Intense Precipitation reports

[alice]

Last night when I got home, I took some measurements as we did some shovelling.  The measurements were about 2 inches of snow.  It was snowing lighter than it had been.  I got in, and read my mail from Steve about intense precipitation reports.  At that point, it had been snowing since morning, and it was actually lighter at that moment than it had been a half hour earlier.

My question:  if I'm in the middle of a weather event, and I think there might be need to report intense precipitation, don't I need to make a "stopping point" as a starting point?  Like this: should I have taken a measurement (that would not represent "intense precipitation" at 2inches over 10 hours) in order to set the gauge back to zero, and monitor for the next hour or two?  Maybe "checkpoint reading" would be a better name.  Same goes for rain.

Since I wasn't sure, and I didn't think it was intense precipitation as much as a lengthy event that would add up to a lot, I didn't post any extra reports.  There is 9 inches total out there as of my morning's reading.

-Alice

[shberg]

Hi Alice,

You raise a good question, and you are correct.   Let's take a day like yesterday.  Say it starts snowing at 12 noon, and it snows steadily but lightly for 4 hours - nothing out of the ordinary and there is 1.5 inches of new snow.  At 4:00 p.m. it starts snowing heavily for an hour, and you pick up 1.5" of snow during that hour. That would qualify for an intense precip report. However, in order to know that you picked up 1.5 inches in that hour, you would have had to measure your snow at some point (say just before 4:00 p.m.) Your measurement of the first 1.5 inches wouldn't have to be reported as Intense precipitation, but when you report the 1.5 inches between 4p and 5p, it would be implicitly included.  You would report 1.5" for the 1 hour period, and a total of 3.0 on the ground.  Bottom line, if the intense precip occurs in the middle of an event (like this snowstorm), you do have to take a measurement before the heavy precip occurs in order to know what fell during the "heavy period".  The criteria for reporting snow as Intense Precip is 0.5 inch per hour, and you will see that more often than 1" per hour. There were probably several periods with this last storm that qualified, but as you pointed out, unless you are taking intermediate measurements you wouldn't know that.

The length of the Intense Precipitation period can be different, too. For example, last night I measured snow at 11:15 p.m.  I also measured again at 4:00 a.m. (yeah, I'm crazy ), and had 3.3 inches more than at 11:15 p.m.  That worked out to a rate of about 0.7 inches per hour, and I submitted an Intense Precipitation report for that period. There probably was a short period where the snow fall was falling at even a greater rate after midnight, but I did have to work today and I'm not -that- crazy  .

You did just fine.