The image above shows totals very different totals on February 10th, 2017 for the Boston Massachusetts area. Is this because a very heavy band of snow set up over Winthrop and completely missed the station at Boston Logan? Nope.
It’s because Boston Logan is an official station for the National Weather Service, but the Winthrop station is part of the CoCoRaHS volunteer network. You will hear me mention CoCoRaHS often because it is an extremely valuable organization. CoCoRAHS daily rainfall or snowfall reports are generally recorded at 7 or 8AM and are based on the previous 24 hours. National Weather Service reports are generally recorded around midnight and are also based on the previous 24 hours. So in the image above, the reports cover the following time period:
Boston Logan: Snow from 12AM on Feb 10th to 11:59PM on Feb 10th
Winthrop: Snow from 8AM on Feb 9th to 8AM on Feb 10th
So the Feb 10th report for Winthrop is actually including snow that fell on Feb 9th after 8AM. The Boston Logan Feb 10th report is NOT including any snow that fell on Feb 9th. That is why we get the big difference in snowfall. Keep this in mind for future weather searches on http://www.theweathercollector.com/ Also feel free to email me at pcarpenter@theweathercollector.com for questions. -Pete