Redoubt ash dusts Anchorage, airport closed

DINGY: Snow went from 'white to gray' in matter of minutes, observers in Anchorage report.

March 28, 2009 

Anchorage finally got a taste and smell of Redoubt volcano Saturday afternoon when the sky darkened and ash began to drift from a massive, menacing cloud that rose up from the south and slowly enveloped the city. It was only a light ash fall, posing little risk to healthy people or most machines.

But the sulfurous air unmistakably said volcano. So did the raspy feeling in throats and eyes all over town and from a wide swath of Southcentral Alaska from the Mat-Su Borough to Valdez. Nikiski, on the Kenai Peninsula, was also affected.

The ash cloud emerged from an eruption at 3:29 p.m., the second on Saturday afternoon, and caught the express east to Anchorage. With a wind advisory also in effect, it took only about an hour before people were phoning in reports of ash from South Anchorage and the Hillside, less than 100 miles northeast of the Cook Inlet volcano.

By 7 p.m., most of the ash cloud had passed on from the city to the Mat-Su Borough to the north, leaving a speckle of dark dirt on the morning's fresh snow.

"We're pretty much done getting ash from this particular eruption," said Bill Ludwig, a National Weather Service meteorologist said in an interview.

If the volcano blew again in the next few hours, Ludwig said, the west winds likely would bring more ash to Anchorage; if it were later than that, the winds would probably shift to the north, skirting the most heavily populated areas.

Ludwig concluded the interview and hung up the phone at 7:23 p.m.

That minute, Redoubt erupted again.

The 7:23 p.m. eruption produced a dust and ash cloud that rose to 45,000 feet. The Weather Service posted a new advisory, warning ash will likely fall in Anchorage, Eagle River and the Mat-Su region until about 1 a.m. this morning.

The winds began shifting in the late evening, signaling that the ash from the 7:23 p.m. eruption might fall mainly north of Anchorage, possibly around Knik Arm, said forecaster Neil Murakami.

The Alaska Volcano Observatory in Anchorage warned that the eruptions had triggered a mudflow that could flood the Drift River, where an evacuated oil terminal is located. About 6 million gallons of crude oil from Cook Inlet wells is stored there in tanks behind a protective dike built in 1990 after Redoubt's last eruption cycle.

A storm predicted for Saturday night was going to change the wind direction. Ash from any further eruptions late Saturday and on Sunday would probably head north, to the Susitna Valley or just west of it, according to the weather service.

Another factor in the mix: high winds predicted for Turnagain Arm could kick up the ash that already had fallen.

People around town reported that "snow went from white to gray in a matter of a few minutes as the ash started to fall on the ground," said Rick Wessels, a geophysicist at the volcano observatory.

By 6 p.m., the ash cloud had spread across Anchorage.

The Weather Service classified the ash fall from the afternoon eruption as minor, between a trace and an eighth of an inch.

"For normal, healthy people and for your cars and things like that, it will have small, minimal effect," Ludwig said about the first ash cloud to coat Anchorage. "It's an annoyance."

Municipal health officials agreed. The ash particles were too big to lodge deeply in lungs where they could do long-term damage, said Steve Morris, the city's air quality program manager.

The city measures air quality in east Anchorage, downtown and in Eagle River. The fine ash particulates were most concentrated downtown between 6 and 7 p.m., but the monitors at times pick up even more dust in the air during the worst parts of spring breakup, Morris said.

The bulk of the ash particulates that came down were too big to breathe in, and even too big to be measured by the city's air quality monitors, he said. That's good, because it means the ash is less likely to cause health problems, he said.

"You can't get that big stuff in your lungs," Morris said.

But the ash is corrosive to jet engines, which suck unfiltered air into rapidly spinning turbines. The ash cloud forced closure of the Anchorage airport just before 6:15 p.m.

Jim Iagulli, operations manager for Ted Stevens Anchorage International Airport, said he made the decision to close the airport after getting reports of a cloud of ash moving across the facility.

"Once the ash started picking up, I directed them to close the airport," he said.

Airport crews said the ash fall appeared to be light.

Crews must wait until the ash settles before assessing how long the airport will remain closed, he said.

For old-time Alaskan Jim Bookey, owner of Wee B's restaurant on O'Malley Road, Anchorage's dusting didn't seem like too big a deal.

"It's here, but it's not much. It's turning the top of the snow gray," he said.

Bookey, who has lived in Alaska most of the last 60 years, can remember earlier eruptions when day turned to night.

"For me it's nothing. Somebody new in town, it's big time."

Redoubt had two eruptions within the span of two hours Saturday afternoon, sending clouds of ash and steam to 35,000 feet.

The volcano observatory said the eruptions occurred at 1:40 p.m. and 3:29 p.m. The Weather Service spotted the 25,000-foot-high cloud from the first blast and the 35,000-foot one from the second. The weather service said winds are generally blowing in a north to northeasterly direction from the volcano, which is about 100 miles southwest of Anchorage.

Most of Redoubt's eruptions in the current week-old cycle have deposited relatively little ash.

The weather service advises residents in an ash fall to seal windows and doors, protect electronics, cover open water and air intakes and minimize driving. Dark brown ash, the color of many soils in the region, is obvious on white snow.

Seismographic tracks from the 3:29 p.m. eruption appear to show a mud and ice melt event occurred too, but it was unclear how strong it was, said Wessels, the geophysicist. Those events, known as lahars, tend to cause flash floods in the Drift River.

The volcano, in a particularly active phase at the moment, had previously erupted at 1:20 a.m. Saturday morning. That had been its fourth blast over an eight-hour span.

Prior to Saturday afternoon's eruption, air travel had begun to return to normal in Southcentral Alaska.

Around 8:15 a.m. this morning, Alaska Airlines sent out a Boeing 737 jetliner on a reconnaissance flight, company spokesman Paul McElroy said. There wasn't much haze or ash to report, McElroy said.

Eight flights were canceled early Saturday because of the eruptions Friday night and into the morning. Later in the day, the airline had to cancel all of its flights into and out of Anchorage.

The airline is still trying to reschedule all the passengers affected by flights canceled earlier in the week due to Redoubt's eruptions, McElroy said.


Find Richard Mauer online at adn.com/contact/rmauer or call 257-4345. Find Lisa Demer online at adn.com/contact/ldemer or call 257-4390.

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