Name: Volcanic Ash in Guam, April 6 to 7, 2005
Start: 2005-04-06T07:00
End: 2005-04-07T00:00
Location: Guam

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 2

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS GUA wrote it up.

Anatahan volcano, located 80 miles north of Saipan and 205 miles north-northeast of Guam, underwent a short but powerful eruption around 0130 SST the morning of April 6th, sending an ash/gas cloud up to above 50,000 feet. The ash cloud moved over Saipan and Tinian during the morning, causing twilight-like darkness until nearly 1200 SST, and depositing 2 to 3 mm of gritty black ash on both islands. Japan Air Lines and Cape Air cancelled flights into and out of Saipan, and most of the public schools sent their students home. The cloud slowly dispersed as it continued south, leaving a trace of ash on Rota during the afternoon, and on Guam that evening.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS GUA wrote its last area forecast discussion before the first event at Apr 6, 3:56 AM SST, 3 hours 4 minutes earlier.

Area forecast discussion, Apr 6, 3:56 AM SST, 3 hours 4 minutes before

AREA SYNOPTIC DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
1 AM GUAM LST THU APR 7 2005

WESTERN NORTH PACIFIC BETWEEN THE EQUATOR AND 25N FROM 130E TO 180.

A NEAR EQUATORIAL TROUGH COMBINED WITH TRADE-WIND CONVERGENCE INTO
THE TROUGH IS PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS
BETWEEN THE EQUATOR AND 5N FROM 138E TO 161E. THIS INCLUDES EXTREME
SOUTHERN PORTIONS OF CHUUK AND POHNPEI STATES.

A SHEAR LINE EXTENDS FROM 25N172E SOUTHWEST TO 18N155E THEN WEST TO
15N140E AND 13N130E. EXTENSIVE CLOUDINESS AND SPOTTY LIGHT SHOWERS
EXTEND UP TO 200 MILES NORTHWEST OF THIS BOUNDARY...INCLUDING THE
MARIANA ISLANDS NORTH OF SAIPAN.

In the hours before

Special weather statement, Apr 6, 1:30 AM SST, 5 hours 30 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE TIYAN GU
1030 PM LST WED APR 6 2005

GUZ001-002-061400-
GUAM-ROTA-
1030 PM LST WED APR 6 2005

...VOLCANIC ASH CLOUD EXITING THE VICINITY OF ROTA BUT STILL HOVERS
NEAR GUAM...

THE ASH CLOUD FROM THE ANATAHAN VOLCANO ERUPTION HAS NOW MOVED AWAY
FROM ROTA. NO OTHER ASH ADVISORY IS EXPECTED FOR ROTA...TINIAN AND
SAIPAN UNLESS ANOTHER ERUPTION OCCURS. VOLCANIC ASH AND GRIT IS
STILL IN THE VICINITY OF GUAM...AND SHOULD MOVE OUT OF THE AREA
LATER TONIGHT.

REFER TO THE VOLCANIC ASH ADVISORY...WMO HEADER WWMY70 PGUM...FOR
DETAILS.

STAY TUNED TO NOAA WEATHER RADIO OR LOCAL NEWS SOURCES FOR THE
LATEST NATIONAL WEATHER SERVICE STATEMENTS AND ADVISORIES. GUAM
RESIDENTS CAN DIAL 811. THE NATIONAL WEATHER SERVICE GUAM WEBSITE IS
AT HTTP://WWW.PRH.NOAA.GOV/GUAM (ALL LOWER CASE).

GUARD

Event by event

2 volcanic ash. Local standard time, as filed.

Volcanic Ash, Northern Marianas

When: April 6, 7:00 AM SST to 3:00 PM SST
Where: Northern Marianas forecast zone
Reported by: NEWSPAPER

Volcanic Ash, Guam

When: April 6, 4:00 PM SST to April 7, 12:00 AM SST
Where: Guam forecast zone
Reported by: NEWSPAPER

What these are

Volcanic Ash: Ash from an eruption that fell on land or reduced visibility.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in Guam in 2005 Every state in 2005 This day in weather history Warnings in Guam, April 2005

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5447490, 5447491.