May 5, 1998

Frustrating chase day in the valley....lots of action not far from me, but I didn't see a darn thing!

Tuesday started with steady lgt rain. TCu tried to build over the area with binovc early in the afternoon, but fizzled as Cs OVC spread over the area - not a promising sign for good convection in the immediate area. But further to the south and west, intense cells began going up in southwestern Stanislaus and Merced Counties between Crows Landing and Los Banos around 1600. This is an area where cold air funnels frequently develop - and knowing that there had been a funnel and tornado in Tracy earlier, I got in my car at 1630 with hopes that these cells might do the same.

To follow these storms, I took Hwy 165 south to Stevinson, then Hwy 140 west to Gustine, then Hwy 33 north to Patterson, then Route J17 back to Turlock.

As I approached these storms from the north on Hwy 165, I saw fqt-cns in-cloud (IC), cloud-to-cloud (CC), and cloud-to-ground (CG) lightning to my south and west. That's about all I saw, as the bases and towers were obscured due to rain/overcast/poor vsby. These features also obscured developing storms that I probably should have chased instead. Although the storm I chased did have a severe t'storm warning on it, I didn't get into any winds (though I did see some trees that had just lost some twigs from 30-35 mph southerly winds SW of Stevinson at 1655) - and the only hail I saw was 1/4 inch in downtown Newman at 1710. Pretty much the entire drive from Stevinson on was through heavy rain, 1 mi or less vsby, and obscured ceilings.

Later on, I learned that there were funnel clouds in Ceres (7 mi NW of Turlock) at 1641 and in Modesto (10 mi NW of Turlock) at 1725, and that a thunderstorm passed over my neighborhood while I was gone. I was surprised that convection developed in these areas since I thought OVC would be a limiting factor. Can't get 'em all, I guess. The major weather story in the area, however, was the flooding/roof collapse in Escalon in southeastern San Joaquin County Tuesday afternoon. Thunderstorms trained over Escalon for two hours, with an estimated 3+ inches in that area.* Sacramento TV stations have been showing pictures of a collapsed roof at a bar in Escalon, along with widespread street flooding and water in homes. There was no video of the Ceres and Modesto funnels shown on any of the local stations Tuesday evening, although there one station showed video of a funnel in Stockton.

Speaking of video of funnels, did any of you see the footage of that tornado is Sunnyvale on Monday?! WOW!!! For those who haven't heard, an F2 tornado touched down in Sunnyvale on Monday - in the Bay Area 10 mi W of San Jose. The local TV stations have been showing clips of a large condensation funnel not in contact with the ground - and another of a narrow but intense debris swirl within 100 ft of the photographer. What was interesting was that all of the footage showed that the tornado had clockwise (anti-cyclonic) rotation. Most tornadoes in the Northern Hemisphere rotate counterclockwise, although many exceptions have been observed and documented.

The upper-level low that has given the Bay Area and Valley thunderstorms each of the past four days is moving inland - but is now closer to the area as it has ever been. Looks like there might actually be less cloud cover over the area today. That would make storms more chaseable (and perhaps more intense) if they develop.

Follow up....Nobody is certain exactly how much rain fell in Escalon between 1600 and 1800 PDT on May 5, 1998. The official rain gauge in Escalon - which has a 3 inch rainfall capacity - fell out of its bracket and shattered after overflowing. Damage from the flooding totaled over $1 million.