The Certified Snowfall Totals Difference

Posted: March 6, 2017, 8:46 am by samd

Today’s world tends to operate under the adage If You’re Not First, You’re Last. Here at WeatherWorks, we don’t appreciate that adage. Instead, one of our main mottos is Accuracy Above All Else. With that said, as the amount of accessible snowfall data on the internet increases, we are often asked why can we only assure our Certified Snowfall Totals 24-48 hours after an event, and not 24-hours or less?

Basically, nothing is ever short-changed at our office. For instance, I’ve personally once used seventeen weather stations to construct a site-specific past weather report (yes, 17). Why? I was not fully confident in the results using fewer stations. The same consideration goes into your Certified Snowfall Totals. If we only used data issued immediately after the storm, plus some observations which are submitted at 7 AM, then sure we can have your totals in 24-hours! But we do much more than that.

The problem with the 24-hour methodology is that it is inherently rushed. Additionally, some data will likely be missed or omitted. Not to mention, even official data can occasionally change. For example, in a recent storm, the Philadelphia International Airport released an official total of 0.8 inches. In National Park, NJ, where the official Philadelphia airport total used to be measured, a total of 2.3” was submitted. The next day, the Philadelphia International Airport total was edited to 2.0”, and I’m sure this would have impacted everyone’s billing by thousands of dollars.

The biggest difference with our totals versus others is the depths we go to in order to assure our totals are the most accurate & reliable. Below, you see an image cycling through a snowfall map, progressively getting fuller and fuller. Map 1 shows you the bare minimum. These totals are released by the National Weather Service shortly after each storm. For this event, about 85 totals were available for Northern NJ. Map 2 adds observations issued at 7 AM or so, generally 90-100 more totals. If we were to race to have total issued in 24-hours, this is where we would stop. However, we keep digging. 

**A side note about these 7 AM totals: They may be incomplete. Additional data submitted at 7 AM the next day will be imperative, and could make the difference between 3.7 inches and 4.3 inches. That means 90-100 potentially incomplete or low totals if our certified totals are posted in 12-24 hours.

Totals are also available through other avenues which we take additional time to scour though. We review photos, hundreds of webcams, and receive more observations from clients and employees around the region. Map 3 shows even more totals added to our review, another 30-40 just in this small block across northern NJ. This is when we begin to paint the full picture. Even with all that information, we continue to review radar data, liquid-equivalent amounts, and satellite data to add certainty and quality to our snowfall totals.

So while we cannot assure you the fastest snowfall totals, you & your clients can rest easy that our Certified Snowfall Totals will be the most accurate & reliable amounts, and that no stone went unturned when preparing your reports.

Meteorologist & Director of Forensic and Data Services
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