BOSTON – From the beginning, the meteorologists at WBZ-TV in Boston had a bad feeling about the snow storm heading to Massachusetts Tuesday. The snowfall predictions took a major turn downwards from Sunday to Monday and many people want to know why.

Snow predictions early discussions

Here’s an example of what we were talking about behind the scenes over the weekend while trying to develop an accurate forecast of snowfall totals.

Saturday 1:21 p.m.

Text from Eric Fisher to me: “I dunno, just feels like a weird headfake storm to me”

Sunday 4:05 p.m.

Text from Eric Fisher to me: “Still feeling kind of leery of a late shift south”

Monday 12:47 a.m. on WBZ-TV News after the Super Bowl

Eric talking to David Wade and Lisa Hughes: “I’m a little worried it’s going to slip farther south; we will watch the trends tomorrow”

Granted some of these conversations were private, but we did try to caution our viewers about the uncertainty with this particular storm. Trust me, I know, in the end, many folks aren’t hanging on every word that is said on TV and most are just waiting for the snow forecast map.

Winter storms are like snowflakes, no two are exactly alike. This is a big part of what makes forecasting in New England so intriguing. You can literally do this job your entire life (see Barry Burbank, well over 40 years), and still have sleepless nights wondering if the atmosphere will behave as you predicted.

Contrary to popular belief, meteorologists don’t just go outside and stick their fingers in the air to determine the forecast. We rely on very complex weather models. These models are run on giant supercomputers capable of churning out quadrillions of calculations per second. Seriously! That’s 15 zeros!

Despite this insane amount of technology, in the end, the weather is still somewhat unpredictable. There are just too many moving parts. We are light years better at forecasting now than we were 10, 20, 30 years ago, but still far from perfect. We would love to be able to accurately predict how much snow your town is going to get four days in advance but that just isn’t possible. This is, after all, still a FORECAST. Things will change. Sometimes dramatically so.

What happened to the snow forecast in Boston

Over the weekend, you likely started seeing snowfall forecast maps popping up here, there and everywhere. By Sunday, most of the model guidance seemed to be converging on a storm track that would produce a widespread 6-to-12″ of snow across southern New England. However, with this storm, there was a very fine line between getting a whole bunch of snow and getting nothing. We knew that there would be some very intense snow bands that would produce 1-to-3″ per hour. If your town ended up underneath this banding, you were in for an intense 3-6 hours of snow. Just a few miles to the north, flurries.

Minor shift, major change in snow predictions

By Sunday night, and more so Monday morning, there was a minor shift in the model output. It appeared that the center of the storm may pass about 50 miles farther south that what was originally forecast. For a storm system several hundred miles across, 50 miles isn’t much. BUT, if those 50 miles just happen to be right over Massachusetts a minor shift becomes a MAJOR story. Shifting the highest snowfall totals (8-12″) 50 miles southward had a major impact of hundreds of thousands of people. For reference…50 miles (as the crow flies) in Massachusetts is like going from Lawrence to Plymouth or Boston to Falmouth.

So, much to the disappointment of some, and the delight of others, we made a significant change to our snowfall forecast Monday afternoon. Basically, everything was shifted about 25-50 miles south.

Unfortunately, many towns, schools and businesses had already chosen to make a decision to close on Tuesday, nearly 24 hours prior to the first flakes. I get it, you want to give folks as much notice as possible to find babysitters, change plans etc. Sure, occasionally you get a multi-day mega-blizzard, and the call is an easy one. Most of the time, however, making those calls a full day in advance is a dangerous proposition and NOT one that any meteorologist would recommend.

Part of me longs for the old days, when we would all wake up at 5 a.m. and flip on WBZ NewsRadio 1030 to hear whether school was canceled or not. Strange that back then, when communication was much more rudimentary, we waited until the last minute to make those decisions. Whereas now, when we can get the word out in seconds via text, robocall, social media etc, we make the calls way sooner.

At the end of nearly every blog I write, I urge everyone to stay tuned to updated forecasts. That isn’t just a throwaway line, we really mean it!

The atmosphere is a crazy place. A thunderstorm unexpectedly forming in Texas on Monday could start a chain reaction that leads to massive changes to Boston’s weather a few days later.

We know and respect that you all have busy lives with kids to care for and businesses to run. Our goal is to provide you with the most accurate information possible and, just as important, keeping you updated when changes occur.