Time Series for Storm Indices, Winter 1996 Returning to the comparison of signal strength with storm indices, we note the general agreement between the rise in the water level and the decrease in signal strength. However, the interference model must be verified in detail and used to extract the strength of the direct ray alone before definite conclusions can be drawn. For instance, there could be a general increase in the wind strength in December, roughening the surface and decreasing the contribution of the reflected ray to the overall signal strength.