The Alaska Aviation Weather Unit performs two roles as part of its mission
to provide timely, accurate forecasts and warnings to the aviation community:
- Volcanic Ash Advisory Center (VAAC)
- Meteorological Watch Office (MWO)
These roles are defined by the International Civil Aviation Authority and the World Meteorological Organization, as well as various U.S. government agencies.
The Federal Aviation Administration, the lead U.S. agency, has designated the National Weather Service to provide the required aviation weather products and services.
AAWU - Volcanic Ash Advisory Center
The goal of the international volcanic ash program is to provide worldwide warnings and advisories
to aviation interests regarding volcanic ash hazards.
Volcanic Ash Advisory Centers are responsible for providing ash movement and dispersion guidance
to Meteorological Watch Offices and neighboring VAACs. Only two VAACs cover the United States:
the Alaska Aviation Weather Unit in Anchorage and
NESDIS Satellite Analysis Branch in Washington DC. This map reflects the worldwide aspect of aviation and drifting volcanic ash.
Each Volcanic Ash Advisory Center performs these functions:
- Develop and execute volcanic ash dispersion models in real-time.
- Continuously use satellite information to identify volcanic ash and to discriminate volcanic ash clouds from weather clouds.
- Issue Volcanic Ash Advisory Statements, and provide guidance to MWOs for SIGMETs involving volcanic ash.
- Provide advisory service to Regional Area Forecast Centers, MWOs and other VAACs.
- Coordinate with the aviation community, the public and neighboring VAACs about volcanic episodes.
Though the area of the Anchorage Volcanic Ash Advisory Center is one of the smallest VAAC areas,
it covers air routes over some of the most active volcanic areas in the world. Alaska has 80
percent of all active U.S. volcanoes, and 8 percent of the active volcanoes world-wide.
Alaska contains over 100 volcanoes and over 40 of these have been active in historic time.
The north Pacific air routes connecting Alaska to the far east carry 10,000 people per day,
and up to 50,000 aircraft per year. Some routes pass over the Kamchatka Peninsula with
its 32 volcanoes. The Anchorage VAAC in cooperation with the
Alaska Volcano Observatory
and the Kamchatka Volcanic Eruption Response Team have initiated a series of informal agreements
to provide advisory assistance about volcanic activity on the Kamchatka Peninsula.
The Alaska Volcano Observatory does an excellent job of continuously monitoring several
of the Aleutian volcanoes and relaying its observations and forecasts
to the National Weather Service and the Federal Aviation Administration.
A variety Federal Aviation Adminstration
offices around Alaska provide us with pilot reports of Volcanic Ash. They also inform the aviation
community about forecasts, warnings and advisories involving volcanic ash dangers.
How the process works:
- AAWU VAAC meteorologists use input from the Alaska Volcano Observatory, satellite pictures,
radar imagery and pilot reports to determine if an eruption has occurred and to understand the
intensity of the eruption.
- An eruption SIGMET is issued to warn pilots about the danger.
- One or more computer models are used to forecast ash movement in the atmosphere HYSPLIT, PUFF and/or CANERM.
- A Volcanic Ash Advisory Statement is issued describing the three-dimensional location of the ash.
- SIGMETs and advisories are updated to keep everyone current with the situation.
There are nine VAACs
world-wide. Each one is named for the city in which it is located. Warning responsability is
passed from office to office as the ash cloud crosses the borders of the VAAC areas.
AAWU
- Meteorological Watch Office
A Meteorological Watch Office is responsible for notifying Air Traffic
Control of inflight hazardous weather conditions. These offices are assigned
specific areas of responsibility which generally coincide with the boundaries
watched by an Air Traffic Control Center. The Anchorage Volcanic Ash Advisory Center is unique.
Our area of responsibility is identical to our Meteorological Watch Office area. This simplifies
coordination for us, but we get very busy when a volcano erupts in our area.
Four Meteorological Watch Offices cover the United States area of responsibility:
Alaska Aviation Weather Unit has an area of responsibility that extends
from Russian airspace to Canada, from the North Pole to the North Pacific
Ocean. AAWU provides aviation meteorological support consisting of Area
Forecasts, Airmets and Sigmets. Besides the continuous meteorological watch
functions, the AAWU prepares graphic weather depiction charts to supplement
its text products and offers pilot weather briefings and outlooks.
Return to the AAWU-VAAC page
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