I don't say this very often but I think this is the most incredible photo I've ever seen of hail "accumulation" (given, it was rolling downhill, but it appears to be 3 feet deep!) Severe thunderstorms moved through southeastern New York State late Tuesday night, causing wind damage and depositing heavy hail in Yonkers, New York. The New York Post has more photos, and this pic of a tree that smashed a car is pretty impressive too (that article is headlined "tornado" but actually the NWS determined the damage done there was straight-line winds). Here's some related video from our affiliates:

http://vortex.accuweather.com/video/video_inline_launchv4.asp?video=3-VPID07082009040546093&hd=false

It's important to remember the difference between sleet and hail when people like the New York Times throw around terms like "wintry" -- although a 3-foot accumulation of hail is ice (i.e. frozen ice) it's not happening because of the cooler (more winter-like) summer that we're having. Hail comes from thunderstorms, which generally don't happen in the winter. Sleet falls from low clouds in the winter, and the ice pellets within are smaller than a BB. Hail is generally larger than a BB.

But with the photos above and another report yesterday out of Hopkinton, Mass. where hail covered the ground, I am getting questions like the one from reader Wade who posted a Comment in my previous entry asking:

I think it's tough to tie any severe weather outbreak to a climatological trend such as El Nino / La Nina, so I'm a little surprised to hear that National Geographic said that. In that New York Times article, the NWS was quoted as saying "Neither El Niño nor global warming, often scapegoats for strange weather, is to blame. The culprit is the polar jet stream: a fast-moving air current that controls the movement of fronts and weather systems and is usually north of New York by summer." But by that, he meant it is causing the unusual number of storms, unusual amount of rain, not anything specific about the storms themselves.

Quantifying "more hail" is difficult given the data given. Do the storms have more hail, or is the chance of storms is normally so low that you wouldn't see hail reports that often? With storms nearly every day this June (and so far July), there's been a pretty good chance you'd have either seen hail or heard about it. Quantifying hail reports is easy through SPC Reports, though they are somewhat population based and they don't speak to the amount or depth of the hail, only a pinpoint report... if we take Pennsylvania as an example, there were 95 hail reports in the state last June, but only 70 so far this year, so in that specific example, there has been "less" hail this year (this map, which shows wind & tornado reports as gray also does a great job illustrating how lame the severe weather season was in June for us here in Central PA).

If there is more hail in the storms this Spring (and there's no way to prove that) it could be because the polar jet stream still hanging around has us in a rare sweet spot where the temperatures in the atmosphere are just right for hail -- the "wet-bulb zero level" is perfect (read more about that here). Or the cooler-than-normal air could simply be melting less of the hail on the way down (most thunderstorms have hail which melts before it reaches the ground).

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