Counting on the Contingencies: How Quickly Evolving IDSS Strategies Enhanced Services during the Record Mississippi River Flood of Spring 2019

A wet fall of 2018 and a cold, snowy winter of 2018-2019 primed the Upper Mississippi River watershed for flooding. Late season heavy snows and a very wet May then caused the longest period of continuous flooding in Mississippi River recorded history.

This flood produced extensive economic impacts and property damage. The duration of the flood with multiple crests led to damages in areas not typically impacted, and temporary flood protection barriers breached in the cities of Davenport and Burlington Iowa, causing millions of dollars of damages. Because of high water, the Lock and Dam system was closed to river traffic for months, creating an economic impact to industries needing to transport materials and goods at a time of the year when barge traffic is typically high due to agricultural needs.

The National Weather Service (NWS) Quad Cities had constant two-way communication with partners about the potential for near record or record flooding beginning in February, at least 6 weeks prior to the first crest. This communication continued throughout the event in order to keep decision-makers informed on the changing risks they would encounter as the long duration event evolved. It was discovered that numerous needs from core partners were not being met by current NWS products and services, particularly concerns about the potential for the river to reach higher levels than deterministic forecasts would indicate. To provide the decision support our partners needed, the NWS Quad Cities developed new methods, including quasi-probabilistic data leading up to each individual crest. These methods delivered the information our partners needed to prepare resources and to take protective measures to reduce their risk.

This flood broke records and pushed the NWS Quad Cities staff to new levels of service as they worked through forecasting and messaging a challenging event involving saturated soils, deep frost, above normal snow, and heavy rainfall that persisted for almost 5 months and included 3 separate top 10 crests. These services did provide the necessary information for partners to take action and minimize the eventual impacts.