Experimental Changes to NWS Warnings

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.
 
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).
 
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..
 
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!
 
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.
 
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
 
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.
 
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
 
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.
 
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?
 
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.
 
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.
 
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...
 
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...
 
Originally posted by nickgrillo
Rob, yep - sorry for not replying to you sooner. Will send you a PM a little later today, perhaps...

Exactly. I haven't heard a warning for <1 inch hail for at least several years now.

Here is a excellent example of what this new warning method could do:

...

That was just an example warning I written up. Doesn't everybody agree this type of warning could come in handy?

..Nick..

I agree Nick... Very high straight line winds (like the 120+ MPH with the May 31, 1998 derecho) can do damage similar to a weak to moderate tornado, and over a larger scale. Since so many warnings are issued for marginal criteria, the public probably treats a severe thunderstorm warning with 60MPH the same as a severe thunderstorm warning for 100+ MPH, when they should really be treating the latter like a tornado warning (and seeking shelter in a basement/etc.)...
 
.5 - .75 inch hail with any kind of wind is going to severely hurt crops, gardens, and will affect travel. I think these storms need to have advisories on them. I've seen a number of warnings that read 'hail to the size of nickels', which is .88 inches.

50 Kts is a good threshold to me. Any time trees start losing branches and rain or dust are being blown around creating a condition of near 0 visibility, the public needs to know about it, and often times convective winds aren't on a large enough scale to warrant a high wind warning. I have also noticed the public pays little attention to high wind warnings.

I do agree that storms with hailstones larger than 3" or so need to be differentiated or emphasized, and when storms are bringing 90-100 MPH winds, that they need to be addressed in clear and concise terms. During the bow echo event in southcentral Nebraska on May 29th, Hastings used the term 'hurricane force winds' frequently in their severe weather statements. But we have to make sure that we aren't issuing too many products for the general public. Enough people have a hard enough time understanding the difference between a watch and a warning. I would rather have people interpreting the severe weather statement, or having the TV meteorologist describe the specific report, which mentions the specific threat, than try to come up with a new warning system that seems likely to result in apathy towards storms that don't meet 'extremely dangerous' criteria.

Besides, we don't 'know' what a storm is doing until it hits something. We don't 'know' if a storm that is reporting .88 inch hail actually has 1.75 inch hail if nobody is in the hail core. And I'd rather have a warning that encompasses not only the present severe weather threat but the potential threat of the storm as well. I really don't like the idea of not only having to determine if a storm is producing .75 inch hail, but that all of the hail in the storm is less than a certain size as well.

There's enough stress in the warning decision making process as it is, and enough problems with radar algorithms as well. The only thing I can think of that I like is the 'Tornado Emergency' Statement, which I think needs to be reserved for metropolitan areas and tornadoes that have had major damage reports with them.
 
I still stand by my original statement that a severe storm is a severe storm and that we don't need seperate classes of warnings. You want to let the public know whether 50 knot or 100 knot winds are expected? Well, don't we already do that? I mean each severe thunderstorm warning I've read indicates the expected level of severity, ie winds of 60, 70, 80 or even 100 mph. Expected hail size is also mentioned when appropriate. So with this info being provided right along with the warning, I think most people can figure out the seriousness of the situation without having to change anything. Again, I am opposed to change just for the sake of change. IMHO, that's all this would be.

Also, in reference to hurricanes, that's not a fair comparison. With hurricanes, we often have days to prepare. With severe thunderstorms, we only have minutes. So the TWC mets, CNN mets and local tv mets don't have quite as much time to explain all of the categories to their audience as with hurricanes. Besides, even if no hurricane intensity category existed, as long as we have information on the wind speed, I doubt we'd suffer much as a result. I mean it's pretty obvious to your average person that a hurricane with 75 mph sustained winds is less a threat than one with 150 mph winds. Therefore having a category scale as a warning device isn't even necessary.

Again, as long as all relevent information is available within the warning (which it is already), I see no great need to start adding categories for warnings. It just further complicates things without giving us anything we don't already have. The public is familiar with current format. They are use to it. And I see no reason to start changing what we know works when the change provides us nothing we don't already possess. And I have yet to see an argument that would convince me otherwise.

Now, as far as releasing probabilistic warning information, I could see a great usefulness there. That would give us something in addition to what we already have. And it would be helpful, as it would show the exact areas within a county for example, that will experience the worst of the weather.....while at the same time allowing those not expected to get the severe weather to relax a bit. This would be much more useful than a blanket warning for an entire county when only a small portion of the county is really in danger. This I would support 100%.

-George
 
George, I believe this is the experimental purpose is of using irregular polygon shapes for the warning area. At our spotter training, the NWS showed us some slides of what the new warning areas will look like, and they seem to be very tailored to the predicted path of the storm - with some margin of safety for possible path changes downstream, kind of like a miniature version of the hurricane landfall probability graphs we see. Within this context, adding probabilities would probably be redundant. In other words, if you're in the box, take cover now.
 
Originally posted by Mike Johnston
George, I believe this is the experimental purpose is of using irregular polygon shapes for the warning area. At our spotter training, the NWS showed us some slides of what the new warning areas will look like, and they seem to be very tailored to the predicted path of the storm - with some margin of safety for possible path changes downstream, kind of like a miniature version of the hurricane landfall probability graphs we see. Within this context, adding probabilities would probably be redundant. In other words, if you're in the box, take cover now.

Yes, that would be pretty much the same thing, as obviously the closer to the center of the projected path you go, the greater the expected danger of experiencing the most severe of the weather. IMHO, this change would be good.
 
Well, good question and unfortunately I didn't think to ask her. Since it is experimental for just a handful of offices this year, I'm not sure at what NWS map levels (ie. national, regional, local etc.) the shapes will be displayed. The NWS person did tell me that communications to the public will still be made with reference to county/city locations for clear understanding. However, localities with siren systems will evidently activate sirens only in the actual area warning.
 
Originally posted by Mike Johnston
However, localities with siren systems will evidently activate sirens only in the actual area warning.

It's about time. When I'm at home the sirens go off every time there's a tornado warning for Dane County. I'll bet a lot of people have started ignoring them. Anyone know if MKX and GRB are among the offices doing this?
 
The polygons have been used for a while, it's just now that some offices are using them for verification too. Programs like GRLevel3 plot them instead of the county line.

- Rob
 
Originally posted by rdale
The polygons have been used for a while, it's just now that some offices are using them for verification too. Programs like GRLevel3 plot them instead of the county line.

- Rob

Yes... They have been doing this for quite some time... The very first time I seen a polygon warning was with the Swift WX software, version 1.

Rob, do you know if GEMPAK is able to plot polygon shaped warnings?
 
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