Description of the GFS LAMP Alphanumeric Message

Station--based LAMP guidance is generated using the most recent station observations for the cycle time, analyses of the observations, simple model output, and MOS data derived from one or more NWP models, e.g., NCEP's Global Forecast System and GSL's High Resolution Rapid Refresh. This guidance is valid for stations in the United States, Puerto Rico, and the U.S. Virgin Islands. Please refer to the following document for the most recent station list. 

The information that follows applies to the LAMP v2.6.0 Alphanumeric Text Messages, which are valid starting September 30, 2024.

For the standard, hourly LAMP guidance, forecast elements are valid from 1 to 25 hours in advance, except from 1 to 38 hours for TMP, DPT, WDR, WSP, WGS, CIG, VIS, OBV, P01, CCG, CVS, and PC1.

Starting with LMP v2.6.0, there are 5 types of ASCII text bulletins. They are:

1. The standard bulletin which covers the 1-25 hour period.
2. The extended bulletin which covers the 26-38 hour period.
3. The full bulletin which covers the 1-38 hour period. This bulletin is currently only available via the LAMP website.
4. 15-min update bulletins containing categorical ceiling height and visibility guidance for hourly projections out to 3 hours.
5. 15-min update bulletins containing categorical Highest Impact Weather (HIW) ceiling height and visibility guidance valid for 15-minute periods out to 6 hours.

    The below example shows the full 1-38 hr bulletin, but the key applies to all bulletins (1)-(4) above.

 KDCA   WASHINGTON            GFS LAMP 1330 UTC   6/06/2023
 DT /JUNE  6                        /JUNE  7                                                                /JUNE  8
 HR   01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38
 UTC  14 15 16 17 18 19 20 21 22 23 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 00 01 02 03
 TMP  71 73 76 78 80 81 84 83 82 81 79 76 74 73 71 69 69 65 64 63 62 63 66 69 71 74 76 77 78 79 79 78 77 76 73 71 69 67
 DPT  45 45 44 45 46 46 45 45 45 44 45 45 46 48 47 47 47 47 47 46 46 46 46 46 44 43 42 42 42 42 42 43 43 44 45 46 47 48
 WDR  31 30 30 30 30 30 29 29 29 29 28 29 30 32 33 34 35 34 33 32 31 32 32 32 32 31 31 30 30 30 27 26 25 24 23 23 23 21
 WSP  08 09 11 12 13 14 14 15 15 12 10 09 07 07 07 07 06 06 04 04 05 05 05 07 07 07 07 07 07 08 08 10 10 10 10 08 07 07
 WGS  16 17 19 20 21 23 22 23 23 20 NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG NG
 PPO   0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0999999999999999999999999999999999999999
 PCO   N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  X  X  X  X  X  X  X  X  X  X  X  X  X
 P01   0  0  0  0  0  0  0  0  0  0  1  1  3  3  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  1  1  1  2  2  2  2
 PC1   N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N
 P06                                 1                 6                 0                 0                 4
 LP1   0  0  0  0  0  0  1  2  2  2  2  2  1  0  0  0  0  0  0  0  0  0  0  0  0999999999999999999999999999999999999999
 LC1   N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  X  X  X  X  X  X  X  X  X  X  X  X  X
 CP1   2  0  0  0  0  1  1  1  1  2  2  2  2  2  1  0  0  0  0  0  0  0  0  0  0999999999999999999999999999999999999999
 CC1   N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  X  X  X  X  X  X  X  X  X  X  X  X  X
 CLD  BK BK BK BK OV BK BK BK BK BK OV BK BK BK BK BK BK BK BK BK BK BK BK BK BK SC SC SC SC SC SC BK BK BK BK BK BK OV
 CIG   8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  7  7
 CCG   8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8
 VIS   7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7
 CVS   7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7
 OBV   N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N

• UTC Hour of the day in UTC time. This is the hour at which the forecast is valid, or if the forecast is valid for a period, the end of the forecast period.
• TMP surface temperature valid at that hour.
• DPT surface dewpoint valid at that hour.
• WDR forecasts of the 10-meter wind direction at the hour, given in tens of degrees.
• WSP forecasts of the 10-meter wind speed at the hour, given in knots.
• WGS forecasts of the 10-meter wind gust at the hour, given in knots.  "NG" means that no gust is forecast.
• PPO probability of precipitation occurring on the hour.  The precipitation need not be measurable.
• PCO categorical forecast of yes (Y) or no (N) indicating if precipitation, not necessarily measurable, will occur on the hour.
• P01 probability of measurable precipitation (PoP) during the 1-h period ending at the indicated time.
• PC1 categorical forecast of yes (Y) or no (N) indicating if measurable precipitation will occur during the 1-h period ending at the indicated time.
• P06 probability of measurable precipitation (PoP) during a 6-h period ending at that time.
• LP1 probability of lightning (at least one total lightning flash) occurring during the 1-hr period ending at the indicated time.
• LC1 categorical forecast of no (N), low (L), medium (M), or high (H) potential for lightning (at least one total lightning flash) occurring during the 1-hr period ending at the indicated time.
• CP1 probability of convection (at least one total lightning flash and/or radar reflectivity of 40dBZ or higher) occurring during the 1-hr period ending at the indicated time.
• CC1 categorical forecast of no (N), low (L), medium (M), or high (H) potential for convection (at least one total lightning flash and/or radar reflectivity of 40dBZ or higher) occurring during the 1-hr period ending at the indicated time.
• POZ* conditional probability of freezing pcp occurring at the hour.  This probability is conditional on precipitation occurring.
• POS* conditional probability of snow occurring at the hour.  This probability is conditional on precipitation occurring.
• TYP* conditional precipitation type at the hour.  This category forecast is conditional on precipitation occurring.
• CLD forecast categories of total sky cover valid at that hour.
• CIG ceiling height categorical forecasts at the hour.
• CCG conditional ceiling height categorical forecasts at the hour.   This category forecast is conditional on precipitation occurring.
• VIS visibility categorical forecasts at the hour.
• CVS conditional visibility categorical forecasts at the hour.   This category forecast is conditional on precipitation occurring.
• OBV obstruction to vision categorical forecasts at the hour.

*In the contiguous United States, these products are available September 1 - May 31.

An example of a 15-min updating HIW bulletin valid for 15-minute periods out to six hours and associated key are shown below.

• UTC - ending hour of the 15-minute period in UTC time
• MIN - ending minute of the 15-minute period in UTC time
• CIG - the lowest forecasted LAMP categorical ceiling height during the 15-minute period
• VIS - the lowest forecasted LAMP categorical visibility during the 15-minute period

Definitions of Categorical Elements