1. Hydrologic Hazard Communication Britt Westergard Service Hydrologist WFO Jackson, KY WAS*IS Workshop, July 2006 NOAA’s National Weather Service

2. Major Challenges NWS issues flood warnings? Really?NWS issues flood warnings? Really? Products vs InformationProducts vs Information Verification vs PerceptionVerification vs Perception (focus on Flash Flood Warnings)

3. Multi-tiered Concept ReadyReady –Outlooks SetSet –Watches GoGo –Warnings –Advisories Products vs. Information

4. NWS Hydrologic Products Hydrologic Outlook (ESF)Hydrologic Outlook (ESF) Areal Flood Watch (FFA)Areal Flood Watch (FFA) Flood Watch for Forecast Points (FFA)Flood Watch for Forecast Points (FFA) Flash Flood Warning (FFW)Flash Flood Warning (FFW) Flash Flood Statement (FFS)Flash Flood Statement (FFS) Flood Warning for Forecast Points (FLW)Flood Warning for Forecast Points (FLW) Flood Statement – Follow-up to Flood Warning for Forecast Points (FLS)Flood Statement – Follow-up to Flood Warning for Forecast Points (FLS) Areal Flood Warning (FLW)Areal Flood Warning (FLW) Flood Statement – Follow-up to Areal Flood Warning (FLS)Flood Statement – Follow-up to Areal Flood Warning (FLS) Flood Statement – Areal Advisories (FLS)Flood Statement – Areal Advisories (FLS) Flood Statement – Flood Advisory for Forecast PointsFlood Statement – Flood Advisory for Forecast Points Hydrologic Statement (RVS)Hydrologic Statement (RVS) Hydrologic Summary (RVA)Hydrologic Summary (RVA) River and Lake Forecast Product (RVD)River and Lake Forecast Product (RVD) Hydrometeorological Data Products (RRx)Hydrometeorological Data Products (RRx) Hydrometeorological Data Summary Products (HYx)Hydrometeorological Data Summary Products (HYx) Products vs. Information

5. Outreach We provide: Actions to take (“Turn Around, Don’t Drown”)Actions to take (“Turn Around, Don’t Drown”) Information sources (NWR, internet)Information sources (NWR, internet) Call-to-action statements in productsCall-to-action statements in products But is the public… bogged down by flash flood vs. areal flood vs. river flood?bogged down by flash flood vs. areal flood vs. river flood? confused by watches and warnings? What about advisories?confused by watches and warnings? What about advisories? Products vs. Information

6. Flash Flood vs. River Flood Short-fused events (FFW) and long-fused events (FLW) River flood warnings – –related to hydrograph - graphical association – –would be relatively simple to introduce uncertainty graphics – –verification = perception (exceed flood stage is cut & dried) Flash flood warnings – –less quantifiable – –Verification and perception diverge? Verification vs. Perception

7. Verification Guidelines A Flash Flood occurs within 6 hours of a causative event: River or stream flows out of its banks and is a threat to life or property. Person or vehicle is swept away by flowing water from runoff that inundates adjacent grounds. A maintained county or state road is closed by high water. Approximately six inches or more of water flows over a road or bridge. This includes low water crossings in a heavy rain event that is more than localized (i.e., radar and observer reports indicate flooding in nearby locations) and poses a threat to life or property. Dam break or ice jam release causes dangerous out of bank stream flows or inundates normally dry areas, creating a hazard to life or property. Any amount of water in contact, flowing into or causing damage of an above ground residence or public building and is runoff from adjacent grounds. Three feet or more of ponded water that poses a threat to life or property. Mudslide, rock slide or debris flow caused by rainfall (could possibly occur in a burned area with only light to moderate rainfall). Verification vs. Perception

8. Opportunities for Change: Bridge gap between products and action takenBridge gap between products and action taken –Determine usefulness of product suite? –Modify outreach strategy? –Reach back to concept of products to re-evaluate? What is a flash flood anyway?What is a flash flood anyway? –Guidelines are based on safety – is there a better basis? Convey uncertainty in short- and long-fused productsConvey uncertainty in short- and long-fused products