Tiny little Watch area

[tom hanlon]

Noticed this watch box tonight.

Seems awful small to warrant a watch rather than a warning.

What are the rules for the definition of a watch area ? How small can they get ? How large can they get. I have seen watch boxes that seemed to be about 200 miles by 200 miles or so. The whole state of ohio for example. This one seems like about 60 miles b 60 miles, maybe smaller.

Just curious. Is there some guidance or standards that the NWS goes through when establishing a watch area o r does the "it depends" rule take precedence in all meteorological decisions ?

--
Tom Hanlon

 

[David Drummond]

Doesn't surprise me. I have seen them issue narrow tornado watches for a single long lived tornadic supercell before.

 

[cdcollura]

Good day,

This was for a persistant and isolated supercell thet developed near Ironton, MO and moved SW at about 10 MPH all the way past Texas, MO. The storm had very large hail and high winds, I was on it myself, despite chasing winding mountain roads! Both an MD and watch were issued for this storm, and yes, very small indeed. The storm, developing along a NE / SW oriented boundary under NNW 500 MB 30-Knot winds, eventually produced hail up to baseball sized near Texas, MO (2.75").

Chris C - KG4PJN

 

[Rich Thompson]

Noticed this watch box tonight.

Seems awful small to warrant a watch rather than a warning.

What are the rules for the definition of a watch area ? How small can they get ? How large can they get. I have seen watch boxes that seemed to be about 200 miles by 200 miles or so. The whole state of ohio for example. This one seems like about 60 miles b 60 miles, maybe smaller.

Just curious. Is there some guidance or standards that the NWS goes through when establishing a watch area o r does the "it depends" rule take precedence in all meteorological decisions ?

--
Tom Hanlon
[/b]

Tom,

Watches typically range in size from 8000 to 40000 square miles. I've seen a few down around 2000-3000 square miles along coasts or international borders, and in rare cases they can be quite small for single storms that are persistent.

Watch size on the high end is limited somewhat by the number of WFOs that are involved in conference calls that precede the watch (too many offices makes it difficult to complete the call in a timely manner). On the small side, it mainly depends on the preferences of individual forecasters, and on slow storm motion.

So, to answer your question, there are no absolute guidelines about watch size except those dictated by common sense.

Rich T.