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Hydrologic Hazard Communication. Britt Westergard Service Hydrologist WFO Jackson, KY WAS*IS Workshop, July 2006. NOAA’s National Weather Service. NOAA’s National Weather Service. Major Challenges. NWS issues flood warnings? Really? Products vs Information Verification vs Perception
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Hydrologic Hazard Communication Britt Westergard Service Hydrologist WFO Jackson, KY WAS*IS Workshop, July 2006 NOAA’s National Weather Service NOAA’s National Weather Service
Major Challenges • NWS issues flood warnings? Really? • Products vs Information • Verification vs Perception (focus on Flash Flood Warnings)
Multi-tiered Concept Products vs. Information • Ready • Outlooks • Set • Watches • Go • Warnings • Advisories
NWS Hydrologic Products Products vs. Information • Hydrologic Outlook (ESF) • Areal Flood Watch (FFA) • Flood Watch for Forecast Points (FFA) • Flash Flood Warning (FFW) • Flash Flood Statement (FFS) • Flood Warning for Forecast Points (FLW) • Flood Statement – Follow-up to Flood Warning for Forecast Points (FLS) • Areal Flood Warning (FLW) • Flood Statement – Follow-up to Areal Flood Warning (FLS) • Flood Statement – Areal Advisories (FLS) • Flood Statement – Flood Advisory for Forecast Points • Hydrologic Statement (RVS) • Hydrologic Summary (RVA) • River and Lake Forecast Product (RVD) • Hydrometeorological Data Products (RRx) • Hydrometeorological Data Summary Products (HYx)
Outreach Products vs. Information We provide: • Actions to take (“Turn Around, Don’t Drown”) • Information sources (NWR, internet) • Call-to-action statements in products But is the public… • bogged down by flash flood vs. areal flood vs. river flood? • confused by watches and warnings? What about advisories?
Flash Flood vs. River Flood Verification vs. Perception • 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 Guidelines Verification vs. Perception • 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).
Opportunities for Change: • Bridge 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? • Guidelines are based on safety – is there a better basis? • Convey uncertainty in short- and long-fused products