We do have a slight chance of seeing an isolated thundershower Thursday as a very weak low drops down offshore California, although the chance of that hitting any one particular spot in western Nevada is pretty slight. Temperatures will warm up to seasonable levels in the low 90s. By Friday, things stabilize here in the Reno area, although a shower north of Pyramid Lake is a possibility.

Sat

The weekend starts to get interesting as a cool low drops down out of the north, cooling us into the mid-80s, and then possibly getting mixed in with the moisture from the remains of Hurricane Dolores coming up from the south. There is still a lot of uncertainty whether that moisture will make it over our area, but if it does, Sunday and Monday could develop more very wet storms.

Butterfly 2

“If a butterfly flaps its wings in Tokyo, it can make it rain in New You’re a week later.” We generally use this after the *&%^$# little bug has screwed up our forecast. So how can an insignificant insect in Japan affect the weather halfway across the world? Well, no one has actually proved it can, but there is some logic behind the concept. Molecules in the atmosphere don’t live in a vacuum… both metaphorically and physically. Even if you know the initial direction and speed of one at one point in time, it is bound to run into one of its neighbors soon, changing its speed and direction. Because they are always interacting with each other, trying to predict their behavior, either individually or corporately, becomes a real challenge.

Billiards

Think of it in terms of a billiard table. With the balls scattered randomly over the table, toss a cue ball onto the table, and try to predict exactly where each ball will be, and what speed they will be going in… say… four seconds time. A challenging, but probably not impossible task if you know the exact speed and direction of the cue ball at time zero. If you didn’t know the exact speed and direction of the cue ball, but could only give an estimate, you might get a reasonably accurate picture four seconds later, but it could also be hugely different if just one ball just kisses another when you thought they’d miss.

But there you are only dealing with 16 balls, in two dimensions. Now blow that up to an unimaginable number (probably on the order of 10 to the 100th power?) of air molecules, and put it in three dimensions, with all of them moving and without the ability to know exactly where they are all moving, and you can see your problems in getting an accurate picture days later.

In essence, that’s the problem we face in trying to rely on computers to get it right exactly every time… it’s impossible to know the exact initial state with the information from a couple of hundred weather balloons. So we have to simplify the atmosphere, “modeling” it to make approximations of the movement of larger chunks of it.

It works pretty well. Until the *^&%$#&# butterflies get involved.

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