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000
NOUS41 KWBC 201740
PNSWSH

Service Change Notice 24-33
National Weather Service Headquarters Silver Spring MD
140 PM EDT Wed Mar 20 2024

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

From:  Ben Kyger
  Director, NCEP Central Operations

Subject:  Minor RTMA Upgrade to Version 2.10.7: Effective on or about
  April 08, 2024

Effective on or about April 08, 2024, beginning with the 1400
Coordinated
Universal Time (UTC) cycle, the National Centers for Environmental
Prediction (NCEP) will upgrade the Real-Time Mesoscale Analysis
(RTMA). In
case of a Critical Weather Day or Enhanced Caution Event, the upgrade
will
be delayed until the next clear weather day. The changes consist of:

1. Updating the “RTMA weather status list” files intended for the
FAA to
re-enable the display of altimeter setting (“ALT”) values
following a
correction to the calculations. This correction adds a necessary step
of
adjusting the analyzed surface pressure to the station elevation
prior to
computing altimeter setting. This change only applies to CONUS, AK,
HI,
and PR; no changes are being made for Guam.

The current “RTMA weather status list” files are located on the
NOAA
Operational Model Archive and Distribution System (NOMADS)/FTPPRD at:
https://nomads.ncep.noaa.gov/pub/data/nccf/com/rtma/prod/airport_temp
s
https://ftp.ncep.noaa.gov/data/nccf/com/rtma/prod/airport_temps/
ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/rtma/prod/airport_temps/

with the following filename format:
(rtma_sector).FAA_T_stn_analysis_values.txt
Where rtma_sector is: akrtma, gurtma, hirtma, prrtma, rtma2p5

The initial notification for the enabling of the altimeter setting
(“ALT”)
was part of the following SCN:
https://www.weather.gov/media/notification/pdf_2023_24/scn23-
112_rtma_and_urma_v2.10.5.pdf

More information about the RTMA, URMA and RTMA-RU is available at:
https://vlab.noaa.gov/web/715073/home

NCEP encourages users to ensure their decoders are flexible and are
able
to adequately handle changes in content order, changes in the scaling
factor component within the product definition section (PDS) of the
gridded binary (GRIB) files, and any volume changes that may be
forthcoming. These elements may change with future NCEP model
implementations. NCEP will make every attempt to alert users to these
changes prior to any implementations.

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:

Daryl Kleist
NCEP/EMC Modeling and Data Assimilation Branch
College Park, MD
rtma.feedback.vlab@noaa.gov

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

Tony Salemi
NCEP Central Operations Dataflow Team Lead (Acting)
ncep.pmb.dataflow@noaa.gov

National Service Change Notices are online at:

https://www.weather.gov/notification