A question on climate change

[haele]

73. Sigh. No, climate change produced the environment for large brush fires by possible arsonists.

Being in San Diego and being passing familiar with the history, ecology, and geology of the area, I can appreciate how unusual this weather pattern is. There's two things going on that are affecting the "base" of the standard fire triangle (fuel) that makes the past week of fires here so unusual.

1. The Santana (or Santa Ana) wind phenomena. For people who are not familiar with the phenomena, this occurs usually twice a year when the North American jet stream pushes a high pressure that sits and stalls over the Mojave Desert, causing somewhat cyclonic high winds at fairly low altitudes. Santanas blow hot, dry 45 - 80mph winds from the desert to the coast, disbursing the normal onshore flow off the cold Pacific ocean and driving them north, over central California.
The largest, longest lasting, and most dangerous ones that cause wild fires into the >1K Acre level usually happen during September/October in a normal year, August/Sept and then early November on off years where there is either a strong El Nino or La Nina which have affected change in temperature of the Pacific Ocean during July/August when it typically warms up along the West Coast.

Slight Santana conditions for a day or two can occur during the winter and early spring when the jet stream dips, usually after a heavy pacific storm from Alaska pushes through, and in those situations, the four major counties affected by Santanas in Southwest CA might get localized slow burn brush fires (at most a couple hundred acres) that are fairly easily controlled - even in year 5 of a drought.

2. The topography of coastal/inland valley San Diego County (where we have had these fires) and Southern Orange County - both are somewhat climate protected coastal environments; where the coastline of California has the greatest amount of inland curving that catches the natural moisture that is always coming up from the equator and creating more of a Mediterranean climate - more stable humidity - in pockets within the inland valley than can be found even in Norther OC and LA counties; our onshore flow creates "May Grey" and "June Gloom" overcast even in the hottest years.

The temperature of the Pacific Ocean has been within normal range for April and May. This year, we should have had enough humidity in the air that even with this unseasonable Santana, we wouldn't be hearing about backhoes, cigarette butts and catalytic converters or even thrill-seeking arsonists sparking out of control brush fires verging on wildfires for four straight days in San Diego County. We shouldn't be seeing temperatures in the upper 90's/100's this time of year.

Maybe in LA County, or Riverside, as they are more coastal or high desert and there is not as much onshore flow that gets trapped into micro-climates to create a marine cloud layer that, true, does little more than pump up humidity in the air, but not in inland San Diego county. Not in May.

That is what is freaking so many of us down here, and what is worrying us about the rest of the year and future years. It's not normal cycle - and we've had over 250 years of written records plus a major climate science institute that has been studying the local environment to prove it. The shift has been way too sudden.
True, it might be a one time weather anomaly, but it sure feels as if the climate wobble that has been studied over the past couple decades has finally tilted.

Haele