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NOXX10 KWBC 051930
1998/10/06 1400
DATA MGT MESSAGE 10-98.3
THE IMPLEMENTATION BELOW IS RESCHEDULED FOR 1400 UTC OCTOBER 20.
THIS POSTPONEMENT IS FOR OPERATIONAL REASONS. THE NWS SYSTEMS
OPERATIONS CENTER CHANGE NOTICES WEB PAGE HAS BEEN UPDATED.
On or about October 1, 1998, a software implementation with several changes will
take place concerning the distribution of moored buoy and C-MAN observations
from stations operated by the National Data Buoy Center (NDBC). One of the
changes will reduce the delay in transmitting the observations to all users.
Another change affects how users will obtain spectral wave observations. Other
changes are relatively minor. A brief description of some of the changes is
given below.
NDBC will release communications headings containing groups of moored buoy
and C-MAN observations every 5 minutes instead of 4 times an hour. Note that
this will not increase the number of NDBC observations transmitted most stations
still transmit one observation per hour but this change will improve the
timeliness of data. Users may need to increase the number of product versions
retained in their AFOS or meteorological workstations to maintain the same time
history of previous observations.
Three-hourly AFOS transmissions of spectral wave data under PIL headings
NMCBSOPO- NMCBSOP7 will cease. The WMO headings of these products are SXVX30
KWBC - SXVX39 KWBC. More detailed spectral wave observations are transmitted
more frequently in WMO FM-65 WAVEOB code. These are available on the Frame
Relay Network for NWS field offices and through the NWSTG for other users. PC
software to decode and plot these observations was developed by the WFO in
Seattle, Washington, and is available from the SSD in the Western Region. The
communications headings for the FM-65 messages are SXVX40 - SXVX49 KWBC and
SXVX60 - SXVX69 KWBC.
FM-65 WAVEOB messages will be released twice an hour for stations reporting
twice an hour. These were previously released only once an hour. For
non-critical applications, real-time spectral wave observations and plots are
available on http://www.ndbc.noaa.gov
The threshold for coding calm sea state will change from a significant wave
height of .25m to a wave height of .15 m.
Wind gusts will always be transmitted regardless of the wind speed.
Because of rounding in light winds, the gusts will sometimes equal the speed.
The three-hour pressure tendency group will always be included if the
current observation and the observation three hours ago contain pressure. The
present coding system requires these pressure measurements plus the measurements
taken in intermediate hours. The WMO-recommended algorithm will continue to use
all the pressures if they are available, but a backup method will be used if any
of the intermediate pressures are missing.
More accurate latitude and longitude values will be used. Users may see a
difference in some positions after the implementation. This will be noted more
in the FM 65 messages which report position in degrees, minutes, and seconds.
The NDBC contacts for these changes are Mr. David Gilhousen (228) 688-2840 and
Ms. Sallie Nolan (228) 688-1721. The e-mail addresses are
dgilhousen@xxxxxxxxxxxxx and snolan@xxxxxxxxxxxxx .
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