Hello all - I'll continue in this topic for now: I've just posted the attached snow sensor charts in the JMT FB groups so am cross-posting here for those not on FB. Admins, if there is a better way to share this info please let me know - the map and chart files are all jpegs, but I also have the charts in a single pdf file (need the jpegs for FB uploads). I'm just going to copy-paste the text from the FB posts, which includes explanatory text for what the charts represent:
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Hello hikers,
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Second snow sensor report of the season. January has been a month of contrasts: two weeks of unbelievable snow, followed by two weeks of not much. A January lull is not unusual in the Sierra, and the same pattern can be seen in some of the charts. The snowpack is still similar to 2017 ¨C outpacing in some locations, falling behind in others, but generally pretty close despite a couple weeks of no snow. A quick scan of forecasts for the next week indicates low storm activity ¨C possibly a little snow this Sunday, but nothing substantial going into Feb. So, we wait and see. As always in the Sierra, don¡¯t count your chickens before they hatch.
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Here¡¯s the standard guidance for reading these charts:
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1)????? The Sensor Maps show the snow sensor locations (three letter acronyms) relative to the JMT (red line). These correspond to the titles of the charts.?
2)????? The charts are in ¡°snow water equivalents¡± (SWE). That is the weight of the snow on the sensor, which is equivalent to the water contained in the snow. The actual thickness of the snowpack depends on the density of the snow: cold, fluffy powder results in a thicker snowpack vs warmer, denser Sierra Cement. As a rule of thumb, multiply the SWE by 3 in winter and 2 in spring to get the snowpack thickness.?
3)????? The charts compare SWE data from 2015 (historical min), and select years from 2017-2023. Missing data on the charts means that it was missing in the CDEC database, which generally means the sensor wasn¡¯t operating at the time (or the frequency of data reporting changed).?
4)????? The scales on the vertical axes (SWE) are not all the same! They are scaled to the data. Hence, the Mammoth Pass (MHP) chart represent about twice as much snow as the Crabtree Meadow (CBT) chart.?
5)????? These snow sensors are used by the state to estimate snowmelt runoff volumes for water supply management purposes and won¡¯t necessarily indicate snow-on-trail conditions. But they are useful for relative comparisons to other years and should give a general idea of how this year will stack up to previous years.
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Lange Jorstad
