An isolated supercell thunderstorm tracked along the North Dakota and South Dakota border over far southwest and far south central North Dakota during the early evening of July 18th. This storm formed north of a surface warm front over South Dakota and ahead of a mid level impulse near southeast Montana.
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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.
The episode as NWS BIS wrote it up.
An isolated supercell thunderstorm tracked along the North Dakota and South Dakota border over far southwest and far south central North Dakota during the early evening of July 18th. This storm formed north of a surface warm front over South Dakota and ahead of a mid level impulse near southeast Montana. Several severe thunderstorm and tornado warnings were issued for this storm. Two reports of large hail were received.
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 Bismarck, ND wrote its last area forecast discussion before the first event at Jul 18, 5:22 PM MST, 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 722 PM CDT MON JUL 18 2011 .UPDATE... UPDATED TRENDS FOR TEMPERATURE AND HUMIDITY. && .DISCUSSION... ISOLATED SUPER CELL OVER EASTERN ADAMS COUNTY CONTINUES TO GROWTH IN AREAL COVERAGE AND HAS EXPANDED TO THE BORDER OF GRANT/SIOUX AND INTO SOUTHEAST HETTINGER COUNTY. && .AVIATION... ISOLATED CONVECTION IN TAF IS REASONABLE AS CONVECTION SETTLES OUT THIS EVENING. WILL UPDATE AS AERODROME SITES CLEAR FROM POSSIBLE CONVECTIVE INITIATION. && .BIS WATCHES/WARNINGS/ADVISORIES... EXCESSIVE HEAT WARNING UNTIL 10 PM CDT /9 PM MDT/ TUESDAY FOR NDZ011>013-019>023-025-034>037-042-045>048-050-051. FLASH FLOOD WATCH UNTIL 7 AM CDT /6 AM MDT/ TUESDAY FOR NDZ019>023-025-034>037-042-045>048-050-051. HEAT ADVISORY UNTIL 10 PM CDT /9 PM MDT/ TUESDAY FOR NDZ001>005- 009-010-017-018-031>033-040-041-043-044. && SHORT TERM...HW AVIATION...BPN
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE BISMARCK ND 432 AM CDT MON JUL 18 2011 NDZ001>005-009>013-017>023-025-031>037-040>048-050-051-190945- DIVIDE-BURKE-RENVILLE-BOTTINEAU-ROLETTE-WILLIAMS-MOUNTRAIL-WARD- MCHENRY-PIERCE-MCKENZIE-DUNN-MERCER-OLIVER-MCLEAN-SHERIDAN-WELLS- FOSTER-GOLDEN VALLEY-BILLINGS-STARK-MORTON-BURLEIGH-KIDDER- STUTSMAN-SLOPE-HETTINGER-GRANT-BOWMAN-ADAMS-SIOUX-EMMONS-LOGAN- LA MOURE-MCINTOSH-DICKEY- 432 AM CDT MON JUL 18 2011 /332 AM MDT MON JUL 18 2011/ THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL NORTH DAKOTA...NORTHWEST NORTH DAKOTA...SOUTH CENTRAL NORTH DAKOTA...SOUTHEAST NORTH DAKOTA AND SOUTHWEST NORTH DAKOTA. .DAY ONE...TODAY AND TONIGHT THERE IS A CHANCE OF THUNDERSTORMS WEST AND CENTRAL THIS MORNING. A FEW STRONGER STORMS ARE POSSIBLE. EXCESSIVE HEAT WARNINGS AND ADVISORIES REMAIN IN EFFECT FOR PORTIONS OF WEST AND CENTRAL NORTH DAKOTA TODAY. HEAT INDEX VALUES OF 100 TO 115 ARE EXPECTED. THE LATEST INFORMATION CAN BE FOUND IN THE BISNPWBIS PRODUCT. THERE IS A CHANCE FOR THUNDERSTORMS OVER MOST AREAS ACROSS WEST AND CENTRAL NORTH DAKOTA FOR MONDAY AND MONDAY NIGHT. A VERY MOIST AND UNSTABLE ATMOSPHERE WILL ONCE AGAIN CAUSE THE MAIN THREATS TO BE LARGE HAIL...STRONG WINDS...HEAVY RAIN...AND POSSIBLY ISOLATED TORNADOES. THE MOST FAVORABLE AREA FOR SEVERE THUNDERSTORMS IF THEY DO DEVELOP TODAY INTO THIS EVENING IS CURRENTLY EXPECTED TO BE OVER FAR WESTERN AND FAR SOUTHERN NORTH DAKOTA INITIALLY. STAY TUNED FOR UPDATES. .DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY AN EXCESSIVE HEAT WARNING REMAINS IN EFFECT INTO TUESDAY EVENING FOR PORTIONS OF WEST AND CENTRAL NORTH DAKOTA. HEAT INDEX VALUES OF 105 TO 120 ARE EXPECTED FOR TUESDAY. CHANCES FOR THUNDERSTORMS CONTINUE THROUGH FRIDAY. STRONG TO SEVERE STORMS WILL REMAIN A THREAT. .SPOTTER INFORMATION STATEMENT... SPOTTERS ARE HIGHLY ENCOURAGED TO REPORT ANY SEVERE WEATHER AND HEAVY RAIN REPORTS. HEINERT
The Bismarck radar (KBIS), 137 km away, was scanning. The volume nearest the first event began at 00:56 UTC.
2 hail. Local standard time, as filed.
There was damage to crops and vehicles.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in North Dakota in 2011Every state in 2011This day in weather historyWarnings in North Dakota, July 2011
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: 331586, 331587.