Montana, 2001

Flash Flooding and Hail in Montana, July 17 to 18, 2001

July 17 to 18, 2001 · NWS GGW · 33 events in 8 counties and zones

20 thunderstorm wind, 10 hail, 3 flash flood, as filed by the National Weather Service.

Where it happened

Every event with a place to put it; 3 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

Open the live radar over this ground

The toll

Deaths
0
Injuries
0
Property damage
$51,000
Crop damage
$45,000
Events
33

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 Glasgow, MT wrote its last area forecast discussion before the first event at Jul 17, 1:22 PM MST, 3 hours 38 minutes earlier.

Area forecast discussion, Jul 17, 1:22 PM MST, 3 hours 38 minutes before
NORTHEAST MONTANA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GLASGOW MT
222 PM MDT TUE JUL 17 2001

CLOSED UPPER LOW CENTERED OVER SRN BC WILL MIGRATE NE INTO CENTRAL
ALBERTA THE NEXT 2 DAYS. ETA SLIGHTLY EAST OF THE AVN WITH THE UPPER
LOW CENTER AFTER 00Z THU. SEVERAL SHORTWAVES IN SW FLOW AFOFT AHEAD
OF THIS LOW WILL AFFECT NE MT THE NEXT SEVERAL DAYS.

MODELS BRING ONE SHORTWAVE OVER NE MT THIS EVENING AND ANOTHER WED
MORNING. ETA SLIGHTLY SLOWER WITH WED MORNING WAVE (15Z) THAN THE
AVN (12Z). WITH BOTH WAVES...MODELS SET UP A DRY-LINE BOUNDARY NEAR
GGW AND JDN WITH A WEAK THETA-E RIDGE JUST EAST OF THE DRY LINE.
AIRMASS PROGGED TO BE UNSTABLE TO THE EAST OF THIS DRY-LINE WITH THE
MOST UNSTABLE AIR OVER SW ND AND SE MT WHERE THERE IS A STRONGER
THETA-E RIDGE. ETA FORECAST CAPES OF 2000-2500 J/KG COVERS THE SE
PART OF GGW CWA THIS EVENING INCLUDING SDY AND GDV WITH THE 1000+
J/KG CAPE AS FAR WEST AS SCOBEY...OLF AND TERRY UNTIL WED MORNING
SHORTWAVE PASSES.

THE FIRST WAVE THIS EVENING WILL HAVE DAYTIME HEATING AND STRONG
UPWARD OMEGA TO HELP SUPPORT IT. THE WED MORNING WAVE WILL HAVE THE
LEFT FRONT QUADRANT OF 70 KNOT UPPER JET FOR ADDITIONAL SUPPORT.
WITH NOT BEING ABLE TO PINPOINT WHERE THE CONVECTION WILL BE AT THIS
TIME...WILL MENTION SCT THUNDERSTORMS FOR BOTH TONIGHT AND WED FOR
ALL ZONES. WILL HAVE 30 PCT CHANCE IN THE WEST AND 40 PCT IN THE
EAST WITH THE BETTER MOISTURE AND INSTABILITY IN THE EAST.

AFTER WED MORNING'S WAVE PASSES...THE MAIN INSTABILITY SHIFTS TO THE
EAST UNTIL ANOTHER SFC TROF DEVELOPS OVER ERN MT ON THU. WEAK
SHORTWAVES WITH SW FLOW ALOFT WILL KEEP A 20 PCT CHANCE OF
SHOWERS AND THUNDERSTORMS OVER GGW CWA WED NIGHT.

THE UNSTABLE AIR RETURNS ON THU...ESP ALONG AND EAST OF THE SFC TROF
AXIS WHICH MODELS PLACE NEAR GGW AND MLS. WILL NOT SPECIFIC WITH
TIMING OF ANY WAVES ON THU. MESOETA FORECAST CAPE AROUND 2000 J/KG
WITH LI OF -8 OVER MLS AND GDV THU AFTERNOON WILL NEED TO BE WATCHED
BY FUTURE SHIFTS. WILL MENTION A CHANCE OF THUNDERSTORMS.

AS FOR TEMPS...WILL FOLLOW WARMER FWC.  FORRESTER

EXTENDED...UPPER LOW REMAINS OVER ALBERTA UNTIL SAT WHEN IT MOVES
EAST AS AN OPEN TROF. THEN AN UPPER TROF DEVELOPS OVER WEST COAST
OVER THE WEEKEND THAT CONTINUES INTO EARLY NEXT WEEK. EXCEPT FOR A
BRIEF PERIOD ON SUNDAY...ERN MT IS IN SW FLOW ALOFT FOR THE ENTIRE
EXTENDED PERIOD WITH FREQUENT SHORTWAVES. GIVEN THE UNSETTLED
PATTERN...WILL NEED TO MENTION A CHANCE OF THUNDERSTORMS EACH DAY.
FORRESTER

KGGW 062/084 060/085 062/082 058/083 056/085 058/084 061/085
      TTTBBBB  793323/7933333
KGDV 063/085 061/085 061/085 057/085 058/085 058/084 060/084
      TTTBBBB  794423/7933333

The radar

The Glasgow radar (KGGW), 158 km away, was scanning. The volume nearest the first event began at 00:01 UTC.

Open the radar archive at this moment

Event by event

20 thunderstorm wind, 10 hail, 3 flash flood. Local standard time, as filed.

Hail, Phillips

When
July 17, 5:00 PM MST
Where
Phillips County, 58 mi S of Malta
Measured
0.75 in hail
Reported by
TRAINED SPOTTER
Coordinates
48.333, -104.500

Thunderstorm Wind, Garfield

When
July 17, 7:20 PM MST
Where
Garfield County, Cohagen
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
48.150, -104.517

Thunderstorm Wind, Garfield

When
July 17, 7:29 PM MST
Where
Garfield County, Jordan Arpt
Measured
52 kt (60 mph)
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
48.433, -104.383

Thunderstorm Wind, Garfield

When
July 17, 7:30 PM MST
Where
Garfield County, 3 mi SE of Cohagen
Measured
61 kt (70 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.867, -104.417

Hail, Richland

When
July 17, 8:00 PM MST
Where
Richland County, 15 mi W of Fairview
Measured
0.88 in hail
Reported by
TRAINED SPOTTER
Coordinates
47.900, -104.450

Thunderstorm Wind, Prairie

When
July 17, 8:15 PM MST
Where
Prairie County, 40 mi NW of Terry
Measured
56 kt (64 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.450, -104.350

Thunderstorm Wind, McCone

When
July 17, 8:25 PM MST
Where
McCone County, 8 mi W of Brockway
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
46.767, -105.017

Thunderstorm Wind, Garfield

When
July 17, 8:30 PM MST
Where
Garfield County, 30 mi E of Jordan
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.483, -104.817

Hail, Prairie

When
July 17, 9:00 PM MST
Where
Prairie County, 3 mi W of Terry
Measured
0.88 in hail
Crop damage
$45,000
Reported by
TRAINED SPOTTER
Coordinates
48.150, -104.517

Some crop damage to wheat fields. Damage was from 30 to 60 percent of the crop over several hundred acres.

Hail, McCone

When
July 17, 9:15 PM MST
Where
McCone County, 8 mi SE of Circle
Measured
0.75 in hail
Reported by
TRAINED SPOTTER
Coordinates
48.133, -104.217

Hail, Dawson

When
July 17, 9:20 PM MST
Where
Dawson County, 12 mi S of Lindsay
Measured
0.75 in hail
Reported by
TRAINED SPOTTER
Coordinates
48.467, -104.433

Thunderstorm Wind, Dawson

When
July 17, 9:25 PM MST
Where
Dawson County, 2 mi NW of Bloomfield
Measured
65 kt (75 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.450, -104.350

Hail, Dawson

When
July 17, 9:25 PM MST
Where
Dawson County, 8 mi N of Lindsay
Measured
0.88 in hail
Reported by
TRAINED SPOTTER
Coordinates
46.783, -105.367

Thunderstorm Wind, Dawson

When
July 17, 9:25 PM MST
Where
Dawson County, 8 mi N of Lindsay
Measured
55 kt (63 mph)
Reported by
TRAINED SPOTTER
Coordinates
46.567, -105.117

Thunderstorm Wind, Richland

When
July 17, 9:30 PM MST
Where
Richland County, 40 mi NW of Sidney
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.700, -105.150

Thunderstorm Wind, Roosevelt

When
July 17, 10:00 PM MST
Where
Roosevelt County, Froid
Property damage
$1,000
Reported by
TRAINED SPOTTER
Coordinates
48.295, -105.016 (the zone’s center; the record gives no point)

Strong downburst winds broke 12-15 inch limbs off of cottonwood trees, and damaged shingles on a roof.

Thunderstorm Wind, Roosevelt

When
July 17, 10:00 PM MST
Where
Roosevelt County, Culbertson
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
48.295, -105.016 (the zone’s center; the record gives no point)

Hail, Prairie

When
July 17, 10:00 PM MST
Where
Prairie County, 7 mi SE of Fallon
Measured
0.75 in hail
Reported by
TRAINED SPOTTER
Coordinates
47.000, -106.550

Thunderstorm Wind, Sheridan

When
July 17, 10:15 PM MST
Where
Sheridan County, 5 mi E of Homestead
Measured
60 kt (69 mph)
Reported by
TRAINED SPOTTER
Coordinates
48.721, -104.505 (the zone’s center; the record gives no point)

Thunderstorm Wind, Richland

When
July 17, 10:15 PM MST
Where
Richland County, 17 mi NW of Sidney
Measured
60 kt (69 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.517, -107.867

Thunderstorm Wind, Richland

When
July 17, 10:15 PM MST
Where
Richland County, Savage
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.333, -106.933

Thunderstorm Wind, Richland

When
July 17, 10:25 PM MST
Where
Richland County, 20 mi NW of Sidney
Measured
53 kt (61 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.033, -106.600

Thunderstorm Wind, Dawson

When
July 17, 10:30 PM MST
Where
Dawson County, 16 mi SE of Richey
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.850, -104.367

Thunderstorm Wind, Dawson

When
July 17, 10:35 PM MST
Where
Dawson County, 5 mi NW of Richey
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.200, -105.900

Thunderstorm Wind, Roosevelt

When
July 17, 10:40 PM MST
Where
Roosevelt County, Bainville
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.300, -105.933

Hail, Sheridan

When
July 17, 11:00 PM MST
Where
Sheridan County, 4 mi SE of Medicine Lake
Measured
0.75 in hail
Reported by
TRAINED SPOTTER
Coordinates
47.317, -106.250

Thunderstorm Wind, Roosevelt

When
July 17, 11:00 PM MST
Where
Roosevelt County, Culbertson
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
48.117, -104.767

Thunderstorm Wind, Richland

When
July 17, 11:00 PM MST
Where
Richland County, Savage
Measured
52 kt (60 mph)
Reported by
TRAINED SPOTTER
Coordinates
47.333, -105.483

Hail, Prairie

When
July 17, 11:00 PM MST
Where
Prairie County, 3 mi W of Terry
Measured
0.88 in hail
Reported by
TRAINED SPOTTER
Coordinates
47.050, -105.150

Flash Flood, Richland

When
July 17, 11:00 PM MST to July 18, 5:00 AM MST
Where
Richland County, North Portion
Property damage
$10,000
Reported by
EMERGENCY MANAGER
Coordinates
47.433, -104.967

Three to four inches of rain in two hours caused a culvert to wash out, causing the road to become washed out.

Flash Flood, Roosevelt

When
July 17, 11:00 PM MST to July 18, 5:00 AM MST
Where
Roosevelt County, Central Portion
Property damage
$30,000
Reported by
EMERGENCY MANAGER
Coordinates
47.333, -105.150

Intense thunderstorms produced 3 to 5 inches of rainfall which caused flash flooding in the Brockton area. Water up to 4 feet deep covered U.S. Highway 2, two miles east of town. Two vehicles were swept off the road. One vehicle ended up in a ditch, and the occupants were not injured. Another vehicle was swept off the road, and underneath a railroad bridge. The two female occupants crawled out of the vehicle before it was swept under the bridge, and swam to solid ground. They stated that they could not touch the ground when they got out of the vehicle. The car ended up 400 feet downstream of the railroad bridge.

Flash Flood, Prairie

When
July 18, 12:00 AM MST to 4:00 AM MST
Where
Prairie County, East Portion
Property damage
$10,000
Reported by
EMERGENCY MANAGER
Coordinates
47.333, -105.150

Heavy rainfall of 2 to 4 inches caused ditches to fill up and water to start running up to two feet deep across Highway 10 east of Terry. Some damage occurred to the road, but it was not washed out.

Hail, Prairie

When
July 18, 12:30 AM MST
Where
Prairie County, 11 mi SW of Mildred
Measured
0.75 in hail
Reported by
TRAINED SPOTTER
Coordinates
46.783, -105.367

What these are

Hail
Hail three-quarters of an inch or larger, or smaller hail that caused damage, filed with the largest stone measured.
Thunderstorm Wind
Winds from a thunderstorm of 50 knots (58 mph) or more, or lower winds that caused damage or casualties. Measured gusts are marked MG, estimated EG.
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 Montana in 2001Every state in 2001This day in weather historyWarnings in Montana, July 2001

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: 5261493, 5262167, 5262168, 5262169, 5262170, 5262171, 5262172, 5262173, 5262177, 5262175, 5262176, 5262178, 5262179, 5262180, 5262174, 5262247, 5262248, 5262253, 5262249, 5262250, 5262252, 5262251, 5262254, 5262255, 5262256, 5262257, 5262258, 5262259, 5262260, 5262262, 5262263, 5262264, 5262261.