How often to measure snow?

[janetjanet998]

I guess it kind of makes sense to clear it 4 times a day. The NWS reports their official measurements every 6hrs. I'm kind of curious as to what we would have measured had this been done. Funny thing is my 8.5" is almost as high as the highest totals in the area. This makes me think everyone else is doing the same thing as I am, otherwise there surely would have been several 10" reports. I think if I would have done the snowboard measuring method (clearing it 3-4 times per day) our total would have been at or over 10". Oh well, in the grand scheme of things the public perception in this area is we picked up about 7-9". That's what the laymen sees when they have to be out shoveling it for example.

you had over 10 inches then....

i thought you might hit the jackpot...

People aren't going to stay up until 06z and wake up at 12z just to clear snowboards like they do at the airports or something

this is one thing that causes variations in snowfall totals while a constant amounts falls

[michsnowfreak]

Are you not supposed to report 10.0 inches for your total? I used to wait until the end of storms to measure, allowing compaction to go on for up to 24 hours, but last winter OceanStWx said I should clear my snowboards after measuring(about 3 times a day, no more than 4 times). Then each of the measurements is added together and reported as the total. As I said, I used to only measure at the end of storms and I usually ended up reporting less than just about everyone in my area. Last year I added up cleaned snowboard measurements and my totals were much more in line with the other spotters around here.

If what he said is true, than it should be 10.5". You measure every 6 hours. Snow depth is supposed to be taken at 7am, so it wont be a surprise if his snow depth tomorrow morning is 7" or so with the settling powder. But the storm total should still be 10.5".

[michsnowfreak]

I've seen conflicting info. Some sites suggest the nws clears their snowboards up to 4 times a day after each official measurement. However, the snow measuring guidelines I received from the nws this fall suggests you don't clear your snowboard until the storm is over.

Wow that is crazy. Ive always heard of the 6-hour rule. The stuff I have from the NWS is the 6-hour increments. Official first-order stations are supposed to report snow at times of 7am, 1pm, 7pm, and 1am. Of course snow doesnt follow a clock, so say a starts at 2pm, you can measure as often as you like, but dont clear the board til 8pm. however, dont wait til 9 of 10pm to clear it, that will low-ball.

[OceanStWx]

Wow that is crazy. Ive always heard of the 6-hour rule. The stuff I have from the NWS is the 6-hour increments. Official first-order stations are supposed to report snow at times of 7am, 1pm, 7pm, and 1am. Of course snow doesnt follow a clock, so say a starts at 2pm, you can measure as often as you like, but dont clear the board til 8pm. however, dont wait til 9 of 10pm to clear it, that will low-ball.

It's fairly confusing if you really dig deep into it, but here's the gist. For COOPs or ASOS sites that are having their observations augmented for precip it is the greatest accumulation since "the last snowfall measurement." This could be one time during the day, but never more than four. Meaning that you should never clear the board more than four times in a day. ASOS sites are required to take observations at the synoptic times (00z, 06z, etc). COOPs are not required to do the same, but can if they choose starting with their regularly scheduled observation time. So you can measure every hour if you like, but you cannot sum those hourly totals to get a final and you cannot clear the board every hour. You must let the snow compact for at least 6 hours, and that will be your "greatest accumulation." If snow is melting after accumulating you can measure each "snow event" and sum those to get the greatest total since your last observation (have I lost anyone yet?). However, if snow continually melts as it lands your accumulation is a "trace."

[Hoosier]

It's fairly confusing if you really dig deep into it, but here's the gist. For COOPs or ASOS sites that are having their observations augmented for precip it is the greatest accumulation since "the last snowfall measurement." This could be one time during the day, but never more than four. Meaning that you should never clear the board more than four times in a day. ASOS sites are required to take observations at the synoptic times (00z, 06z, etc). COOPs are not required to do the same, but can if they choose starting with their regularly scheduled observation time. So you can measure every hour if you like, but you cannot sum those hourly totals to get a final and you cannot clear the board every hour. You must let the snow compact for at least 6 hours, and that will be your "greatest accumulation." If snow is melting after accumulating you can measure each "snow event" and sum those to get the greatest total since your last observation (have I lost anyone yet?). However, if snow continually melts as it lands your accumulation is a "trace."

Very useful info...it can get a bit confusing but you did a good job explaining it. Maybe I should split all these measuring posts into another thread for quick future reference.

[janetjanet998]

It's fairly confusing if you really dig deep into it, but here's the gist. For COOPs or ASOS sites that are having their observations augmented for precip it is the greatest accumulation since "the last snowfall measurement." This could be one time during the day, but never more than four. Meaning that you should never clear the board more than four times in a day. ASOS sites are required to take observations at the synoptic times (00z, 06z, etc). COOPs are not required to do the same, but can if they choose starting with their regularly scheduled observation time. So you can measure every hour if you like, but you cannot sum those hourly totals to get a final and you cannot clear the board every hour. You must let the snow compact for at least 6 hours, and that will be your "greatest accumulation." If snow is melting after accumulating you can measure each "snow event" and sum those to get the greatest total since your last observation (have I lost anyone yet?). However, if snow continually melts as it lands your accumulation is a "trace."

Ok so when the NWS says they expect 10 inches of snow over 24 hours do they mean one measurement after the snow ends...(which will really be more then 10 inches) or do they mean 10 inches if you clear the snow baord every 6 hours and add them up?

[michsnowfreak]

Ok so when the NWS says they expect 10 inches of snow over 24 hours do they mean one measurement after the snow ends...(which will really be more then 10 inches) or do they mean 10 inches if you clear the snow baord every 6 hours and add them up?

They mean total snowfall, so it would mean every 6 hours. Sometimes they will even say, esp after a long duration snowstorm, total snowfall accumulations of XX inches, though depth on the ground may be a bit less after compacting.

For instance, these lake effect warnings that are out in parts of MI, IN, OH that say the jackpot areas can see a total of 1-2 feet by Tuesday....that does NOT mean they will stick a yardstick in the ground Tuesday morning and have it read 24". Fluffy lake snow falling for 60 hours, I could see total accumulation of 24.0" with a snow depth Tuesday morning of 15" or so.

[Aaron]

In the Air Force we measure depth

Every hour cleaning an area of the snow board each time but report every 3 hrs. This allows us to keep and eye on warning criteria.

We also take a precip eqiv reading every hours and report it every hour. This allows us to watch the ratio of 1/10 , 1/20 ect if there is an increase in the water equivalency ratio we can issue further warnings as necessary.

Sent from my FroyoEris using Tapatalk

[hawkeye_wx]

The info I received in the mail (sent to all spotters) from the NWS this year says the following...

First, they'd like snow reports at about 9am, 3pm, and 8pm, plus at the end of the event.

They provide this example...

- Snow begins at 5am.

- At 9am you measure 3 inches and call it in.

- It continues to snow during the afternoon.

- At 3pm you measure again in the same area, and now it is up to 5 inches for the storm total so far.

- The snow ends around 7pm and your final snowfall measurement is 6 inches. You call in 6 inches for your storm total.

- You clear off your snow board and are ready for the next storm.

So in the example the snow event lasts for 14 hours, but the instructions given to the spotters suggests they let the snow pile up on their board for the duration. If a spotter is at work during the day he pretty much has no choice other than to let the snow pile up and get a final measurement in the evening. However, if a spotter is home all day would it be better if he took a measurement and cleaned the board about halfway through the storm, around noon? That is what I would have done last winter and was planning to do again this winter. I guess if a spotter wants to strictly adhere to the 6-hour rule he could measure and clean the board at 11am, then again at 5pm, then again when the storm finished at 7pm?

[janetjanet998]

still conflicting info...

as an experiment it would be interesting to see how much a difference it makes

so maybe some of you could clear off part of your snowbaords every 6 hours and add the totals...but in one area don't and take one measuremnt after the snow ends

[cyclone77]

IMHO, the whole snowboard thing only really works when the wind is very light, or near calm. If there's any wind at all measurements need to be taken in numerous locations in areas that look the least impacted by the wind/drifting as possible. You would need 5-10 snowboards strategically placed to make the snowboard method work the best in this type of scenario.

Yesterday's situation was very easy, as there was no wind at all. The only issue was settling. My early morning measurement of 8.0" was very accurate, as the snow had not begun to settle yet. After that it becomes hazy, as I was gone for 9+hrs, and by the time I returned home settling had clearly already commenced. I measured in the same areas I had early in the morning and only averaged 8.5". Yet, the 2" on the shoveled patio revealed that in all reality the snow total may have been 10"+. The way I looked at it was even though an additional 2" fell during the day, it seemed peculiar calling it 10", when only 8.5" was on the ground. Especially when no one else around reported anything over 8-9".

[aslkahuna]

IMHO, the whole snowboard thing only really works when the wind is very light, or near calm. If there's any wind at all measurements need to be taken in numerous locations in areas that look the least impacted by the wind/drifting as possible. You would need 5-10 snowboards strategically placed to make the snowboard method work the best in this type of scenario.

Yesterday's situation was very easy, as there was no wind at all. The only issue was settling. My early morning measurement of 8.0" was very accurate, as the snow had not begun to settle yet. After that it becomes hazy, as I was gone for 9+hrs, and by the time I returned home settling had clearly already commenced. I measured in the same areas I had early in the morning and only averaged 8.5". Yet, the 2" on the shoveled patio revealed that in all reality the snow total may have been 10"+. The way I looked at it was even though an additional 2" fell during the day, it seemed peculiar calling it 10", when only 8.5" was on the ground. Especially when no one else around reported anything over 8-9".

Back in the old Circular N days (which goes way back) the rule for measuring snow that was wind drifted was to take measurements in a number of places to include both any bare spots and drifted areas.

Steve

[OceanStWx]

The info I received in the mail (sent to all spotters) from the NWS this year says the following...

First, they'd like snow reports at about 9am, 3pm, and 8pm, plus at the end of the event.

They provide this example...

- Snow begins at 5am.

- At 9am you measure 3 inches and call it in.

- It continues to snow during the afternoon.

- At 3pm you measure again in the same area, and now it is up to 5 inches for the storm total so far.

- The snow ends around 7pm and your final snowfall measurement is 6 inches. You call in 6 inches for your storm total.

- You clear off your snow board and are ready for the next storm.

So in the example the snow event lasts for 14 hours, but the instructions given to the spotters suggests they let the snow pile up on their board for the duration. If a spotter is at work during the day he pretty much has no choice other than to let the snow pile up and get a final measurement in the evening. However, if a spotter is home all day would it be better if he took a measurement and cleaned the board about halfway through the storm, around noon? That is what I would have done last winter and was planning to do again this winter. I guess if a spotter wants to strictly adhere to the 6-hour rule he could measure and clean the board at 11am, then again at 5pm, then again when the storm finished at 7pm?

My guess would be because these directions are the easiest. And one measurement during the day is sufficient, but you have the option of clearing it up to 4 times (every 6 hours) during the day if you would like. The reason for the 9 AM, 3 and 8 PM call in times is so that we can get a summary LSR message out for the media to report on snow totals at noon, 6 and 10 PM.