Secondary Eyewalls in HWRF and HMON, Too Few? Too Many?

While in the past years mesoscale numerical models have struggled to generate secondary eyewalls, it has been shown that HWRF successfully generates secondary eyewalls. In this work we show that HMON, the other NCEP mesoscale model exclusively designed for hurricane forecast, also generates secondary eyewalls. While in recent years there have been concerns that HWRF generates too few secondary eyewalls in its operational setting, with only few cycles generating them at the time they are observed in nature, in this talk we show how some storms have remarkably consistent secondary eyewall forecasts and even some storms where more secondary eyewalls than observed are numerically generated. We focus on Harvey, Irma and Maria, given their exceptionally well observed concentric eyewalls and including multiple secondary eyewalls in case of Irma.