Upper-air analysis the morning of the 18th showed a longwave trough over much of the western CONUS. At the surface, a cold front was noted across the central and northern Plains, moving to the east/southeast.
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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 OAX wrote it up.
Upper-air analysis the morning of the 18th showed a longwave trough over much of the western CONUS. At the surface, a cold front was noted across the central and northern Plains, moving to the east/southeast. In the afternoon hours, widespread thunderstorm development occurred with multiple linear complexes racing across eastern Nebraska into Iowa. While the majority of these storms remained below severe limits, severe winds were observed in Seward and Lancaster County at the apex of one of the bowing segments.
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 Omaha, NE wrote its last area forecast discussion before the first event at Jun 18, 1:58 PM CST, 2 hours 8 minutes earlier. Its key messages:
Area Forecast Discussion National Weather Service Omaha/Valley NE 258 PM CDT Tue Jun 18 2024 .KEY MESSAGES... - Strong to severe thunderstorms through around 8 PM today. Widespread rain is expected, with some local areas potentially receiving 3+ inches. - Rain chances continue every day through Saturday, especially across northern parts of the area. Severe storms are unlikely though. - Temperatures will be much cooler on Wednesday, but warming back up by the end of the week. && .DISCUSSION... Issued at 229 PM CDT Tue Jun 18 2024 At 2 PM, the cold front extended from near Sioux City to Columbus to Hastings. This front continues to progress east across northeast NE, but has stalled a bit over south central NE. Thunderstorms have developed along the entire front, and are expected to intensify and organize a bit in the next few hours. MLCAPE in advance of the front is greater than 2000 J/kg with limited inhibition and effective shear only around 30 kts. Immediately behind the front, the deep layer shear including the northwesterly surface winds and a stronger belt of southwesterly flow at 500 hPa, is a fair amount stronger. Individual cell motion within the line will be nearly parallel to the front, and thus expect a majority of the updrafts to become elevated over and slightly behind the frontal boundary over time...especially as storms develop more organized downdrafts to push it quicker to the east at the surface. Assuming slightly elevated updrafts, especially as the evening progresses, believe that true effective shear will struggle to be strong enough to influence the updrafts into persistent mesocyclones. If this is the end result, then large hail would struggle to be much of a hazard aside from the initial onset of stronger updrafts, especially with ample seeding from nearby updrafts and a rather warm airmass aloft. Post-frontal updrafts would also limit the overall tornado potential (although see note a few lines below). Rather, the primary severe weather hazard would likely be areas of 55-70 mph wind gusts where the stronger updrafts can develop in close proximity, produce an organized conglomerated downdraft cold pool, and push it to the east northeast in the higher CAPE environments. This may become a bit more of a hazard during the time frame in early evening when low level winds increase but instability remains in place. And, if these bowing segments develop during the early evening with increasing low level wind shear, a mesovortex tornado or two could become possible. This currently appears to be a lower end potential, but non-zero. Finally, with front-parallel flow and a slow moving boundary amidst a very moist environment with ample low level moisture transport, heavy rain and isolated flash flooding will be possible. It seems that rainfall rates in the strongest storms could approach 2 inches per hour...so if a couple of stronger updrafts can train over the same areas before the cold pool organizes and pushes east quicker, those area the areas where flash flooding will become possible with local amounts greater than 3" possible. To recap, expect a few storms to produce rain capable of flash flooding and wind gusts of 55-70 mph. Large hail and tornadoes are unlikely...but the threat is non-zero. By 8 PM or so, most of the stronger storms should push east of the area and/or weaken, but off and on showers and thunderstorms will continue across a large part of the area, and will probably see an increase in coverage late tonight into early Wednesday. Expect a few showers or a storm around the region on Wednesday but most of the day will be dry. Then overnight, expect another complex of non-severe thunderstorms to develop and move into the area early Thursday morning. Non-severe thunderstorm chances continue intermittently through Saturday, although the greatest chances do shift north to the Dakotas. By Saturday, a front pushes through with decreasing storm chances thereafter (although the environment does seem to re-build its instability profile so if a subtle system is capable of developing storms, might need to watch for a bit of severe potential). && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1246 PM CDT Tue Jun 18 2024 Primary focus this TAF issuance is on timing and intensity of thunderstorms. Have attempted to focus the greatest potential into a 2 hour window. It appears that the window for stronger storms, while around 2 hours long, may come in off-and-on greater intensity so maintained a tempo for the lowest conditions. After storms, there are questions about if/when/how long MVFR ceilings may persist. Especially at LNK/OMA, could have some MVFR or briefly IFR ceilings over the course of several hours, but feel that VFR is more likely for a majority of the time so have been a bit conservative with ceiling heights at this time. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && DISCUSSION...Barjenbruch AVIATION...Barjenbruch
Hazardous Weather Outlook National Weather Service Omaha/Valley NE 1145 AM CDT Tue Jun 18 2024 IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034- 042>045-050>053-065>068-078-088>093-190645- Monona-Harrison-Shelby-Pottawattamie-Mills-Montgomery-Fremont- Page-Knox-Cedar-Thurston-Antelope-Pierce-Wayne-Boone-Madison- Stanton-Cuming-Burt-Platte-Colfax-Dodge-Washington-Butler- Saunders-Douglas-Sarpy-Seward-Lancaster-Cass-Otoe-Saline- Jefferson-Gage-Johnson-Nemaha-Pawnee-Richardson- 1145 AM CDT Tue Jun 18 2024 This Hazardous Weather Outlook is for portions of southwest Iowa...west central Iowa...east central Nebraska...northeast Nebraska and southeast Nebraska. .DAY ONE...Tuesday Afternoon Through Tuesday Night Thunderstorms will develop this afternoon from northeast Nebraska into south central Nebraska, gradually moving east through this evening. These storms could possibly be severe with damaging winds, isolated large hail, and widespread 1 to 2 inch rains. Localized totals of up to 5 inches of rain are possible and could produce flash flooding. While thunderstorms will persist into the evening and overnight, severe weather potential will decrease as we get farther into the evening hours with little to no severe potential after midnight. .DAYS TWO THROUGH SEVEN...Wednesday through Monday Thunderstorms remain in the forecast Wednesday. While severe storms aren't expected, additional heavy rainfall could occur. The active weather pattern remains in the area with a daily chance for storms from Thursday through Saturday. .SPOTTER INFORMATION STATEMENT... Spotters may be needed this afternoon or tonight.
The Omaha radar (KOAX), 98 km away, was scanning. The volume nearest the first event began at 22:06 UTC.
2 thunderstorm wind. Local standard time, as filed.
Law enforcement reported a semi that had flipped along Interstate 80 near the Utica exit.
The office received a delayed report of a tree blown down near 84th Street and Waverly Road. The trunk was measured to be 35 inches in diameter.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2024Every state in 2024This day in weather historyWarnings in Nebraska, June 2024
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: 1198492, 1198493.