MDL's Localized Aviation MOS Program (LAMP) and Gridded LAMP (GLMP) Upgraded at NWS

Dec 16, 2024

This image shows an example GLMP forecast for the probability of ceiling height <= 3000 ft from the 0000 UTC cycle on October 10, 2024, valid for the 15-minute period 0330-0345 UTC

An upgrade to the Localized Aviation Model Output Statistics (MOS) Program (LAMP) and Gridded LAMP (GLMP) systems was implemented into NWS operations on Monday, September 30, 2024.  LAMP is a statistical system which provides forecast guidance for sensible weather elements  and updates the Global Forecast System (GFS)-based MOS on an hourly basis (every 15 minutes for C&V elements).  The guidance is produced on the NOAA/NWS/NCEP Weather and Climate Operational Supercomputer System (WCOSS) and is disseminated centrally from NCEP.  LAMP provides guidance for over 2000 stations in the CONUS, Alaska, Hawaii, and Puerto Rico as well as gridded observations and gridded forecast guidance out to 38 hours (for most elements), and serves as an important input to the National Blend of Models (NBM) in the first 36 hours of the forecast.  

Aviation decision-making operators, including Helicopter Air Ambulance operators, use the NWS Aviation Weather Center (AWC) Graphical Forecasts for Aviation - Low Altitude (GFA-LA) platform, which currently uses GLMP data to update every 15 minutes with the latest gridded observational and hourly forecast data.  GFA-LA users requested higher temporal resolution ceiling height and visibility (C&V) information to support decision making.  To help fill this gap in the GFA-LA tool, the Meteorological Development Laboratory (MDL) was tasked by the Federal Aviation Administration Aviation Weather Research Program (FAA AWRP) to increase the temporal resolution of GLMP C&V guidance from one hour time steps to 15 minute time steps in the first six hours of the forecast period.  

Traditionally, LAMP and GLMP guidance projections have been valid for a point in time at the top of each hour, derived from top-of-the-hour observations.  However, forecasts focused on predicting C&V at the top of each hour may miss impactful events that occur during the hour.  For example, an analysis of visibility observations for the Core 30 airports over a one year period showed that when the top of the hour visibility was Marginal Visual Flight Rules (MVFR) (visibility between 3 and 5 miles), the intra-hour visibility was a lower flight category over 30% of the time at some stations and was a lower flight category ~15% of the time on average.  In an effort to address this gap and fulfill the FAA AWRP deliverable, MDL developed new LAMP/GLMP “High Impact Weather (HIW)” C&V guidance, defined as the lowest ceiling height and lowest visibility condition that is forecast to occur during a 15-minute period (as opposed to being valid at the top of the hour).  

This new LAMP/GLMP upgrade (v2.6) marks a milestone in that it is the first time that LAMP has produced guidance over a period of time as short as 15 minutes!  This upgrade includes station-based and gridded HIW C&V guidance valid for 15-minute periods out to six hours, updating every 15 minutes (96 cycles per day) with the most recent observations and leveraging sub-hourly output from the High Resolution Rapid Refresh (HRRR) model.  The station guidance is produced in a text bulletin format that displays ceiling height and visibility categories valid for 15-minute periods out to six hours for 1818 contiguous U.S. (CONUS) stations.  An example 15-minute text bulletin and key with the definitions of the C&V categories is shown below:

An example 15-minute text bulletin and key with the definitions of the CV categories

Where:
UTC = The ending hour of the 15-minute period
MIN = The ending minute of the 15-minute period
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 

With the categorical definitions being found here:

Screenshot of the definitions of the C&V categories

The new HIW GLMP guidance provides probabilistic and deterministic grids for ceiling height and visibility valid for 15-minute periods out to six hours, in gridded binary version 2 (GRIB2) format on the NBM CONUS grid (note the spatial extent of the guidance is limited to the extent of the sub-hourly HRRR). The image below shows an example GLMP forecast for the probability of ceiling height <= 3000 ft from the 0000 UTC cycle on October 10, 2024, valid for the 15-minute period 0330-0345 UTC:

an example GLMP forecast for the probability of ceiling height <= 3000 ft from the 0000 UTC cycle on October 10, 2024, valid for the 15-minute period 0330-0345 UTC

Users can access the new 15-minute text bulletins and GRIB2 products on NCEP Web Services at the following locations:


The upgrade also includes minor bug fixes to improve the quality of the station and gridded guidance for users.  Additional details about the upgrade can be found in the Service Change Notice (SCN) here.  For questions about this model upgrade, please contact the LAMP Team at nws.lamp@noaa.gov.