LAMP GRIB Convective and Lightning - MDL
LAMP Convection and Lightning GRIB2 Encoding Details
The LAMP convection and lightning guidance is provided on the 2.5km NDFD grid in GRIB2 format. The products are disseminated via two mechanisms. GRIB2 files are available on the NWS FTP server. For current status of the files on the server, and descriptions of the file locations and names please refer to here. The files on the ftp server contain multiple grids in each file, grouped by element. The LAMP convection and lightning 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. For more details on WMO headers please refer to Section C (pdf).
This webpage seeks to provide users with some of the settings we are using to encode our products in GRIB2. Users should consult NCEP's WMO GRIB2 documentation for the complete details on GRIB2 encoding.
Section 0 - Indicator Section
For all LAMP Convection and Lightning 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, Hour, 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 Convection and Lightning products.
Section 3 - Grid Definition Section
The LAMP Convection and Lightning guidance is presented on the 2.5-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 Octets 13-14 |
| 7-10 | 2953665 | 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 octets 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 | 2145 | NX |
| 35-38 | 1377 | 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 | 2539703 | Dx - grid length in x direction |
| 60-63 | 2539703 | Dy - grid length in y direction |
| 64 | 0 | Projection center flag |
| 65 | 64 | data scan mode |
| 66-69 | 25000000 | Tangent Lat1 |
| 70-73 | 25000000 | Tangent Lat2 |
| 74-77 | -90000000 | Latitude of south pole |
| 78-81 | 0 | Longitude of south pole |
Section 4 - Product Definition Section
The LAMP Convection and Lightning products are packed using Product Definition Template (PDT) 4.8. The following table lists the settings for each element.
| Guidance Valid Over a Period of Time | ||||
|---|---|---|---|---|
| Octet No. | 1-hr and 2-hr Convection Probability Forecast (%) | 1-hr and 2-hr Convection Potential Forecast (No/Low/Med/High) |
1-hr and 2-hr Lightning Probability Forecast (%) | 1-hr and 2-hr Lightning Potential Forecast (No/Low/Med/High) |
| 1-4 |
|
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| 5 | 4 | 4 | 4 | 4 |
| 6-7 | 0 | 0 | 0 | 0 |
| 8-9 | 8 | 8 | 8 | 8 |
| 10 | 19 | 19 | 19 | 19 |
| 11 | 221 | 222 | 2 | 203 |
| 12 | 5 | 2 | 5 | 2 |
| 13 | missing | missing | missing | missing |
| 14 | 108 | 108 | 108 | 108 |
| 15-16 | missing | missing | missing | missing |
| 17 | missing | missing | missing | missing |
| 18 | 1 | 1 | 1 | 1 |
| 19-22 |
|
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| 23 | 1 | 1 | 1 | 1 |
| 24 | 0 | 0 | 0 | 0 |
| 25-28 | 0 | 0 | 0 | 0 |
| 29 | missing | missing | missing | missing |
| 30 | 0 | 0 | 0 | 0 |
| 31-34 | 0 | 0 | 0 | 0 |
| 35-36 |
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| 37 |
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| 38 |
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| 39 |
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| 40 |
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| 41 |
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| 42 | 1 | 1 | 1 | 1 |
| 43-46 | 0 | 0 | 0 | 0 |
| 47 | missing | missing | missing | missing |
| 48 | missing | missing | missing | missing |
| 49 | 1 | 1 | 1 | 1 |
| 50-53 | 2 | 2 | 2 | 2 |
| 54 | missing | missing | missing | missing |
| 55-58 | missing | missing | 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 a decimal scale factor of 0 for all elements.