An initially unimpressive thunderstorm complex over northeast Nebraska rapidly intensified during the morning of August 10, 2020. After a few sporadic early morning damage reports, the intensifying storms began to more readily produce damaging winds in excess of 50 kts around 1340Z.
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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.
An initially unimpressive thunderstorm complex over northeast Nebraska rapidly intensified during the morning of August 10, 2020. After a few sporadic early morning damage reports, the intensifying storms began to more readily produce damaging winds in excess of 50 kts around 1340Z. Those damaging winds increased in coverage and intensity as the storms moved east into Iowa. The portion of the thunderstorm complex that moved through the NWS Omaha forecast area marked the approximate beginning of an intense derecho that tracked across portions of Iowa, Illinois, Wisconsin, Indiana, Michigan, and Ohio. Within the NWS Omaha forecast area, there were more than 20 local storm reports of wind damage and measured severe wind gusts, including more than 50,000 power outages.
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 Aug 10, 2:24 AM CST, 2 hours 46 minutes earlier.
Area Forecast Discussion National Weather Service Omaha/Valley NE 324 AM CDT Mon Aug 10 2020 ...Updated Forecast Discussion... .DISCUSSION... Issued at 210 AM CDT Mon Aug 10 2020 A surface cold front is currently draped across the area starting from northeast Colorado extending northeastward to to just east of Minneapolis, Minnesota. A nocturnal 850mb jet is oriented parallel to the cold front and becomes westerly as it reaches far eastern Nebraska/western Iowa. These two factors are combining to force some modest convection along NE/SD border, with more convection beginning to sprout up, extending westward into south-central South Dakota. The orientation of the low-level jet is providing some convergence along the front, but since it is oriented parallel to it, that convergence is not overly strong. Surface CIN values are lowest just ahead of the front at around 140 J/kg in far northeast Nebraska and increase along the front as you go southwestward. Surface based CAPE values associated with the CAPE minimum have slightly declined to around 3500 J/kg but still allow for strong convection to occur. The latest runs of the HRRR, ESRL HRRR, and RAP suggest that a cluster of storms may move eastward along with the zonal flow aloft, but if robust convection does get going a strong cold pool may allow for a more southeastward propagation to occur with the primary hazard being damaging wind gusts. As the today continues, the cold front is expected to march southeast and is expected to make its way to northwest Missouri by 00z Tuesday, and will bring cooler temperatures ranging from the upper 70's in the northwestern CWA to the mid to upper 80's in the far southeastern corner. Isolated to scattered showers and storms will be possible as the front passes through the area but with limited development in the model solutions, limited activity is expected. Looking beyond today's forecast, Tuesday is expected to be dry after any lingering precipitation from the frontal passage exits the area early in the morning. Highs in the mid to upper 80's are expected throughout eastern Nebraska as southeasterly surface flow returns. Global deterministic models are currently hinting at the possibility of a nocturnal MCS that could begin in western NE/SD and propagate ESE forming an MCV and bringing overnight and early morning rain chances to eastern Nebraska. This scenario is also depicted once again Wednesday evening/Thursday morning with the main difference being the propagation of the nocturnal MCS, with the GFS keeping it north of the area and the ECMWF passing it through southeastern Nebraska. Beginning Wednesday, mid-level ridging begins building over southern New Mexico and will slowly begin shifting the mid-level flow northwesterly. Beyond the Wednesday and Thursday nights' storm chances, the bulk of any activity is expected to stay more into Iowa as different shortwave impulses push through the mid- level flow. High temperatures are expected to stay in the upper 80's to around 90, with no real scorchers expected. Model solutions begin to diverge Sunday, with the ECMWF depicting a cold front to pass through the area, while the other global solutions depict a very limited response in surface temperatures and wind direction. If this front comes to fruition, we could enjoy another trip into the lower 80's for highs to start off next week. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 1143 PM CDT Sun Aug 9 2020 Convection has developed along the NE/SD border, moving quite slowly, but should remain north of the KOFK TAF. Additional thunderstorms are expected north of both KOFK and KOMA, although KOFK could see an isolated shower 11-14z. There is a cold front coincident with this activity, and this front will shift winds to the north and increase to 12-14 knots with the initial surge, then settling back into the 9-12 knot range by 16z. Otherwise, VFR through the period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && DISCUSSION...Petersen AVIATION...DeWald
Hazardous Weather Outlook National Weather Service Omaha/Valley NE 434 AM CDT Mon Aug 10 2020 IAZ043-055-056-069-079-080-090-091-NEZ011-012-015>018-030>034- 042>045-050>053-065>068-078-088>093-102345- 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- 434 AM CDT Mon Aug 10 2020 This Hazardous Weather Outlook is for portions of southwest Iowa...west central Iowa...east central Nebraska...northeast Nebraska and southeast Nebraska. .DAY ONE...Today and Tonight Isolated showers and storms are possible this morning and today as a cold front continues to move southeast through the area. The front is expected to reach far southeast Nebraska by 7pm and may stall out after the it crosses into northeast Kansas/northwest Missouri. While an isolated storm or two may become severe, widespread severe activity is not expected at this time. The best chance for any severe activity will be in far southeast Nebraska, extending into KS/MO. .DAYS TWO THROUGH SEVEN...Tuesday through Sunday Periodic showers and storms continue to be possible into this weekend. Severe storm potential is uncertain at this time. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The Sioux Falls radar (KFSD), 140 km away, was scanning. The volume nearest the first event began at 11:10 UTC.
14 thunderstorm wind. Local standard time, as filed.
Public reported a large tree down by the Missouri River near Niobrara, NE.
Emergency Manager reported a large old tree blown down.
Emergency manager reported a large tree down from wind.
Personal weather station measured a wind of 54 kts.
Public personal weather station measured a wind gust of 54 kts.
Tekamah ASOS measured a wind of 59 kts.
Public personal weather station measured a wind of 67 knots.
Public personal weather station measured a wind of 54 knots.
Former NWS Employee called in estimating winds at 60 mph.
Omaha Eppley Airfield ASOS measured a wind gust of 58 kts.
Public called in with reports of large tree branched, up to 10 inches in diameter, broken from winds.
Lincoln Airport ASOS measured a wind gust of 54 kts.
Emergency management reported tress and power lines down in Bellevue, La Vista, and Papillion. Some homes were damaged by trees.
Omaha Public Power District reported crews responding to widespread power outages in Omaha due to straight line wind damage.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nebraska in 2020Every state in 2020This day in weather historyWarnings in Nebraska, August 2020
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: 915763, 915725, 915726, 915727, 915747, 915728, 915729, 915730, 915738, 915748, 915740, 915741, 915743, 915745.