Debris Flow and Hail in Idaho, August 5, 2003

Name: Debris Flow and Hail in Idaho, August 5, 2003
Start: 2003-08-05T16:39
End: 2003-08-05T19:45
Location: Idaho

August 5, 2003 · NWS MSO · 2 events in 2 counties and zones

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: 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.

Thunderstorms with heavy rain and hail moved through Idaho and Lemhi Counties during the late afternoon and evening hours. Penny to nickle sized hail, heavy rain and strong winds were reported from a weather spotter in Elk City. West of Shoup in Lemhi County, a big land and mudslide from heavy rain blocked the Salmon River road and partially blocked the Salmon River in the Long Tom area.

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 5, 1:00 PM MST, 3 hours 39 minutes earlier.

Area forecast discussion, Aug 5, 1:00 PM MST, 3 hours 39 minutes before

WESTERN MONTANA AND NORTH CENTRAL IDAHO FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
200 PM MDT TUE AUG 5 2003

.SHORT TERM...CONDITIONS STILL LOOK FAVORABLE THIS AFTERNOON FOR
STRONG TO SEVERE THUNDERSTORM DEVELOPMENT. MODEL SOUNDING CAPES STILL
APPROACHING 2000 JOULES/KG IN SOME LOCATIONS. GOOD SHEAR ENVIRONMENT
WILL HELP TO SUPPORT CELLS THAT DEVELOP. THE ATMOSPHERE IS A LITTLE
DRIER IN SOUTHWEST MONTANA AND CENTRAL IDAHO WHICH WOULD MAKE WINDS
MORE OF A THREAT...BUT INTO NORTH CENTRAL IDAHO AND WEST CENTRAL
MONTANA HAIL LOOKS TO BE MORE THE THREAT. SEVERE THREAT SHOULD
DIMINISH BY MIDNIGHT...BUT SHOWERS AND THUNDERSTORMS LOOK TO CONTINUE
THROUGH THE NIGHT AS INSTABILITY REMAINS OVER WESTERN MONTANA AND
PORTIONS OF CENTRAL IDAHO.  WEDNESDAY ALSO LOOKS GOOD FOR
THUNDERSTORMS AS THE PATTERN CHANGES VERY LITTLE. THERE IS SOME MODEL
INCONSISTENCY IN THE PLACEMENT OF THE CONVECTION...BUT OVERALL IT
LOOKS FURTHER TO THE NORTH AND INTO WESTERN MONTANA THAN TODAY. WEAK
WAVES OF ENERGY WILL KEEP SHOWERS AND THUNDERSTORMS GOING THROUGH THE
NIGHT INTO THURSDAY...ESPECIALLY IN NORTHWEST MONTANA. FRIDAY A 70KT
JET NOSES INTO SOUTHWEST MONTANA AND EAST CENTRAL IDAHO FOR A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS...HOWEVER MOISTURE MAY BE
LIMITED WITH THIS EVENT HINDERING ANY DEVELOPMENT. OVER ALL...THE
FLOW PATTERN CHANGES VERY LITTLE KEEPING TEMPERATURES NEAR TO
SLIGHTLY ABOVE NORMAL WITH A SLIGHT WARMING TREND THROUGH THE PERIOD.
GILCHRIST

.LONG TERM...UPPER LEVEL PATTERN REMAINS FAVORABLE FOR SHOWERS AND
THUNDERSTORMS THROUGH THE EXTENDED. THERE IS INDICATION THAT THE
RIDGE MAY DOMINATE SOUTHWEST MONTANA LATE THIS WEEKEND AND EARLY
NEXT WEEK...RESULTING IN WARMER TEMPERATURES. THE BIG QUESTION
YESTERDAY WAS THE AVAILABILITY OF MOISTURE...WHICH IS TYPICALLY NOT
MUCH OF A PROBLEM UNDER THIS PATTERN. HOWEVER...IT LOOKS AS IF THERE
WILL BE SUFFICIENT AMOUNTS TO WARRANT SLIGHT CHANCE WORDING EACH DAY.
THE BEST CHANCES ATTM...ARE FRIDAY AND MONDAY WITH GOOD UPPER JET
INFLUENCES. THE THUNDERSTORMS OVER SOUTHWEST MONTANA MAY BE DRY LATE
THIS WEEKEND AND EARLY NEXT WEEK...BUT WILL HOLD OFF ON THAT MENTION
FOR NOW. STILL SEE AFTERNOON AND EVENING WINDS WITH THE STRONGER FLOW
AND GOOD MIXING.  DICKSON

.MSO...NONE.

...7-DAY SPOT TEMPS AND POPS...
LIB BBB 054/087 054/087 054/087 33433221
     BBBB 053/088 054/090 054/087 056/088 3722222112
FCA BBB 053/084 052/084 052/085 33433221
     BBBB 051/086 052/087 052/084 051/085 3712222222
POL BBB 056/085 055/085 055/085 33433221
     BBBB 054/086 055/087 055/084 054/088 3712222222
MSO BBB 053/086 054/087 053/087 33433221
     BBBB 053/088 054/090 054/087 053/089 3711122222
HMM BBB 052/087 053/088 052/089 33333221
     BBBB 054/090 055/092 055/089 053/089 3711111221
BTM BBB 049/083 049/084 048/085 33344222
     BBBB 048/086 049/089 049/086 048/086 3722211221
ORO BBB 064/088 059/091 059/091 33321111
     BBBB 057/090 058/091 058/088 060/095 3712222112
GRV BBB 056/083 053/085 053/086 33322111
     BBBB 051/086 052/088 052/085 052/089 3712222222
SMN BBB 052/086 050/087 050/088 33322112
     BBBB 052/087 053/089 053/086 052/089 3721111111

Hazardous weather outlook, Aug 5, 7:30 AM MST, 9 hours 9 minutes before

MTZ001>007-043-IDZ005>010-061200-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MISSOULA MT
830 AM MDT TUE AUG 5 2003

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

.DAY ONE... TODAY

SCATTERED THUNDERSTORMS CAN BE EXPECTED OVER PORTIONS OF NORTH-
CENTRAL IDAHO AND WEST-CENTRAL MONTANA TODAY AND THIS EVENING. AS THE
AIR MASS DESTABILIZES...MOISTURE MOVING NORTH OUT OF OREGON WILL
PROVIDE FAVORABLE CONDITIONS FOR THUNDERSTORMS DEVELOPMENT...SOME
POTENTIALLY STRONG WITH HAIL AND STRONG GUSTY WINDS.

.DAYS TWO THROUGH SEVEN... WEDNESDAY THROUGH MONDAY

WEDNESDAY THE POTENTIAL AGAIN EXISTS FOR THUNDERSTORM DEVELOPMENT AS
THE NORTHERN ROCKIES REMAINS IN A MOIST SOUTHWEST FLOW ALOFT.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

The radar

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

Open the radar archive at this moment

Event by event

1 hail, 1 debris flow. Local standard time, as filed.

Hail, Idaho

When: August 5, 4:39 PM MST
Where: Idaho County, Elk City
Measured: 1 in hail
Reported by: TRAINED SPOTTER
Coordinates: 45.833, -115.433

Debris Flow, Western Lemhi County

When: August 5, 7:45 PM MST
Where: Western Lemhi County forecast zone
Reported by: PARK/FOREST SERVICE
Coordinates: 44.943, -113.933 (the zone’s center; the record gives no point)

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Debris Flow: A fast-moving slurry of mud, rock and debris, usually on a slope soaked by heavy rain or stripped by a fire.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Idaho in 2003 Every state in 2003 This day in weather history Warnings 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: 5332919, 5332920.