30 January 2015
My wife says that most of her friends have no idea about how I make a forecast, and I suspect that some believe I just get it from the NWS, without thinking how even they might do it. Many folks do understand we use numerical models but beyond that it’s hazy, and they think that if the forecast is wrong, it’s because the model was bad, not the interpretation of it. I prefer to call numerical weather models guidance because that’s what (and ALL) they are.
The info-graphic above does a great job trying to explain what forecasting really is, and in many ways synoptic forecasting is similar to the process your GP goes through when you make an office visit. It’s both an art and a science where data from observations of the atmosphere or your blood play an important role. That said, the blizzard forecast last Monday is a warning call that we meteorologists need to do a much better job of communicating forecast uncertainty.
Make no mistake, the forecasts were badly wrong in many areas, but nothing drives forecasters crazier than getting blamed for a bad forecast some armchair weather guesser posted on Facebook. Often, we get blamed for missing a forecast that was actually not bad, and while some of that is due to the fact that the complainer didn’t really pay attention to what you said, there is ALWAYS the opportunity to communicate it better. In science, any measurement or prediction is worthless without an accompanying statement of the uncertainty involved, and if you’ve ever measured a room you want to buy carpet for, you inherently understand this!
While we often use percentages in weather forecasts, there seems to be very little of this in forecasting snow, wind, heavy rain etc. The graphic below is one I used Monday night on air for my viewers in Delaware and Eastern Maryland. While my forecast was a bust in the Dover area, it showed only a 50% chance of an inch of snow over areas to the south. Combining this with a map showing accumulations is IMHO a better way of sharing my thinking about the forecast with my audience.
Now, this does not work with everyone, and if you are a young second grader named Elisha Jones (and hoping for a day off from school), then there is nothing that will alleviate your disappointment! I received a packet of letters from some cute young kids this week, and this is Elisha’s view.
Sometimes a forecast is going to be wrong, but we actually do a much better job of forecasting significant weather events than many people think. Failing to communicate our forecasts properly is not the entire reason, but it’s a substantial one. Yes, there will always be some who will blame you for someone else’s forecast (or even for a forecast that was basically correct) and better communicating uncertainty will not make this disappear, but for the majority it will be a great help.
Something I often tell viewers this time of year:
In the summer, if my rainfall forecast is off by 0.2 inches, no one will notice, but in winter that error means I miss two inches of snow!