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Service Change Notice 17-105 Updated

National Weather Service Headquarters Silver Spring MD

1210 AM EDT Fri Oct 6 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: RTMA, URMA and NAM DNG upgrade and

           Introduction of RTMA with Rapid Updates:

           Effective November 14, 2017

 

Updated to include more details about the changes to the URMA

precipitation output and change the implementation date to

November 14, 2017

 

Effective on or about Tuesday, November 14, 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), the Unrestricted Mesoscale

Analysis (URMA), North American Model (NAM) Downscaled Numerical

Guidance (DNG) and introduce the RTMA with Rapid Updates 

(RTMA-RU).

 

- Changes to model components

- Addition of new product fields and changes

- Product removals, including NOAAPORT

- Precipitation output changes

 

1) Changes to Model Components

 

- The new RTMA-RU is an RTMA analysis run every 15 minutes using

the latest available observational data.  RTMA-RU will run over

CONUS only.  With this upgrade 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 and new products are provided below.

 

- A new terrain dataset and land/sea mask will be used in RTMA

and URMA for the continental United States (CONUS), Puerto Rico

(PR), and Hawaii (HI).  The same terrain and land/sea mask will

be implemented in the National Blend of Models during a future

upgrade.

 

- In URMA (but not RTMA), new pseudo-observations of wind,

temperature and moisture will be used over the Great Lakes in an

attempt to simulate over-water conditions over those lakes.  The

pseudo-observations are generated based on water temperature and

nearby land-based observations.  The adjustment formula

originated with the Great Lakes Environmental Research Lab and

is also currently used in Great Lakes nowcasts.

 

- Hourly precipitation URMA is added to PR and CONUS domains.

For Puerto Rico, coverage is from the Southeast River Forecast

Center (SERFC) hourly Quantitative Precipitation Estimate (QPE). 

For CONUS, hourly gauge-corrected Multi-Radar Multi-Sensor

(MRMS) is used to disaggregate the 6-hourly QPEs from Northwest

RFC (NWRFC) and California-Nevada RFC (CNRFC) into hourlies (no

reliable hourly QPEs from these two RFCs), and combine these

with hourly QPEs from the other 10 CONUS RFCs into a CONUS

mosaic.  

 

The filling of the NWRFC/CNRFC is done on the hourly Stage IV

CONUS mosaic, as the precipitation URMA is the Stage IV mapped

to the NDFD grids.  The Stage IV file names remain unchanged,

but now the hourly Stage IV will have NWRFC and CNRFC areas

filled with time-disaggregated data, rather than left as data-

free.  In the earlier runs of the hourly Stage IV/precip URMA,

before the corresponding 6h QPE from these two RFCs become

available (as well as on occasion when there is one or more

missing MRMS file in the 6h period), the CNRFC/NWRFC will still

have these areas shown as data-free.  The land-only data mask is

removed from the PR precipitation Stage IV/URMA in order to

provide full PR domain coverage for National Blend of Models

(NBM).

 

A note on precipitation URMA and Stage IV: NCEP Stage IV

http://www.emc.ncep.noaa.gov/mmb/ylin/pcpanl/stage4/

is a 4.6km precipitation analysis based on the QPEs produced by

the River Forecast Centers. Alaska and Puerto Rico Stage IV are

from the QPEs produced by APRFC and SERFC for the AK and PR

regions, respectively; CONUS Stage IV is a mosaic of QPEs from

the 12 CONUS RFCs, with the exception of hourly Stage IV over

CNRFC/NWRFC as described above (using MRMS to do time-

disaggregation, not simply input from RFCs).

 

- The built-in coastal steepening of the background error

covariances is reduced in RTMA and URMA CONUS, HI, PR and AK

domains to reduce the appearance of zero-increment artifacts

around coastlines.

 

- Additional observations from the NOAA Cooperative Observer

(COOP) network and the UrbaNet Mesonet will be available for use

in URMA but not RTMA.

     

- Associated change to the NAM DNG will be as follows:

a) The NAM DNG is used as input to the RTMA/URMA CONUS, AK, PR,

and HI domains and will be upgraded to be consistent with the

same new land/sea mask and terrain dataset used in RTMA, URMA

and RTMA-RU.

b) Decimal scaling (DEC) is changed from 3.0 to 6.0 for

increased precision of specific humidity and to prevent zero

values of specific humidity from being written out. 

c) A bug is corrected in the specific humidity computation

(specific humidity was using surface pressure from NAM Nest

rather than the downscaled surface pressure).  The NAM DNG

products can be found on the NCEP Web Services with a

data/nccf/nam/prod/*smart* pattern.

 

 

2) Product Changes and Additions

 

The following changes will apply to products on the NCEP Web

Services at:

http://nomads.ncep.noaa.gov/pub/data/nccf/com/

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

 

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

 

Under rtma/prod, urma/prod, nam/prod respectively.

 

- A new parameter, cloud ceiling height (CEIL), will be added to

RTMA and URMA over Alaska.  Ceiling uses a Rapid Refresh (RAP)

based first guess, and includes observations from METAR sites. 

Ceiling is listed in meters above ground level.

Files under akurma.YYYYMMDD/ like:

  akurma.tHHz.[2dvaranl|2dvarges|2dvarerr]_ndfd_3p0.grb2

Files under akrtma.YYYYMMDD/ like:

  akrtma.tHHz.[2dvaranl|2dvarges|2dvarerr]_ndfd_3p0.grb2

Where YYYYMMDD is year, month and day. And HH is cycle from 00-

23 (always 2 digits).

 

 - A new parameter, significant wave height (HTSGW), will be

added to URMA (but not RTMA) over CONUS.  Significant wave

height uses WaveWatch 3 output as a first guess field, and

includes observations from buoys and satellite altimeters.

Files under urma2p5.YYYYYMMDD/ like:

  urma2p5.tHHz.[2dvaranl|2dvarges|2dvarerr]_ndfd.grb2_ext

  urma2p5.tHHz.[2dvaranl|2dvarges|2dvarerr]_ndfd.grb2_wexp

  urma2p5.tHHz.[2dvaranl|2dvarges|2dvarerr]_ndfd.grb2

  urma2p5.tHHz.[2dvaranl|2dvarges|2dvarerr]_nwrfc.grb2

Where YYYYMMDD is year, month and day. And HH is cycle from 00-

23 (always 2 digits).

 

 - A new parameter, minimum and maximum daily relative humidity,

will be added to URMA (not RTMA) over CONUS, Alaska, Hawaii and

Puerto Rico.  Maximum relative humidity will be produced once

daily with the 2000 UTC analysis and is valid for the previous

0600-1800 UTC period.  Minimum relative humidity will be

produced once daily with the 0800 UTC analysis and is valid the

previous 1800-0600 UTC period.  Note that no first guess or

analysis error files will be available for minimum and maximum

relative humidity, and minimum and maximum relative humidity

will be in a separate file from other variables that match these

names on the NCEP Web Services:

     urma2p5.tCCz.[min|max]RH_ndfd.grb2

     urma2p5.tCCz.[min|max]RH_ndfd.grb2_ext

     urma2p5.tCCz.[min|max]RH_ndfd.grb2_wexp

     urma2p5.tCCz.[min|max]RH_nwrfc.grb2

     akurma.tCCz.[min|max]RH_ndfd_3p0.grb2

     hiurma.tCCz.[min|max]RH_ndfd.grb2

     prurma.tCCz.[min|max]RH_ndfd.grb2

   Where CC=08 for minRH, and CC=20 for maxRH

     

 - New 2.5 km grids, updating every 15 minutes, referred to as

the Real Time Mesoscale Analysis with Rapid Updates (RTMA-RU). 

RTMA-RU represents a rapidly updating surface analysis system

over CONUS that includes the latest available observed data. 

Grids of 2m temperature, 2m dew point, 2m specific humidity, 10m

wind speed, 10m wind direction, 10m wind gust, 10m u-wind

component, 10m v-wind component, surface visibility, cloud

ceiling height, and surface pressure will be made and

distributed 20 minutes after analysis time.  RTMA-RU also

leverages the 15 min forecast output from the HRRR for ceiling

and visibility first guess fields and selects the corresponding

ceiling and visibility observations valid closest to analysis

time in order to closely fit these data.

 

Data will be available on the NCEP Web Services under directory:

  rtma/prod/rtma2p5_ru.YYYYMMDD

With file names like:

  rtma2p5_ru.tHHMMz.2dvaranl_ndfd.grb2 -- analysis field

  rtma2p5_ru.tHHMMz.2dvarges_ndfd.grb2 -- first guess field

Users should note the use of 4-digits (2-digit hour HH and 2-

digit minute MM) used for analysis time in RTMA-RU files. There

is no analysis error file for RTMA-RU and files are available

only on the westward-expanded domain described below. Files

should be available approximately 20 minutes after analysis

time.

     

 - Users should note that the hourly RTMA will run concurrently

with but separately from the RTMA-RU at the top of every hour. 

Hourly RTMA will still be available at the same time and

location, and hourly RTMA output may differ from RTMA-RU output

at the top of the hour.

 

- 200 additional columns have been added to the CONUS output

grid over the Pacific Ocean in a westward expansion of that

domain.  Analysis, first guess, and analysis error files

including the westward expansion will now be available and are

named:

 

[rtma2p5|urma2p5].tHHz.[2dvaranl|2dvarges|2dvarerr]_ndfd.grb2_we

xp

Files will still be distributed on their original CONUS grids

(NDFD, NWRFC) along with the new expanded grid.  However users

should note that NCEP plans to discontinue distribution of the

smaller, legacy grids during a future upgrade.

 

- The new RTMA-RU will be available for download within the grib

filter service under NCEP NOMADS:

  http://nomads.ncep.noaa.gov/cgi-bin/filter_rtma_ru.pl

 

- The urma2p5 GRIB2 data on the NCEP Web Services will be

reduced from 11 days available to 2 days available to make it

more consistent with the other domains. All RTMA and URMA

precipitation data will be available for 14 days of archive.

 

3) Product Removals

 

- The 5km RTMA precipitation will be discontinued on the NCEP

Web Services with this upgrade.

     pcpanl.YYYYMMDD/pcprtma.YYYYMMDDHH

Users should begin using the 2.5km products that are located on

the same web server here:

  rtma/prod/rtma2p5.YYYYMMDD/rtma2p5.YYYYMMDDHH.pcp.184.grb2

 

- Over NOAAPORT/SBN the hourly 5km CONUS RTMA precipitation will

be discontinued. Users should instead be using the 2.5km

resolution output available on NOAAPORT.

  Accumulated Precipitation (APCP) WMO Header removed: LEMA98

KWBR

 

4) Precipitation Output Changes

 

The RTMA and URMA precipitation analysis files will be moving to

properly align with the directory structure that follows the

RTMA and URMA. Please see below for those changes.

 

- The RTMA precipitation GIF images will now be created from the

2.5km RTMA. The location of the files will move directories:

  pcpanl.YYYYMMDD/pcprtma.YYYYMMDDHH.gif ->

  rtma/prod/rtma2p5.YYYYMMDD/pcprtma.YYYYMMDDHH.gif

   

- The Alaska URMA precipitation will change directories and file

names:

 pcpanl.YYYYMMDD/pcpurma_ak.YYYYMMDDHH.06h ->

 urma/prod/akurma.YYYYMMDD/pcpurma_ak.YYYYMMDDHH.06h.grb2

   

-  The Puerto Rico precipitation will change directories and

file names:

  pcpanl.YYYYMMDD/pcpurma_pr.2017091006.06h -> 

  urma/prod/prurma.YYYYMMDD/pcpurma_pr.2017091006.06h.grb2

 

- New 1 hourly URMA precipitation analysis files will be

available in their parent domain directories:

 

urma/prod/urma2p5.YYYYMMDD/urma2p5.2017091100.pcp_01h.[184|188].

grb2

 urma/prod/prurma.YYYYMMDD/pcpurma_pr.2017091223.01h.grb2

 

 

 

More information about the RTMA, URMA and RTMA-RU is available at:

https://vlab.ncep.noaa.gov/web/715073/home

 

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

server beginning Sept 14 via the following URLs:

 

RTMA and RTMA-RU:

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

 

CONUS hourly RTMA data will be under sub-directory

rtma2p5.YYYYMMDD

15-minute RTMA-RU data will be under sub-directory

rtma2p5_ru.YYYYMMDD

 

URMA:

http://para.nomads.ncep.noaa.gov/pub/data/nccf/com/urma/para/

 

NAM DNG:

http://para.nomads.ncep.noaa.gov/pub/data/nccf/com/nam/para/

 

Stage IV:

http://para.nomads.ncep.noaa.gov/pub/data/nccf/com/pcpanl/para/

 

Parallel (RTMA/URMA) Precip Analysis data will be under its

various parent domain directories as noted above.

 

NCEP urges all users to ensure their decoders can handle changes

in content order 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.

 

Questions, comments or requests regarding this change should be

directed to the contacts below.  We will review feedback and

decide whether to proceed.

 

For questions regarding science changes, please contact:

 

   Vijay Tallapragada

   NCEP/EMC Modeling and Data Assimilation Branch

   College Park, Maryland

   301-683-3762

   rtma.feedback.vlab@noaa.gov

 

For questions regarding the data flow aspects of these data

sets, please contact:

 

   Carissa Klemmer

   NCEP/NCO Dataflow Team Lead

   College Park, Maryland

   301-683-0567

   ncep.list.pmb-dataflow@noaa.gov

 

 

NWS National Service Change Notices are online at:

 

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

 

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