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Greetings! See inline below: > At various times, two snow accumulation variables appear in the dataset. > https://thredds.ucar.edu/thredds/ncss/grib/NCEP/NBM/CONUS/Best/dataset.html > > 1. Total_snowfall_surface_1_Hour_Accumulation (with Time coordinate > time7) > 2. Total_snowfall_surface_Mixed_intervals_Accumulation (with Time > coordinate time6) > > Neither of these variables is documented in the NCEP nbm documentation. > 1. Exactly what data is represented in these variables? I'm not sure why there was a separate hourly accumulation, but currently on the mixed interval version is available. This is the standard snow accumulation that is documented here: https://vlab.noaa.gov/web/mdl/nbm-wx-elements > 2. How many hours does each variable cover in a dataset? > 3. Which hourly runs produce which variables? Here is NCEP's documentation for how many hours each variable extends to for each forecast run--for what's distributed on NOAAPORT, which is what provides the data we host on THREDDS: https://www.weather.gov/media/mdl/nbm/docs_v40/NBM_v40_Elements_on_SBN_by_Cycle_ALL.pdf > 4. What does time7 and time6 mean? time6 means it was the 6th unique time coordinate identified by netcdf-java as it scanned through the grib file; time7 is the 7th. These are just trying to come up with unique dimension names given the diverse set of different times (reference time and valid time) in the GRIB collection. > 5. To always get the latest model run, what time range should I request? If you use the "Best" dataset, as linked, you'll get a collection of the times closest to the range requested, with the smallest forecast offset (e.g. 12 hour vs. 96 hour) > 6. What is the "stride"? How big a step to take through the data. If your requested time range of 0-12 with hourly data, a request with a stride of 3 will give (0, 3, 6, 9, 12). > 7. How would I select a previous model run? Either manually find the appropriate run time that contains the data you need from the full list here: https://thredds.ucar.edu/thredds/catalog/grib/NCEP/NBM/CONUS/catalog.html Or use the Full collection, and subset using the reftime for the forecast you want: https://thredds.ucar.edu/thredds/catalog/grib/NCEP/NBM/CONUS/catalog.html Hope this helps! Ryan Ticket Details =================== Ticket ID: DBI-852054 Department: Support THREDDS Priority: Normal Status: Closed =================== NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.