NOUS41 KWBC 051923



Technical Implementation Notice 14-25

National Weather Service Headquarters Washington DC

330 PM EDT Thu Jun 5 2014


To:††††† Subscribers:

†††††††† - Family of Services

†††††††† - NOAA Weather Wire Service

†††††††† - Emergency Managers Weather Information Network

†††††††† - NOAAPORT

†††††††† Other NWS Partners, Users and Employees


From:††† Timothy McClung

†††††††† Chief, Science Plans Branch

†††††††† Office of Science and Technology


Subject: Upgrade the Real-Time Ocean Forecast System:

†††††††† Effective July 8, 2014


On or about Tuesday, July 8, 2014, beginning with the 1200

Coordinated Universal Time (UTC) run, the GRIB2 products being

disseminated from the National Centers for Environmental

Predictionís (NCEP) Real-Time Ocean Forecast System (RTOFS) will

change. This includes the GRIB2 products hosted on the NCEP

servers and the GRIB2 RTOFS files distributed on NOAAPORT.


Two changes will be made to the GRIB encoding. First, the

generating process of 85 for Real Time Ocean Forecast System was

incorrectly set in octet 13 of PDT 4.0. It will now be set in the

correct location of octet 1 for all forecast and nowcast

products. Second, forecasts and nowcasts had the same value for

octet 12 in PDT 4.0--the type of generating process. With this

change, the nowcast products will use a value of 14 in octet 12

to distinguish them from the forecast products.


The grid domain has been extended in the Hudson-Baffin sub-region

for the nowcasts and forecasts.


The sea surface temperature (SST) will be sent in degrees Kelvin

instead of the current degrees Celsius for all sub-regions for

the nowcasts and forecasts.


Sample files with these changes are available at:


The filenames start with grib2_rtofs_glo*.


The following WMO headers are used for the GRIB2 RTOFS products



E***01 KWBW, where


the first * specifies the parameters:

†††† H - Sea Surface Height Relative to Geoid (SSHG)

†††† S - Salinity (SALTY)

†††† T - Water Temperature (T)

†††† U - U-Component of Current (UOGRD)

†††† V - V-Component of Current (VOGRD)

†††† U - Barotropic U Velocity (UBARO)

†††† V - Barotropic V Velocity (VBARO)

The second * specifies the grid:

†††† A - Alaska 0.3 km grid

†††† B - Bering 0.08 km grid

†††† C - Western CONUS 0.08 km grid

†††† D - Arctic 0.08 km grid

†††† G - Guam 0.08 km grid

†††† I - Gulf of Alaska 0.5 km grid

†††† K - Western Atlantic 0.08 km grid

†††† H - Honolulu 0.08 km grid

†††† S - Samoa 0.08 km grid

†††† T - Tropical Pacific 1.0 km grid

†††† J - Hudson-Baffin 0.25 degree grid

The third * specifies the forecast hours:

††† B through T, depending on forecast hour


For more information on the RTOFS Global model please visit:


NCEP encourage all users to ensure their decoders are flexible

and are able to adequately handle changes in content, parameter

fields changing order, changes in the scaling factor component

within the Product Definition Section of the GRIB files and any

volume changes which 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



For questions regarding the scientific content of the modeling

system please contact:


†††† Avichal Mehra


†††† College Park, MD

†††† Email:


For questions regarding the dataflow aspects of these data sets

please contact:


†††† NCEP/ NCO Dataflow Team

†††† College Park, MD

†††† Phone: 301-683-0567

†††† Email:


NWS Technical Implementation Notices are available online at: