It wasn't the earth opening up to swallow us, though you may have wished it was at around 4 a.m. this morning. It was just the sound of a rare thunderstorm hitting the Bay Area, complete with buckets of rain and hail, and there was some lightening too. The Chronicle explains this had something to do with a cold front from the Gulf of Alaska hitting the warmer air down here, but maybe, as some in my Facebook feed suggested this morning, it was simply an appropriately horror movie-esque opening to this godawful day.

Thunderstorms are uncommon in these parts because they tend to ride on hot, humid air, of which we have very little in the course of a year. And since I am not a weather man I can not explain where this hot air came from last night, because I myself was quite cold out of doors.

CBS 5 refers to what happened starting at 3:20 a.m. as a "vicious squall line," and it caused some flash flood warnings and downed trees. Apparently Daly City got the center of the storm, and we just got the outer edge of it in SF.

As KRON 4 tells us, you can expect scattered showers now throughout today and tomorrow, with a third storm moving in Sunday that is expected to bring heavier rain and wind.