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Iowa derecho, Aug 10, 2020

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Iowa derecho, Aug 10, 2020

Iowa derecho, Aug 10, 2020

Chapter 1 · Out of Nebraska

The derecho's line begins in eastern Nebraska.

The Storm Prediction Center's line starts early in the morning. The storms race east across Iowa, with wind damage reported in Des Moines before noon.

13:16UTC · Mon, Aug 10, 2020 · 8:16 AM CDT

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Replay of past events. For current weather and warnings, see weather.gov. Links are rule-based facts. About and credits

Replay · DE20200810

Iowa derecho: the story

Aug 10, 13:00 UTC – Aug 11, 03:00 UTC. Radar, severe thunderstorm and tornado warnings, storm reports and ground stops, in order, with 432 links that show their evidence.

  • 233 NWS warnings
  • 859 storm reports
  • 3 FAA airport programs
  • 1 derecho track (SPC)
  • 432 rule-based links
  • 756,193 customers out at the peak, in Illinois
  • 421 radar frames

Out of Nebraska

Aug 10

  1. The derecho's line begins (Storm Prediction Center).Replay from here

Across Iowa

Aug 10

  1. The strongest measured gust: 126 mph at Atkins, IA.Replay from here

Illinois

Aug 10

  1. NWS La Crosse, WI issues the first Tornado Warning.Replay from here
  2. The largest hail reported: 2 in at 1 NE Freeport, IL.Replay from here

Into the night

Aug 10–11

  1. Peak outages: 756,193 customers out of power in Illinois. The most in one county: Cook County, IL, 279,858 out (13% of its customers) at 02:30 UTC.Replay from here
  2. The derecho's line ends, 690 mi from where it began.Replay from here

How we link records

RuleWhat it checksLinks
R4 solidA storm report inside a warning polygon while it was in effect424
R2 dashedAn airport program inside a warning that had been in effect for over 60 min (context)3
R1c solidA weather airport program inside a convective warning or watch, within 60 min of issuance5

Solid lines mark rules that passed an independent check; dashed lines are context. Links are rule-based facts: each shows two records that overlap in place and time. How we know

Where this storm's data comes from

Every layer, the provider behind it and the period it covers.

LayerProviderPeriodRecords
MRMS SeamlessHSRNOAA/NSSL via Iowa Environmental MesonetAug 10, 13:00 UTC – Aug 11, 03:00 UTC421
NWS storm-based warning polygonsNOAA National Weather Service via Iowa Environmental MesonetAug 10, 13:00 UTC – Aug 11, 03:00 UTC233
NWS Local Storm ReportsNOAA National Weather Service via Iowa Environmental MesonetAug 10, 13:00 UTC – Aug 11, 03:00 UTC859
SPC derecho tableNOAA Storm Prediction CenterAug 10, 13:00 UTC – Aug 11, 03:00 UTC1
FAA airport programs (ground stops and ground delay programs)FAA Air Traffic Control System Command CenterAug 10, 13:00 UTC – Aug 11, 03:00 UTC3
ORNL EAGLE-IOak Ridge National LaboratoryAug 10, 13:00 UTC – Aug 11, 03:00 UTC546
  • Radar: NOAA/NSSL MRMS SeamlessHSR, via the Iowa Environmental Mesonet (IEM), Iowa State University
  • Warnings: NOAA/NWS, storm-based polygons via the Iowa Environmental Mesonet
  • Storm reports: NOAA/NWS Local Storm Reports via the Iowa Environmental Mesonet
  • Airport programs: FAA Air Traffic Control System Command Center
  • Derecho path: NOAA/NWS Storm Prediction Center derecho table (Squitieri et al. 2026)
  • Power outages: Oak Ridge National Laboratory, EAGLE-I (CC BY 4.0)
  • County boundaries: U.S. Census Bureau