Greg Carbin

In his job, Carbin reaches out to reporters, emergency managers, and private and government meteorologists to provide them with reliable information and messages about severe weather. I talked with Carbin about his experience during Wednesday’s devastating tornado outbreak in the South.

(note: an abbreviated version of this interview appeared in today’s print edition)

Q. Describe what Wednesday was like at the Storm Prediction Center.

We’ve been extremely busy. This active pattern we’ve been in for the whole month. We’ve had a lot of events already. We’ve been looking ahead at what could be devastating events.

But Wednesday was a quiet day in terms of interacting with the media. It was kind of the lull before the storm. It was kind of eerie.

But when I looked at the weather maps, it was screaming there would be a significant severe weather outbreak within hours, especially in Mississippi/Alabama. When I did interviews, I started using words and language I’ve never used before, like “significant long-track tornadoes” and “violent tornadoes” — words designed to make people pay attention.

Do you think you played up the risk enough?

Yes. What we try to do is ramp up in communicating the risk. It’s very difficult to pull back cry-wolf forecasts. What works best is a gradual approach. Otherwise, you have the potential to warn too often.

Why has this tornado season been so bad?

What’s really occurred in April 2011 is a convergence of circumstances, some predictable, some not. We know April/May are active months for severe weather. With that as a starting point, superimpose an atmospheric pattern that favors storm development over the central U.S. That’s essentially what we’ve seen – an active jet stream . . . that’s remained [stationary]. The atmosphere does that sometimes.

What about the set-up in the atmosphere Wednesday led to such a severe, historic outbreak?

The devil’s in the detail. We know that the atmospheric can be transitory. Occasionally what you’ll see is the tendency for a large scale trough [or dip in the jet stream] to center in middle in country and you have perturbations – disturbances moving through the trough - that then prime the pump — each system will tap moisture from Gulf of Mexico, setting up the atmosphere to be extremely unstable.

Once you’ve primed the pump with the leading systems, then you bring in the big intense upper level system accompanied by extreme wind shear… setting the stage for a major outbreak with this kind of pattern.

The rapid succession of intense perturbations pivoting through the large scale trough was interesting and unusual. It was very unusual to see the same place hit two nights in the row

Should we expect a continuation of active severe weather?

There will be tornadoes in May. But to use April as a predictor for activity in the month of May will fail. . . . The correlation between April and May tornadoes is almost nonexistent.

I think we’re in a fuzzy period, in a very gray area with respect to the oscillations and their role in tornadoes at this time of year.

How well do you think SPC did its job? Did it provide sufficient warning and lead time?

Let me preface by saying I’m very sympathetic to what Mississippi and Alabama have to be dealing with in the coming weeks. The loss of life is very humbling to see. We do this work because we don’t want to see that.

The messaging and the forecast was good. We did our job and did it as well as we could given the technology we have. It’s mind-boggling to contemplate how far we’ve come in forecasting since the Super Outbreak in 1974. The advances are amazing.

We want to figure out what we can do to better get the word out. There are many unknowns about the circumstances that led to the fatalities. We need to know why people died and how.