ON388 - Appendix A

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 character ‘E’ for oceanographic GRIB2 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 Example: a five part message would have the parts indicated by PAA, PAB, PAC, PAD, PZE. part of the message will have xx=Zn, where n is the next letter in the appropriate sequence.
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" for Oceanographic GRIB bulletins intended for general International and National Exchange
                                              and for use in the NWS AWIPS program.
                                      "E" for oceanographic GRIB2 bulletins intended for general International and National Exchange
                                              and for use in the NWS AWIPS program
                                      "L", "M", "Y" or "Z" for GRIB bulletins destined for the NWS AWIPS program.

     T₂:   Type of data/parameter

     A₁: Grid

    A₂:   Analysis or forecast hour

      ii:    Numeric. Usually a 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	Refer to GRIB PDS

* 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)				FOR "CCCC" = KWBS	FOR "CCCC" = KWBR	FOR "CCCC" = KWBE
	FOS and International (H)	AWIPS (O)	AWIPS (E)	AWIPS (L, M, Y, Z)	AWIPS (L, M)	AWIPS (L, M)	AWIPS (L, M)
A	21	228 - 2.5x2.5 deg lat/lon global	11 - 0.5 deg - Lat/Lon Global grid	201 - 381 km Northern Hemisphere	HIRES - 5 km Eastern US	198 (RTMA) 6 km Alaska	198 - 6 km Alaska
B	22	218 - 12-km CONUS	12 - 0.167 deg - US East Coast	218 - 12-km CONUS	HIRES - 5 km Western US		218 - 12-km CONUS
C	23	219 - N. Hemisphere High Res	13 - 0.167 deg - US West Coast	175 - 10 km lat/lon Guam	HIRES - 5 km Alaska	195 (RTMA) 2.5 km Puerto Rico	195 - 2.5 km Puerto Rico
D	24	220 - S. Hemisphere High Res	14 - 0.167 deg - Eastern Pacific (includes Hawaii and extends to the Pacific islands of Guam)	130 - 13-km CONUS	HIRES - 5 km Pacific (HI/Guam)
E	25	221 - N. American High Res	15 - 0.25 x 0.167 deg - Alaska	185 - 12 km CONUS (DGEX)	HIRES - 5 km Puerto Rico
F	26	229 - 1.0x1.0 deg lat/lon global	16 - 0.133 x 0.167 deg - Alaska	186 – 12 km Alaska (DGEX)
G	50	230 - 0.5x0.5 deg lat/lon global	17 - 0.067 deg - US West Coast	160 - 47.5 km Alaska NPS		199 (RTMA) 2.5 km Guam
H		231 - 0.5x0.5 deg lat/lon N.H.	18 - 0.067 deg - US East Coast	213 - 95 km CONUS		196 (RTMA) 2.5 km Hawaii	196 - 2.5 km Hawaii
I	37	232 - 1.0x1.0 deg lat/lon N.H.	176 - .050 x .035 degree grid - Great Lakes	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		227 (RTMA) 5 km Conus	227 5 km Conus
N	42	239 - Alaska Regional lat/lon		207 - 95 km Alaska			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			237 - 32 km Puerto Rico
Q		253 - Eastern North Pacific lat/lon		211 - 80 km CONUS			211 - 80 km CONUS
R		212 - 40 km CONUS	260 - 25 km North Atlantic (OPC)	212 - 40 km CONUS			212 - 40 km CONUS
S		253 - Eastern North Pacific lat/lon		242 - 11.25 km Alaska			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	261 - 25 km North Pacific (OPC)	215 - 20 km CONUS			215 - 20 km CONUS
V	63	216 - 45 km Alaska		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 - A2
(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)
	FOS, International (H) and AWIPS (L or Y)	Octet 8-11 = KWBM	Octet 8-11 = KWBJ	AWIPS (M or Z)
A	00 hour analysis	00 hour analysis	00 hour analysis	02 hour fcst
B	06 hour fcst	01,02,..,12 hour fcst	01,02,03 hour fcst	03 hour fcst
C	12 hour fcst	13,14,..,24 hour fcst	04,05,06 hour fcst	04 hour fcst
D	18 hour fcst	25,26,..,36 hour fcst	07,08,09 hour fcst	08 hour fcst
E	24 hour fcst	37,38,..,48 hour fcst	10,11,12 hour fcst	09 hour fcst
F	30 hour fcst	49,50,..,60 hour fcst	13,14,15 hour fcst	10 hour fcst
G	36 hour fcst	61,62,..,72 hour fcst	16,17,18 hour fcst	14 hour fcst
H	42 hour fcst	73,74,..,84 hour fcst	19,20,..,23 hour fcst	15 hour fcst
I	48 hour fcst	85,86,..,96 hour fcst	24,25,..,29 hour fcst	16 hour fcst
J	60 hour fcst	108 hour fcst	30,31,..,35 hour fcst	20 hour fcst
K	72 hour fcst	120 hour fcst	36,37,..,41 hour fcst	21 hour fcst
L	84 hour fcst	144 hour fcst	42,43,..,47 hour fcst	27 hour fcst
M	96 hour fcst	168 hour fcst	48,49,..,59 hour fcst	54 hour fcst
N	108 hour fcst	192 hour fcst	60,61,..,71 hour fcst	66 hour fcst
O	120 hour fcst	216 hour fcst	72,73,..,83 hour fcst	33 hour fcst
P	132 hour fcst	240 hour fcst	84,85,..,95 hour fcst	39 hour fcst
Q	144 hour fcst	264 hour fcst	96,97,..,119 hour fcst	45 hour fcst
R	156 hour fcst	288 hour fcst	120,121,..,131 hour fcst	51 hour fcst
S	168 hour fcst	312 hour fcst	132,133,..,143 hour fcst	57 hour fcst
T	180 hour fcst	336 hour fcst	144,145,..,155 hour fcst	78 hour fcst
U	192 hour fcst	360 hour fcst	156,157,..,167 hour fcst	90 hour fcst
V	204 hour fcst	384 hour fcst	168, 174 hour fcst	102 hour fcst
W	216 hour fcst	-	180 hour fcst	114 hour fcst
X	228 hour fcst	-	54, 57 hour fcst
Y	240 hour fcst	-	66, 69 hour fcst	-
Z	Refer to GRIB PDS	Refer to GRIB PDS	108, 114 hour fcst	Refer to GRIB PDS

The WMO headings for NAM 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 NAM 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/Extratropical Storm Surge Model
N	Used by NDFD Program
O	Merge of Models
P	EPA/CMAQ
Q	MDL Gridded MOS Products
R	Real Time Mesoscale Analysis / Analysis of Error
S	Hires Window Model (ARW, NMM); Five Domains (West/East US, AK, HI, PR)
T-W	Reserved for Future Use
X	ECMWF
Y	Reserved for Future Use
Z	Refer to GRIB PDS