Flash Flood in Guam, September 15, 2002

Name: Flash Flood in Guam, September 15, 2002
Start: 2002-09-15T12:00
End: 2002-09-15T14:00
Location: Guam

September 15, 2002 · NWS GUA · 1 event in 1 county or zone

Around noon time heavy showers fell over Saipan. Tree trunks, vegetation, rocks and all sorts of debris washed down by water from the As Mahetog hill filled two northbound lanes in Saipan.

The toll

Deaths: 0
Injuries: 0
Property damage: $12,000
Crop damage: None recorded
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.

Around noon time heavy showers fell over Saipan. Tree trunks, vegetation, rocks and all sorts of debris washed down by water from the As Mahetog hill filled two northbound lanes in Saipan.

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 Sep 15, 3:47 AM SST, 8 hours 13 minutes earlier.

Area forecast discussion, Sep 15, 3:47 AM SST, 8 hours 13 minutes before

AREA SYNOPTIC DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
1 AM GUAM LST MON SEP 16 2002

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

A MONSOON TROUGH EXTENDS ACROSS THE ENTIRE DISCUSSION AREA...FROM
12N130E TO JUST SOUTH OF GUAM NEAR 12N145E TO 12N155E THEN
SOUTHEASTWARD TO 10N170E TO 10N180. LOW-LEVEL CONVERGENCE ALONG AND
SOUTH OF THE MONSOON TROUGH IS PRODUCING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS MUCH OF MICRONESIA BETWEEN THE EQUATOR
AND 15N FROM 130E TO 140E AND BETWEEN THE EQUATOR AND 13N FORM 140E
TO 160E. THIS AREA INCLUDES THE REPUBLIC OF PALAU...AS WELL AS
YAP...CHUUK AND POHNPEI STATES.

FAVORABLE WINDS EAST OF AN UPPER-LEVEL TROUGH OF LOW PRESSURE ARE
GENERATING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS BETWEEN
15N AND 25N FROM 165E TO 175E. THIS AREA INCLUDES WAKE ISLAND.

LOW-LEVEL CONVERGENCE IS PRODUCING SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS BETWEEN 15N AND 22N FROM 133E TO 147E. THIS AREA
INCLUDES THE NORTHERN MARIANA ISLANDS.

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Saipan

When: September 15, 12:00 PM SST to 2:00 PM SST
Where: Saipan County, Countywide
Property damage: $12,000
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 2002 Every state in 2002 This day in weather history Warnings in Guam, September 2002

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: 5325264.