Idaho, 2003

Flash Flooding in Idaho, August 23, 2003

August 23, 2003 · NWS MSO · 2 events in 2 counties and zones

Sheriff reported flash flooding and 2 miles of rock slides along the Big Salmon River near French Creek in Idaho County, and flash flooding and a mudslide at the Elk Bend area between Salmon and Challis in Lemhi County.

Where it happened

Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

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  • 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
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 MSO wrote it up.

Sheriff reported flash flooding and 2 miles of rock slides along the Big Salmon River near French Creek in Idaho County, and flash flooding and a mudslide at the Elk Bend area between Salmon and Challis in Lemhi County.

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 Missoula, MT wrote its last area forecast discussion before the first event at Aug 23, 1:00 PM MST, 5 hours 45 minutes earlier.

Area forecast discussion, Aug 23, 1:00 PM MST, 5 hours 45 minutes before
WESTERN MONTANA AND NORTH CENTRAL IDAHO FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
200 PM MDT SAT AUG 23 2003

.SHORT TERM...MAINLY DRY FORECAST THROUGH TUESDAY. A FEW SHOWERS MAY
LINGER IN THE MOUNTAINS OF WESTERN MONTANA EARLY THIS EVENING...BUT
DIE AFTER SUNSET. MAIN CONCERN SUNDAY WILL BE WEST WINDS IN THE
NORTHERN ZONES. WEST WINDS 10-15 MPH WITH GUSTS 20 TO 35 MPH HAVE
BEEN OBSERVED AT VARIOUS RAWS SITES THIS AFTERNOON. EXPECT THESE TO
CONTINUE THROUGH TONIGHT...MAINLY AT THE HIGHER ELEVATIONS...BUT NOT
QUITE AS STRONG SUNDAY. WINDS IN CENTRAL AND SOUTHERN REGIONS WILL
SUBSIDE WITH TIME BY THIS EVENING.  RIDGING ALOFT AND A SURFACE HIGH
BUILD FOR MONDAY FOR CONTINUED WARMING AND DRYING CONDITIONS.
WESTERLY ZONAL FLOW SETS UP FOR SUNDAY WITH THE STRONGEST WINDS
NORTH. WILL BE LEANING TOWARD THE GFS SOLUTION WHICH HAS AN UPPER LOW
IN WESTERN BRITISH COLUMBIA AMPLIFYING TUESDAY. THIS WILL SHIFT WINDS
MORE TO A DRY SOUTHWEST FLOW. TEMPERATURES WILL WARM WITH THE
SOUTHWEST FLOW. RPN

.LONG TERM...SOUTHWEST FLOW TUESDAY NIGHT AS UPPER LEVEL TROUGH
CONTINUES TO MOVE EAST ACROSS CANADA. WEDNESDAY A RIDGE BUILDS ALONG
THE WEST COAST FOR NORTHWEST TO ZONAL FLOW THROUGH SATURDAY.
SLIGHTLY ABOVE NORMAL TEMPERATURES AND NO PRECIPITATION EXPECTED
IN THE EXTENDED.  KOCH

.MSO...NONE.

...7-DAY SPOT TEMPS AND POPS...
LIB BUU 046/081 046/078 045/083 40000000
     UUUU 047/084 050/086 049/087 050/088 3600000000
FCA BBU 045/077 044/074 039/079 40000000
     UUUU 041/080 046/082 045/083 046/084 3600000000
POL BUU 052/079 055/076 048/080 40000000
     UUUU 050/081 053/083 052/084 053/085 3600000000
MSO BUB 048/079 048/077 045/084 40000000
     UUUU 047/083 050/085 049/087 050/088 3600000000
HMM BUB 049/080 048/078 047/085 40000000
     UUUU 049/083 052/086 051/088 052/089 3600000000
BTM BUB 045/079 046/075 040/081 40011000
     UBBB 042/080 044/083 044/084 045/085 3600000000
ORO BUU 056/084 055/081 052/089 40000000
     UUUU 054/088 056/090 054/092 056/092 3600000000
GRV BUU 047/077 049/075 045/085 40000000
     UUUU 047/085 050/087 049/089 050/089 3600000000
SMN BUB 048/083 048/080 048/085 40000000
     UUBB 050/083 053/085 052/088 053/089 3600000000
Hazardous weather outlook, Aug 23, 5:00 AM MST, 13 hours 45 minutes before
MTZ001>007-043-IDZ005>010-241200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MISSOULA MT
600 AM MDT SAT AUG 23 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN MONTANA AND NORTH
CENTRAL IDAHO

.DAY ONE... TODAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN... SUNDAY THROUGH FRIDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

2 flash flood. Local standard time, as filed.

Flash Flood, Idaho

When
August 23, 6:45 PM MST to 7:00 PM MST
Where
Idaho County, 10 mi E of Riggins
Reported by
LAW ENFORCEMENT
Coordinates
45.844, -115.467 (the zone’s center; the record gives no point)

Flash Flood, Lemhi

When
August 23, 7:45 PM MST to 8:00 PM MST
Where
Lemhi County, 20 mi S of Salmon
Reported by
LAW ENFORCEMENT
Coordinates
44.943, -113.933 (the zone’s center; the record gives no point)

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

More

Every storm in Idaho in 2003Every state in 2003This day in weather historyWarnings in Idaho, August 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: 5332927, 5332928.