Lightning's the joker when it comes to fire season forecasting

By JAYSON JACOBY
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Noel Livingston understands that the conventional wisdom, when it comes to predicting the severity of wildfire seasons in Northeastern Oregon, isn’t all that, well, wise.

The notion, for instance, that years with deep snowpacks and wet, cool springs will be quiet ones for firefighters does not reflect reality around here.

In fact, the correlation seems to be the opposite.

Several of the more hectic fire seasons over the past 40 years on the Wallowa-Whitman National Forest, where Livingston works as deputy fire staff for operations, coincided with years when snow and water were abundant, and temperatures were moderate.

Conversely, severe drought years, which are sometimes implicated in major fire outbreaks, rarely have been marked by major blazes on the Wallowa-Whitman.

The potential for confusion is great, Livingston said, in part because, although fire season predictions are widely reported in the media every year, a subtle but important part of the story sometimes gets neglected.

That part has to do with what fire experts actually predict.

It’s neither their goal nor their job to gauge how many fires will burn, or how many acres those blazes will char.

What they actually estimate is how quickly any fires that start are likely to spread.

That’s known as “fire potential,” Livingston said, and it’s a vital index for fire managers.

But here’s the thing: Fire potential has never ignited a single blaze.

“You can be extremely dry, but if you don’t get any sparks you won’t have any fires,” said John Saltenberger, a meteorologist at the Northwest Interagency Coordination Center’s Predictive Services group in Portland.

What the public wants to know, of course, is whether it’s likely that their favorite patch of woods will burn this summer.

And although there’s no reliable way to assess that threat, the most accurate indicator for what sort of fire season the Wallowa-Whitman will have is neither snowpack from the previous winter, nor how soggy the spring was.

It’s lightning.

In particular “dry” lightning — the kind that’s not accompanied by the downpours common with thunderstorms.

The Wallowa-Whitman is unusual among national forests in that lightning, not people, sparks most wildfires — about 80 percent of the fires over the past 40 years.

(The situation is different on private lands in Northeastern Oregon where the Oregon Department of Forestry is responsible for fire protection. There, people are to blame for a significant percentage of blazes — more than half in some years.)

Unfortunately, predicting lightning, especially predicting its frequency in a particular national forest a couple months in advance, is well beyond the current reach of meteorology, Saltenberger said.

The fire season outlooks he helps to write, by contrast, cover all of Oregon and Washington.

“Getting down to the finer scale of an individual national forest, it just becomes much more difficult to do,” he said.

That there will be bolts of lightning on the Wallowa-Whitman each summer is a near certainty, though.

Wednesday’s storms produced quite a few, actually.

Any of those bolts could have started a fire, Livingston said.

But the chances that a blaze would have spread fast that day were near to nothing, he said.

On the subject of fire potential, Livingston and other experts speak with vastly more confidence than they do regarding the likelihood of lightning.

That potential is very low today, he said, and probably will remain so for the next month or so.

“We had such a wet spring, and our snowpack has been well above normal,” Livingston said. “That has certainly delayed the start of fire season.”

Through Thursday, the rainfall total for 2011 at the Baker City Airport was 8.44 inches. That’s about 33 percent above average.

Both Livingston and Saltenberger expect the fire potential will rise substantially by about the first of August.

Fire season could last a bit longer than usual — through September — if the forecast for drier-than-average weather during August and September is accurate, Livingston said.

One technique that both weather and fire forecasters regularly employ is the use of “analog” years — basically, finding past years with similar weather conditions and then basing the forecast for the coming year on what happened in the analog years.

Saltenberger said the Predictive Services group in Portland picked 1989 as a comparison for the 2011 fire season.

Like this year, 1989 had an abundant snowpack and a relatively cool, wet spring.

The 1989 fire season, based on what happened throughout Oregon and Washington, was a tranquil one, with less lightning and fewer fires than average, and about half as many acres burned across the region.

But the situation was far from calm in Northeastern Oregon.

In one sense, 1989 epitomizes Livingston’s point that the frequency of lightning, more than any other factor, determines the severity of fire seasons on the Wallowa-Whitman.

While much of the rest of the two-state region was having a reasonably quiet fire season in 1989, the Wallowa-Whitman’s was transformed by a single electrical storm started the night of July 25 and continued into the next day.

That storm spawned thousands of lightning strikes but almost no rain.

It ignited more than 100 fires, three of which — Dooley Mountain, Canal and Tanner Gulch — each burned more than 10,000 acres.

Such a season doesn’t diminish the value of the forecasts that Saltenberger and his colleagues compile, Livingston said.

But anamolies such as the Wallowa-Whitman’s 1989 fire season do highlight the inherent limitations of a regional forecast being applied to one national forest, Saltenberger said.

“Mother Nature can always throw those jokers out of a deck of cards at us,” he said.