816
NOUS41 KWBC 021830
PNSWSH

Service Change Notice 24-48
National Weather Service Headquarters Silver Spring MD
230 PM EDT Thu May 2 2024

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

FROM:   Mike Hopkins, NOAA
   Director, Surface and Upper Air Division
   Office of Observations

SUBJECT:   Cooperative Hurricane Upper Air Stations (CHUAS) to
Transition
   from the GRAW DFM09 to the GRAW DFM17 (Capless) Radiosonde
and
   Supporting Software Version by July 27, 2024

All ten CHUAS sites will convert to an updated software version and
new
radiosonde through the next three months.  The first part of this
transition will be to start the implementation of the software
upgrade the
week of May 5, 2024.  The quantity of legacy radiosondes that remain
at
each site will determine the order of the phased implementation. The
anticipated completion date is estimated to be July 27, 2024, based
on the
radiosonde inventories at each of the CHUAS observing stations.

The GRAW DFM17 (Capless) radiosonde will provide an exposed Relative
Humidity sensor that will be more sensitive to changes in moisture
concentrations encountered in the atmospheric sounding.  The
intention is
to provide a better representation of relative humidity values than
given
by the legacy radiosonde.

The required software upgrade (Version GRAWMET 5.16.04.22) to
initialize
the GRAW DFM17 (Capless) radiosonde will increase the number of
Significant (SGL) levels in the World Meteorological Organization
(WMO)
Traditional Alphanumeric Codes (TAC) coded messages.

This change of radiosonde models will align the CHUAS networks
radiosonde
software version with the GRAW sites in the contiguous United States.

This change will not have any impact on observing services because
each
site will remain operational during its transition.

If you have questions or feedback, please contact:

Hiram Escabi, Jr., NCE, CET
Upper Air Program Manager
NWS Program Management Branch
Silver Spring, Maryland
(301) 427-9195
hiram.escabi@noaa.gov
National Service Change Notices are online at:

https://www.weather.gov/notification/