2009

The anticipated cool-down and transition to a period of cooler and windy weather has begun. The culprit–a deep and slightly retrogressive low north of CA, will slide south over the Sierras over the next 48 hours and eventually pinch off coastal SoCal. This will bring very windy conditions–and serious fire weather concerns–to much of CA. Cooler temperatures are expected statewide, getting quite chilly at night in the north. Some snow showers are possible over the mountains, as well. Given the dynamics associated with the low, a few unexpected showers are possible over lowland parts of NorCal this weekend, but given the extremely limited moisture, this appears unlikely. A slightly better chance of showers may occur over SoCal as the low pinches off next week, but even this looks no better than a slight chance attm. Warming conditions, with possible offshore winds, are possible late next week as high pressure appears to build back into CA. Fall is certainly here, but precipitation may still be a ways off.

A side note: a fairly remarkable earthquake swarm is presently occurring in the Eastern Sierras. Over the last 48 hours, dozens of extremely shallow earthquakes have been reported almost directly underneath Keeler, CA. At least two of these have had a magnitude of 5 or greater and 30 have had a magnitude 3 or greater, and the swarm continues in earnest at this hour. It’s important not to read too much into swarms such as these, but there is a demonstrated correlation (though small) between non-volcanic earthquake swarms and significant earthquakes. I think people would be a lot more nervous if this were occurring under Los Angeles or San Francisco. In all likelihood, it’s just a curiosity, but it is also perhaps something to keep an eye on.

Unlikely to be merely a curiosity, however, is Typhoon Parma in the Western Pacific, which is currently making landfall on the northernmost Philippine island of Luzon. This is the exact same region hit extremely hard by tropical-storm induced flash flooding earlier in the week. It does appear that this typhoon will lead to even worse flooding in the region. More as the situation develops…