Flash Flooding and Hail in North Dakota, July 19, 2011

Name: Flash Flooding and Hail in North Dakota, July 19, 2011
Start: 2011-07-19T01:40
End: 2011-07-19T09:00
Location: North Dakota

July 19, 2011 · NWS FGF · 9 events in 1 county or zone

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: $226,000
Crop damage: $150,000
Events: 9

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 FGF wrote it up.

Another night in the long duration heat wave brought another round of nocturnal convection. Early in the morning of the 19th, a weak surface boundary set up across northern South Dakota into west central Minnesota. As the low level jet and warm advection increased after midnight, thunderstorms began to fire. The air mass was extremely unstable with precipitable water values over two inches. The thunderstorms moved very slowly, and with the high amount of available moisture, heavy rain and flash flooding were also an issue.

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 Grand Forks, ND wrote its last area forecast discussion before the first event at Jul 19, 12:56 AM CST, 44 minutes earlier.

Area forecast discussion, Jul 19, 12:56 AM CST, 44 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
156 AM CDT TUE JUL 19 2011

.SHORT TERM...MAIN CONCERN WILL BE NEAR TERM THUNDER/SEVERE
POTENTIAL. HEAT HEADLINES AND THUNDER POTENTIAL THROUGH WEDNESDAY
WILL BE THE OTHER CONCERNS. 00Z MODELS IN DECENT AGREEMENT AND
WILL USE A BLEND.

THROUGH THE MORNING HOURS...HIGHER RESOLUTION SHORT TERM MODELS
INDICATING THAT CONVECTION WILL INITIATE ACROSS SOUTH CENTRAL
NORTH DAKOTA BY 09Z...AND THEN MOVE INTO THE SOUTHERN FA. THIS
MAKES THE MOST SENSE AS 850MB JET AND ASSOCIATED WARM AIR
ADVECTION ARE INCREASING INTO THIS REGION. SEVERE POTENTIAL EXISTS
CONSIDERING VERY UNSTABLE AIRMASS AND MODERATE DEEP LAYER
SHEAR. THINK MAIN THREAT WILL BE HEAVY RAINFALL CONSIDERING HIGH
FREEZING LEVELS...PWATS JUST OVER 2 INCHES...AND EXPECTED STORM
SPEED AROUND 10 KNOTS. WILL MENTION HEAVY RAIN IN THE GRIDS...BUT
LEAVE OUT T+ UNTIL/IF A WATCH IS ISSUED.

ONCE THIS COMPLEX EXITS THE REGION...THINK MUCH OF THE AFTERNOON
WILL BE DRY CONSIDERING 700MB TEMPS +14C TO +15C. MODELS DO SHOW A
LOW-LEVEL JET AGAIN STRENGTHENING INTO THE FA BY 00Z WED...AND ANY
IMPULSES IN FLOW ALOFT COULD SET OFF THUNDER LATER THIS AFTERNOON
INTO THE OVERNIGHT HOURS. MODELS DIFFER WITH DETAILS...BUT DID
EXPAND THE 20% POPS TO INCLUDE MOST OF THE FA TONIGHT. VERY WARM
MID-LEVEL TEMPS SHOULD LIMIT COVERAGE. SPC PLACES AREAS ALONG AND
EAST OF THE RED RIVER VALLEY IN A SEVERE SLIGHT RISK FOR
TODAY/TONIGHT.

COLD FRONT MOVES THROUGH THE REGION ON WED...AND CONVECTIVE
POTENTIAL UNCLEAR. VERY WARM 700MB TEMPS MAY LIMIT
POTENTIAL...ESPECIALLY SOUTH. VERY UNSTABLE AIRMASS WILL STILL BE
IN PLACE ALONG WITH INCREASING DEEP LAYER SHEAR. HIGHEST POPS
NEAR THE INTERNATIONAL BORDER WHERE CAPPING WILL BE WEAKEST. SPC
INDICATES A SLIGHT RISK FOR SEVERE STORMS NEAR THE INTERNATIONAL
BORDER.

HEAT HEADLINES STILL VALID AS HIGHER DEWPOINT VALUES RETURN TO THE
REGION TODAY AND INTO WEDNESDAY.

COOLER/DRIER AIRMASS BEHIND THE COLD FRONT FOR THURSDAY.

.LONG TERM...NO CHANGES AS INCOMING MODEL GUIDANCE GENERALLY
SUPPORTS ONGOING FORECAST.

&&

.AVIATION...TAF SITES SHOULD BE GENERALLY VFR THROUGH THE PERIOD.
THUNDER POTENTIAL EXISTS...ESPECIALLY FOR KFAR DURING THE MORNING
HOURS. WILL MONITOR POTENTIAL AND AMEND FORECAST AS NEEDED.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...EXCESSIVE HEAT WARNING UNTIL 1 AM CDT THURSDAY FOR NDZ024-
     026>030-038-039-049-052-053.

     HEAT ADVISORY UNTIL 1 AM CDT THURSDAY FOR NDZ006>008-014>016-054.

MN...EXCESSIVE HEAT WARNING UNTIL 1 AM CDT THURSDAY FOR MNZ001>003-
     014-015-022>024-027>032-040.

     HEAT ADVISORY UNTIL 1 AM CDT THURSDAY FOR MNZ004>009-013-016-017.

&&

TG

Hazardous weather outlook, Jul 18, 4:40 AM CST, 21 hours before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND FORKS ND
540 AM CDT MON JUL 18 2011

MNZ001>009-013>017-022>024-027>032-040-NDZ006>008-014>016-024-
026>030-038-039-049-052>054-191200-
WEST POLK-NORMAN-CLAY-KITTSON-ROSEAU-LAKE OF THE WOODS-
WEST MARSHALL-EAST MARSHALL-NORTH BELTRAMI-PENNINGTON-RED LAKE-
EAST POLK-NORTH CLEARWATER-SOUTH BELTRAMI-MAHNOMEN-
SOUTH CLEARWATER-HUBBARD-WEST BECKER-EAST BECKER-WILKIN-
WEST OTTER TAIL-EAST OTTER TAIL-WADENA-GRANT-TOWNER-CAVALIER-
PEMBINA-BENSON-RAMSEY-EASTERN WALSH-EDDY-NELSON-GRAND FORKS-
GRIGGS-STEELE-TRAILL-BARNES-CASS-RANSOM-SARGENT-RICHLAND-
WESTERN WALSH-
540 AM CDT MON JUL 18 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN NORTH
DAKOTA...WEST CENTRAL AND NORTHWEST MINNESOTA.

.DAY ONE...TODAY AND TONIGHT

THE POTENTIAL EXISTS FOR A THUNDERSTORM COMPLEX TO MOVE THROUGH
THE REGION TONIGHT. THE MOST LIKELY AREA TO BE AFFECTED WILL BE
SOUTHEASTERN NORTH DAKOTA INTO WEST CENTRAL MINNESOTA. A SLIGHT
RISK FOR SEVERE THUNDERSTORMS EXIST ACROSS PORTIONS OF
SOUTHEASTERN NORTH DAKOTA INTO THE SOUTHERN RED RIVER VALLEY. THE
MAIN THREATS WILL BE STRONG WIND...LARGE HAIL...AN ISOLATED
TORNADO...AND HEAVY RAINFALL.

THE HUMID CONDITIONS AND HOT TEMPERATURES WILL ALLOW HEAT INDEX
VALUES TO CLIMB TO NEAR 100 OR EVEN 105 DEGREES ACROSS A LARGE
PORTION OF THE FORECAST AREA. EXCESSIVE HEAT WARNINGS AND HEAT
ADVISORIES ARE IN EFFECT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS ON WEDNESDAY.

THE HUMID CONDITIONS AND TEMPERATURES REACHING THE 90S WILL ALLOW
HEAT INDEX VALUES TO CLIMB ABOVE 100 OR EVEN 105 DEGREES ACROSS A
LARGE PORTION OF THE FORECAST AREA. EXCESSIVE HEAT WARNINGS AND
HEAT ADVISORIES ARE IN EFFECT THROUGH WEDNESDAY EVENING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED TONIGHT.

TG

The radar

The Fargo/Grand Forks radar (KMVX), 61 km away, was scanning. The volume nearest the first event began at 07:40 UTC.

Open the radar archive at this moment

Event by event

4 thunderstorm wind, 3 flash flood, 2 hail. Local standard time, as filed.

Hail, Cass

When: July 19, 1:40 AM CST
Where: Cass County, 0.47 mi W of Absaraka
Measured: 1 in hail
Reported by: Public
Coordinates: 46.980, -97.390

Hail, Cass

When: July 19, 2:15 AM CST
Where: Cass County, 7.61 mi S of Walden
Measured: 1 in hail
Reported by: Public
Coordinates: 47.070, -97.710

Dime to quarter sized hail fell.

Thunderstorm Wind, Cass

When: July 19, 2:20 AM CST
Where: Cass County, 1.58 mi ENE of Wheatland
Measured: 52 kt (60 mph) estimated gust
Reported by: NWS Storm Survey
Coordinates: 46.910, -97.320

A few large tree limbs were blown down.

Thunderstorm Wind, Cass

When: July 19, 3:08 AM CST
Where: Cass County, 0.84 mi SW of Casselton
Measured: 56 kt (64 mph) measured gust
Reported by: Mesonet
Coordinates: 46.890, -97.210

Thunderstorm Wind, Cass

When: July 19, 3:35 AM CST
Where: Cass County, 1.58 mi WNW of Osgood
Measured: 55 kt (63 mph) estimated gust
Property damage: $200,000
Crop damage: $100,000
Reported by: NWS Storm Survey
Coordinates: 46.830, -96.900

Sections of yard fences were blown down between 36th and 40th avenues south. Numerous 3 to 5 inch diameter tree branches were broken down.

Thunderstorm Wind, Cass

When: July 19, 3:42 AM CST
Where: Cass County, 2.74 mi ESE of Osgood
Measured: 60 kt (69 mph) estimated gust
Reported by: Public
Coordinates: 46.800, -96.820

Shed doors were blown off.

Flash Flood, Cass

When: July 19, 4:14 AM CST to 8:00 AM CST
Where: Cass County, 3 mi WNW of Fargo to 2 mi WSW of Fargo
Cause: Heavy Rain
Property damage: $20,000
Crop damage: $5,000
Reported by: Broadcast Media
Coordinates: 46.887, -96.839

Two to three inches of rain fell in less than an hour causing extensive street flooding.

Flash Flood, Cass

When: July 19, 5:30 AM CST to 9:00 AM CST
Where: Cass County, 6 mi SSW of Fargo to 2.76 mi NW of Wild Rice
Cause: Heavy Rain
Property damage: $5,000
Crop damage: $25,000
Reported by: Broadcast Media
Coordinates: 46.790, -96.829

Two to three inches of rain fell within an hour causing local street flooding. Several sections of farmland and farm access roads near the confluence of the Wild Rice River (ND) and the Red River were also inundated as these local rivers were already above local flood stage.

Flash Flood, Cass

When: July 19, 6:00 AM CST to 9:00 AM CST
Where: Cass County, 5 mi N of Casselton to 8 mi E of Casselton
Cause: Heavy Rain
Property damage: $1,000
Crop damage: $20,000
Reported by: Trained Spotter
Coordinates: 46.972, -97.200

Water flowed over several sections of county and township roads in southern and central Harmony township. Numerous farm access roads and fields were flooded.

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

Every storm in North Dakota in 2011 Every state in 2011 This day in weather history Warnings in North Dakota, July 2011

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: 314120, 314121, 314128, 314122, 314123, 314124, 314125, 333729, 314127.