Jun 2020

Famous 27-Year-Old Weather Monitor II Finally Retires

A moment of silence, please. One of the great weather stations of the San Francisco Bay Area has gone to rest.

Jeffrey Sato’s Weather Monitor II , one of Davis’s original weather stations, had been on his house in Sunnyvale, just north of San Jose, for over 25 years. Although his faithful friend was still working, if you don’t count rain, Jeffrey took his shelter-in-place time to finally take it down and replace it with a Vantage Pro2. (As for the rain, when Jeffrey took the station down, he found the rain collector was totally plugged with debris - but the poor little thing was still reporting (low) rain. Now, with a Vantage Pro2, Jeffrey can site his anemometer on the roof and the rain collector and temp/hum sensors at 6' where he can easily keep that rain collector clean!)

It’s not terribly unusual for a Weather Monitor II to continue to provide weather data for that long. But this particular weather station is unusual because of its moment of notoriety when it was hit by a tornado back in 1998. Yes, a tornado. In Sunnyvale, California.

The very unusual weather event sparked a lot of interest among the meteorological community here in the Bay Area. The tornado was one of two that touched down in Sunnyvale. They were rated as F1 or F2, based on the damage they did. Tornadoes are rare in the Bay Area, and these were super rare because they were anticyclonic (meaning rotating clockwise in the Northern Hemisphere). They are on a short list of just 18 anticyclonic tornadoes recorded in the United States.

A rare tornado took down Jeffrey's five-year-old Weather Monitor II in 1998, but not before it recorded 76 mph (122 kph).

Don't worry, he put it back up and it continued to serve him for another 22 years. He mounted the rain collector and anemometer on the roof and the temp/hum sensors under the eaves of the house.

“After the tornado,” Jeffrey told us, “a guy came by my house and said he heard I had a weather station and wanted to know if I had any info on it. I told him I did, and that my weather station had recorded at 4:33 P.M., a wind speed of 76 mph before the mast came down (found my original notes). It turns out it got to San Francisco State University and they published it on their website for the 1998 Sunnyvale tornado. If you look at the link, it shows the path of the tornado citing the speed and time. If you click on the enlargement, the diagram points to my house as the location of the wind speed.”

You can see some dramatic photos of the tornado, including a few looking directly up into the vortex, and a summary of the event on this webpage by John Monteverdi of San Francisco State’s Department of Geosciences. You can also read more in-depth about this event in this article in the AMS Monthly Weather Review.

Rest in peace, little Weather Monitor II. You’ve served us well. Now it’s time to let a Vantage Pro2 take over your tornado watch.

Do you have a long-lasting Davis weather station? We'd love to know about it! Drop us an email. If you are thinking maybe it's time for it to retire, check out the latest and greatest Vantage Pro2.  Or if you think it has a few more years in it, how about giving your older Vantage Pro2 an upgrade with a new AeroCone rain collector, new tipping spoon, or a Sonic Anemometer?

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