Flash Flood in Idaho, July 31, 1998

Name: Flash Flood in Idaho, July 31, 1998
Start: 1998-07-31T18:00
End: 1998-07-31T18:00
Location: Idaho

July 31, 1998 · NWS BOI · 1 event in 1 county or zone

1 flash flood, as filed by the National Weather Service.

Where it happened

Every event with a place to put it; 1 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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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.

The radar

The Boise radar (KCBX), 69 km away, was scanning. The volume nearest the first event began at 01:01 UTC.

Open the radar archive at this moment

Event by event

1 flash flood. Local standard time, as filed.

Flash Flood, Boise

When: July 31, 6:00 PM MST
Where: Boise County, 20 mi SE of Idaho City
Reported by: NWS STORM SURVEY
Coordinates: 43.989, -115.730 (the zone’s center; the record gives no point)

A National Weather Service storm survey team found evidence of a flash flood across the Middle Fork of the Boise River Road which happened on the evening of the 31st. A small creek flowing under the road through a culvert apparently swelled to over 30 feet wide and 10 feet deep depositing debris over the road.

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 Idaho in 1998 Every state in 1998 This day in weather history Warnings in Idaho, July 1998

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: 5662390.