your assumption that the total variability of the storms can be fit into little boxes is fallacious.
No two storms are identical and each individual storm is constantly variable such that a classification is continuously variable.
wind speed is the only measurable variable
See post 9 and get back to me. Plus, N'oreaster forecasts factor in fetch for severity of surge and waves, so it is do-able. Water is the biggest killer and most damaging component of most hurricanes. So forecasts need to do more to factor in surge and rainfall.