Information about the new snow 1-day map (HN)

The map is published every day at 10:00 a.m. and shows the new snow (HN) that has fallen over the last 24 hours. It’s a useful datum for hikers, mountaineers and ski tourers because they can get an idea of the new snow amounts they could find in order to imagine how hard it will be to make the track or how much fresh snow could be transported by the wind with the formation of potentially unstable accumulations.

The map shows:

- spatialized new snow data obtained from the S3M model (Snow Multidata Mapping and Modeling). S3M uses a dynamic model that describes, in a simplified way, the evolution of the snowpack, through the snow observations (from automatic weather stations) and the MODIS satellite images (to distinguish snow-free areas from snow-covered ones). Also the manual observations from Modello1 AINEVA (MOD1) affect the result of the S3M model. In fact they are used by ARPA, together with the data coming from the Automatic Weather Stations (AWS), for the weekly calculation of the Snow Water Equivalent (SWE). The SWE data is assimilated by the S3M model once a week. S3M runs, since 2009, on a national scale with a spatial resolution of 500x500 meters and time resolution of one hour. The map shows the simulation at 06.00 a.m. The height of the new snow is calculated as a positive variation, over 24 hours, of the snowpack thickness modeled by S3M. The model is operational at the Centro funzionale regionale as part of an agreement signed with the Fondazione Cima;

- daily manual observations coming from Modello1 AINEVA (MOD1) regarding the height of new snow. Every morning, between 07:00 and 09:00 a.m., the observers measure how many cm of fresh snow have fallen since the last measurement, by using a white colored tablet, in order to limit the effects of irradiation, which is replaced on the snow surface after each measurement. The measurements fields are fixed and are usually located at an altitude between 1000 and 2500 m a.s.l.. If at these altitudes the new snow is wet or if it has rained, less fresh snow than at higher altitudes is measured. The measurements fields are located mainly in flat areas, possibly sheltered from the wind. The observations collected are punctual values: to define their position the best compromise was sought, but it must be remembered that, because of the extreme variability of the snow cover (due to the wind, solar radiation, etc.), the observations can differ significantly from other adjacent areas.

Corresponding map

NB - Only the HN punctual values from MOD1 correctly collected and entered in the relative database are shown on the map, so the number may vary from day to day. Since the observations are manually detected they are rather reliable, however, the presence of possible errors is not excluded. The acronym N/A (Not Available) is used when computer problems, for which it is not possible to access the data (even if present) of S3M and MOD1, occur.


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