Initial Evaluation of NOAA Probabilistic Rip Current Forecast Model: Path to National Implementation
Jung-Sun Im, NOAA/NWS/OSTI/MDL, Silver Spring, MD
Michael Churma, NOAA/NWS/OSTI/MDL
Stephan Smith, NOAA/NWS/OSTI/MDL
Gregory Dusek, NOAA/NOS/CO-OPS
Andre van der Westhyusen, IMSG@NWS/NCEP/EMC

Abstract
The National Weather Service (NWS) and the National Ocean Service (NOS), in a collaborative effort, are transitioning the NOAA probabilistic rip current forecast model into NWS operations.This model predicts the statistical likelihood of hazardous rip currents, using a logistic regression technique with predictor inputs of significant wave height, mean wave direction, water level, and a bathymetry proxy.In a staged implementation along the US coasts, the model is now being run experimentally as a component of the National Center for Environmental Prediction (NCEP)ís Nearshore Wave Prediction System (NWPS) in select areas.††

As the hazardous rip current probability forecasts have been generated, rip current observation reports have been collected from lifeguards in coordination with local NWS Weather Forecast Offices (WFOs).The NWS Meteorological Development Laboratory (MDL) is using these rip current observations to perform validation studies of the model at pilot beaches across the US. The beaches are in widespread locations that can present rip current modeling challenges due to varied wave and beach bathymetry conditions.This presentation will show methods for assessing the quality of lifeguard rip current intensity observations, including challenges of analyzing sparse observation datasets; provide initial verification results such as Brier Scores and Reliability Diagrams for different stratification categories; discuss the interpretation with regard to strengths, weaknesses, and room for improvement; and finally suggest how to improve the model based on the verification scores and detailed investigations.The presentation will conclude with future plans towards operational implementation.