First Storm of the Day

[Michael Wilkinson]

On chase days in May/June my greatest indecision and paralysis occurs when the first storm of the day starts up.

I’m trying to find ways to fix this weakness. I’m wondering if there are some general rules of thumb that can provide some guidance.

What does the first storm tell you about your forecast?

Is the purpose of your forecast to get you as near as possible to the first storm, then ignore your forecast from there and chase that storm?

Are there specific points in your forecast that you should always reevaluate based on the first storm?

Should the first storm usually be avoided for some reason?

 

[Bob Schafer]

I wouldn't want to try to pose simple answers to your questions.

Speaking for myself, I can say that my strategy mostly hinges on the forecast parameters. The morning of a chase I try to picture everything in my head and then go to my target. If a storm pops up 80 miles away I first try to remember what the parameters are supposed to be "over there". Most of the time I will then ignore the storm because there was something perceived as "wrong" with the parameters. That's why it wasn't my target. Still, I will get on the internet and see what may have changed. Maybe it's a good storm to chase after all, and I go for it.

There are about a hundred reasons for me to ignore a storm (or spend the day at home!). Maybe the surface winds are from the wrong direction or too light. Maybe there is no upper level support for venting. Maybe the road network "over there" sucks, etc. etc.

It's never my goal to be on the first storm. It is always my goal to be on the storm most likely to produce a significant tornado. Of course, failure is what happens about 90% of the time. Try again tomorrow.

 

[Randy Jennings]

There isn't a simple answer to this and we have all be burned when either jumping on the first storm or holding out for the next one. I think the key is the first storm is time to review your forecast with current observations. Where is the front and dryline at? What do the dew points looks like? What does wind direction look like (at multiple altitudes), Etc. A lot of the time the first storm to go up is on the wrong side of the front and isn't surface based. In that case it might be best to wait for the next one. I often will also consider the road network to hedge my bet. If going after the first one is going to put me out of play on second one, I have to be really convinced that is the right choice. Sometime the best strategy is to split the difference for a while (warning - that can bite you too - it did me on a system this May when I was between 2 storms and the one than produced a tor was on my south and I couldn't see it from the left flank nor could I get across the Red River to get to it).

 

[Jeff Duda]

I agree with Randy in that there is no "one-size-fits-all"/rule-of-thumb answer that always works. You really do need to evaluate every case independently. I would examine the following aspects:

-What does the surface environment look like around and downstream of the storm?
-What about the thermodynamics/shear near and downstream of the storm?
-If your target area decision was based on a CAM that explicitly represents convection, did this storm appear in the CAM forecasts you looked at? Does it appear that the model may be on track so far or is this storm not anticipated by the CAM?
-Does CI appear imminent in your actual target area?

Keep in mind that timing errors and displacement errors in storms don't mean the same things. A storm going up in an area that will become the main target area by late afternoon early evening may not be a supportive environment in the early afternoon. The semi-high-risk bust of 18 May 2017 strikes me as a good example -- the environment was forecast to be supportive of widespread high-intensity/long-track supercells that day in OK...but not until near 00Z. Storms initially went up at about 19-20Z before the good wind profile/shear had a chance to develop. Thus the early storms struggled to match expectations of storms that were forecast by CAMs to form closer to 00Z. Not only that, but these early storms overturned the atmosphere and spoiled the thermodynamics so that by the time the good wind profiles were in place, there wasn't much CAPE left for new storms to develop.

On the other hand, the first storm of the day might go up in a different area than you had anticipated, but at the correct time. In that case you need to ask yourself if the environment in the area of the unanticipated storm is still supportive of supercells/tornadoes. Even if your main target area is supportive of supercells/tornadoes, if there doesn't appear to be a hint of imminent CI in your area, it doesn't make sense to wait it out if the unanticipated storm is within catching distance. If, however, you also see hints of CI very soon in your area, then it's probably worth it to stay put.

 

[Dan Robinson]

It matters more *where* a storm goes up (where tornado potential is maximized such as along an outflow boundary, warm front, dryline bulge, etc) than whether or not it is the first of the day. For example - If you have a dryline+OFB intersection, SW flow aloft, backed surface winds and bubbling cumulus right there (a la Dodge City, Bennington I and II, etc), that's the obvious play. You really aren't concerned much with what is going on elsewhere, even if a storm fires 100 miles to the south and goes tornado warned an hour before your target goes. You know that when your target storm eventually fires, it is going to have a very good chance of producing.

On big outbreak days where the entire warm sector is primed for tornadoes (April 14, 2012 for example), it becomes trickier. In those situations it's more of the luck of the draw, even if you have signals pointing to one area over another. You just try to find a storm that doesn't have seeding issues or fouling convection to its south.

Again, a lot of days come down to storms interacting with boundaries. Supercells in open warm sectors are almost never the better play if you have a good prospect of a storm on a boundary. You stick with that boundary even if supercells are firing everywhere else, especially if you have agitated cumulus signaling initiation in the next hour or two. Only once my cumulus field starts drying up do I consider leaving for another area.

 

[Michael Towers]

Unless I have serious capping concerns I’m happy when the first storm(s) fire outside my target area, the less crowds in my area the better. But if there’s a strong cap and I’m sitting under blue skies there’s a chance I’ll make an attempt to intercept as long as I can get to it early enough in its lifespan and the area is chase worthy. Conversely, unless I have serious capping concerns I hate to see the first storm pop up right over me, especially if it remains the only decent storm for awhile. The hordes swarm into the area and the chase becomes more difficult, more dangerous and less enjoyable.

Ultimately, I think the pivotal issue in general is whether you think the storm is initiating in a favorable area (both geographically and environmentally) and whether it can be intercepted early enough to see tornadoes. Typically if the answer to the latter is yes then the answer to the former is also yes and then for me it’s hard not to make a go for it. Usually I do and more often than not I’ve been rewarded but I’ve also been burned. That came real close to happening at Rozel where supercells were already in progress to the north near I-70 and storms were just starting to go up to the south around the panhandle. I remember I didn’t care much for the parameters up north but the environment to the south was decent and close enough to my location in Larned to go for the intercept. Fortunately I stayed put and the reward was sweet but I came so very close to taking the bait and missing one of the top five storm events of my life.

 

[Warren Faidley]

A lot depends on timing. On many of the big days, early convection is normal and unless it lingers or totally stabilizes the atmosphere, smart chasers will stay put for the big show later in the day. Monitoring the true / deep dryline is critical. One of most painful mistakes I ever made was on 5-10-91 in western Texas when I was fooled into thinking the dryline had moved east. Mid-day convection looked good so I moved east as storms formed. The main energy moved across west Texas later (with a retreating dryline and outflow boundaries) and produced the famous Lazbuddie Carousell event where every classic supercell had a tornado, sometimes offering 3x on the ground at once. The storms were impossible to intercept as moving back west was blocked by flash floods and massive hail. This was before mobile data and radar. I am a DL chaser so results may vary for other set-ups.

 

[Michael Wilkinson]

Thank you everybody for the detailed responses! All are very helpful. You’ve provided me with good things to think about. This weekend I’ll have this thread open as I’m reevaluating the days I chased last May and June.

I have RadarScope screen shots of my locations and all my handwritten notes from every chase. I’m excited that I now have the information you guys have shared here so that I can see how my decisions could have been different and better informed. Your helpfulness on this forum is greatly appreciated!

 

[Joey Ketcham]

A lot depends on timing. On many of the big days, early convection is normal and unless it lingers or totally stabilizes the atmosphere, smart chasers will stay put for the big show later in the day.

The few first years when I began storm chasing, my biggest weakness would be to go after the first storm that fired up. I was so eager to see something, that I didn't want to miss out on any potential. Most of the time this resulted in nothing, and sometimes even missed bigger and better storms. That changed after the first few years of chasing, unless something stood out with that first storm of the day that would make it worth going after, I would stay put and wait for something better. This proved to be more successful to me than going after the first storm.

 

[James Wilson]

The environment, front placement, moisture tongue all have been discussed here already but sometimes real time things (not seen on mesoanalysis or others) change and that is the part you have to figure out. I will always sample a first storm if it is not too far away from my target area and I can get back to target easily. I love all super cells and will at least see what it looks like. Now if it is to be an explosive development day I stay put because you probably will miss something in your target area if you go after that first one. Bottom line take the look if it means you do not regret it later when a tornado drops in your target and always be prepared to fly back. Good luck.

 

[Jeff House]

All the posts above are excellent. Remember the parameters, both forecast and actual.

Also remember your own conceptual model and the computer models. If they agreed in the morning, probably stick to the plan. Challenging forecast requires more weighing of options.

First storm is not always the best. Sometimes they all work out (back in the day) and it's less pressure. Rozel day we heard about the one farther north first, a beautiful cone. Elected to sit tight for Rozel. Luckily both were rewarding cells. Other times like DDC first is first.