Rip Currents--Killer Currents Jim Lushine

Outline of Presentation Rip Current Fatalities Data Forecasting Verification NWS Products Future Work

Rip Current Fatalities

Southeast Florida Rip Current Fatalities

Florida Rip Current Fatalities

Florida Weather-related Fatalities

United States Rip Current Fatalities

Weather-related Formation Factors 1. Local Gradient Wind 2. Swell

Non-Weather-related Formation Factors Time of Low Tide* Persistence Tidal Currents Deep Water Currents (e.g. Gulf Stream) Seismological Factors *SE Florida Coast

Data

Florida Marine Observations

Four Factors in Forecasting Rip Currents

Wind Factor

Gradient Wind vs Rip Current Fatalities along SE Florida Coast

Gradient Wind vs Non-Rip Current Fatalities along SE Florida Coast

Sea Breeze Effect

Convective Wind Initiation

Swell Factor

Swell Height* vs Rip Currents <2 Feet---No effect on rip currents 2-7 Feet---Mdt Risk of rip currents >7 Feet---High Risk of rip currents *Swell Period also important

Tidal Factor

Faster Rip Current near Low Tide

Tidal Variation of Fatalities

Weaker Swimmers Can go Farther Offshore?

Persistence Factor

Days Between Initiation of Rip Currents and the First Fatality

Gradient Winds vs Residual Rip Current Fatalities in SE Florida

Beach Patrol Rescue Reports

Daily Rip Current Risk 1=Low 2=Moderate 3=High

Verification

NWS Rip Current-Related Products Surf Forecast Hazardous Weather Outlook Marine Weather Statement Zone Forecasts (Headlines)

Decision to Include in ZFP Weekday vs Weekend/Holiday Improving Weather from yesterday Change in surf conditions from yesterday Low Tide in the afternoon

Future Work

Tidal Variation of Fatalities= Hourly Rip Current Risk?

Beach Geomorphology Renourishment Type of Sand Persistence of Rip Channels

Upcoming Rip Current Events Technical Workshop (April 6-7, 2004) NWS Media Event (May 24, 2004) FACVB meeting (June 10, 2004) COMET Module (Summer 2004)

Florida’s Uniform Flag Warning System

The End