Complex sentence: On October 24, a low-level center was no longer present, and only a small area of convective activity persisted, thus, the system dissipated, and was a remnant low pressure system when the National Hurricane Center issued their last advisories of Alpha.
Split into simpler sentences: On October 24 the low-level center had completely dissolved, and only a small area of convective activity persisted. Thus the system had dissipated, and was a remnant low pressure system when the National Hurricane Center issued their last advisories of Alpha.