When a hurricane strikes the East Coast or the South, residents are warned for days ahead of time to prepare for the upcoming disaster. But out here on the West Coast, unfortunately, our disasters usually come in the form of earthquakes, which arrive suddenly and with no warning.

So it is with a rare and uneasy feeling that Californians are currently awaiting one of the few West Coast disasters which has been reliably predicted ahead of time. Except this catastrophe is not going to come courtesy of Mother Nature, but instead as what our president might call a “man-made disaster” — in this case, a riot.

Nearly everyone in the Bay Area agrees that a major Oakland riot is brewing if the verdict in the trial of policeman Johannes Mehserle, accused of murdering BART passenger Oscar Grant on New Year’s Day, 2009, comes back anything other than “GUILTY!” The problem for Oakland’s sense of security is that Mehserle is almost certainly not guilty of murder, and the jury is likely to give him a comparatively light sentence or even let him go completely.

The case has received wall-to-wall coverage in California for the last 18 months, but here’s a quick primer for those of you elsewhere in the country who may be unfamiliar with it:

In the early hours of January 1, 2009, a large group of young men got into a brawl on BART, the Bay Area’s subway system. Police were summoned and stopped the train at Oakland’s Fruitvale station, where a chaotic mass-arrest scene spilled onto the platform. As hundreds of passengers watched — many of whom were filming the proceedings with their cell-phone video cameras — several harassed BART police officers tried to subdue and then arrest dozens of brawlers. In the midst of the melee, one of the cops (Johannes Mehserle) pulled out a pistol and shot one of the men being arrested (Oscar Grant), killing him.

Sounds bad, right? Not so fast. As revealed in some of the videos taken of the incident, Mehserle was absolutely flabbergasted to see a gun when he looked down at his hand, because he had been instead reaching for his taser, which is also gun-shaped and kept in a belt-level holster. As several witnesses, including a weeping Mehserle himself, testified at the trial, the shooting was entirely accidental, and Mehserle was instead trying to tase Grant, whom he felt was out of control and resisting arrest. You can see the moment yourself in the last few seconds of the most famous video, when Mehserle looks at the gun in horror and then puts his hands to his forehead in dismay. The gestures only take a few seconds, but the entire case rests on this.

Because of public outcry, Mehserle was put on trial for murder, even though the threshold for murder was self-evidently not met in this case. Is Mehserle guilty of killing Oscar Grant? Certainly. Should he be convicted of involuntary manslaughter or negligent homicide? Probably. But a murder conviction requires proof of intent and malice aforethought — that you not only wanted to kill the victim but also planned it ahead of time. And it’s quite obvious first of all that Mehserle hadn’t planned anything, since he had never even met Oscar Grant until moments before the shooting; and that Mehserle’s distress afterwards — as well as the testimony of eyewitnesses who heard Mehserle saying “I meant to tase him!” — prove beyond any reasonable doubt that he had not intended to kill Grant at all.

For the incident to count as “murder,” these thoughts must have gone through Mehserle’s mind: “Here I am surrounded by hundreds of eyewitnesses, half of whom are filming me, as well as several policemen including my superior officer; I think this is a good time to murder a stranger in cold blood in front of everyone, just because I’m a homicidal maniac!” Highly dubious, to put it mildly.

In the court of public opinion, however, facts play a minor role. Oscar Grant’s grieving family, egged on by ambulance-chasing lawyers, radical political groups, and every race-baiting organization on the West Coast, pressed for the maximum charges against Mehserle, in a gamble for a full murder conviction, even though it was inappropriate and they had a slam-dunk case for a lesser charge (such as involuntary manslaughter). However the judge’s jury instructions, not public opinion, will determine whether “lesser included charges” like manslaughter can be considered. The trial was moved to Los Angeles because of overexposure in northern California, and it is due to wrap up in a day or two.

When it’s over and the jury comes back with a verdict — watch out. Things are likely to get ugly. Very ugly.

Rumors of a riot after the verdict have been swirling for months, and have increased exponentially in the last few days:

All over the city, there’s talk of a riot if Mehserle is not found guilty of murder or manslaughter. Flyers and graffiti are posted everywhere demanding justice for Grant. Bloggers and columnist[s] are already speculating about how deep the civil unrest will become. Rodney King’s name is tossed about and the police are getting ready to crack heads if a riot goes down.

To get a taste of the mood around Oakland, look at the photos which have been scattered throughout this post. They were taken from this YouTube video and show graffiti sprayed earlier this week around Oakland’s most scenic spot, Lake Merritt. The sentiments range from “Mehserle Must Die!” to “LA Better Get It Right! Or else!” to the chilling “Oscar’s revenge? Mehserle’s kid!” And with the words “Cops bleed too” adorning the city streets, I have the feeling we may indeed be in for a repeat of the 1992 Rodney King Riots.

What’s your take on the case and on the inevitable civil unrest that will follow, whatever the verdict may be? What charge should Mehserle be convicted of, if any? If I was on the jury, I’d vote for negligent homicide, a few years in jail, and a guarantee that he’d never work in law enforcement again. (If he’s incompetent enough to draw the wrong weapon in a stressful environment, he should not be trusted to safeguard the public.) But murder? Forget it.