 It's inevitable. Every time it snows hard and the wind blows, the word blizzard creeps into the conversation. Usually it's from non-mediarologists, but even folks in the business occasionally use the word when it's not warranted. Last week gave us two chances to look deeper into when we should and shouldn't say blizzard. Now officially a blizzard requires three consecutive hours with sustained winds or frequent gusts of 35 miles per hour or higher accompanied by falling or blowing snow that reduces visibility to a quarter mile or less. There is no temperature requirement. I think it's telling that by this definition, the blizzard of 96, arguably the most famous Pennsylvania snowstorm in recent decades, wasn't officially a blizzard anywhere in Pennsylvania, though a few stations satisfied the blizzard criteria for less than the necessary three straight hours. Now let's look at last week's historic Northeaster, already dubbed the blizzard of 2013. Here's the areas that were under blizzard warnings. New York City and Long Island, all of Connecticut and Rhode Island and parts of five other states. And just to establish where a lot of snow fell, here's the one foot line everywhere, south and east of that line, got a foot of snow or more. Now here's all the official observing sites that were in the blizzard warning and measure visibility, wind and precipitation. There's a total of 55 places from eastern Maine to northern New Jersey. So these are places where we can assess whether there really was a blizzard. But first we need to clarify some ambiguities in the definition. For example, what does frequent mean? Well, I'll take a pretty lenient definition, just one gust of 35 miles per hour in an hour. Also as long as there's just one observation per hour with the proper combination of wind and visibility, I'll count that hour as having a blizzard, even if other observations that hour fall below the blizzard requirement. Now with that fairly relaxed interpretation, here's where blizzard conditions verified in last week's Nor'easter, about half of the observing sites in the warnings. And that's actually a pretty high percentage based on my experience. There were also three observing sites that had blizzard conditions but weren't in the warnings. All three of those were in Massachusetts. Now as that nor'easter was winding down, another powerful storm was strengthening in the plains. And blizzard warnings were issued there for parts of four states from northern Nebraska to western Minnesota, with about 40 observing sites in the warning area where we have enough data to evaluate the blizzard criteria. Now in this case, just three stations officially had a blizzard. At about half the other stations there was a period of very low visibility due to heavy snow and there was also a time of very strong winds. The period simply did not overlap. Now please don't get me wrong here. I'm not saying that these weren't extremely disruptive storms nor am I being critical of the weather service's forecasts. My point is simply that true blizzard conditions are fairly rare and pretty darn hard to achieve. Fred is back next with the extended forecast.