour 12 for the Alaska, Hawaii and Puerto Rico domains. In

addition, 10m wind gusts and surface visibility will be added

hourly out to forecast hour 12, while today it is only available

every 3 hours.  The NAM DNG products can be found at

 

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

 

with filenames with *smart* in the name.

 

More information about the RTMA and URMA is available at:

 

http://www.emc.ncep.noaa.gov/mmb/rtma/para/

 

A consistent parallel feed of data will be available on the NCEP

server via the following URLs:

 

http://www.ftp.ncep.noaa.gov/data/nccf/com/rtma/para/

 

ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/rtma/para/

 

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, changes

to the GRIB Bit Map Section (BMS), 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.

 

Table 1: WMO Headings assigned to grids of wind gust and

visibility for all available domains. Here, * is C for Puerto

Rico, G for Guam, H for Hawaii, I for 2.5km CONUS RTMA, and K for

3km Alaska.  For URMA, * is Q for 2.5km CONUS URMA.

 

WMO HEADING      RTMA PARAMETERS

LN*A98 KWBR      wind gust analysis

LN*A98 KWBR      wind gust analysis uncertainty

LK*A98 KWBR      visibility analysis

LK*A98 KWBR      visibility analysis uncertainty

 

Table 2: WMO Headings assigned to RTMA grids for 3km Alaska, and

to URMA grids for 2.5km CONUS. Here, * is Q for 2.5km CONUS URMA,

and K for 3km Alaska RTMA.

 

WMO HEADING      RTMA PARAMETERS

LT*A98 KWBR      temperature analysis

LT*A98 KWBR      temperature analysis uncertainty

LR*A98 KWBR      dewpoint temperature analysis

LR*A98 KWBR      dewpoint temperature analysis uncertainty

LN*A98 KWBR      wind speed analysis

LN*A98 KWBR      wind speed analysis uncertainty

LN*A98 KWBR      wind direction analysis

LN*A98 KWBR      wind direction analysis uncertainty

LU*A98 KWBR      u wind component analysis

LV*A98 KWBR      v wind component analysis

LP*A98 KWBR      surface pressure analysis

LP*A98 KWBR      surface pressure analysis uncertainty

LH*A98 KWBR      RTMA model terrain height

LEIA98 KWBR      6-hour Accumulated precipitation (2.5km for

                 CONUS only)

 

For questions regarding these changes, please contact:

 

    Geoff DiMego

    NCEP/EMC Mesoscale Modeling Branch

    College Park, Maryland

    301-683-3764

    geoff.dimego@noaa.gov

 

For questions regarding the dataflow aspects of these datasets,

please contact:

 

     Rebecca Cosgrove

     NCEP/NCO Dataflow Team

     College Park, Maryland

     301-683-0567

     ncep.pmb.dataflow@noaa.gov

 

NWS National Technical Implementation Notices are online at:

 

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

 

$$