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A Focus on Flash Flood Operations

A Focus on Flash Flood Operations. Session Chair: George McKillop Facilitator: Alan Rezek. The Areal Flood vs. Flash Flood Dilemma. Flash Flood/Areal Flood Definitions Lack of Standardization Related to Product Issuance WFO Collaboration Headwater Points & Response Times in Under 6 Hours

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A Focus on Flash Flood Operations

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  1. A Focus on Flash Flood Operations Session Chair: George McKillop Facilitator: Alan Rezek

  2. The Areal Flood vs. Flash Flood Dilemma • Flash Flood/Areal Flood Definitions • Lack of Standardization Related to Product Issuance • WFO Collaboration • Headwater Points & Response Times in Under 6 Hours • Improving Flash Flood GPRA

  3. Facilitated Discussion Instructions • Flash Flood Definition 8:15 – 8:30am • Topical Breakout/Work Groups 8:30 – 9:55am • Lack of Product Standardization • WFO Collaboration • Headwater Points & Response Times < 6 hrs • Improving FFW GPRA • Breakout Session 8:30 – 9:15am • Facilitated Group Brainstorming • General Session 9:15 – 9:55am • 5 minute report out; 5 minute discussion

  4. Issue: Flash Flood/Areal Flood Definition • Briefly describe any problems your office has dealt with regarding the vagueness of the Areal and Flash Flood definitions and also elaborate on any methodologies your office uses to deal with this vagueness to assist in the watch/warning and verification phases.

  5. Flash Flood Definition • Homework assignment • Summary of input from all office • Definitions from NWSI 10-950 and 10-922 • Definitions from NWSI 10-1605 (Storm Data) • Differences fell into 3 categories • Time to onset • Severity • Character

  6. Flash Flood Definition • Timing (time to onset) • 6 hours or less most common answer • 6 hours – 12 offices • 3-5 hours – 1 office • 3 hours – 2 offices • Few hours – 1 office • < 9 hours – 1 office • “Wall of water” – 1 office • Non-specific – 5 offices

  7. Flash Flood Definition • Severity • 10 offices reference severity or damages • 4 offices do not • 2 offices referenced geographic scope as a factor • Character • 5 offices specifically used the term “Convective” • Additional offices referenced the “convective season”

  8. 10-950 vs 10-922 vs 10-1605 • 10-950 “Definition and General Terminology” • Provides a definition of a flash flood • 10-922 “WFO Hydrologic Products Specification” • Provides flood product specification • Provides issuance criteria • 10-1605 “Storm Data Preparation” • Provides a definition of a flash flood • Provides general guidelines for the determination of a flash flood • Provides suggested specific guidelines • Low-impact flooding vs. threat to life or property • Beginning time and ending time

  9. Flash Flood Definition • 10-950 & 10-1605 are similar. A good definition? • Flash Flood – a rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within 6 hours of the causative event (e.g., intense rainfall, dam failure, ice jam), However, the actual time threshold may vary in different parts of the country. Ongoing flooding can intensify to flash flooding in cases where intense rainfall results in a rapid surge of rising flood water.

  10. Facilitated Discussion Instructions • Flash Flood Definition 8:15 – 8:30am • Topical Breakout/Work Groups 8:30 – 9:55am • Lack of Product Standardization (Steve Kreighton) • WFO Collaboration (Dave Radell) • Headwater Points & Response Times < 6 hrs (Laurie Hogan) • Improving FFW GPRA (David Vallee) • Breakout Session 8:30 – 9:15am • Facilitated Group Brainstorming • General Session 9:15 – 9:55am • 5 minute report out; 5 minute discussion

  11. 10-1605 vs Team Recommendation • 2003 ER FFW/FLW Policy Team • Pete Jung (Team Leader) • John Chiarmonte, Julia Dian-Reed, Keith Lynch, Mike Moneypenny, Walt Nickelsberg, John Sikora, Laurie Hogan • No RFC presence? – how did we let that happen? • Deliverables • A letter of findings and recommendations • A 3-page reference document, which included definitions, examples, verification criteria and guidelines (flash, areal, minor & urban) • Recommendations very similar to 10-1605 • Decision was made to forgo adopting policy on the strength of 10-1605

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