Any weather/geological fanatics or experts out there?

Question

I have lived in San Diego county for almost 8 years now. In those 8 years, there has probably been a total of 5 thunderstorms. We get plenty of rain storms, but lightning is VERY rare. I always assumed it had something to do with being so close to the ocean, and the storm needing to pass over land to build up the electricity for lightning or something like that.

In any case... I am intrigued because since this past Sunday there have been 3 lightning/thunder storms. 3 in 5 days after only 5 in 8 years?!?!

Can anybody explain why the change?? I love lightning, I am completely fascinated by it and always missed it when I moved from Colorado to California as a teenager... but I am just curious why there is a sudden frequency of lightning.

Answer 1

I happen to be a weather/geology fanatic and live in San Diego county too. Lightning is not exactly rare in the county, it's rare along the coast. For example, if you go back to last summer I believe there was a period of 3 consecutive weeks with lightning EVERY DAY in the county. Typically the summer thunderstorms only form over the mountains and deserts. The coastal areas almost always have what's called an inversion during the summer months, that means that there is some part of the lower atmosphere where the temperature goes UP as you go higher in altitude. Inversions act as a lid, stopping any convection that would generate thunderstorms. The mountains lie above the inversion so they don't have that effect and get thunderstorms quite often in July and August.

So to get thunderstorms on the coast, somehow you have to get around the problem of the inversion. There are a couple ways of doing that. Last Sunday, there was an upper level low pressure system off the coast that destabilized the layer above the inversion, causing thunderstorms to form even before daytime heating had begun. It didn't matter that there was an inversion because it wasn't surface air convecting, and above the inversion there has been plenty of very moist air. Later this week, thunderstorms occurred due to another effect: there was a strong easterly flow that brought developed thunderstorms from the mountains and deserts to the coastal sections. They were also forming farther west because the temperatures were so high in the foothills. These things are fairly random so I think we've just gotten lucky the past week. You can always do what I do this time of year--hop in your car and drive up to the mountains when you see the big clouds forming.

Answer 2

I don't know if you have enough information to attach any kind of pattern to this anomaly of thunderstorms youve experienced lately.... it basically depends on what weather patterns are present in the San Diego area. Typically, the weather pattern is very predictable. Due to ocean currents and geography, San Diego is essentially a desert with very little precipitaion. Minor changes in predominant weather patterns can produce anomalous weather such as rain/storms. So, don't expect this pattern to stick around, it was just a random occurrence, and soon, your weather will go back to, well, perfect!