Severe Thunderstorm Watch Area (?)

[Sam Sagnella]

SPC has issued a blue box for SE Louisiana, but only 5 counties. I've never seen a watch this small before, and was wondering if any of you have either.

http://www.spc.noaa.gov/products/watch/ww0040.html

 

[Jeff Snyder]

I was thinking about posting on this as well... Why not just let warnings cover this? I suppose it's probably partly a statistics game, in that it'll increase the PoD (probability of detection), but I just found it odd to issue such a tiny watch.

 

[James McCormick]

I think any time that you can give that little extra lead time with the 'watch' box out, it's a good thing to have. I never like just letting warnings cover it if at all avoidable. In this case the threat is isolated to and just offshore, but it was known in advance, so I think it's a good box. It might have trouble verifying since the strongest part of the bow echo is offshore.

Typically watches this small are confined to cases either along a coastline or just outside of another, larger watch box.

 

[Tom Tackett]

Some situations are difficult and challenging to "Watch!" If no watch were in effect and there were several reports, many would scream......"Why wasn't a Watch issued?!?!" Once in a while, they issue a watch and nothing much happens. SPC does an incredible job and I would rather have a watch in effect with no damage or severe reports as opposed to no watch in effect and lots of damage and/or reports.

In 2003, there were some fairly "small" and large watches issued with regards to the square miles contained within the watch area.

Watch # 22, Tornado, Feb. 22, 2003, Virginia, 3 Hours/5 Minutes, only 6,600 Square Miles.
Watch # 76, Severe, March 25, 2003, Texas and Louisiana, 76,000 Square Miles---Very large area.
Watch # 218, Severe, May 2, 2003, Georgia, 9,300 Square Miles.
Watch # 545, Severe, June 18, 2003, Idaho, Wahington State, Oregon, and Montana, 91,000 Square Miles---Very large area.
Watch # 607, Tornado, June 30, 2003, Florida, Alabama, 8,100 Square Miles. Associated with Tropical Storm BILL.
Watch # 629, Severe, July 3, 2003, Iowa, Minnesota, South Dakota, and Nebraska, 114,000 Square Miles. Most likely---the "Largest" watch issued in 2003.
Watch # 929, Severe, Sept. 26, 2003, Kansas and Missouri, 6,600 Square Miles. Very small geographical area.

There were more than a few watches with 9,000 to 12,000 Square Miles of geographical area covered by the watch.

+++ NOTE: All "Watch Square Mile Numbers" are approximations.

As far as I know, it is usually the SPC Lead Forecaster on duty A N D the Local NWS Forecast Offices who decides whether or not a watch is issued, its location, and duration.

And, I have to agree, the watch issued today for Louisiana and the surrounding coastal waters only covered a small land area, although the island areas as well as the ocean areas are also covered in the watch. Got some people living on some islands in addition to off-shore oil drilling operations and marine activity to take into consideration. Again, all branches of NWS do a great job with their overall mission.

Tom in Ft. Worth.

 

[Jason McKittrick]

Earlier this month I had an opportunity to visit with our Warning Coordinator Meteologist at The Weather Service Office here in Omaha. He mentioned to me that effective sometime in February there were going to be changes to the way watches are issued. They are no longer going to issue "boxes" atleast there won't be any 70 mi either side of a line business. They are now going to issue watches for groups of counties. This is supposed to give the local offices some control over which counties are placed in the watch. It is also supposed to allow them to better place the watches for instances such as this morning. At least that is my understanding.

 

[Roger Edwards]

The actual watch is for a group of counties. The SPC only uses the "watch box" as a first guess approximation anymore. The "70 MILES EITHER SIDE OF A LINE" language has a disclaimer for that in the wording of the watch message: as an approximation. The "watch box" in this framework probably will stick around indefinitely thanks to all the decoders out there that still plot watches by parallelogram. Who knows how long it will take to wean folks off the "watch box" plots? Your guess is as good as mine. Again, however, the official watch is the list of counties ( in the WOU = Watch Outline Update).

 

[Robert Dewey]

I am not sure if it's still similar to N-AWIPS, but you select the region to place under a watch, generate a county list, and then you can add or subtract counties by clicking on them. The watch box is more for the public to get a generalized view of things, as most WFO are already aware of the developing situation (though coordination with SPC helps)...

 

[Roger Edwards]

Right, indeed, Robert. In fact, N-AWIPS is used exactly like that at SPC for generating the initial Watch County List (WCL), an internal watch proposal that zips to field offices and alarms their AWIPSes to avise of the impending coordiantion conference call. [Ideally, the WFO already is aware of the situation and prepared for a possible watch because of a combination of preceding convective outlooks, mesoscale discussions, and their own mesoanalyses and mesoprognoses.] Then comes the conference call, then the aviation watch, then public watch that you and the world sees. The WOU that results is the actual watch because it gives the list of counties agreed upon between SPC and the local office(s) involved. The "watch box" simply is a legacy offering, inexorably destined for the dustbin of history once everybody is relying on the counties listed in the WOUs for latest watch info.

 

[Robert Dewey]

Since I had NMAP2 opened, I decided to whip up a "fake" tornado watch...

First, I selected the area... Then, I removed several counties in the center of the watch...
http://69.14.190.10/images/SPC_WATCH/example1.jpg

I can then click on the watch, and enter the "parameters", like hail size/etc...
http://69.14.190.10/images/SPC_WATCH/example2.jpg

The above generates several files:
http://69.14.190.10/images/SPC_WATCH/WW0999.WOU.txt
http://69.14.190.10/images/SPC_WATCH/WW0999.SEL.txt
http://69.14.190.10/images/SPC_WATCH/WW0999.SAW.txt
http://69.14.190.10/images/SPC_WATCH/WW0999.PWN.txt
http://69.14.190.10/images/SPC_WATCH/WW0999.AWN.txt

It also gives you the area size, in square nautical miles, of the watch - In this case, it was close to 49K square nautical miles.

It's interesting to fiddle around with...

 

[Dan Cook]

I'm so getting that one day.

 

[Jeff Snyder]

Originally posted by rdewey
Since I had NMAP2 opened, I decided to whip up a \"fake\" tornado watch...

It's interesting to fiddle around with...

LOL I love NMAP2! I made a bunch of super-PDS watches for the fun of it the other day... It's great for making weather composite maps, etc...

 

[Dan Cook]

Hey Rob make the PDS Tornado watch of Death; like have it cover the whole midwest.

 

[Robert Dewey]

Originally posted by Dan Cook
Hey Rob make the PDS Tornado watch of Death; like have it cover the whole midwest.

LOL...

Here we go, this just in:

http://69.14.190.10/images/SPC_WATCH/PDS_FROM_HELL.jpg

And the Public watch file:
http://69.14.190.10/images/SPC_WATCH/W0665.SEL.txt
http://69.14.190.10/images/SPC_WATCH/W0666.SEL.txt

I had to break it up into two seprate boxes, Anything over 150K sq. miles and it doesn't want to add all of the counties for some reason. Total area for both watches is around 300K sq. miles. I overlayed a nice snowy radar image as well :lol:

 

[Andy Wehrle]

A.K.'s Death Watch

http://ww2.convectionconnection.com:8080/w...deathwatch.html

:lol:

 

[Dan Cook]

Re: A.K.'s Death Watch

Originally posted by Andy Wehrle
http://ww2.convectionconnection.com:8080/wxguesser/deathwatch.html

:lol:

That's where I got the idea.