Dave Sabol

As I have been watching the preliminary ideas on the “blizzard”, “snow storm”, “system” that is supposed to effect the Northeast and Mid-Atlantic come in from a myriad (Accuweather, NWS, Weather Channel, etc.) I have noticed that there is a tremendous deviation on how each are interpreting the same raw data that is being provided by the forecast models and how that deviation has greatly affected what we are being told about the weather.

A forecast model is a complex computer programs that is run on supercomputers and provide predictions on many atmospheric variables such as temperature, pressure, wind, and rainfall. A forecaster examines how the features predicted by the computer will interact to produce the day’s weather. Each model has it adherents based on its known strengths, biases, and track record and no one model is used to predict the weather forecast by any of the agencies listed above. To get an idea of all of the different models, take a look at the Penn State University Weather Wall which provides a pretty good look at many of them and their resultant data.

Depending on your source for weather there are significant differences in what forecast you will receive. I consider myself to be somewhat of a weather zealot (someone who has an above average understanding of meteorology and forecasting and doesn’t necessarily trust weather provided by typical consumer outlets, but is in no way a trained meteorologist) and therefore immediately discount TV weather forecasts and the like. Even for folks with less of a scientific interest in the weather but who would still like an accurate forecast to plan their days activities the source makes all of the difference and trust me, there is a difference.

I digress. So, as I have watched the interpretations of the forecast come in on Sunday and early this morning, I have noticed yet another battle being waged between the models and the meteorologists. As is the case time and time again, the models provide an initial solution and change with every given run (generally forecast models are run on fixed intervals to all the models the ability to factor in new data) and the forecasters are left with a decision: trust the models or trust their instincts.

Saturday (10 February 2007) and yesterday morning (Sunday, 11 Februrary 2007) there was pretty widespread agreement that the “Valentines Day” storm would yield a significant all snow event for the Mid-Atlantic and Northeast. This gave many meteorologists the confidence to issue initial forecasts that cranked up the snow amounts for these areas. However, as the day (and model runs) progressed, many of the forecasters began to change their tune. The new solution developed the primary low pressure system (responsible for bad weather) further west and further south and as a result developed the secondary low pressure system closer to the coast which would allow warm air to infiltrate. The net-result of this shift took an all snow event for much of the area referenced above and changed it to an all snow event inland and a mix along the coast up the I-95 corridor for the big cities. One of the first groups of meteorologists who jumped on this bandwaggon was the NWS and slowly a few others followed.

Yet while the models were saying one thing others stuck to their guns and felt that the model runs didn’t factor in things like how cold the air is coming down from Canada thereby affecting where the actual low-pressure system actually forms which in turn would determine who gets a lot of snow, who gets a mix and ultimately where the line of demarcation is between the two. Rest assured all you snow lovers out there, all of the forecast sources I have been watching still think it will be a good storm, but the deviations between each forecast call into question the amount of snow that will actually fall and who will be impacted the most.

My reason for calling this into question is pretty simple. Who do you trust? Do you trust forecasters and agencies who rely heavily on the forecast models to make their predictions, do you rely on those who use a combination of the models and their judgment, or do you trust those who are willing to throw the models out and rely on their past experience and understanding of all of the dynamics that are at play? For the upcoming storm, this appears to be the $100k question.

Personally, I think I trust the latter as opposed to the former. Sure I am a technologist who relies on the power of computers every given day, but at the same time, being a true technologists also requires an acknogledgement that computers simply don’t know everything. It becomes a case of GIGO (garbage in, garbage out). To turn the situation to something more personal, I would much rather go to a doctor who allows me to self-diagnose and uses his/her knowledge and experience in the medical field, than one that relies completely on hard science to make a diagnosis.

I respect scientists and the work that they do, but somewhere in the mix science has to give way to expert judgment. Science only gets you so far…it provides a key to the door, but ultimately how that key is used and what door the key is used on really do matter. I suspect this is the case with the upcoming forecast (and any forecast for that matter). As with the case with many things in life, only time will tell, but for the upcoming storm, I am sticking with the forecasters who aren’t afraid to deviate from the norm and trust their gut.

Wow, it looks like we could be in for quite a storm over the next few days. I suspected as much given the excitement late last week at Accuweather.com. Some how they just knew this was going to be the “big daddy storm” everyone in the mid-Atlantic was waiting for. Now, I guess all that remains to be seen is if it turns out the way they have forecasted it.
Here is a graphic depiction of the storm:

Here is a forecast map with predicted amounts of snow for the affected areas that was complied by Accuweather.com ’s Senior Meterologist and Severe Weather Expert Henry Margusity :

Finally, here is Henry’s predictions with regard to how much snow specific cities in the stroms path could get. In all fairness to Henry, these were posted Saturday evening and are obviously his best guess based on the information he had available at the time.

Take notice to the specific predictions for Allentown, Philadelphia and Washington, DC. I highlighted these areas because a few colleagues and myself are supposed to be travelling to a conference in DC tomorrow afternoon that runs through Valentines Day (February 14th). Obviously, if these amounts are even close to accurate (which I fear they are), it is going to make for a pretty memorable experience should we decide to go.

I will offer one counterpoint, which I think is important to have when one is dealing with the weather. Elliot Abrams, Expert Senior Meterologist at Accuweather.com offers a word of caution.

Remember how models at first showed the storm farther south? Well the models yesterday trended north to suggest the area from Maryland to Maine could get heavy snow. However, suppose the trend of the models toward a more northerly track continues? Then, warm air that would have stayed south of places like Philadelphia and New York City would actually encroach northward and change the snow to rain at the height of the storm.

I don’t think it’s time to write off a giant storm just yet, but I believe too many people get caught up in “snow fever” and forget that storms of this size and nature are rather unpredictable despite the advanced technology we use to forecast them. In the end, I guess it is better to hope for the best (in this case I really want a big storm) and prepare for the worst (in this situation a snow to rain transition or a total miss). Stay tuned, I am going to keep on top of this one because I think it could be a storm to remember.

I’m not sure if it’s just me or not, but I can’t take a winter without snow. I guess from my perspective if we are going to be forced to deal with shorter days and the cold the snow might as well come along as a package deal. One of my hobbies (passions) is the weather. I spend countless hours per week checking the weather at Accuweather.com and reading the blog postings (Community Blog, Henry Margusity, Elliot Abrams and Joe Bastardi) by many of their best meterorologists. I’m not sure exactly what it is about the weather that has always captivated my attention but I do remember that my interest in the weather started around when I was 8 years old around the same time that the Weather Channel was first broadcast in 1982. It was around that same time that I became a fan of Jim Cantore, someone to this day that I still respect and admire.

From that point forward I gained a much greater respect for the nuances and intricacies of the weather, learned the terminology and fundamentals of the science and even went so far as to track hurricanes on my own. I’m not sure why I never pursued a career in meteorology, but I do think that my love of the weather guided my love of history and geography, two subjects that I enjoyed as a student and I was eventually fortunate enough to teach as well. Regardless, lets just say that I have more than a passing fascination with the weather.

Needless to say at the onset of the winter I was pretty excited to see and hear that most of the best thought that the 2006-2007 winter was going to be one to be reckoned with. Granted I am not a masochist and don’t necessarily love what the weather can do to a morning or evening commute between Allentown and Philadelphia, but there is something pretty remarkable about a good old fashioned winter storm that gets me excited. However, as December and January came and went without nary a flake of snow, any hopes that I had of seeing the white stuff this winter season began to diminish significantly. It wasn’t just the lack of snow that had me concerned but also the warmth that we experienced through January. I don’t remember what the departure from normal or average high temperatures were, but I do know that it was well outside of what I consider seasonal.

As the end of January drew near, I started hearing some of my “sources” start to suggest that we would experience a turning point in February and perhaps a return to what we consider a normal winter at least from the perspective of snow and cold. Now, I am not one to criticize especially when my criticism lie outside of my area of expertise, but lets just say I was skeptical. I guess you could say that the prognostications of the past weren’t even close to the reality of what had happened and when one’s credibility takes such a huge hit, it’s easy to understand why folks have a tough time believing. They weren’t getting it all wrong, but they were really having a tough time nailing down what was happening in the Mid-Atlantic and New England.

Oddly enough, I had no sooner departed for Hong Kong that the weather decided to change, at least partially. The temperatures finally began to drop as the jet stream moved into a more seasonal flow and started to allow some of that cold air that had been damned up in Canada escape into the U.S. Then finally snow flakes began to fly. Nothing substantial, but when you go from the prospects of no snow to even a trace amount, it’s exciting. Then finally this week they locked onto something. We had the makings of a great winter storm and it was really a matter of time to see how it played out. Suffice it to say, it wasn’t a big snowstorm like they initially thought, but they finally predicted a snowfall.

When all was said and done, I think we may have picked up somewhere between ^1/2 to 1.0 inch, and for the evening all was right in the world. Hopefully, this is the start (albeit a late on) to what will be a relatively normal winter. Sadly, I think this may be the beginning of the end of winters, at least if we (the human race) don’t get our acts together and start making some substantive changes in the way we are treating our home.

I just hope the message gets out and people really take a good hard look at their actions and how it could ultimately affect the earth in the future. The sad part is, since the really impact won’t be felt for years to come many people don’t consider it to be their problem. As for me, I want my son and grandchildren to be able to enjoy all that the world has to offer. We (my family) have always been pretty environmentally concerned and if anything the recent news is just reinforcing the actions we are already doing.

For now however, I am going to keep watching the weather and hoping for that one big snow storm. I know it’s out there somewhere, it’s just a matter of time. Oh yeah, while I am thinking about it since yesterday was officially Groundhog Day – a minor holiday in most parts of the country but something more in Pennsylvania – I don’t believe Punxatawney Phil this year. He is saying that we are in for a early spring. Normally, I say why not believe the crazy groundhog – he’s as accurate as any other source of long-range forecasting – but considering that his predication came just the day before the mercury dipped to a balmy 30°, and the forecast for the next few days doesn’t show the temperatures getting above 20°, I say he missed the boat on this winter. I guess nobody has a perfect track record!