LAMP GRIB2 Encoding Details
The GFS-based LAMP thunderstorm guidance is provided on the 5km NDFD grid in GRIB2 format. The products are disseminated via two
mechanisms. GRIB2 files are available on the NWS FTP server. Current status of the files on the server, and descriptions of the file
locations and names are available here. The files on the ftp server contain multiple grids in each file, grouped by element. The LAMP
thunderstorm products are also available via the NWS Satellite Broadcast Network (SBN) and NOAAPORT. The guidance is sent with each grid as a separate product with its own unique WMO
header. Click here for more details about the WMO headers, and refer to Section C.
This webpage seeks to provide users with some of the settings we are using to encode our products in GRIB2. Users should consult the WMO's GRIB2 handbook for the complete details on GRIB2 encoding.
Section 0 - Indicator Section
For all LAMP Thunderstorm GRIB2 products we set octet 7, Discipline, to 0 for Meteorological. We use GRIB edition 2 in octet 8.
Section 1 - Identification Section
|
Octet No.
|
Value
|
Explanation
|
|
6-7
|
7
|
Originating Center - NCEP
|
|
8-9
|
14
|
Originating Sub-center - MDL
|
|
10
|
1
|
initial operational version number
|
|
11
|
0
|
Version of local tables
|
|
12
|
1
|
Significance of date in Octets 13-19
|
|
13-19
|
Year, Month, Day, Hr, Min, Sec
|
Date of model run on which guidance is based
|
|
20
|
0
|
Operational products
|
|
21
|
1
|
Forecast products
|
Section 2 - Local Use Section
This section is not used in the LAMP Thunderstorm products.
Section 3 - Grid Definition Section
The LAMP Thunderstorm guidance is presented on the 5-km NDFD grid. The following are the grid specifications used to pack the guidance
into GRIB2.
|
Octet No.
|
Value
|
Explanation
|
|
1-4
|
TBD
|
Length of section in octets
|
|
5
|
3
|
Number of Section
|
|
6
|
0
|
Grid definition template defined in Octet 13-14
|
|
7-10
|
739297
|
Number of data points
|
|
11
|
0
|
Number of non-rectangular points
|
|
12
|
0
|
No appended list of points
|
|
13-14
|
30
|
Lambert Conformal GDT
|
|
15
|
6
|
Spherical earth, radius in Octet 16-20
|
|
16
|
0
|
Scale factor of radius of spherical earth
|
|
17-20
|
6371200
|
Scaled value of radius of spherical earth
|
|
21
|
missing
|
|
|
22-25
|
missing
|
|
|
26
|
missing
|
|
|
27-30
|
missing
|
|
|
31-34
|
1073
|
NX
|
|
35-38
|
689
|
NY
|
|
39-42
|
20192000
|
Latitude of first grid point
|
|
43-46
|
238446000
|
Longitude of first grid point
|
|
47
|
48
|
Resolution and component flags
|
|
48-51
|
25000000
|
Latitude where Dx and Dy are specified
|
|
52-55
|
265000000
|
Longitude of parallel meridian
|
|
56-59
|
5079406
|
Dx - grid length in x direction
|
|
60-63
|
5079406
|
Dy - grid length in y direction
|
|
64
|
0
|
Projection centre flag
|
|
65
|
80
|
data scanned boustrophedonically
|
|
66-69
|
25000000
|
Latin 1
|
|
70-73
|
25000000
|
Latin 2
|
|
74-77
|
-90000000
|
Latitude of southern pole
|
|
78-81
|
0
|
Longitude of southern pole
|
Section 4 - Product Definition Section
The LAMP Thunderstorm products are packed using Product Definition Template (PDT) 4.8. The
following tables list the settings for each element.
|
Guidance Valid Over a Period of Time
|
|
Octet No.
|
2-hr Thunderstorm Probability Forecast (%)
|
2-hr Categorical Thunderstorm Forecast (Yes/No)
|
|
1-4
|
Length of section in octets
|
Length of section in octets
|
|
5
|
4
|
4
|
|
6-7
|
0
|
0
|
|
8-9
|
8
|
8
|
|
10
|
19
|
19
|
|
11
|
2
|
203
|
|
12
|
5
|
2
|
|
13
|
missing
|
missing
|
|
14
|
108
|
108
|
|
15-16
|
missing
|
missing
|
|
17
|
missing
|
missing
|
|
18
|
1
|
1
|
|
19-22
|
hours from reference time to beginning of forecast period
|
|
23
|
1
|
1
|
|
24
|
0
|
0
|
|
25-28
|
0
|
0
|
|
29
|
missing
|
missing
|
|
30
|
0
|
0
|
|
31-34
|
0
|
0
|
|
35-36
|
Year of end of forecast period
|
Year of end of forecast period
|
|
37
|
Month of end of forecast period
|
Month of end of forecast period
|
|
38
|
Day of end of forecast period
|
Day of end of forecast period
|
|
39
|
Hour of end of forecast period
|
Hour of end of forecast period
|
|
40
|
Minute of end of forecast period
|
Minute of end of forecast period
|
|
41
|
Second of end of forecast period
|
Second of end of forecast period
|
|
42
|
1
|
1
|
|
43-46
|
0
|
0
|
|
47
|
missing
|
missing
|
|
48
|
missing
|
missing
|
|
49
|
1
|
1
|
|
50-53
|
2
|
2
|
|
54
|
missing
|
missing
|
|
55-58
|
missing
|
missing
|
Section 5 - Data Representation Section
We use Data Representation Template 5.3: Gridpoint data - complex packing and spatial differencing.
For scaling, we use the following decimal scaling factors:
|
2-hr Thunderstorm Probability Forecast (%)
|
2-hr Categorical Thunderstorm Forecast (Yes/No)
|
|
0
|
0
|
|
www.nws.noaa.gov
