Flood and Lightning Strike in Guam, July 5 to 6, 1999

Name: Flood and Lightning Strike in Guam, July 5 to 6, 1999
Start: 1999-07-05T22:00
End: 1999-07-06T00:00
Location: Guam

July 5 to 6, 1999 · NWS GUA · 2 events in 1 county or zone

Strong thunderstorms moved across the island from 2200 to midnight. Frequent lightning and heavy rain pushed across the island.

The toll

Deaths: 0
Injuries: 0
Property damage: $50,000
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.

Strong thunderstorms moved across the island from 2200 to midnight. Frequent lightning and heavy rain pushed across the island. Lightning hit a 115 kilovolt main transmission line that runs from the Cabras Power Plant to Nimitz Hill at around 2315. This caused power to go off over two thirds of the island. The power generators and transmission lines were all intact and power was restored to most places shortly after midnight on the 6th. The rain was very heavy with 0.99 of an inch of rain falling at the National Weather Service Office at Tiyan from 2200 to midnight. There were a few reports of people losing their computer modems and a few even losing the entire computer as a result of lightning strikes and resulting power surges. It is possible that one of the Weather Service's Handar Stations (an automated observing station) was damaged by lightning. An upper level low moving through the region caused thunderstormsto develop over Guam.

Event by event

1 lightning, 1 flood. Local standard time, as filed.

Lightning, Guam

When: July 5, 10:00 PM SST to July 6, 12:00 AM SST
Where: Guam County, Countywide
Property damage: $50,000
Reported by: NEWSPAPER

Flood, Guam

When: July 5, 10:00 PM SST to July 6, 12:00 AM SST
Where: Guam County, Countywide
Reported by: OFFICIAL NWS OBS.

What these are

Lightning: A lightning strike that killed, injured or caused damage.
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 1999 Every state in 1999 This day in weather history Warnings in Guam, July 1999

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: 5701314, 5701315.