Tornado warning dilemma...

[Andrea Griffa]

I open this thread to discuss about chasing strategies as regards tornado warning.
Imagine you're stopped with your car and you're waiting for convection...Suddenly convection starts at north and at south of you, and you really don't know what you gotta do. Synoptic situation is really good and probably the towers you're seeing are two supercells in formation. You don't know if it's better going northward or southward:both of these seems very good.... for this reason you decide to wait some other precious minutes for listen to some tornado warnings at the radio. Tornado warning starts for Northern supercell and you head there.

This behaving can be useful for chasing the best supercell (probably tornadic) but sometimes you could arrive in late....

So it's better to chase the supercell that you rate the best or you've to wait tornado warning? A big dilemma..What do you think about guys?
I know for example that in a line of supercell, the southern one has more probabilities to became tornadic but this is no a postulate. I made this consideration one time and I was wrong losing the tornado...

 

[rdale]

Why was the warning issued? Doppler indicated or observed?

What direction are the cells moving? Away or towards you?

What's the road network like for the different cells?

What was your forecast?

What obs can you make in the field that might assist you if you don't have data?

 

[Andrea Griffa]

Originally posted by rdale
Why was the warning issued? Doppler indicated or observed?

What direction are the cells moving? Away or towards you?

What's the road network like for the different cells?

What was your forecast?

What obs can you make in the field that might assist you if you don't have data?

Doppler radar indicated rotation on the northern cell, so the first tornado warning was issued. The southern cell(younger) tornado warning arrived in late and only this cell was tornadic: so I lost the tornado.

Cells moved away from me, and I was in the right target. It goes without sayng that I had data thanks to internet connection with the laptop so I could see all the data.

 

[rdale]

What was your determination of the rotation on radar?

Anything in the sky give you clues?

I'm not asking questions specific to this event - just putting up questions you can ask yourself when it happens to help the process along. There's no clear-cut answer to anything in weather.

 

[Mike Peregrine]

Andrea - this is a tough call that most every chaser is forced to face every year on the Plains as well ... in general, after facing similar scenarios time after time, chasers eventually get a gut feel for what they want to do in cases like this - sometimes it pays off and sometimes it doesn't. The rules in Italy may be different than the States, but in general I will go after the first cell to go severe, in the hopes that it will consume the environment and grow. Sometimes other factors enter into the picture, though ... if the storms are forming ahead of an angled boundary, then I may opt to go for the southern cell if it has access to better quality air/wind. If a northern cell is riding a warm frontal boundary, however, I'd definitely stick with it as the warm/cold air mix often makes supercells go ape crazy. It all depends on the situation, but I doubt there is a single chaser out there who can say they consistently make the right decision every time. You end up winning some and losing some ... it's just inevitable.

 

[Andrea Griffa]

Originally posted by rdale
What was your determination of the rotation on radar?

Anything in the sky give you clues?

I'm not asking questions specific to this event - just putting up questions you can ask yourself when it happens to help the process along. There's no clear-cut answer to anything in weather.

Cell was still young but first signs of rotation at doppler(weather tap) were starting to become evident. As regards the sky, I was in a sunny zone and I saw one of the two supercell with a well defined tower and a beginning incus. The other was younger and I saw a tower growing up: what I wanna tell you is that from an external view you could see both of the supercells with a strong structure...So here is the dilemma. :?:

 

[Amos Magliocco]

Originally posted by Andrea Griffa

So it's better to chase the supercell that you rate the best or you've to wait tornado warning? A big dilemma..What do you think about guys?
I know for example that in a line of supercell, the southern one has more probabilities to became tornadic but this is no a postulate. I made this consideration one time and I was wrong losing the tornado...

Andrea, I think the actual warning would not be the best way to judge the storm's potential to produce a tornado. I'm not criticizing the warning process, but we all know that a warning does not equal a touchdown for myriad reasons, nor does the warning intend to imply this. Chasing warnings is usually counterproductive, in my experience, though it does give you some important information about the strength of the storm. Of course if the warning mentions a tornado is on the ground, that's a different story. But if you're so far that you can't see it, it will likely be gone by the time you arrive. Then you ask yourself, is this a cyclic supercell likely to produce again? Then you're back to examining your environment. Round and round we go.

I have dropped to a southern storm and had the northern storm produce a tornado, and also stayed with the northern storm while a more southerly option ripped like mad. Chasing can be very frustrating that way. The best scenario is to be aware of all localized influences that could favor one of the two storms, like mesoscale boundaries or unimpeded or uncontaminated inflow.

During Project VORTEX, researchers found tremendous variability of storm relative helicity values from one storm to another within the very same 'synoptically supportive' environment. This is one example of why it is so difficult it is to pick the 'right' storm. Any number of things can influence SRH values close to the storm, and during VORTEX they discovered large variations of this component that would have been impossible to forecast in advance or even measure in real-time given normal horizontal density of observational data. So our laptops have their limits in this regard.

My gut feeling is that the best chasers develop, over long experience, some combination of analytical skill and observational acumen to make the right choices more often than not. Even so they still screw up sometimes.

In the most general terms, all other conditions being equal, the southern storm is often a good choice, as "Tail end Charlie" may have uncontaminated inflow. However if one of your northern storms is riding an outflow boundary, and the southern storm is in higher LCL conditions, you could miss out. See Jon Davies' research for some cool discussion of this.

There aren't many rules to this game, I'm afraid.

 

[Andrea Griffa]

Originally posted by Mike Peregrine
Andrea - this is a tough call that most every chaser is forced to face every year on the Plains as well ... in general, after facing similar scenarios time after time, chasers eventually get a gut feel for what they want to do in cases like this - sometimes it pays off and sometimes it doesn't. The rules in Italy may be different than the States, but in general I will go after the first cell to go severe, in the hopes that it will consume the environment and grow. Sometimes other factors enter into the picture, though ... if the storms are forming ahead of an angled boundary, then I may opt to go for the southern cell if it has access to better quality air/wind. If a northern cell is riding a warm frontal boundary, however, I'd definitely stick with it as the warm/cold air mix often makes supercells go ape crazy. It all depends on the situation, but I doubt there is a single chaser out there who can say they consistently make the right decision every time. You end up winning some and losing some ... it's just inevitable.

Thanks for these consideration, I agree with you. So if a northern cell is riding a warm frontal boundary, I've to stick with it as the warm/cold air mix often makes supercells go ape crazy.

"if the storms are forming ahead of an angled boundary"

Mike what do you mean about an angled boundary?

 

[Andrea Griffa]

Originally posted by Amos Magliocco+--><div class='quotetop'>QUOTE(Amos Magliocco)</div>

<!--QuoteBegin-Andrea Griffa

So it's better to chase the supercell that you rate the best or you've to wait tornado warning? A big dilemma..What do you think about guys?
I know for example that in a line of supercell, the southern one has more probabilities to became tornadic but this is no a postulate. I made this consideration one time and I was wrong losing the tornado...

Andrea, I think the actual warning would not be the best way to judge the storm's potential to produce a tornado. I'm not criticizing the warning process, but we all know that a warning does not equal a touchdown for myriad reasons, nor does the warning intend to imply this. Chasing warnings is usually counterproductive, in my experience, though it does give you some important information about the strength of the storm. Of course if the warning mentions a tornado is on the ground, that's a different story. But if you're so far that you can't see it, it will likely be gone by the time you arrive. Then you ask yourself, is this a cyclic supercell likely to produce again? Then you're back to examining your environment. Round and round we go.

I have dropped to a southern storm and had the northern storm produce a tornado, and also stayed with the northern storm while a more southerly option ripped like mad. Chasing can be very frustrating that way. The best scenario is to be aware of all localized influences that could favor one of the two storms, like mesoscale boundaries or unimpeded or uncontaminated inflow.

During Project VORTEX, researchers found tremendous variability of storm relative helicity values from one storm to another within the very same 'synoptically supportive' environment. This is one example of why it is so difficult it is to pick the 'right' storm. Any number of things can influence SRH values close to the storm, and during VORTEX they discovered large variations of this component that would have been impossible to forecast in advance or even measure in real-time given normal horizontal density of observational data. So our laptops have their limits in this regard.

My gut feeling is that the best chasers develop, over long experience, some combination of analytical skill and observational acumen to make the right choices more often than not. Even so they still screw up sometimes.

In the most general terms, all other conditions being equal, the southern storm is often a good choice, as "Tail end Charlie" may have uncontaminated inflow. However if one of your northern storms is riding an outflow boundary, and the southern storm is in higher LCL conditions, you could miss out. See Jon Davies' research for some cool discussion of this.

There aren't many rules to this game, I'm afraid.[/b]

Cool consideration, Amos!
I know there are a lot of conditions that can make you missing out on the right storms, but sometimes the exciting moment of chasing can close your eyes and make you understand nothing more.

 

[George Tincher]

Nice discussion guys. Trying to figure out which storm to get on among multiple options has to be one of the most frustrating decisions that must be made. It's nice hearing everyone's strategies.

 

[Bob Schafer]

This is a topic that is at once fascinating, frustrating, and complex.

There are always a great many variables that ought to be processed by a chaser's consciousness during initiation/maturation, but one that I, personally, rarely enlist for such a decision is tornado warnings. It happens (that I will chase a warning), but more often than not a tornado warning or two is information that advises me of what I have missed. Most times, chasing a warning will only allow you to observe an outflow-dominant mess 45 minutes or an hour after the tornado(es).

Here are but a few of the considerations for choosing a storm when you have split the difference between two good-looking towers: (Good job, BTW; You have obviously chosen your target area well!)

*Which tower is exhibiting the stronger updraft?
*Which tower will be in the more favorable conditions in the near future?
*Which tower will be in the more favorable conditions in 45 minutes or an hour and a half?
(And, some of the answers to the above questions depend on sfc temps and moisture, sfc flow [advection], mid and upper level flow, and boundaries.)
*Which storm will be chaseable, taking into account your present position vs. storm motion, road networks, and concerns for your safety?
*Are the two towers oriented in such a way that one will likely choke or eat the other?

On the day of the Happy TX tornado (May 5, 2002?) I was approaching Vega from the west, traveling I-40. Nice looking towers went up N and S of me, equi-distant from my position. I chose to chase the northerly one, for no other reason than that I could get a nice SE-of-core position established and maintained. I missed "Happy". I was sad. (Sorry) The storm I chased produced, but not like Happy, and not until after I suffered car problems (another story....)

I wondered what tactical error had befallen me.

Fast-forward to Denver, 2003, and Tim V's class.

We did that day as a case study. Tim pointed out that "Happy" was fed by SSE or SE sfc flow, whereas the storm I had chased was fed by SSW flow. The Td's had been very similar upon initiation, but the difference in sfc flow basically sealed my fate. It is a mistake that I try to avoid on every chase now.

But there are legions of mistakes that can be made, especially during the excitement of multiple towers shooting toward the heavens.

May 29, 2001: I was all over the "White Deer" storm from the git-go. I gave up on it as it crossed 87/287 because it looked occluded to me, and the storm over AMA was pretty wild looking, but I guess I had mistaken HP characteristics for occlusion. Similar to "Happy" day in that I had to choose north vs. south storms, and both times I "blew it".

I've been fortunate to have had many successful days, too, but those two days will forever haunt me.

The moral of the story according to me:

Stay calm during your chases, or you won't think clearly, and it might.....no, WILL... cost you. Maybe not every time, but sometimes. Always keep in mind that there are a LOT of things to consider. Try to let your brain remember and utilize all that data you looked at earlier, and interpret how that data meshes with what your eyes are currently seeing and your laptop, radios and nowcaster are telling you.

Bob

 

[Mike Peregrine]

Originally posted by Andrea Griffa
Mike what do you mean about an angled boundary?

Sorry - I should be more specific ... I was just referring to a frontal boundary that is oriented from southwest to northeast, which results in an angled line of supercells ahead of the boundary. When this happens all of the storms can maintain isolation and support rotation, so a chaser just has to make the call whether the southern cell is the best way to go or not, mostly by thinking through the atmospheric and visual clues that Bob and Amos discuss - - and then weighing the circumstances against their experience. If storms are linear and the line has more of a north to south orientation, then I would most likely go for the 'tail end charlie' that Amos mentioned -

Many times simple circumstance plays a big part too - like how close you are to each cell, for example - occasionally I will make a play for a storm that I might feel has less of a chance for some reason - just for the sake of convenience (I know - gasp) ... but sometimes it just makes more sense to me for one reason or another. It sounds like you made an educated choice for the cell to stick with ... it just didn't pay off for you this time. Only with time and experience can chasers really get a chance to hone these skills. The advantage here is that if we make a bad call one day, there will soon be another opportunity to learn from the mistake and give it another go ... in Italy you may not get that luxury and be forced to live with your choice for the rest of your life - in other words, the stakes are MUCH higher for you, I would assume. Here we can just chalk it up as another bust and move on to the next event - which I think helps a person to see why you would naturally be highly interested in this discussion and in making good decisions this way on your future storms.

Thanks for bringing up the discussion - all the best on your next chance!

 

[Mike Peregrine]

By the way - just one more little scenario that comes up sometimes that really affects a choice you will make this way:

Last year on May 29th we were initially on a storm that went severe fairly early on over highway 36 to the west of Belleville, Kansas ... HOWEVER, a cell to the south grew rapidly and also became severe - and we could visually determine that the anvil of the southern storm was moving dangerously close to the updraft of the northern, severe storm. This caused us to decide to quickly head south - the best decision we could have possibly made - because the storm to the south soon dominated - the original cell we were on became seeded by the southern anvil and subsequently was absorbed into the new supercell, which then produced the tornadoes. If we had stuck with the northern cell, we would have probably been disappointed and missed a lot of the opportunities to the south.

Just thought I'd add it for the sake of discussion -

 

[Andrea Griffa]

Originally posted by Bob Schafer
This is a topic that is at once fascinating, frustrating, and complex.

There are always a great many variables that ought to be processed by a chaser's consciousness during initiation/maturation, but one that I, personally, rarely enlist for such a decision is tornado warnings. It happens (that I will chase a warning), but more often than not a tornado warning or two is information that advises me of what I have missed. Most times, chasing a warning will only allow you to observe an outflow-dominant mess 45 minutes or an hour after the tornado(es).

Here are but a few of the considerations for choosing a storm when you have split the difference between two good-looking towers: (Good job, BTW; You have obviously chosen your target area well!)

*Which tower is exhibiting the stronger updraft?
*Which tower will be in the more favorable conditions in the near future?
*Which tower will be in the more favorable conditions in 45 minutes or an hour and a half?
(And, some of the answers to the above questions depend on sfc temps and moisture, sfc flow [advection], mid and upper level flow, and boundaries.)
*Which storm will be chaseable, taking into account your present position vs. storm motion, road networks, and concerns for your safety?
*Are the two towers oriented in such a way that one will likely choke or eat the other?

On the day of the Happy TX tornado (May 5, 2002?) I was approaching Vega from the west, traveling I-40. Nice looking towers went up N and S of me, equi-distant from my position. I chose to chase the northerly one, for no other reason than that I could get a nice SE-of-core position established and maintained. I missed \"Happy\". I was sad. (Sorry) The storm I chased produced, but not like Happy, and not until after I suffered car problems (another story....)

I wondered what tactical error had befallen me.

Fast-forward to Denver, 2003, and Tim V's class.

We did that day as a case study. Tim pointed out that \"Happy\" was fed by SSE or SE sfc flow, whereas the storm I had chased was fed by SSW flow. The Td's had been very similar upon initiation, but the difference in sfc flow basically sealed my fate. It is a mistake that I try to avoid on every chase now.

But there are legions of mistakes that can be made, especially during the excitement of multiple towers shooting toward the heavens.

May 29, 2001: I was all over the \"White Deer\" storm from the git-go. I gave up on it as it crossed 87/287 because it looked occluded to me, and the storm over AMA was pretty wild looking, but I guess I had mistaken HP characteristics for occlusion. Similar to \"Happy\" day in that I had to choose north vs. south storms, and both times I \"blew it\".

I've been fortunate to have had many successful days, too, but those two days will forever haunt me.

The moral of the story according to me:

Stay calm during your chases, or you won't think clearly, and it might.....no, WILL... cost you. Maybe not every time, but sometimes. Always keep in mind that there are a LOT of things to consider. Try to let your brain remember and utilize all that data you looked at earlier, and interpret how that data meshes with what your eyes are currently seeing and your laptop, radios and nowcaster are telling you.

Bob

Wise considerations, Bob

 

[Andrea Griffa]

Originally posted by Mike Peregrine
By the way - just one more little scenario that comes up sometimes that really affects a choice you will make this way:

Last year on May 29th we were initially on a storm that went severe fairly early on over highway 36 to the west of Belleville, Kansas ... HOWEVER, a cell to the south grew rapidly and also became severe - and we could visually determine that the anvil of the southern storm was moving dangerously close to the updraft of the northern, severe storm. This caused us to decide to quickly head south - the best decision we could have possibly made - because the storm to the south soon dominated - the original cell we were on became seeded by the southern anvil and subsequently was absorbed into the new supercell, which then produced the tornadoes. If we had stuck with the northern cell, we would have probably been disappointed and missed a lot of the opportunities to the south.

Just thought I'd add it for the sake of discussion -

This is an interesting thing: anvil of the southern cell was going upon the updraft of the northern cell so you made the best choice to head toward southern cell. It looks like an intelligent choice. I'll keep this in a high consideration this year.
If someone has some other interesting thing to tell us, we are here to listen :wink: