All Over Albany

Watch vs. warning

The National Weather Service issued a tornado watch today for large parts of eastern New York, including parts of the Capital Region, until 6 pm.

We noticed a bunch of people mentioning this on Twitter today, and a few people were getting it not quite correct. That's understandable -- a tornado watch is rare here (if you lived in the Midwest, you'd know this by heart).

OK, a quick review with lightly edited entries from a National Weather Service glossary:

Tornado watch This is issued by the National Weather Service when conditions are favorable for the development of tornadoes in and close to the watch area. The area can vary depending on the weather situation. The watches are usually issued for a duration of 4 to 8 hours. They normally are issued well in advance of the actual occurrence of severe weather. During the watch, people should review tornado safety rules and be prepared to move a place of safety if threatening weather approaches.

Appropriate reaction: Oh, OK, I'll keep it in mind.

Tornado warning This is issued when a tornado is indicated by radar or sighted by spotters; people in the affected area should seek safe shelter immediately. The warning can be issued without a Tornado Watch being already in effect. The warnings are usually issued for a duration of around 30 minutes -- they will include where the tornado was located and what towns will be in its path.

Appropriate reaction: Near here? Head for cover! (You know, calmly, but with purpose.)

(Severe thunderstorm watches and warnings work the same way.)

Here's a NWS brochure on severe weather safety, including what to do in the event of a tornado (not just a watch, an actual report of a tornado). The short story: head for the basement, or -- if you don't have a basement -- an interior room without windows on the first floor (bathrooms are often a good spot).

Curious about how many watches end up including tornadoes, we looked up the stats on the NWS site. According to one study of data from 1980-1999, about 56 percent of watches ended up having at least one tornado somewhere in the watch area.

Bonus: The Tornado FAQ from the NWS' Storm Prediction Center.

archive photo: NOAA Photo Library, NOAA Central Library; OAR/ERL/National Severe Storms Laboratory (NSSL)