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(I don't mind at all, just curious, pretty confident you're right) why did 31 resolve no? looked like T to me

@jacksonpolack are we looking at the same page? I see 0.0 here: https://climate.weather.gc.ca/climate_data/daily_data_e.html?StationID=51157&timeframe=2&StartYear=1840&EndYear=2023&Day=1&Year=2024&Month=1

@draaglom The link in the description points to December, which had “T” on the 31st. Perhaps that’s where the confusion stems from, @jacksonpolack?

yep

Jan 28th snow amount is listed as M for 'Missing'.

I will leave it unresolved for now, if it is still showing M by the time I am resolving for Jan 29th I will resolve it N/A.

@Kable Sounds good to me. No clear indication there was snow, but sometimes those still resolve to Trace.

RIP my mana, that's tragic.

Blowing snow does not imply any snow will land in the measuring device I guess (?)

@draaglom It's not an automatic process. Snow is usually measured on a snow board and measured manually by a person. So yes, in theory, blowing snow could land on the board and get measured as new snowfall. However, the weather observer should disregard this if they knew that no new precipitation actually fell.

@kalassak I see. Looking at your profile you appear to be a domain expert. I'd be grateful if you could help me update my mental model:

1. I assume at least the "easy" weather observations are generally automated? i.e. there's not a person looking at a thermometer and typing it into a weather report?
2. Are snowfall reports automated in at least some places at least some of the time? That was my impression reading e.g. this.
3. If automated at least some of the time, is it a low penetration rate? just during off hours? just outside of "important" weather stations such as airports?

@draaglom I'm no expert but I found this stuff:

https://www.canada.ca/en/environment-climate-change/services/weather-general-tools-resources/frequently-asked-questions.html#toc4

And also this (not Canadian but weather is weather): https://www.weather.gov/dvn/snowmeasure#:~:text=Snowfall%20(newly%20fallen%20snow)%20is,(such%20as%200.22%22).

So whether they are using automated observation or manual measurement they will always be doing it in an open area, so if there is any blowing snow it would not accumulate where the measurement is being made, and might even lower the snow depth by removing some off the top. Someone can correct me if I'm wrong, this is mostly speculation.

@draaglom Just a disclaimer, I'm not 100% familiar with ECCC's methodology, so working off how it works in the US:

1. Yeah, the temperature would be automated (though presumably a person is looking at it and doing QC before sending it out in the daily report). The hourly reports you see from the airports are likely automated for most parameters (temp, wind, precip, etc) but can be augmented at times (usually during the day) or even 24/7, depending on the airport. You can sort of guess at when an observer has augmented the report in cases where the hourly observation lists things like blowing snow which are not easily determined by an automated sensor. That doesn't necessarily mean that the person adding that to the observation is the same person taking the snow measurements, or the same person compiling the daily climate report. They certainly aren't where I work, and that can lead to discrepancies between the hourly observations and the daily climate report.
2. I'm not sure... automated snowfall measurements are very error-prone and are typically only snow depth (total on the ground) measurements, not actual new snowfall measurements. I have been working off the assumption that for the ECCC climate sites that report new snowfall that a person is physically measuring them, but I don't know for sure.
3. See above, but also yeah definitely outside of the main airports that have these measurements I'm sure they are just automated with something like a SNOTEL.

Responding a bit to the above comment as well: In an open area there would still be at least some grains of snow accumulating on an otherwise fresh/clean surface if the snow was blowing or drifting around. That could be read as a trace or even a sub-centimeter amount by either an automated sensor or a weather observer, if they just took it at face value.