STORM TRACK: January 31, 1984 (Volume 7 Issue 2)

Here's another installment on last issue's response to questions from Iowa's Douglas W. Beadle, on this subject. First of all, here are some additional comments from Eric Rasmussen, who has been as close as any chaser to "the big spike."

"A couple of things come to mind regarding chase safety and my experience. The greatest danger I've faced is being positioned in the path of tornadoes. This was intentional, but it's very hard to judge tornado distance and speed from that vantage point. Twice, I've almost been overtaken before realizing the danger. I don't intend to volunteer again for placing instruments in the path. Chasers who don't need to be in the path should never place themselves there! I have one last bit of advice, in case a chaser is ever overtaken by a tornado. It is probably best to leave the vehicle and lie flat in the lowest ground, before the last possible second. If you wait until the vehicle is uncontrollable in the strong winds, it is probably too late to get out. --Also, watch out for other drivers doing very strange maneuvers when they spot tornadoes; e.g. reckless U-turns, backing down the driving lane, etc.."

The last ST addressed "safe distances and directions from storms" (lightning safety, approach-direction to storm, floods and water hazards) and "dangerous areas to be near" (wall cloud, hail and wind). This response addresses two additional questions, which are related and combined here:

(3) Changes in storm base and warning signs, which mean "get the heck out," and available lead times to do this.

(a) Roadmap: One good bit of advice, when working in close: keep your eye on the roadmap. Don't get so fascinated with the storm that you end up on a dead end east-west farm road, with a rotating wall cloud bearing down on you from the direction you just came.--------------------------------

I've done it once, and it is one very helpless feeling; a lesson you won't soon forget. So, don't let your exit route be cut off. Also, don't count too much on small side-road bridges still being there. Get a little ahead of the storm to allow time for changing routes, should your bridge be out.

(b) Damaging wind signs - Remember to approach the southwest flank of a northeast or easterly moving severe storm from the southeast, south, southwest or west. If it moves from the northwest, look for the west flank and approach from the south or west. The east and northeast quadrants from the cell base will be dropping large hail and heavy rain. Avoid this area where visibility is poor; what you can't see can hurt you (hail shattering windows, flash floods, other motorists stopped in the middle of the road, etc). As you approach the rain-free base, look for ground dust beneath the lowest and darkest part. Even if not rotating, these may indicate microbursts, which can trigger subsequent rotation nearby. When you see this, don't approach any closer than 2-3 miles from the lowest part of the base. Also, even if no tornado occurs, those downbursts can produce hurricane

speed winds (up to 150 mph) and fling cars or lift and carry deadly projectiles. Even if you don't think your car would overturn, highway signs, small sheds or barrels, etc. can easily become airborne and slam into your car (through your windshield and through you!). So be wary of debris targets near where you've stopped to take pictures or ride out the storm (e.g. lumber yards, trailer courts, trees, etc.). Don't be downwind of likely projectiles, if things get bad fast.

If you've seen no ground dust and must get in closer, keep your eye on the storm base and sense the wind speed. If it drops off rapidly, you've moved past the inflow boundary into the updraft region beneath the wall cloud. This is the "calm before the storm" most people talk about. It is the area where the gusty 25-40 mph surface inflow, which you've been driving through for the past hour, begins to rise into the core updraft. Its a calm that may only last a minute or two, however, before the tornado or microburst descends. Start looking up for early signs of rotation. It won't start spinning like a top, so stand still for several seconds and fix your game on one part of the base. If you see slow rotation starting, it's time to leave. You should have at least 5-10 minutes from initial rotation before damaging winds strike the ground. So don't "clutch up," just take deliberate action to remove yourself from underneath. Don't flood the carburator, just "ease on down the road." Move 1-2 miles to the southeast of the base, and then you can continue to follow and stay ahead of the storm.

Oh, yes! Even when you're just outside of the wall cloud (even a mile or two from the tornado), watch out for satellite rotation around the edges of the wall. When a large tornado comes down, don't be so entranced by this that you occasionally forget to look up. Sometimes, boundary layer synchronous rotation can spin up quickly and touch ground with damaging winds (often without a condensation tube).

(c) Lightning (Addendum) - Do you really need to use a tripod!? -on a wet surface? What a great lightning rod it makes! I know you want, steady, razor sharp pictures (in all that wind), but consider the risk. Yes, I have one but have only used it 2-3 times in the past 27 years. Think about it.

(d) Floods (Addendum) - One additional flood hint. As you approach a water course, rushing across a dip in the road -- before driving through, stop and take a few seconds to study it and its rate of rise. If you can see it deepening, consider again whether you want to ford it and risk stalling out in risky water. I paused once on a road northwest of Canadian, Texas, and it was one of the best decisions I ever made. Moreover, the storms I was seeking on the other side of the torrent that day never did do anything. And I'm still here to write about it!