The City & County of Honolulu Department of Emergency Management has its own volunteer program, organized into six geographical districts. The Radio Amateur Civil Emergency Service is a federal program, although RACES groups are administered at the local level. Oahu RACES falls under DEM, and is therefore another one of its volunteer resources. Although my primary position is with the District 1 volunteer group, I am registered as a RACES member, because of federal rules that limit participation in RACES operations to hams who are registered in the RACES program. During an emergency, the FCC could theoretically order amateur radio operators not engaged in RACES operations off the air. The leaders of Oahu RACES are aware of the fact that in the event of an activation, I will be serving with District 1. There are in fact, many RACES members with predetermined assignments. In the event that a situation existed in which RACES was activated while District 1 was not, I would then be available to serve as a general assignment RACES volunteer.
The function of RACES (pronounced RAY-seez) is to facilitate the operation of government during emergencies when normal communications channels are disrupted or overwhelmed. ARES, the Amateur Radio Emergency Service (pronounced AIR-eez) is a non-governmental program sponsored by the American Radio Relay League, which provides disaster communications services under the general rules of the amateur radio service, rather than more restrictive rules that apply specifically to RACES operations. Many hams are members of both RACES and ARES, so they can "switch hats" and serve the government when government needs them and serve other disaster relief organizations after RACES operations cease.
Skywarn is a program of the National Weather Service. Skywarn volunteers receive training so they can observe weather conditions and provide valuable information to NWS forecasters during events such as flood-producing heavy rains, damaging winds, or the formation of funnel clouds. Many Skywarn volunteers are ham radio operators, and if conditions warrant, hams may station themselves at the NWS office so other hams can report their observations via radio.
Of course, disasters are unpredictable, and you may find yourself unable to do what you planned to do. For that reason, many emergency service volunteers practice at fulfilling different roles: hams who plan to report to an emergency operating center practice and prepare to operate from an evacuation shelter; hams who plan on reporting to a hospital may practice taking weather reports at the NWS; hams who plan to operate from a shelter practice using the radio consoles at the DEM main EOC; some of us have participated in drills with the American Red Cross; many hams have taken classes at the police academy to direct traffic.
One of the reasons I provide communications support at many parades and athletic events is because it's good practice for responding to emergencies. I get to test out my equipment, and get to exercise my skills during a limited-duration event under moderately challenging conditions.