Frequently-Asked Questions
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SNOTEL and SCAN Data Collection
Q |
What is the precision of the sensors used at SNOTEL and SCAN sites? |
A |
Sensor precision and units for key elements at SNOTEL and SCAN sites are:
Site |
Element |
Precision/Unit |
SNOTEL |
Air Temperature |
Tenth of a degree Celsius (0.1 °C) |
SCAN |
Air Temperature |
Tenth of a degree Celsius (0.1 °C) |
SNOTEL |
Precipitation |
Tenth of an inch (0.1 in) |
SCAN |
Precipitation |
Hundredth of an inch (0.01 in) |
SNOTEL |
Snow Water Equivalent |
Tenth of an inch (0.1 in) |
More on SNOTEL sensors
More on SCAN sensors
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Q |
What time zone is used for displaying SNOTEL and SCAN data? |
A |
SNOTEL data are reported in PST, Pacific Standard Time (UTC-08:00), for sites in all western states, except Alaska. Alaska SNOTEL sites are report in YST, Yukon Standard Time (UTC-09:00). SCAN data are reported in local standard time for the SCAN site location. |
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Q |
What is the difference between the Accumulated Precipitation and the Snow Water Equivalent (SWE) measured at a SNOTEL site? |
A |
At a SNOTEL site, the accumulated precipitation consists of both rain and snow that has entered the precipitation gage. The weight of the snow on the pillow sensor at a SNOTEL site is converted into inches of snow water equivalent (SWE), the column of water if the snow was melted. Sometimes the snow can include rain, if there has been a recent ‘rain-on-snow’ event. However, for the most part, the SWE sensor tracks snow only |
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Q |
In addition to Natural Resources Conservation Service (NRCS) networks, such as SNOTEL and SCAN, from what other data networks do you collection information? |
A |
SNOTEL and SCAN data are stored in the NRCS Water and Climate Information System (WCIS) database. This database contains data from many sources, including non-real time sources such as snow courses and aerial markers and other automated data collection networks. Precipitation, streamflow, and reservoir data are collected from the U.S. Army Corps of Engineers (USACE), the U.S. Bureau of Reclamation (BOR), the National Weather Service (NWS), the Applied Climate Information System (ACIS), the U.S. Geological Survey (USGS) and various water districts and other entities.

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Q |
Is there a standard list of definitions for the climatic data elements used in SNOTEL and SCAN reports? |
A |
Yes. Here's the Glossary of element definitions, parameter definitions, and parameter rules. |