Monday, March 23, 2009

Mount Redoubt Erupts, Spews Ash And Steam To 50,000 Feet; Ash Cloud Will Pass Near Anchorage And Ashfall Expected In Susitna Valley, Flights Cancelled

Click HERE to view all previous posts on the 2009 Mt. Redoubt episode in inverse chronological order, with the most recent post appearing first.

This is the real deal. Mount Redoubt has finally stopped teasing us and popped its cork, erupting three separate times in a two-hour period late on Sunday March 22nd, 2009. An eruption cloud of ash and steam is now reported to have risen to 50,000 feet and is expected to spread northeast, brushing by Anchorage and depositing light ashfall on the Susitna Valley. CNN story already slightly dated. KTUU reports that flights into Stevens International Airport are being cancelled, although the Anchorage Daily News reports that the ash cloud might just pass far enough to the west to miss Anchorage. But the margin of error is too narrow; Anchorage should prepare anyway.

Other pertinent links:
-- National Weather Service Redoubt Page
-- Alaska Volcano Observatory Redoubt Page
-- Latest NOAA Ash Trajectory Forecasts
-- Mt Redoubt Webcam #1 (Hut)
-- Mt Redoubt Webcam #2 (CI)
-- Webicorder Graph Output

Here's the most current report from the Alaska Volcano Observatory:

Volcano: Redoubt (CAVW #1103-03-)

Current Volcano Alert Level: WARNING

Current Aviation Color Code: RED

Issued: Sunday, March 22, 2009, 11:26 PM AKDT (20090322/0726Z)
Source: Alaska Volcano Observatory
Notice Number: 2009/A12
Location: N 60 deg 29 min W 152 deg 44 min
Elevation: 10197 ft (3108 m)
Area: Cook Inlet-South Central Alaska

Volcanic Activity Summary: The eruption of Mt. Redoubt continues. The height of the eruption cloud is estimated to be 50,000 ft above sea level. Further reports will be issued as more information becomes available.

Recent Observations:
[Volcanic cloud height] The height of the eruption cloud is estimated to be 50,000 ft above sea level. Further reports will be issued as more information becomes available.
[Other volcanic cloud information] Nil
[Mudflow] Mudflows are possible on Drift and Crescent Rivers.
[Ash fall] Ashfall likely in the vicinity of and downwind from the volcano.


The Ash Trajectory Forecasts for the next 24 hours indicate that Anchorage would only be vulnerable to possible ashfall if the eruption cloud was to be dispersed at the 40,000 foot level. Dispersal at the 20,000 to 30,000 ft. level would carry it more towards the Susitna Valley. If the eruption cloud is carried over Anchorage, the velocity of the steering winds would determine how much, if any of it, would fall on Anchorage.

The National Weather Service has issued an ashfall advisory for the Susitna Valley:

WWAK71 PAFC 230733
NPWAER

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE ANCHORAGE AK
1133 PM AKDT SUN MAR 22 2009

AKZ145-231200-
/X.NEW.PAFC.AF.Y.0001.090323T0733Z-090323T1200Z/
SUSITNA VALLEY-
INCLUDING THE CITIES OF...TALKEETNA...WILLOW...CANTWELL
1133 PM AKDT SUN MAR 22 2009

...ASHFALL ADVISORY IN EFFECT UNTIL 4 AM AKDT MONDAY...

THE NATIONAL WEATHER SERVICE IN ANCHORAGE HAS ISSUED AN ASHFALL
ADVISORY...WHICH IS IN EFFECT UNTIL 4 AM AKDT MONDAY.
UPDATE: EXTENDED TO 8 AM

REDOUBT VOLCANO AT 60.5N 152.7W HAS ERUPTED AT AROUND 1040 PM
AKDT. VOLCANIC ASH IS FALLING AND IS EXPECTED TO REACH THE SURFACE
ACROSS THE SUSITNA VALLEY. PRELIMINARY INDICATIONS ARE THAT
ASHFALL WILL BE VERY LIGHT.
UPDATE: ASHFALL REPORTED AT SKWENTNA

PRECAUTIONARY/PREPAREDNESS ACTIONS...

AN ASHFALL ADVISORY MEANS THAT ASH WILL BE DEPOSITED IN THE
ADVISORY AREA. PEOPLE IN AREAS OF ASHFALL SHOULD SEAL WINDOWS AND
DOORS. PROTECT ELECTRONICS AND COVER AIR INTAKES AND OPEN WATER
SUPPLIES. MINIMIZE DRIVING. LISTEN TO YOUR RADIO STATION FOR
FURTHER INFORMATION.


The end time of 4 A.M. does NOT mean the threat ends at that time. If Mt. Redoubt continues to erupt, the threat would continue, and the NWS would issue another advisory.

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