DROUGHT STOKES FIRE FEARS

Exceptionally dry winter may have dangerous legacy

In case 80-degree weather in February hadn’t already made it obvious, this winter could go down as one of Arizona’s driest on record. It could also be the precursor to an especially costly fire season, but it likely won’t pose a threat to the state’s water supply.

Arizona is in the 21st year of a long-term drought, according to the Arizona State Climate Office, and experts aren’t holding their breath that the winter will suddenly turn around.

“The only really good news here is that last year was a pretty good winter,” state climatologist Nancy Selover said.

This winter’s dry conditions — exacerbated by a high-pressure system outside San Francisco that’s preventing storms and cooler air from reaching Arizona — could give bark beetles what they need to make a comeback in the state’s forests and pave the way for wildfires reminiscent of 2002’s disastrous Rodeo-Chediski Fire.

Although researchers generally view this winter dismally, last winter’s runoff into reservoirs on the Colorado and Salt and Verde rivers should keep the state’s water supply safe.

Here are five things to know about the long-term drought this winter:

1. This winter could be one of the driest ever.

Arizonans are more than used to dry weather.

But numbers from this winter and this water year paint a bleak picture.

Officials measure water in a “water year” running from Oct. 1 through Sept. 30. As of Jan. 26, this winter ranked as Phoenix’s fourth-driest start to the water year, with 0.44 inch of rain.

The average through Jan. 26 is 2.85 inches, National Weather Service Phoenix meteorologist Mark O’Malley said.

The conditions are similar throughout Arizona, he said.

A new analysis released last week by the National Drought Mitigation Center showed southern and eastern portions of Arizona are now in extreme drought. More than half the state is in severe drought.

“This probably will not end up being the driest winter ever,” said Charlie Ester, Salt River Project’s Surface Water Resources manager. “But it’s going to be so close to it that it may as well be.”

2. Unless spring brings heavy rain, fires will be brutal.

Spring rain and snow can go a long way in limiting the upcoming summer’s fires.

But unless spring brings heavy rain and snow, forests will likely get drier and provide more kindling for fires over the summer.

Selover said April, May and June are typically Arizona’s driest months, so getting rain then can limit burning through the summer.

Officials also want to see higher snowpack levels. Water in the snow doesn’t have the chance to immediately seep into the ground like rain does. Once it melts, the runoff can flow into the reservoirs, she said.

However, Tony Merriman, warning coordination meteorologist for the National Weather Service in Flagstaff, said snow has been scarce this winter.

From the start of the water year through Jan. 26, this winter has produced the sixth-lowest level of liquid equivalent — the amount of liquid produced after snow melts — on record at 1.72 inches, he said.

1996 and 2002 were Arizona’s driest years on record. In 2002, the Rodeo-Chediski Fire raged, burning across 468,638 acres. It was the largest wildfire in state history until 2011’s Wallow Fire, which burned 538,049 acres.

“If it stays this dry, we’re in for a terrible fire season,” said Ester, the SRP manager. “I hate to say this, but I think the fire season coming up, without the right moisture — it could rival 2011 with the Wallow Fire.”

Drought also weakens trees and lets bark beetles attack in numbers large enough to severely damage forests. The beetles’ presence, and effect on trees, often feeds fires in already-dry forests.

Arizona had a massive bark-beetle outbreak in 2002, the same year as Rodeo-Chediski, according to the U.S. Forest Service.

“I believe the conditions right now are probably dry enough that you could carry a fire right now,” Ester said. “It’s not approaching 2002 levels yet, but it can get there.”

3. Late winter likely won’t make up for lost time.

Before winter is over, Arizonans could yet make their periodic deluge of status updates, tweets and Snapchat stories bursting with astonishment at the fact that water is actually falling from the sky.

But it isn’t likely that any amount of moisture will be enough to make up for the previous bone-dry days this winter.

“We’ll get some more (precipitation),” said Selover, the state climatologist. “It’s certainly not going to make up the deficit.”

Selover said Lake Mead could enter the first level of a water shortage by winter’s end, signaling a potential blow to agricultural water users.

4. Last winter broke worst stretch of runoff dry spell in 700 years.

Runoff into the Colorado and SaltVerde reservoirs was above-average last winter — in fact, there was so much, it broke a six-year period of below-average runoff.

Although that might sound like a boring factoid, centuries of tree-ring data show it was the worst such stretch in hundreds of years.

Dave Meko, research professor at the University of Arizona’s Laboratory of Tree-Ring Research, said it was the longest string of dry years uninterrupted by wet years since the 1300s.

Meko and Katie Hirschboeck, a professor of climatology with the tree-ring lab, studied tell-tale signs of drought through tree rings dating back to the 1300s.

That six-year stretch was the longest consecutive streak of years below average, he said.

Though they finished that particular study years back, Meko said that this winter has been exceptionally dry.

“It was kind of eye-opening to see just how bad it is this year,” he said.

5. If there’s a silver lining, it’s in the reservoirs.

This winter isn’t expected to correct course, but last winter filled SRP reservoirs enough to keep the water supply safe, Ester said.

At the start of last winter, reservoirs were at 44 percent full.

By the end of the much-needed runoff, they were more than three-quarters full, he said.

SRP’s water report places them at 61 percent full this week, the same as one year ago.

That runoff is continuing to help the reservoirs, even when there isn’t a lot of snow to help them now.

“Would I rather have snow in the mountains?” Ester asked. “Oh my god. Yes.”

Even if this year doesn’t have the above-average levels of runoff that last winter did, it’s common to go through three or four-year dry spells, he said.

The reservoirs have operated with levels lower than 61 percent for most of their history, he said.

Although this dry winter will likely pose a threat to Arizona’s forests come fire season, the state’s water supply should be safe, Ester said.

“We’re nowhere south of where we were a year ago,” he said. “We’re nowhere near a crisis situation.”

Environmental coverage on azcen tral.com and in The Arizona Republic i s supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow the azcentral and Arizona Republic environmental reporting team at OurGrandAZ on Facebook, Twitter and Instagram.