As the temperatures begin to back off a bit (highs should drop to the upper 90s Friday and then fall to the low 90s over the weekend), thunderstorm activity will pick up as a low pressure center moves slowly up the California coastline, steering some monsoonal moisture into the region and adding a little bit of dynamic on the side. Scattered Friday afternoon thunderstorms become more frequent over the weekend. In addition smoke from several large fires in Idaho and Oregon will keep our skies hazy to the next day at least.

More on lightning: On the one hand you might think that it would be easy to figure out just how a bolt of lightning will act. After all, it’s just electricity, isn’t it? And electricity is governed by some pretty well understood equations. But when Ohm wrote his law (V=IR), he was working with circuits in controlled environments. In nature, while the same basic laws apply, the variables V (voltage of the bolt), R (resistance of the air, etc) and I (current of the strike) are all unknown from one lightning bolt to another. It’s very similar to weather prediction. The basic physics of air molecules moving around the earth, and what that movement can do to produce changes in temperature, pressure and moisture content, are pretty well understood. But once you throw in a few gazillion variables that make up the chaotic system that is our atmosphere, it gets a lot tougher to predict how the butterfly flapping its wings will affect Sunday’s picnic.