Why Snowfall is so Tough to Forecast

One of my favorite things to do after a snowstorm is to look and see where the most challenging gradient of snowfall occurs…in other words, the greatest change in snowfall totals over the shortest distance. This storm provided another good lesson in that. Check out the map below. I’ve plotted some select snow totals from the Mount Holly and Upton CWA’s from the event for Orange County, NY, and Sussex, Warren, Hunterdon, Somerset, Middlesex, Union, Essex, Morris, and Passaic Counties in NJ. Location on the map is approximate, and you can enlarge the map by clicking on it:

Check out some of the disparities. In one instance you go from 22″ to about 11″ over the course of *maybe* 10 miles. In the most extreme instance, Pottersville, NJ in extreme NW Somerset County reported 4.5″ (NWS Co-Op site). Elizabeth, NJ near Newark Airport in Union County reported 32.0″ (trained spotter). The distance between both locations is approximately 30 miles as the crow flies. That’s incredible. It’s common though. In snowstorms, especially ones of this intensity, you get intense areas of what we call mesoscale banding…bands of extremely heavy snow (sometimes with thunder) that impact small areas. To take this to another level, which I won’t do, you can also have something known intriguingly enough as “CSI,” or conditional symmetric instability…or slantwise convection. You often get this in intense snowstorms. I won’t bore you with details right now, but if you’re interested, a whole website is devoted to the topic here. It will be interesting to see the number of papers that I’m sure will come out in a year or three about this storm and the ones of last winter. Anyway, this basically means, some areas get absolutely walloped, while others get shafted.

Anyway, back to the topic at hand, you could probably replicate a map like this across southwest NJ and in parts of New England too. But this just goes to show you, for meteorologists making a snowfall forecast map, these are some of the complexities that we all have to deal with.

Lastly, the poll question continues. Do you all prefer the current system of occasional blog posts, or would you rather have occasional blog posts and a Facebook “like” page with occasional links/discussion/question areas? Vote below, and we’ll see where this goes.


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