Flood in Guam, March 11, 2003

Name: Flood in Guam, March 11, 2003
Start: 2003-03-11T10:00
End: 2003-03-11T14:00
Location: Guam

March 11, 2003 · NWS GUA · 1 event in 1 county or zone

Heavy rain drenched part of the island. An intermittent downpour caused flooding in parts of central Guam, forcing pedestrians to skip over streams of water, and congesting traffic on deluged roads.

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
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.

Heavy rain drenched part of the island. An intermittent downpour caused flooding in parts of central Guam, forcing pedestrians to skip over streams of water, and congesting traffic on deluged roads. Two inches of rain fell between 1000 and 1600 at the National Weather Service Office in Tiyan with 0.70 inches of that between 1400 and 1500. A weather observer in Agana Heights recorded 0.97 inches fall between 1015 and 1045. The total rainfall for the day at the National Weather Service Office was 2.03 inches, which was record for the day. The heavy rain was the result of moisture south of a shear line in the vicinity of Guam being heated during

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 Mar 11, 4:00 AM SST, 6 hours earlier.

Area forecast discussion, Mar 11, 4:00 AM SST, 6 hours before

AREA SYNOPTIC DISCUSSION
NATIONAL WEATHER SERVICE TIYAN GU
1 AM GUAM LST WED MAR 12 2003

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

A COLD FRONT/SHEAR LINE EXTENDS FROM 24N180 TO JUST NORTH OF WAKE
ISLAND AT 20N167E TO NEAR GUAM AT 13N145E TO 4N130E. SCATTERED
SHOWERS ARE FOUND ALONG AND UP TO 200 MILES NORTH OF THE BOUNDARY.

TRADE WIND CONVERGENCE IS GENERATING SCATTERED SHOWERS SOUTH OF CHUUK
BETWEEN THE EQUATOR AND 5N FROM 150E TO 155E.

LOW-LEVEL CONVERGENCE IS PRODUCING LOW CLOUDS AND SCATTERED SHOWERS
BETWEEN THE EQUATOR AND 10N FROM 158E TO 180...WHICH IS AFFECTING
KOSRAE AND SOUTHERN PORTIONS OF THE REPUBLIC OF THE MARSHALL ISLANDS.

Event by event

1 flood. Local standard time, as filed.

Flood, Guam

When: March 11, 10:00 AM SST to 2:00 PM SST
Where: Guam forecast zone
Reported by: NEWSPAPER

What these are

Flood: Flooding that develops more slowly than a flash flood: rivers leaving their banks, or water standing over land for an extended time.

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, March 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: 5355612.