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Does the very act of storm chasing affect potential storms in the future? According to Chaos Theory the answer is yes. Imagine someone this month (January) down in the Australian outback speeding down a dirt road, moving towards a nice storm off in the distance. In the rear of their van a micro low pressure system is formed in the drag, as the dust swirls into a vortex and vanishes in the mirror. As this parcel of air dissipates and slowly makes its way around the globe ( let’s say 7 times by late spring ) it interacts with the much larger atmosphere. As air masses collide in the great plains this spring, the results will be somewhat different if this chase event had that not happened. (These are the kind of important thoughts one sometimes wonders during the looong wait till spring convection. According to some books I’ve been reading this scenario could hold true.

In the early days of computer forecasting, they would run data results out for weeks and months . One day someone reran some data a second time and got very different results. They couldn’t figure out why the same data would yield two different results, until someone realized a very small decimal point in the data had been rounded off. The graph looked identical for weeks, but then started to diverge into a completely different path. Extremely small variations in the initial conditions didn’t show up until it played out far in the future.

On this note, I read that a meteorologist awhile back thought that if you could obtain accurate data from a 100 kilometer cubic grid you could finally, accurately predict the future weather. He couldn’t have known that those small differences in between the grids on a smaller scale, would still change the results. We now know why.

This illustrates the problem of complexity in forecasting. There are so many variables which can have a wide range of effects on the outcome, like pressure, temperature, wind speed, relative humidity, topography, yesterdays storms, El Nino, etc. Also, there are factors that can have an infinitely small effect , like heat from cites, solar storms, and now chasers themselves to add to that list!

As an amateur weather enthusiast, I never realized how complex the atmosphere and forecasting is until I started researching in preparation for chase seasons. I now have a much deeper appreciation for those who have it as their profession. I’m wondering if the atmosphere is the most chaotic system we know of.

The more variables, the more complex the math (involving vicious mathematical feedback loops and non-linear equations). Also every scale has to be taken into effect, since an extremely small scale event can also set off a cascade that effects the larger . One small change earlier in the day in upper level winds, temperature, or pressure could mean the difference between a town getting rained on, or struck by a large tornado, or a chaser “catching” a suntan. It’s like the few snowflakes that triggered the avalanche. The term “instability” or “loaded gun” is so appropriate. This all makes for weather living up to its reputation as fickle and unpredictable.

Even 2700 years ago King Solomon wrote a proverb, “you do not know the path of the wind…” Some centuries later a Man came along who reportedly had authority over the storms spoke that, ” The wind blows where it wills, you do not know where it comes from or where it goes…” These words still ring true today .

As one who has had to plan a storm chase vacation, based on a three day forecast and drive out west from the east coast, severe outbreaks are still often a coin toss at this point. However, as computers get more advanced and can crunch calculations involving those staggering number of variables, its getting a lot better since I started chasing around ten years ago, and that’s good news for chasers .

Maybe a very accurate 3-5 day storm forecast is not too far off , but I think its going to be a looooong time before it is accurate to weeks in advance, if ever. So to you chasers down in the outback, the phrase “be careful chasing” now has another added dimension.

Article by Tom Windsor

(also posted on Stormtrack website)