Key Features of HURREVAC

HURREVAC (short for Hurricane Evacuation) is a storm tracking and decision support tool. The program combines live feeds of tropical cyclone forecast information with data from various state Hurricane Evacuation Studies (HES) to assist the local emergency manager in determining the most prudent evacuation decision time and the potential for significant storm effects such as wind and storm surge.

HURREVAC in an EOCMany Emergency Operations Centers use HURREVAC as a situational awareness and briefing tool.

Program access is restricted to officials in government emergency management. As a general rule, if you are the Emergency Manager for a county in the hurricane prone states (Texas to Maine), in Puerto Rico or the Virgin Islands, state Emergency Management Agency (EMA), a FEMA office, Corps of Engineers office, or National Weather Service office, you are eligible to use the HURREVAC program.

The program is distributed free-of-charge to eligible users who register here.

What can HURREVAC do?

HURREVAC tracks hurricanes using the National Hurricane Center's Forecast Advisories. The software translates forecast track and wind extent information from the NHC's text-based products into interactive maps and reports that are used to chart the progress of an advancing storm. The program also assembles rainfall, flood, tide, and river forecast information from various sources to assist users in evaluating inland flooding threats.

The most key feature of HURREVAC, however, is its ability to keep to the local emergency manager apprised of how many hours (or days) a community has for preparation and planning in advance of a threatening storm. As new forecast information becomes available, HURREVAC continually updates and reports on the community's Evacuation Start Time, or last possible time by which an evacuation could be initiated if it is to be completed before the arrival of the storm hazards.

The decision to evacuate a community is not always an easy or obvious one and the advantage of fine-tuning your Evacuation Start Time in HURREVAC is that you can base decisions upon the closest (and therefore most accurate) projections for the storm track, intensity, and size.

HURREVAC cannot make the evacuation decision for you. It is merely one tool that you may elect to use to help you in the hurricane decision-making process. Evacuation decisions are very complex and should only be made after consultation with all officials involved in the process, from NHC and the Weather Service, to state and local emergency management officials.

How is the Evacuation Start Time calculated?

HURREVAC arrives at an evacuation decision time using input from the official hurricane forecast and the Hurricane Evacuation Study for the county or parish of interest.

In Legacy desktop HURREVAC: To determine the arrival time of tropical storm force winds, the program takes a worst-case scenario of a direct hit in which the movement speed and wind extents of the official forecast are retained, but the track is straightened and redirected to the county of interest. A clearance time (or number of hours to evacuate) is selected from a matrix of times in the local HES based upon storm intensity (SS Category) and various local factors. Subtracting the number of clearance time hours from the arrival of the first hazards, we arrive at an earlier point in time....the Evacuation Start Time.

In new web-based HURREVAC: There are a few key differences (and advantages) to how the Evacuation Start Time calculation is handled on the new platform. The first difference is for timing the start of the hazards: NHC's wind probability product is used to determine the most likely time of onset as far as 120 hours into a forecast period. The other change is with how clearance times are selected and used in the analysis. Whereas desktop HURREVAC requires the selection of single clearance times for its calculations, web-based HURREVAC allows the user to retain a range of clearance times to consider in reports.