  On October 14th, 2016, the station of Tofino (British Columbia, Canada)
issued the first ever real-time tsunami alert triggered by a coastal
High-Frequency Radar system, based on the identification of abnormal surface
current patterns. The detection occurred in the absence of any reported seismic
event but coincided with a strong atmospheric perturbation, which qualified the
event as meteo-tsunami. We re-analyze this case in the light of a new radar
signal processing method which was designed recently for inverting fast-varying
sea surface currents from the complex voltage time series received on the
antennas. This method, based on an Auto-regressive modeling combined with a
Maximum Entropy Method, yields a dramatic improvement in both the
Signal-to-Noise Ratio and the quality of the surface current estimation for
very short integration time. This makes it possible to evidence the propagation
of a sharp wave front of surface current during the event and to map its
magnitude and arrival time over the radar coverage. We show that the amplitude
and speed of the inferred residual current do not comply with a Proudman
resonance mechanism but are consistent with the propagation of a low-pressure
atmospheric front and wind vectors as revealed by satellite imagery. This
indicates that the event that triggered a tsunami alert is more likely a storm
surge than a true meteo-tsunami. Beyond this specific case, another outcome of
the analysis is the promising use of oceanographic radars as proxy's for the
characterization of atmospheric fronts.
