A very impressive severe thunderstorm outbreak took place in Southern California today. These storms were not confined to favored mountain and desert areas, but even produced severe weather near the beach. The retrograding cutoff initiated some strong instability (via cold temps aloft and wildly steep lapse rates) and a west-moving boundary of some sort initiated the storms on a line oriented N-S about 50 miles inland from the coast, which drifted slowly southwest all day. The storms were quite strong at times, producing various types of very rare severe weather reports and even some significant damage. Torrential downpours, on the order of 3 inches per hour, generated widespread flash flooding in many areas, and some serious mudflows occurred in recent burn areas. Even more impressive, however, is what followed the initial downpours. Large hail–some as large as golf balls–pelted inland areas (especially around Redlands–a friend recieved an excited phone call this afternoon from his parents in Redlands that “golf balls” were falling from the sky–and that hail had accumulated as much as 2-3 inches on the ground). Two tornados were reported in SW Riverside County, one of which may have actually been quite strong (especially for California) as news reports and live video showed train cars and semi trucks on the highway overturned. Snow fell at resort level in SoCal (and in the Sierras, too). The storms have died out since sunset, but the action is not over yet. Models are in remarkable agreement that another impulse or two will rotate around the low into SoCal over the next 48 hours, bringing another round or two of thunderstorm activity to coastal areas as well as inland areas. Timing is an issue, so watch the radar screens this weekend. As the core of the low sits around and picks up a bit of moisture, numerous thunderstorms are likely over the mountains in NorCal late Friday through Monday, and some isolated to widely scattered storms are possible just about anywhere. Given the lateness of the season (intensity of insolation) and the unpredictable behavior of cut-off lows, another outbreak of localized severe storms is not out of the question at some point before this system moves out of the picture sometime during the middle of next week.
P.S. The large wildfire in Santa Cruz County burned incredibly intensely today, and this raises serious concerns about the potential fire behavior later this summer and in the fall. Also, if anyone has pictures of the active weather today (or at any time) they would like to share, feel free to send them to me at danielswain@comcast DOT net