The weather in Stanislaus County took a turn for the bizarre on Thursday afternoon, leaving meteorologists, law enforcement, and residents of Oakdale scratching their heads in disbelief.
On Thursday morning, one could tell that the weather was far from what could be considered the norm. The San Joaquin Valley was under an unusally warm, moist airmass - an airmass which kept the temperature in Turlock from dropping any lower than 56F. Enough sunlight was able to shine through a broken layer of stratocumulus to allow the temperature to reach 69F by 1300. The dewpoint was 61F at this time - too high to rule out any surprise shower or thunderstorm activity. I turned on The Weather Channel at around 1400 to monitor radar images on the Local Forecast Segment. At 1445, radar indicated an isolated shower beginning to develop to my NW over Modesto. The cell appeared to be moving northeast towards the towns of Riverbank and Oakdale (remember these names) in northern Stanislaus County. The isolated shower was definitely worth a look, so I got it my car at 1500 and drove north on Route J14 towards the town of Oakdale.
As I headed northbound out of Turlock, I was able to get a good view of an isolated Cb to my NW. It didn't seem to be producing much in the way of precipitation, but the cloud appeared to be developing a lowering on its southwest periphery. I kept a wary eye on this apparent wall cloud throughout my journey from Turlock to Oakdale. Once I got to Oakdale, I began to encounter moderate rain. When I got to the intersection of Route J14 and SR 108, the intensity of the rain increased dramatically. I was now driving through a raging downpour. I turned left at the intersection and headed west to get out of the heavy rain. As I left Oakdale, I noticed that some of the side streets were beginning to flood. Once I arrived at the town of Riverbank, the rain had let up. I was now west of the storm....exactly where I wanted to be. At the intersection of SR 108 and Oakdale Road, I turned left and headed south towards the city of Modesto.
Once southbound on Oakdale Road, I periodically looked off to the east to get a view of the storm. I was unable to see the cloud base or horizon due to trees and houses. At 1540, I encountered a brief break of the obstructions to witness the unthinkable....a huge, black, cone-shaped tornado! My glimpse of the tornado was very brief, but just long enough to see a spectacular funnel extending from cloud to ground - backlit by blue sky to boot! I proceeded to make a mad dash back towards Oakdale in pursuit of an unobstructed view to the east and northeast. Unfortunately, I was never able to get much more than fleeting glimpses of the tornado - and by the time I had an unlimited view to the northeast, the tornado had lifted back up into the clouds. However, by this time the storm had taken on an entirely different form. The wall cloud which the tornado dropped out of was still rotating, and a shaft of heavy rain and hail was visible to the northeast of the wall cloud. It wasn't a tornado, but it was still a breathtaking sight.
I headed back into Oakdale at 1600 to search for damage. However, it appeared as if another tornado was imminent, so I pulled off to the side of the road to get some video. But just my luck - my videocamera's battery was low. I did get a few second's worth of footage of the wall cloud before the battery ran out. I continued to watch the wall cloud as its rotation became more vertical. There was a pay phone nearby, so I notified the National Weather Service in Sacramento about the tornado I saw and about the violently rotating wall cloud. The forecaster told me that they were monitoring the storm on radar and they had a warning out for the storm. I then walked back to my car to watch the storm as it moved northeast towards the foothills. As one would expect, the mountainous terrain tore up the low level rotation within the supercell, which turned out to produce only one tornado. The Cb continued to maintain itself after sunset as it moved into Calaveras County, but I never saw any lightning in association with the storm.
Throughout the evening, Sacramento TV stations showed various home video footage of the tornado near Oakdale. Every video clip I saw showed pretty much the same thing I had seen - a thick, black funnel perhaps 1/4 mi wide. There were also some clips of livestock injuries and damage to trees, a barn, and garage at a dairy southeast of Oakdale. Since the footage was taken after dark, it was difficult to tell the extent of the damage. Hopefully, I will be able to survey the damage myself on Friday.
Rainfall amounts continue to be impressive for so early in the season. As of Dec 12, 1996, the monthly total was 2.40 inches, and the season rainfall total was 6.25 inches. The Tuolumne River in Stanislaus County is running very high, and there is concern for flooding. Will check in with updates if necessary.