Best way to approach a storm (supercell)

[Maggie Kahman]

I got to thinking the other day, what is the best way to approach a supercell? I know where you should be in relation to the tornado (SE looking NW), and how to get away should you need too (stair-step your way to the SE) but as far as actually approaching one, how would you go about doing it?

 

[Danny Neal]

I am not sure what you mean by approaching it.....Depends on many different situations.....were you chasing previously and broke off for this new storm? Was it the first storm that went up and you want to go after it? Is it in your target area.....I guess in the perfect situation you would want to be south of a NE moving storm. You don't ever want to play catch up so I personally would get just to the east or southeast of the suspected path of the storm where all the downdraft and forward flank precip is passing just to my North and West and gives me a clear view to the W-SW. Only problem with this idea is you have to know your storm structure and environment as more than half of the supercells out there will deviate to the right and put you up ***** creek. I don't know if this answered your question or not.

 

[Melissa Moon]

Well, it depends on which way the supercell is moving. So, for this example, I will assume that it's a classic supercell that moves from SW to NE. If I am coming from the north of the cell, what I like to do is get out way east of the cell (including the core area with all the rain), and as I drop south, the storm moves towards me so that I wind up being in a safe southeasterly position. If done right, I get southeast of the storm before the core engulfs me as I am going south. That way, I avoid having to deal with hail (except maybe some anvil hail but that's always somewhat of a risk). If i am approacing from the south, I go north/northeast and always try to stay southeast of the storm.

I don't have time right now (@ work) but I could make some graphics for you later if you'd like

 

[Terry Tyler]

there are so many different scenarios that i couldent give you a clear cut answer...

i would hope that you would know the answer to this question before you actually tried to go out and see one...but really, your best bet is to stay away from the storm itself...learn how they move and whatnot...

whatever you do, avoid the core and hell, i dont know...just be safe out there...i highly reccomend chasing with some kind of wireless internet going on...that takes alot of the guesswork out...

 

[David Wolfson]

The #1 guideline IMHO is to know (and develop a plan for) what you're looking at and what storm motion/storm cycling will be. Doing that is not always easy or according to the textbook 20-30 degrees right of 0-6km flow (??? not my expertise). There're splits, redevelopments along outflows, down-line propagations, etc.

The #2 guideline IMHO if you appreciate your vehicle and your limited chase funds is to respect that fact that, whereas most supercells don't produce tornados, most produce large hail sometime in their lifecycles. Know (and develop a plan for) where the hail core is going and be somewhere else.

 

[Shane Adams]

I got to thinking the other day, what is the best way to approach a supercell?

To know the best way to approach a sup, you need to know a few things:

1 - Your position from the storm (direction/distance)
2 - The storm's movement (direction/speed)

Once you have that figured out, you can make your plan. The obvious preferred method is to approach from the right rear quadrant, because this gives you a great view of the updraft region as well as keeps you out of the rain/hail. But this isn't always the situation.

Sometimes you will find yourself well northeast of a storm. This can be a tricky position because immediately, you have to make that tough decision: go south to get in front (but take longer to get there), or drive southwest directly at the storm (getting there faster but risking a core clobber if the storm turns right). In my experiences, if the storm is more than 10 miles away, it's better to go south. You risk missing anything that happens while you're driving south but you keep in the clear air. If you take the plunge and decide to drive straight at the storm to get there faster and it turns, not only do you risk getting pounded by hail, but if you survive that, you've ended up on the backside of the storm, and have no view of the tornado (in most cases).

When you're dealing with HP storms, it's especially important to stay ahead of them, because they will typically, over the course of a few hours, turn right and increase their forward speed. What started as a 10mph moving storm heading ENE when you started at it can become a 35mph moving storm moving SE, and before you realize it, you're getting cored out while the "business end" is wrapped in precip south of you. Also, many times with HP storms, the tornado appears on the forward flank, so you'd actually want to be north or northeast of the storm, looking back south into the updraft.

LP storms are easy, because there's little (if any) precip to block your view of storm features. However they are notorious for large hail, and you have to be careful not to be seduced into driving up close from the northeast side (where the largest hail will be falling).

These are all methods to use if you have position on the storm and are ahead of its movement.

The toughest intercept is a situation when you're northwest of a mature supercell. Even if it's a slow mover, you still have to negotiate twists, turns, rain, hail, towns, and other obstacles, all while the storm continues to creep along as the crow flies. It's easy to lose ground even on a slow mover when your road network isn't cooperating. Once you do catch the storm, you're faced with having to endure the back side wrap around precip core, which can be just as nasty as the one in front. Some storms have clearly-visible updraft regions/tornadoes from the backside, while others do not. The trick with approaching supercells from the backside is - don't get caught behind them in the first place

 

[Chris C Sanner]

The toughest intercept is a situation when you're northwest of a mature supercell. Even if it's a slow mover, you still have to negotiate twists, turns, rain, hail, towns, and other obstacles, all while the storm continues to creep along as the crow flies. It's easy to lose ground even on a slow mover when your road network isn't cooperating. Once you do catch the storm, you're faced with having to endure the back side wrap around precip core, which can be just as nasty as the one in front. Some storms have clearly-visible updraft regions/tornadoes from the backside, while others do not. The trick with approaching supercells from the backside is - don't get caught behind them in the first place

So true Shane, this is a lesson I learned in my early years. A big part of getting in the right position is getting the forecast right and being ahead of the storm when you start. I know that sounds obvious but there were many times I would find myself out of position during the first and second year I chased and I would end up chasing a storm from the backside, not a fun place to be. I've learned it all begins with the forecasting at the beginning of the day. You can sometimes make up for a bad decision while driving whilst you can hardly ever make up for a bad forecast.

 

[Maggie Kahman]

Wow...Lots of really helpful answers. Thank you.

Terry Tyler
i would hope that you would know the answer to this question before you actually tried to go out and see one...

That was the whole point to my question, Terry

 

[Karen Politte]

In my opinion, the safest way to approach a supercell is first with DATA. Preferably a good, hi-res radar image of the storm you are approaching, coupled with a good knowledge of the storm's directional and speed movement. The latter can be obtained from merely listening keenly to NWR (NOAA Weather Radio) broadcasts and the points and times mentioned in the warning text for the storm you are targeting. Listen for the communities it will be affecting and at what times - and, with a good DETAILED road map of the area in front of you (I have found that GPS systems on laptops don't work out too well when you're trying to average-out a track for your storm with a grubby finger that was a moment ago amidst an Allsup's Burrito), you should be able to deduce roughly where the storm will be by the time you catch up to it taking into consideration the type and quality of roads that lie between you and it.

The former may seem a little more complicated - but it's not if you have begun to and continue to educate yourself in radar interpretation. The average chaser who is really interested in the subject they are pursuing should be able to glance at a radar image and tell you which side of it they would ideally like to be on. Of course this will always differ from person to person. Given a regular old CL tornadic supercell moving east-northeast, I would like to be east-northeast of the storm and approach it from that angle (or set up on a vantage point and simply let it come to me). This should allow me to stay out of the main core, out of the pesky anvil precip., away from dangerous hail and also afford me the best view of the inflow region leading to any lowerings and/or wall clouds (caveat emptor here of course when dealing with cyclic storms - they can throw off occluding mesos into the precip. core and have numerous areas of rotation and lowerings at any given time).

But - *ideally* one would approach a storm from an angle that allows you to maintain a visual on the area of rotation (which should be in the "notch" of HP storms on radar), and yet remain dry and unworried by big hail. Of course - *ideally* rarely happens when out chasing! You would also look to try and avoid your vision to the potential tornado being obscured by the hook precip - which can be very, VERY thick and completely blinding. Huge wedges, white cones, all kinds of tornadoes and wall clouds can be totally obscured by simple hook precip and/or hail.

As a chaser you should become VERY familiarized with all types of supercellular radar structure and interpretation. Most chasers are able to pick up one or two radar grabs of their target storm along the way to intercept - and if you're really lucky a velocity shot too. These two images alone should tell you almost everything you would want to know about the storm's PRECIPITATION structure, and thusly, allow you to try and keep dry on approach. If you keep dry - you usually can maintain better points of view to the storm than if you are in precip. That's a very broad and grossly oversimplified rule of thumb, however. Every storm is individual and will require a different attitude and approach. The important thing is that YOU know what to look for and what to expect when you approach a supercell - and you will only learn this from intensive radar interpretation lessons and being out in the field making your own mistakes with cores and gorilla hail. Just think of it as a great opportunity to learn from your mistakes and have fun doing it!

The infamously-titled core-punchng probably deserves a whole other thread to itself - so therefore I'm not going to touch it here.

KL

 

[Laura Duchesne]

My friends and I prefer coming from the southeast (if it's a classic NE mover) to get in position. If it's a classic supercell, the core would be to my north and the wall cloud just to my northwest. Karen raised excellent points about intercepting through precip cores... it basically sucks. I like the clearer view to be able to spot any wall cloud or funnel formation. I don't like to get too close, because I love to be able to see the entire picture of what is going on, ie. see the rotation updraft, flanking line, etc. Perhaps about 3 miles away, but then again, I'm a storm structure freak. It just takes a bit of planning for the most part to get into this position and if it isn't rain wrapped. It all boils down to your timing, road options and which way the storm is moving and it's structure... don't forget about planning escape routes as well, if you need to turn around and get yourself out of harm's way.

Look for good warm winds gusting towards the storm's main updraft... those would be your backing winds coming from the southeast... inflow "stingers" as I like to call them are good indicators. As long as you're feeling that, and see a nice clear slot opening up, it should be fair game to see something of interest, although not always the case. Mother nature always wins. And if you've got outflow, well that is usually not good news for tornado viewing.

I do need to admit that having Baron mobile threat net does help in determining storm structure when you're too far away yet to tell what's going on and it can aid in planning your intercept because of it's hi res radar and update frequency... but when you're close enough to the storm, having an eye on the sky is a huge help and, sometimes, lifesaver. The Baron at least gives you an idea of what the story is... but it's not cheap.

Chris hit the nail on the head though about trying to catch up to storms from the backside... it's just way too difficult. If you're ahead of the game and near or in the forecasted target, that should be half the battle right there. Basically, you need to plan, plan and plan. Then hope for the best.

 

[Karen Politte]

It all boils down to your timing, road options and which way the storm is moving and it's structure... don't forget about planning escape routes as well, if you need to turn around and get yourself out of harm's way.

Look for good warm winds gusting towards the storm's main updraft... those would be your backing winds coming from the southeast... inflow "stingers" as I like to call them are good indicators.

Laura raises another great point about always having an "escape route" planned. Intercepting a storm is only 50% of the project - the rest is 25% maintaining pace with the storm and the other 25% is having an emergency route away - preferably at right-angles to the storm's path - away from it should things go "pear-shaped", as us Brits say.

I think maybe we need to clarify some terminology here although it is true that it's somewhat in the eye (or mind) of the beholder. The term "backing winds" is reserved usually for winds on a surface ob (or flag or, in a pinch, a wet finger) which "back" - this means that they generally switch to a location on the compass counterclockwise from where they were previously (i.e. a wind switching from south to east is "backing"). This can be caused by gust fronts, mesolows, warm fronts etc. - and a good indication that a washed-out gust front is nearby is that the chaser will see when looking at a surface map one or more obs that are easterly in orientation when all the surrounding obs are southeasterly. Not only do these "backing winds" frequently help with an increase in dewpoint, but it also vastly improves storm-relative shear of the low-level winds in most cases. Any storm moving across this area of backed winds can find itself fuel-injected with increased low-level shear and higher moisture. This happened in the case of June 22nd, 2002 with the Brown Co. SD tornadic supercell I was on, and many other storms in recent and past years.

Warm (or, if you're really unlucky, cold) wind that is flowing into the main updraft of the storm you are looking at is called "inflow". This is merely the type of air your storm is ingesting to sustain itself and it's updraft. Generally, the stronger a storm the more one can expect a good, strong inflow wind in the inflow region.

Just wanted to clarify a few points......not much on the topic of positioning I'm afraid........but then it's all interrelated anyhow.

KL

 

[Gene Moore]

Lots of good stuff here....probably more than you ever wanted to know. One more thing about staying ahead of the storm. In HP (heavy precip) supercells as mentioned earlier, you don't want to get behind and then there's flooding, not to mention the view of the wall cloud or tornado will get cut off. Problem is, just getting out in front of an HP may lead to other problems. That is, rain out of the anvil canopy, or as some call it the FFD (forward flank downdraft)....but to me it's the storm anvil and it's way up there. For that reason there is considerable light getting in under that part of the storm, so from a distance it looks good. That said, be careful to watch for long streamers coming out of the anvil downstream. It is likely rain, but in a strong supercell it may be (very) large hail. In fact some of the largest hail will be released in this area downstream from the main precip core. Some chasers like to be in giant hail, you may not at this point in your chase career. Additionally, even light rain from the anvil will sooner or later begin to spit out lightning. So, you have yet a few more reasons why most chasers dislike HP chasing. There is but a narrow corridor to the SE where the visibility is good and the lightning is minimal.