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Flash Flood Warning Best Practices

Flash Flood in ILN

Flash flooding is the second most deadliest form of severe weather in the United States over the past 70 years. Flash Flood Warnings and their follow-up statements are some of the most visible products issued by the National Weather Service (NWS). Issues with these products can result in confusion on the part of the general public and our partners, and result in increased risk to life and property. Best practices and recommendations have been made based on the assessment of performance and warning practices documented in some of NOAA’s NWS Service Assessments, such as the Southeast United States Floods of September 18-23, 2009 and the Record Floods of Greater Nashville: Including Flooding in Middle Tennessee and Western Kentucky of May 1-4, 2010 assessments.

As part of the FY11 National Strategic Training Educational Plan (NSTEP), the NWS Warning Decision Training Division (WDTD) has developed training on best practices for issuing basin-based flash flood warnings, such as the explicit use of  enhanced wording (“Flash Flood Emergency”). Much of the training on the use of “Flash Flood Emergency” are based on updates to NWS Instruction 10-922 and NWS Service Assessments. The lessons from this course are an extension of the storm-based warning training and the Flash Flood Warning Decision Making using FFMP-Advanced training. These lessons are intended to help the warning forecaster with these specific job-related tasks:

Performance Objectives for Course:

  1. Forecasters will identify the criteria needed for issuing a "Flash Flood Emergency."
  2. Forecasters will demonstrate proficiency at using enhanced wording in warnings and follow-up products (e.g., "Flash Flood Emergency" or "life-threatening") so the threat is put in the appropriate context.
  3. Forecasters will identify strategies for best communicating the severity of an event.
  4. Forecasters will demonstrate proficiency at drawing warning polygons that will encompass the threat area (not always entire counties) and their immediate downstream basins.
  5. Forecasters will identify and apply threat assessment strategies to anticipate severe flash flooding.

LMS Note to NWS Personnel:

To receive credit for completing the Flash Flood Warning Best Practices Training, you must complete the course requirements through the NWS Learning Center!

Notes About LMS Completions for this Course - Use this page to help with enrolling a student into a development plan and the WES ILT session for the course.

LMS Course Launch Page

Course Completion Instructions:

  1. Complete the Tornado and Severe Thunderstorm Warning Best Practices course.
  2. Review the standardized anomalies approach shown in AWOC Winter IC 4.2 - Building and Applying a Climatology:
  3. Complete all lessons in Flash Flood Warning Best Practices course, including the WES simulation.

Flash Flood Warning Best Practices Course Outline:

Use the tabs below to view the details on each part of this best practices course. For the online modules, you have the ability to view or download the presentations from here. Remember to login to the LMS to receive credit for the course and the WES simulation.

Part 1: FFMP and Issuing Basin-Based Flash Flood Warnings

Description: This lesson is an updated version of Lesson 4: Best Practices with FFMP-A and Issuing Basin Based Flash Flood Warnings from the Flash Flood Warning Decision Making Using FFMP-Advanced training created in 2008. This lesson steps you through the process for integrating FFMP-A data into the actual flash flood warning process. Warning polygon and text strategies for issuing basin-based flash flood warnings are also described here.

Time of Lesson: 35 minutes

Download Best Practices Rationale Lesson(8.8 MB ZIP file) or Play Presentation

Part 2: How and When to Use "Flash Flood Emergency"

Description: This lesson focuses on the usage of the "Flash Flood Emergency" wording during an extreme, high-impact flash flood event. The lesson will describe the criteria for using a "Flash Flood Emergency" as well as ways of specifically communicating the severity of the impact. Examples of previous flash flood emergencies used in a variety of scenarios, such as anomalously high rainfall and high-impact dam failures, are described in this lesson.

Time of Lesson: 30 minutes

Download Best Practices Rationale Lesson(11.0 MB ZIP file) or Play Presentation

Part 3: The Meteorology Behind Extreme Rain Events

Description: This lesson provides a basic strategy on being able to identify and anticipate severe flash flooding characterized by anomalously high rainfall. The course breaks down the individual meteorological components that impact rainfall duration and rain rates through atmospheric analysis and standardized anomalies. This course also focuses on pattern recognition and rainfall climatology in identifying significant rainfall and flash flood events.

Time of Lesson: 40 minutes

Download Best Practices Rationale Lesson(61.2 MB ZIP file) or Play Presentation

Application via WES Simulation

Description: A WES simulation was developed using a recent flash flood event located in the Wilmington, Ohio (ILN) county warning area to compliment the online training material for this course. Participants will have an opportunity in this simulation to analyze the mesoscale environment and utilize radar and FFMP data to issue flash flood warnings and follow-up statements. Emphasis is placed on identifying an extreme rainfall/flooding situation and issuing a "Flash Flood Emergency" based on observations and local storm reports.

Time of Simulation: 2.5 hours

The 18 GB case is available on one DVD that was mailed to the SOO (or training facilitator) at each forecast office and other select locations. The simulation guides for the WES case were delivered to each location on a CD. You can also obtain a copy of the facilitator and student simulation guides here by clicking on the download buttons below.

Facilitator Guide --Download Limiting the Number of Countiesi in Warnings Lesson(22.6 MB PDF)
Student Guide --Download Limiting the Number of Countiesi in Warnings Lesson(3.0 MB PDF)

*** NEW: PDF document of WES Simulation Performance Objectives where the student can type his/her answer into the document. The document has the ability to be emailed afterwards to a WDTD instructor via a button on the top of the first page.

Performance Objective Sheet --Download Limiting the Number of Countiesi in Warnings Lesson(0.3 MB PDF)


At the end of the simulation, the student has access to two post-brief interactive maps. These maps provide additional information on the case, including details for each local storm report, CoCoRaHS rain gauge data, stage hydrographs from USGS river gauge data, and basin trace graph animations. The links for the two post-brief maps are provided here:

If you were not on the initial mailing list for the WES Simulation, please contact us so we can deliver you a copy of the simulation and associated guides.

You can access the references and material used for the course by clicking on this link for the Reference Page.


WDTD welcomes your feedback on how well this training and simulation supported your understanding of flash flood warning decision making. Please send us your comments! Thanks!


* Image above is courtesy of Dennis Brown at the Lewis County Herald

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Page last modified: April 3, 2015 10:05

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