Flash Flood in Guam, October 29 to 30, 2003

Name: Flash Flood in Guam, October 29 to 30, 2003
Start: 2003-10-29T12:00
End: 2003-10-30T00:00
Location: Guam

October 29 to 30, 2003 · NWS GUA · 1 event in 1 county or zone

Thunderstorms developed along an active monsoon trough that was in near Pohnpei. The showers started during the afternoon of the 29th and continued throughout the day.

The toll

Deaths: 0
Injuries: 0
Property damage: $200,000
Crop damage: $75,000
Events: 1

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.

Thunderstorms developed along an active monsoon trough that was in near Pohnpei. The showers started during the afternoon of the 29th and continued throughout the day. Thunderstorms moved across Pohnpei during the night. The heavy rain caused a multitude of landslides and floods across the island. The landslides and floods created blockages of rock, sediment and soil on the roads, filled in small streams and overpowered houses and pigpens built close to the river bank. The National Weather Service Office in Kolonia reported 7.85 inches of rainfall with 6.31 inches falling in six hours. Some of the hardest hit areas were Eirike, Engepel, Pahnmeitol-Awak Pah, Paliais, Nankiwi, Liwi and Nan Kepin Awak. The hardest hit area was Pahnmeitol-Awak Pah where the mountain was stripped of its natural soil and plants, leaving the underlying rock bare. The falling debris covered a massive swath of native trees and grass and destroyed much of the natural habitat of animals and birds.

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 Oct 29, 3:48 AM SST, 8 hours 12 minutes earlier.

Area forecast discussion, Oct 29, 3:48 AM SST, 8 hours 12 minutes before

AREA SYNOPTIC DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
1 AM GUAM LST THU OCT 30 2003

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

TYPHOON PARMA IS CENTERED NEAR 25N149E AND MOVING NORTH-NORTHWEST AT
12 MPH WITH MAXIMUM SUSTAINED WINDS OF 125 MPH. HEAVY RAIN AND
SCATTERED THUNDERSTORMS EXTEND OUTWARD 120 MILES FROM THE CENTER.
SEE JOINT TYPHOON WARNING CENTER BULLETIN WTPN32 PGTW FOR ADDITIONAL
INFORMATION.

LOW-LEVEL CONVERGENCE ASSOCIATED WITH A DEVELOPING LOW PRESSURE AREA
CENTERED NEAR 11N131E IS GENERATING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS NORTHWEST OF PALAU BETWEEN 12N AND 17N FROM 130E TO
133E.

A WEAK MONSOON TROUGH EXTENDS EASTWARD ACROSS MICRONESIA FROM 11N130E
TO 14N156E TO 8N180. CONVERGENT LOW LEVEL FLOW SOUTH OF THE TROUGH
AXIS IS PRODUCING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS SOUTH
OF CHUUK AND POHNPEI BETWEEN THE EQUATOR AND 7N FROM 145E TO 161E...
AND IN THE MARSHALL ISLANDS BETWEEN 3N AND 7N FROM 169E TO 177E.

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Micronesia

When: October 29, 12:00 PM SST to October 30, 12:00 AM SST
Where: Micronesia County, Pohnpei
Property damage: $200,000
Crop damage: $75,000
Reported by: NEWSPAPER

What these are

Flash Flood: Flooding that begins within six hours of the rain that causes it, or of a dam or levee failure or ice jam release, often with deadly speed.

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

The same day elsewhere

Every storm in Guam in 2003 Every state in 2003 This day in weather history Warnings in Guam, October 2003

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: 5338999.