Program Overview

This page contains answers to common questions asked about HURREVAC programs:

What is HURREVAC?
How does HURREVAC work?
Who can use these HURREVAC programs?
Does HURREVAC make an evacuation decision for me?

What Is HURREVAC?

HURREVAC stands for HURRicane EVACuation program on a computer. The program was developed by Sea Island Software, Inc. beginning in 1988, in response to a need for computer based management of data produced by various federal Hurricane Evacuation Studies.

These studies were produced for discrete regions of the country (usually a state, or in the case of Florida, a portion of a state). The purpose of the studies, and of HURREVAC, is to assist government emergency managers in making decisions for their states/communities when under a hurricane threat.

First major use of the program came with Hurricane Hugo (1989) in South Carolina and Georgia. Subsequently, the program was developed for 13 states, the US Virgin Islands and Puerto Rico.

Because the program uses information specific to a community, large portions of the program had to be designed specifically for each area and had to await a federal hurricane evacuation study for the area in question. 10 years later, in 1998, a new HURREVAC, for the Windows 95/98/NT platform, dubbed HurWin95, was developed by Sea Island Software, incorporating features developed over the previous 10 years in Hurrevac and Hurrevac Inland Winds (1994). HURREVAC for Win 95/NT is more generic, applying to all states and counties, with specific data and map plug-ins available to customize the program for state/local use. In 2000, Hurrevac 2000 was introduced, an upgrade which added NWS official rainfall forecasts out to 3 days and East and Central Pacific tracking capability.

How does HURREVAC work?

HURREVAC tracks hurricanes on computer plot maps using information from the National Hurricane Center (National Weather Service, NOAA) and does its job of estimating when various evacuation decisions should be made, using data from the federal hurricane evacuation study for the area. The process works this way:

  1. The arrival of gale (34 knots or 39mph) winds in your area is computed using the NHC projections with adjustment for a direct-hit or worst-case approach to your community
  2. Clearance times (the time it takes to get occupants out) are computed using Saffir-Simpson Scale Category of Storm, Response of the public, and Occupancy readings for the area. The basic data for the clearance times is produced by a local Hurricane Evacuation Study, usually performed by the Corps of Engineers, National Weather Service and FEMA.
  3. The clearance time is subtracted from the gale arrival time to reach a suggested Evacuation Decision Time. This approach is based on the need to have the at-risk population out of vulnerable areas before gales reach the coast (when trees begin to block roads and causeways begin to inundate).

Storm Surge Inundation graphics, where available, are also displayed by the program, using data from the National Weather Service SLOSH (Sea, Lake and Overland Surge from Hurricanes) model.

Who can use HURREVAC?

HURREVAC 2000, HURREVAC for Win95/98/NT , DOS HURREVAC and HURREVAC Inland Winds are programs restricted for use by the official government emergency management community.

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.

Does HURREVAC make an evacuation decision for me?

No. 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. The program's output is only as accurate as the forecasts (from the NHC) they are based on.

If the NHC is producing accurate forecasts, the program's output will also be close to the mark...but if forecast errors are great, the program will also perform poorly since it is based on the NHC data. The program quantifies the standard NHC error and displays it within the program to show you what errors could occur.