Experimental Changes to NWS Warnings

[Mike Johnston]

At my local storm spotters' training this evening, I learned from the NWS representative that our area (Pleasant Hill / Kansas City MO forecast office) will be participating in some experimental changes to severe warning parameters this season, including:

1. Severe threshold for hail will be 1" rather than the standard 3/4"

2. Warning areas will be drawn in polygon shapes rather than issued for the standard county/portions of county areas.

Regarding #2, she said broadcast communications to the public will still reference the county, but the official warning area will be used for a) verification, and B) warning siren activation purposes.

There are evidently 6 or 7 other local offices in the central region participating in this experiment.

 

[Jeff Snyder]

Originally posted by Mike Johnston

1. Severe threshold for hail will be 1\" rather than the standard 3/4\"

2. Warning areas will be drawn in polygon shapes rather than issued for the standard county/portions of county areas.

IT'S ABOUT TIME!!

Here's some good comments on this topic by SPC Forecaster Roger Edwards, titled "PROPOSALS FOR CHANGES IN SEVERE LOCAL STORM WARNINGS, WARNING CRITERIA AND VERIFICATION"
http://www.stormeyes.org/tornado/verf/

These comments also address the idea of a 'very severe thunderstorm' warning for the extreme events (huge hail, very damaging winds, etc).

 

[nickgrillo]

Detroit/Pontiac NWS has had 1" inch hail for the severe threshold since 2003...

I am really glad some other offices are gonna finally go with doing the same. I hope the "EXTREMELY DANGEROUS THUNDERSTORM WARNING" idea comes to pass, also...

..Nick..

 

[Mike Johnston]

Oh, by the way, the area covered by the Pleasant Hill/Kansas City office had 31 confirmed tornadoes in 2004, and all 31 were preceded by warnings. Not a bad track record!

 

[Jeremy Lemanski]

Originally posted by nickgrillo
Detroit/Pontiac NWS has had 1\" inch hail for the severe threshold since 2003...
..Nick..

Nick, DTX still uses the 3/4 inch as there warning "limit".

I too would like to see the min. size for hail raised, either to .88 or one inch. Very severe thunderstorm warnings would also be very helpful, for times when winds are forecasted to be over 75mph or hail is 2 inches and larger. I know St. paul's office in minn. already issure such a thing.

 

[George Tincher]

I don't know about some of this stuff. I like the idea of making the minimum hail size for severe warnings 1". But I have concerns about "very severe" warnings and things of that nature.

Remember, we are all weather enthusiasts and make a great effort in understanding anything related to severe weather. But most of the average public doesn't. In fact, to the average person, the system is already as complicated as it can be while still remaining effective. I mean look at how often people confuse watches and warnings.

And also, by adding a seperate class of severe warning, you risk making people ignore regular severe thunderstorm warnings. IMHO, severe is severe. Set whatever criteria you wish that makes a storm severe and stick with it. Either it is severe or it isn't. There shouldn't be different classifications of warnings. Otherwise people will totally ignore the regular warnings and somehow think storms that don't receive the "the very severe" label are somehow less dangerous or unworthy of their attention. IMHO, that's just a bad idea.

Again, such a classification would work among people like us. But people who understand, comprehend and appreciate such things when it comes to weather is very much the exception, rather than the rule. So let's keep it simple. That's my two cents.

-George

 

[Joey Ketcham]

Originally posted by Mike Johnston
At my local storm spotters' training this evening, I learned from the NWS representative that our area (Pleasant Hill / Kansas City MO forecast office) will be participating in some experimental changes to severe warning parameters this season, including:

1. Severe threshold for hail will be 1\" rather than the standard 3/4\"

2. Warning areas will be drawn in polygon shapes rather than issued for the standard county/portions of county areas.

Regarding #2, she said broadcast communications to the public will still reference the county, but the official warning area will be used for a) verification, and B) warning siren activation purposes.

There are evidently 6 or 7 other local offices in the central region participating in this experiment.

Wichita's NWS is doing this same thing. I think this is great! The current warning standards have needed to be changed for a long time.

 

[Glen Romine]

Originally posted by George Tincher
And also, by adding a seperate class of severe warning, you risk making people ignore regular severe thunderstorm warnings. IMHO, severe is severe. Set whatever criteria you wish that makes a storm severe and stick with it.

-George

You may feel that way, but when stronger wording is used in warnings, post surveys have indicated that the public did often notice - and it made them more apt to take safety precautions. An example is the use of tornado emergency by the OUN office during the May 3 outbreak. As long as the terminology is used sparingly - I think it is a good way to distinguish the upper 5% of severe weather events.

Glen

 

[Greg Stumpf]

Originally posted by George Tincher
And also, by adding a seperate class of severe warning, you risk making people ignore regular severe thunderstorm warnings. IMHO, severe is severe.

"Severe is severe"?

So you are telling us that a storm with 50 kt winds is the same thing as a storm with 100 kt winds? A storm with 1" hail is the same as a storm with 5" hail? A storm that can cause a river to rise 1 ft in 1 hour is the same as a storm that can cause a 10 ft rise in 15 minutes? Why categorize hurricanes then for that matter? Yet, all of these examples can cause harm, just to different levels of severity.

The public and other entities will adjust their actions based on a percieved level of severity. For example, if I know that a storm is going to produce 50 kts winds, I may just go inside and wait it out. If the storm is going to produce 100 kt winds, I may find a more reinforced shelter, bring some outside objects inside, etc.

While we're at it, what about probabilistic warnings? We already do this for precipitation. The users of the forecasts all have different thresholds for taking action, so why not provide users with more information than just a categorical decision for warnings as well? Forecasters should quantify the severity, and also express their level of uncertainty via probabilities (since weather forecasting is far from perfect). Then you, as the individual, have the freedom to set your own threshold for taking certain actions.

 

[Jeremy Lemanski]

http://www.crh.noaa.gov/dtx/?page=wwa_defi...ions/convective

There is your definitions, 3/4 inch it is.

 

[Robert Dewey]

The criteria is still 3/4 of an inch, but Nick is right - They haven't issued a warning for anything under an inch as far back as I can remember. Even with the forecast for one inch hail, I have still yet to see anything bigger than dimes...

Also, a tad bit off topic - Nick, have you checked your Private Messages?

 

[Tony Laubach]

Depending on where in the area you are, they will issue warnings for 3/4 hail only when its coming down in buckets and will end up accumulating on the roads. This is typical during summer-time storms. Outside of the Urban Cooridor, I don't think 3/4 hail is a big deal to anyone. Sometimes I've heard 3/4 hail for areas out east along I-70 and I-76, but again, only when it's going to amount to accumulate on the roads. I usually don't report it as severe, but will mention it, especially in the city.

 

[Jeremy Lemanski]

agree, even though the crit. is 3/4 inch, it really doesn't do much by itself. if there is 50mph winds or more with the hail, then you can start to get dents and broken winds due to the extra force of the wind driving the hail. any kind of hail is also bad for crops.

 

[Jeff Snyder]

Originally posted by Jeremy Lemanski
agree, even though the crit. is 3/4 inch, it really doesn't do much by itself. if there is 50mph winds or more with the hail, then you can start to get dents and broken winds due to the extra force of the wind driving the hail. any kind of hail is also bad for crops.

Even with 3/4" hail and 50kt winds, I have a hard time believing that anything will be dented (maybe a styrofoam cooler...)... I'm supporting the following:

Strong Thunderstorm Advisory: Winds 40-60mph or Hail <1.00"
Severe Thunderstorm Warning: Winds 60-74mph or hail 1"-1.75"
Very Severe Thunderstorm Warning: Winds >75mph or hail >=2"

I think people play the public for stupid too much sometimes... If there is adequate 'advertisement' / publicity about the scale, I'm sure most folks will be able to pick it up. If nothing else, just add a "Very severe" warning to denote those situations when there is an enhanced threat to life and property (very large hail, very damaging winds, etc.). The local TV stations in OKC do their own strong thunderstorm advisories, which I believe are rather arbitrary, but it's nice to see. I suppose, it'd be simplest to just do the following if the advisory category would make things too complicated:

Severe TStorm Warning: 1"-2" hail or winds 58mph-73mph
Enhanced Svr Warning: >=2.25" hail or winds >74mph

Just my opinion...

 

[Robert Dewey]

I agree with Jeff as well... I think the wind criteria should really be >=75MPH. In my mind 58MPH just doesn't cut it - Sure you may get a few branches down, but trees won't really uproot until around 75MPH (depending on tree and soil conditions, of course). I'm guessing that is why hurricane force winds don't start until 74MPH...