OUTLINE OF WMO BULLETIN HEADERS
USED WITH
NCEP GRIB


Revised 04/21/2006
Red text depicts changes made since 04/07/2006


WMO BULLETIN HEADER


           The WMO abbreviated heading is used to identify the NCEP GRIB messages; however, it is not a complete description of their content.  The user is cautioned against using the header as the sole determiner of the record content; one should, of course, rely on the Product Definition Section for that purpose.

            Note: In the following, a hexadecimal number is enclosed in parentheses followed by the designation "hex".  The information needed to identify the NCEP product is contained in 21 octets.  The characters are encoded using the CCITT-ITA No. 5, also known (in the US) as ASCII characters, and are defined as follows:

Octet
 Header Content
1
 The character 'H' for GRIB bulletins sent to the NWS Family of Services, used for the WAFS program, and for general International Exchange
            or
The character ‘O’ for oceanographic GRIB bulletins intended for general International and National Exchange and for use in the NWS AWIPS program
            or
The characters 'L', 'M', 'Y' or 'Z' for meteorological GRIB bulletins intended for the NWS AWIPS program.
2
 A letter character specifying the type parameter as shown in Table A.1.
3
 A letter character specifying the grid area as defined in Table A.2.
4
 A letter or numeric character indicating the time difference between the reference time and valid time of the data as listed in Table A.3, i.e., the forecast length.
5-6
 Numeric characters as defined in Table A.4.  Usually the pressure level, sometimes just a sequence number.  Some values have special level or layer meanings.
7
 Blank (20)hex
8-11
 Four characters identifying the originating center.  The first three characters are always ‘KWB’ for NCEP-produced messages.  The last character is a letter specifying the NCEP model as defined in Table A.5.
12
 Blank (20)hex
13-14
 Two numeric characters providing the reference day of the month (01-31) of the data.
15-18
 Four numeric characters providing the reference hour and minute of the data.
19-22
 Four OPTIONAL characters: one blank (20)hex, then 'Pxx', where xx=AA, AB, AC ... AY,AZ, BA, BB, BC ... etc.  Used to indicate sequential parts of a very long message that has been subdivided. The last part of the message will have xx=Zn, where n is the next letter in the appropriate sequence.  Example: a five part message would have the parts indicated by PAA, PAB, PAC, PAD, PZE.
19-21 or 23-25
 Two ASCII carriage returns and a line feed, (0D0D0A)hex.


The first six characters are commonly referred to as:

T1 T2 A1 A2  ii

In summary...

Generic Meaning of   T1  T2  A1  A2  ii:

                        T1:        Type of bulletin:  "H" for GRIB messages for
                                                                        Family of Services, WAFS, and
                                                                        International Exchange;
                                                                “O” and "E" for Oceanographic GRIB messages
                                                                        for National and International Exchange
                                                                        and for AWIPS GRIB messages; or
                                                                "L", "M", "Y" or "Z" for AWIPS GRIB messages

                        T2:        Type of data/parameter

                        A1:       Grid

                        A2:       Analysis or forecast hour

ii:          Numeric.  Usually the pressure level, sometimes just a sequence number.  Some values have special level or layer meanings.

            In the following tables, the columns headed AWIPS are augmentations to the common Family of Services (FOS), National, and International Exchange variables.  FOS, National and International GRIB messages (with H as the initial character) draw upon the left hand columns only.  National, International, and AWIPS GRIB messages (with O as the initial character) draw upon the middle column only.  AWIPS GRIB messages (with Y or Z as the initial character) use letters from both the left and right columns.  If each column contains entries for the same designator, the T1 character (H, O, L, M, Y, or Z) indicates which entry to use.


TABLE A.1   TYPE PARAMETERS - T2
(Header Octet 2)

Designator PARAMETER

FOS & International (H) AWIPS (E or O) AWIPS (L, M, Y or Z)
A
U-wind/current component Cloud of non-conforming ICWF* parameters
B
V-wind/current component Vertical Wind Shear
C
 Vorticity Total Significant Wave Height Vorticity
D
Depth Probability Parameters
E
 Total Precipitation Ice Concentration Total Precipitation
F
 Long Wave Radiation Ice Thickness Precipitable Water
G
 Convective Precipitation Ice Drift Convective Precipitation
H
 Height (geopotential) Ice Growth Height (geopotential)
I
Ice Convergence Non-Convective Precipitation
J
 Significant Wave Height Period of Spectral Peak of the Ocean Waves Precipitation  Rate
K
 Primary Wave Period Direction of Spectral Peak of the Ocean Waves Visibility
L
 Primary Wave Direction Height of Significant Wind Waves Soil Parameters
M
 Secondary Wave Period Mean Period of Wind Waves Catagorical Parameters (yes/no)
N
 Secondary Wave Direction Mean Direction of Wind Waves Wind Speed or Gust
O
 Vertical Velocity Height of Significant Swell Waves Vertical Velocity
P
 Pressure Mean Direction of Swell Waves Pressure
Q
Wind Speed Stability Index
R
 Relative Humidity Wind Direction Relative Humidity
S
 Snow Salinity Snow
T
 Air Temperature Ocean Temperature
U
 U Wind Component Vessel Icing U Wind Component
V
 V Wind Component Visibility V Wind Component
W
Ocean Temperature Warming CAPE
X
 Surface Lifted Index Mixed Data Surface Parameters
Y
 UV Index Mean Period of Swell Waves CIN
Z
 Refer to GRIB PDS Refer to GRIB PDS Helicity

* Surface wind direction, surface wind speed, surface dew-point temperature,
   maximum surface temperature, and minimum surface temperature


TABLE A.2   GRID DESIGNATOR - A1
(Header Octet 3)

Designator Grid Number (See Table B)

FOS and International (H) AWIPS (O) AWIPS (L, M, Y or Z)
A
 21
 228 - 2.5x2.5 deg lat/lon global 201 - 381 km Northern Hemisphere
B
 22
 218 - 12-km CONUS 218 - 12-km CONUS
C
 23
 219 - N. Hemisphere High Res 175 - 10 km lat/lon Guam
D
 24
 220 - S. Hemisphere High Res 130 - 13-km CONUS
E
 25
 221 - N. American High Res 185 - 12 km CONUS (DGEX)
F
 26
 229 - 1.0x1.0 deg lat/lon global 186 – 12 km Alaska (DGEX)
G
 50
 230 - 0.5x0.5 deg lat/lon global 160 - 47.5 km Alaska NPS
H
231 - 0.5x0.5 deg lat/lon N.H. 213 - 95 km CONUS
I
 37
 232 - 1.0x1.0 deg lat/lon N.H. 202 - 191 km CONUS
J
 38
 233 - 1.25x1.00 deg lat/lon global 203 - 191 km Alaska
K
 39
 234 - 0.25x0.25 deg lat/lon ECGM regional 204 - 160 km Hawaii
L
 40
 235 - 0.5x0.5 deg lat/lon global 205 - 191 km Puerto Rico
M
 41
 238 - Western North Atlantic lat/lon 227 - 5 km CONUS
N
 42
 239 - Alaska Regional lat/lon 207 - 95 km Alaska
O
 43
 244 - North Atlantic lat/lon 254 - 40 km Mercator Pacific Region
P
 44
 251 - COFS lat/lon 237 - 32 km Puerto Rico
Q
253 - Eastern North Pacific lat/lon 211 - 80 km CONUS
R
212 - 40 km CONUS 212 - 40 km CONUS
S
253 - Eastern North Pacific lat/lon 242 - 11.25 km Alaska
T
 61
 214 - 48 km Alaska 161 - 0.5 degree lat/lon Puerto Rico
U
 62
 215 - 20 km CONUS 215 - 20 km CONUS
V
 63
 216 - 45 km Alaska 216 - 45 km Alaska
W
 64
 173 - 1/12 degree global lat/lon 236 - 40 km CONUS
X

243 - 0.4 degree NE Pacific
Y

217 - 22 km Alaska
Z
 Refer to GRIB PDS


Table A.3 FORECAST HOUR DESIGNATOR
(Header Octet 4)

DESIGNATOR FORECAST HOUR
FOS, International (H) and AWIPS (L or Y) National, International (O) and
AWIPS (E or O)		 AWIPS (M or Z)
Octet 8-11 = KWBM
Octet 8-11 = KWBJ
A
 00 hour analysis 00 hour analysis 00 hour analysis 02 hour fcst
B
 06 hour fcst 12 hour fcst 03 hour fcst 03 hour fcst
C
 12 hour fcst 24 hour fcst 06 hour fcst 04 hour fcst
D
 18 hour fcst 36 hour fcst 09 hour fcst 08 hour fcst
E
 24 hour fcst 48 hour fcst 12 hour fcst 09 hour fcst
F
 30 hour fcst 60 hour fcst 15 hour fcst 10 hour fcst
G
 36 hour fcst 72 hour fcst 18 hour fcst 14 hour fcst
H
 42 hour fcst 84 hour fcst 21 hour fcst 15 hour fcst
I
 48 hour fcst 96 hour fcst 24 hour fcst 16 hour fcst
J
 60 hour fcst 108 hour fcst 30 hour fcst 20 hour fcst
K
 72 hour fcst 120 hour fcst 36 hour fcst 21 hour fcst
L
 84 hour fcst 144 hour fcst 42 hour fcst 27 hour fcst
M
 96 hour fcst 168 hour fcst 48 hour fcst 54 hour fcst
N
 108 hour fcst 192 hour fcst 60 hour fcst 66 hour fcst
O
 120 hour fcst 216 hour fcst 72 hour fcst 33 hour fcst
P
 132 hour fcst 240 hour fcst 84 hour fcst 39 hour fcst
Q
 144 hour fcst 264 hour fcst 96 hour fcst 45 hour fcst
R
 156 hour fcst 288 hour fcst 120 hour fcst 51 hour fcst
S
 168 hour fcst 312 hour fcst 132 hour fcst 57 hour fcst
T
 180 hour fcst 336 hour fcst 144 hour fcst 78 hour fcst
U
 192 hour fcst 360 hour fcst 156 hour fcst 90 hour fcst
V
 204 hour fcst 384 hour fcst 168 hour fcst 102 hour fcst
W
 216 hour fcst -
 -
 114 hour fcst
X
 228 hour fcst -
 54 hour fcst
Y
 240 hour fcst -
 66 hour fcst -
Z
 Refer to GRIB PDS Refer to GRIB PDS 108 hour fcst Refer to GRIB PDS


The WMO headings for Eta model products generated on grid 237 (Puerto Rico) and RUC model products generated on grid 236 (CONUS 40 km)
and grid 130 (CONUS 13 km) use a special table for the FORECAST HOUR DESIGNATOR - A2 (Header Octet 4). 
This table is defined as follows:

DESIGNATOR FORECAST HOUR
AWIPS (Y or Z)		 DESIGNATOR FORECAST HOUR
AWIPS (Y or Z)
A
 00 Hour Analysis N
 18 Hour Forecast
B
 01 Hour Forecast O
 24 Hour Forecast
C
 02 Hour Forecast P
 30 Hour Forecast
D
 03 Hour Forecast Q
 36 Hour Forecast
E
 04 Hour Forecast R
 42 Hour Forecast
F
 05 Hour Forecast S
 48 Hour Forecast
G
 06 Hour Forecast T
 60 Hour Forecast
H
 07 Hour Forecast U
 72 Hour Forecast
I
 08 Hour Forecast V
 84 Hour Forecast
J
 09 Hour Forecast W
 96 Hour Forecast
K
 10 Hour Forecast X
 108 Hour Forecast
L
 11 Hour Forecast Y
 120 Hour Forecast
M
 12 Hour Forecast Z
 Refer to GRIB PDS

The above table is maintained by the NWS Office of the Chief Information Officer and can be found online at:

   http://www.weather.gov/tg/tablec10.html


TABLE A.4   LEVEL DESIGNATORS - ii
(Header Octets 5 and 6)

            The following version of Table A.4 contains changes implemented by the WMO on November 3, 1993.  Unless indicated in Table A.4 below, the designator given is the hundreds and tens digits of the hPa level in the atmosphere, e.g. 70=700hPa; 03=30hPa, etc.

DESIGNATOR LEVEL or LAYER
99
 1000 hPa
98
 Air Properties at the Surface of Earth
97
 Level of the Tropopause
96
 Level of the Maximum Wind
94
 Level of the 0 deg. C isotherm
93
 975 hPa
92
 925 hPa
91
 875 hPa
89
 Any Parameter Reduced to Sea Level
88
 Land/Water Properties at the Surface of the Earth/Ocean
87
 1000-500 hPa thickness
86
 Boundary Layer
82
 825 hPa
77
 775 hPa
74
 Cloud Top Level
73
 Cloud Bottom Level (high, med, or low)
72
 725 hPa
67
 675 hPa
62
 625 hPa
57
 575 hPa
52
 525 hPa
47
 475 hPa
42
 425 hPa
37
 375 hPa
32
 325 hPa
27
 275 hPa
22
 225 hPa
17
 175 hPa
12
 125 hPa
01
 Refer to GRIB PDS
00
 Entire Atmosphere
Note: The following levels are used to indicate geometric height for aviation flight levels, not pressure levels
81
 6000 ft FL (approximately 810 hPa)
73
 9000 ft FL (approximately 730 hPa)
64
 12000 ft FL (approximately 640 hPa)
51
 18000 ft FL (approximately 510 hPa)


TABLE A.5   MODEL IDENTIFIERS
  (Header Octet 11)

            All NCEP GRIB products have a CCCC that starts with KWB(?).  The fourth letter of this identifier is defined as follows.

DESIGNATOR NCEP MODEL
A
 Reserved for Future Use
B
 Reserved for Future Use
C
 Global Forecast System Model
D
 Downscaled GFS using Eta eXtension (DGEX)
E
 North American Mesoscale (NAM) Model
F
 Nested Grid Model (NGM)
G
 Rapid Update Cycle
H
 Medium Range Forecast (MRF)
I
 Sea Surface Temperature Analysis
J
 Wind-Wave Forecast Model
K
 Global Ensemble Forecasts
L
 Regional Ensemble Forecasts
M
 Ocean Models
N
 Used by NDFD Program
O
 Merge of Models
P
 EPA/CMAQ
Q
 Reserved for Future Use
R
 Real Time Mesoscale Analysis / Analysis of Error
S-Y
 Reserved for Future Use
Z
 Refer to GRIB PDS