Name: Hail in Montana, August 20, 2004
Start: 2004-08-20T17:33
End: 2004-08-20T17:33
Location: Montana

Where it happened

Every event with a place to put it. 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

Open the live radar over this ground

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 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 20, 1:00 PM MST, 4 hours 33 minutes earlier.

Area forecast discussion, Aug 20, 1:00 PM MST, 4 hours 33 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
200 PM MDT FRI AUG 20 2004

.SHORT TERM...TONIGHT THROUGH SUNDAY...STILL PLENTY OF INSTABILITY
AND LOW LEVEL MOISTURE OVER THE NORTHERN ROCKIES.  THIS IS CAUSING
QUITE A BIT OF CUMULUS DEVELOPMENT...PARTICULARLY FROM MISSOULA
SOUTH.  WITH MAINLY SURFACE HEATING FOR LIFT...STILL THINK ISOLATED
THUNDERSTORM COVERAGE WILL SUFFICE...WITH MAIN THREAT FROM THE
STORMS AGAIN BEING BRIEF HEAVY RAINS.  CONVECTION WILL DIMINISH
AS THE WE APPROACH SUNSET...HOWEVER...WEAK UPPER LEVEL ENERGY WILL
CONTINUE A SMALL THREAT OF PRECIPITATION OVERNIGHT.  BRIEF RIDGING
WILL MOVE OVER THE AREA SATURDAY AHEAD OF THE SUNDAYS BIG WEATHER
CHANGER.  STILL AN UNSTABLE AIR MASS...BUT STORM THREAT IS MINIMAL.

SUNDAY WILL BE THE BEGINNING OF A FAIRLY LONGTERM WEATHER CHANGE.  A
WELL DEVELOPED TROUGH WILL BEGIN SPREADING PRECIPITATION INTO IDAHO
AND NORTHWEST MONTANA SUNDAY MORNING...THEN OVER THE ENTIRE AREA
SUNDAY AFTERNOON.  WINDS WILL INCREASE SOMEWHAT SUNDAY...BUT MAY BE
STRONGER MONDAY AS BETTER COLD AIR ADVECTION TAKES PLACE.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY...THE UPPER-LEVEL FLOW
WILL MAKE A SIGNIFICANT TRANSITION TO A LONG-WAVE TROUGH OVER THE
REGION. TIMING OF SHORT-WAVE FEATURE EMBEDDED IN THE FLOW WILL BE
DIFFICULT...BUT OROGRAPHIC ENHANCEMENT OF PRECIPITATION CAN BE
EXPECTED GIVEN THE STRONGER WESTERLY FLOW. AS A RESULT...UNSEASONABLY
COOL WET AND BREEZY CONDITIONS WILL HIGHLIGHT THE PERIOD.
&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

SHORT TERM/WHITMORE
LONG TERM/MSJ

In the hours before

Special weather statement, Aug 20, 11:54 AM MST, 5 hours 39 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
1255 PM MDT (1155 AM PDT) FRI AUG 20 2004

IDZ005>010-MTZ001>007-043-210430-
WESTERN MONTANA AND NORTH CENTRAL IDAHO-
1255 PM MDT (1155 AM PDT) FRI AUG 20 2004

...MUCH COOLER TEMPERATURES AND WETTER CONDITIONS EXPECTED FOR
WESTERN MONTANA AND NORTH CENTRAL IDAHO BEGINNING SUNDAY...

THE RIDGE OF HIGH PRESSURE THAT HAS BEEN OVER THE REGION FOR THE
LAST SEVERAL WEEKS WILL FINALLY BREAK DOWN AND MOVE TO THE EAST THIS
WEEKEND. A COLD FRONT WILL MOVE INTO THE AREA SUNDAY INCREASING
SHOWERS COVERAGE ACROSS THE AREA. TEMPERATURES WILL BE 10 TO 20
DEGREES BELOW NORMAL BY MONDAY...WITH CONTINUED COOL CONDITIONS
THROUGH MID-WEEK. SEVERAL WEATHER DISTURBANCES ARE EXPECTED TO MOVE
ACROSS THE AREA THROUGHOUT THE WEEK...BRINGING A CHANCE OF RAIN TO
THE VALLEYS AND LIKELY PRECIPITATION TO THE HIGHER TERRAIN. THERE IS
ALSO THE POSSIBILITY OF SNOW DURING THE EARLY MORNING HOURS ABOVE
8000 FEET THIS COMING WEEK.

SMITH

The radar

The Missoula radar (KMSX), 88 km away, was scanning. The volume nearest the first event began at 00:32 UTC.

Open the radar archive at this moment

Event by event

1 hail. Local standard time, as filed.

Hail, Lake

When: August 20, 5:33 PM MST
Where: Lake County, Big Arm
Measured: 0.75 in hail
Reported by: TRAINED SPOTTER
Coordinates: 47.800, -114.300

What these are

Hail: Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.

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

The same day elsewhere

More

Every storm in Montana in 2004 Every state in 2004 This day in weather history Warnings in Montana, August 2004

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: 5420030.