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Emergency Management
Essential Tools


In this section, you will learn about some of the main tools emergency managers use in their decision making, planning, and preparedness efforts for potential impacts from tropical storms in their communities:
- Hurricane Evacuation Studies (HES) serve as the foundation for effective hurricane planning (including potential evacuations) for your community. These studies include surveys and analyses that provide the basis for decision-support tools including surge mapping and calculations of evacuation clearance times. This information is also used to anticipate scenarios for planning and preparedness and in HURREVAC (described below) to aid with decision-making during tropical cyclone threats.
- The Technical Data Report provides tools and products of specific HES findings as they apply to a community. This includes surge maps, evacuation zones, and evacuation clearance times.
- HURREVAC is a decision support program, based on the HES, that assists with the evacuation decision-making process. This tool provides county-specific guidance by graphically displaying NHC forecast information along with HES data to better understand evacuation timing scenarios, decision point triggers, and local impacts of weather hazards that may need to be considered when preparing your community.
- Post-storm Assessments serve as vital "after action reports" to evaluate how effectively the products of the HES were used, assess the accuracy of the study data, and collect valuable post-storm data about the behavior of residents, post-storm weather data, and efficiency of the evacuation. This is compiled into recommendations that are used to improve future planning and preparedness.
Hurricane Evacuation Studies

Coastal counties map from Alabama HES
FEMA’s National Hurricane Program conducts Hurricane Evacuation Studies (HES) that are designed to guide the decision-making process for protecting the public when a hurricane threatens an area. These studies are a partnership between various federal, state, and local organizations including the U.S. Army Corps of Engineers, NOAA, the National Weather Service, and state and local emergency management agencies, and the findings are tailored to the specific needs of each coastal community. Organizations can create evacuation and operations plans based on the most relevant information from their comprehensive HES. The HES serve as the basis for emergency management planning efforts-but they are not a plan!
The studies help communities establish specific evacuation plans by:
- Assisting coastal communities in developing evacuation zones, which helps determine where and when the public should be ordered to evacuate as a storm approaches
- Determining the probable effects of hurricanes of various categories, tracks, and forward speeds
- Assessing impacts from storm surge and high winds
- Predicting public response to the threat and advisories
- Identifying appropriate sheltering resources in the community
- Analyzing the utilization and viability of existing road networks and alternative transportation systems
The information in the HES helps officials determine:
- Who is likely to evacuate
- Where individuals are most likely to go when evacuating from a storm, and
- When they need to leave to safely reach their destination
An HES is formally comprised of several components, which are described on the next pages.
Hazard Analysis
WAKULLA COUNTY | |||||||
POINT | POINT | HURRICANE EVENT | |||||
No. | NAME | TS | CAT1 | CAT2 | CAT3 | CAT4 | CAT5 |
1 | Ochlockonee Bridge @ U.S. 98 | 7.1 | 8.4 | 14.1 | 18.9 | 23.2 | 27 |
2 | Turtle Island | 6.8 | 7.7 | 14.3 | 19.3 | 23.8 | 27.5 |
3 | Sopchoppy River | 6.8 | 8.2 | 14.8 | 19.5 | 24.1 | 28.2 |
4 | Ochlockonee River@U.S.319 | 5.1 | 6.3 | 13.3 | 18.7 | 23.2 | 27.3 |
5 | State Rd. 375 @ Hwy 22 | NA | NA | 14.9 | 19.1 | 24.4 | 28.4 |
6 | Bone Bluff | 3.8 | 4.5 | 10.7 | 18.7 | 23.5 | 27.5 |
7 | Sanborn | 3.8 | 4 | 11.9 | 18.9 | 24.6 | 28.6 |
8 | Red Lake | NA | NA | 10.8 | 16.9 | 21.1 | 26.1 |
Surge heights for different category storms at some of the critical locations (points) in Wakulla County, Florida
The hazard analysis is designed to provide a better understanding of a community's vulnerability to storm surge inundation and other weather hazards such as high winds, inland flooding, and tornadoes. The hazards analysis can serve as a valuable planning and preparedness aid to help determine appropriate evacuation zones based on vulnerability due to hazards specific to your local area.
One of the primary goals of the hazard analysis is to determine worst-case storm surge effects. By analyzing surge heights for historical and hypothetical hurricanes that could occur in the study area, along with considering the potential for freshwater flooding, this analysis generates storm surge atlases, discussed later in this section. These surge maps help you determine what category storm may cause storm surge to affect local evacuation routes or which critical facilities might be flooded.
Vulnerability Analysis

Vulnerable evacuating populations in the Delaware, Maryland, and Virginia coastal areas
The primary purpose of the vulnerability analysis is to identify areas, populations, and facilities that are in harm's way, especially those that could be inundated by storm surge or sustain wind damage.
Storm surge data from the hazard analysis is used to develop evacuation scenarios and create a map of potential surge inundation. From there, major medical, institutional, and other critical facilities that are potentially vulnerable to storm surge are identified in addition to populations, transportation networks, and shelters that may be at risk. This is done in partnership with the local emergency managers to ensure that the most relevant evacuation scenarios are used and important populations are targeted.
This information can be used for planning purposes to pre-identify specific needs such as people who may need evacuation assistance, staging areas for special equipment and recovery resources, operational support, and other activities that are critical for evacuation planning. Ideally, this part of the process includes leadership from the community to obtain buy-in and inform decision-making- well before the need to make decisions about evacuations!
Behavioral Analysis

Example behavioral survey data related to evacuation decision-making for residents who indicate they would or would not evacuate based on various storm categories
The Behavioral Analysis is one of the most important and informative portions of the HES. It provides an understanding of residents' attitudes and the potential evacuation response of a community, including residents, visitors, tourists, and those with special needs. The analysis is based on public surveys that often uncover valuable, and sometimes surprising, information about what people believe they will do in response to a tropical cyclone threat. This information is used to create evacuation scenarios that are then used to create baseline evacuation timing estimates.
The Behavioral Analysis provides an estimate of:
- How the public may respond to certain hurricane scenarios
- How likely they are to evacuate
- Details about where they might go, how they might get there, what they might take with them, and when they might leave
- Where they gather hurricane information
This critical data is used in the shelter and transportation analyses and can further guide decision-making and public awareness efforts.

The "Behavioral Response Curve" used to model rapid, medium, and slow evacuation behaviors in response to an evacuation order. This data can be used to model transportation behavior.
The data from the behavioral surveys can also be used to model evacuation behavior. For example, in the graph above, response curves (yellow, blue, and red lines) represent the response time to an evacuation order (or for those who will evacuate prior to an order). In this location, nearly 100% of the population will evacuated within three hours of hearing an evacuation order if they respond quickly (red line), but it could take as much as 9 hours for them to evacuate if their response time is slow (yellow line).
The surveys also reveal other details about evacuations, such as the type of refuge evacuees will seek (shelter, friend/family, hotel, etc.) and how far they will travel. Post-Storm Assessments are another type of study that may also conduct behavioral analyses to determine what people actually did in response to an approaching storm. This can validate the behavioral study results from the HES. Together these analyses can be used to gain a better understanding of when to call for evacuations, when they must be completed, resource planning, timing, decision-making points, and effective safety measures that will need to be taken in a particular community. In the example below, the public was asked about their evacuation for Hurricane Opal in 1995:
Type of refuge in Opal by County (percent) | ||||
Mobile Baldwin | Escambia Santa Rosa | Okaloosa Walton | Bay | |
Evacuate to Public Shelter | 2 | 5 | 7 | 6 |
Stay with Friend or Relatives | 64 | 61 | 57 | 51 |
Go to a Hotel or Motel | 21 | 22 | 21 | 27 |
Other (such as churches or work place) | 13 | 12 | 15 | 16 |
Type of Refuge in Opal by Risk Area (percent) | |||
Beaches | Mainland Surge | Non-Surge | |
Evacuate to Public Shelter | 4 | 8 | 3 |
Stay with Friend or Relatives | 58 | 55 | 68 |
Go to a Hotel or Motel | 26 | 18 | 17 |
Other (such as churches or work place) | 12 | 20 | 12 |
Examples of data from a Behavioral Study that is used to better understand transportation issues (from the Hurricane Opal Post Storm Assessment)
This is valuable information that can then be used in conjunction with other aspects of the study to gain a better understanding of when to call for evacuations, when they must be completed, resource planning, timing, decision-making points, and effective safety measures that will need to be taken in a particular community.
Sheltering Analysis

Public shelter demand and capacity by county
Once a determination has been made about which residents are vulnerable and what residents in evacuated areas will do in response to a threat, the shelter analysis provides estimates of the number of people who will seek public shelter and how many shelter spaces and other resources are needed to accommodate them. State and County emergency management offices can use this information to anticipate sheltering needs and to develop plans to ensure that evacuees seeking public shelter will have adequate and safe shelter space.
One consistent finding from the behavioral analyses has been the trend of very low public shelter demand in many areas. While this finding came as a surprise initially, it makes sense when you consider how people have actually behaved over the past several hurricane seasons. This is one example of information that can be used to anticipate and plan ahead for shelter demand and the evacuation in general.
The shelter analysis also identifies:
- In-county shelter locations
- Out-of-county "host" shelter locations
- Shelter capacities
- Facility vulnerabilities to hazards
- Hotel capacities
- Shelter usage (public schools, community colleges, other alternatives)
- Potential impact of "shadow" evacuees-those who are not from areas where evacuation is recommended-and/or evacuation behavior of neighboring states
Transportation Analysis
During a hurricane evacuation, often a significant number of vehicles have to move on the road network in a relatively short period of time. For this process to be successful (i.e., all residents reach safety quickly and safely), planning and coordination is crucial.
Effective evacuation planning includes many variables including:
- The peak summer travel and vacation season
- Daily traffic demands (background traffic)
- Construction
- Road capacities and local features of the road network
- Coordination of public transportation, rail, and bus activity
- Tolls, bridges, and isolated areas
In some areas, massive bottlenecks or traffic congestion could occur, which could be disastrous if people are caught on the roads when the storm hits. The transportation analysis helps avoid this by providing evacuation clearance times that are used to plan for the timing needed for an evacuation based on a number of scenarios. The single largest factor influencing evacuation clearance times for many areas is tourist occupancy, followed by storm category.
The diagram below demonstrates some of the inputs from the HES that are inputs for a transportation analysis. The output is numbers and data that will be used in the transportation model as input to determine the evacuation clearance time.

Inputs and outputs from the HES into the Transportation Analysis
Much like the many variables involved in traffic, traffic modeling is also a complex issue. The number of evacuating vehicles will vary depending on the intensity of the hurricane, publicity and warnings given about the storm, and certain behavioral response characteristics of the vulnerable population. During a typical evacuation, vehicles enter, leave, and move across the road network at different times and at speeds dependent on the rate of traffic flowing on various roadway segments and the number of vehicles per hour those segments can handle.
Technical Data Report

Technical Data Report from the Delaware, Maryland, Virginia study
The Technical Data Report (TDR) contains the final findings of the specific analyses from the HES. This includes a detailed description of how the study was conducted, the methodology, and the study results. The report is delivered to state and local partners on a variety of platforms to increase its operational usability, as well as leverage the latest technology to enhance visualization and usage of planning tools.
There are several tools included in the TDR, which are discussed on the next pages.
Storm Surge Atlas

Portion of the Storm Surge Atlas for Jackson Co., MS depicting storm surge mapped over local features and topography
Information from the hazards and vulnerability analysis, along with data from the SLOSH model, are used to create a detailed map called the "storm surge atlas". This atlas can be used to visualize the potential extent of inundation from storm surge for different categories of hurricanes. Surge atlases are useful for planning efforts to help determine evacuation zone boundaries and for long-term planning and identification of hazards and local vulnerability.
Hurricane surge mapping depicts the maximum extent of storm surge flooding at high tide that is expected to be produced by any category hurricane regardless of its track or forward speed based on the MOM surge potential. (What is a MOM? See Hazards/Storm Surge). The surge atlas displays MOM values for each category plus high tide, which results in a guide for potential peak surge flooding for a community.
As part of the HES, a family of storms with representative tracks for the region and varying intensities, eye diameters, and speeds are modeled to produce worst-case water heights for any tropical cyclone occurrence. The results of these studies are typically generated from several thousand SLOSH runs.
Evacuation Zones

Portion of the Evacuation Map for Jackson Co., MS based on the storm surge atlas for the area
The information contained in the HES, along with the potential surge vulnerability, is used to define evacuation zones. These zones are created primarily to move people out of areas that are vulnerable to storm surge, and so they often correlate to the intensity of storms. Some communities may take other factors and hazards, such as wind, into consideration when looking at their unique features and specific vulnerability for zone planning.
Evacuation zones work best when they:
- Are based on the surge vulnerability for local areas but are designed to meet the community’s needs
- Include easily identified local landmarks, geographic features, political boundaries, and major roads
- Are easy to communicate to the public-including tourists and visitors
- Promote a "phased approach" to evacuating citizens by first getting them out of the areas most vulnerable to storm surge
Evacuation zones are unique, and customized to each local area. They are determined through collaboration between multiple stakeholders in the community. Local emergency managers in conjunction with decision-makers are the most knowledgeable about the best way to apply information from their Behavioral, Shelter, and Transportation analyses from the latest study data to their Hazard, Vulnerability and Surge Mapping. Using this data, evacuation zones are adopted by local areas and must have a large accompanying public outreach effort in order to be most effective.
Evacuation Clearance Times

Clearance time process
Evacuation clearance times are determined by calculating the time (in hours) required to get residents out of storm-surge vulnerable areas to a place of safety. The calculation begins with the time the first evacuating vehicle enters the road network and ends when the last vehicle reaches an assumed point of safety. It includes travel time, local and regional bottlenecks, and waiting in traffic congestion. The times are based on local evacuation zones, Saffir-Simpson Scale categories of storms, public response, and other information from the HES Transportation Analysis.
The "clearance time" accounts for the time it takes people to mobilize and travel—factors identified in the transportation modeling process. When the pre-landfall hazards are cross-referenced with the clearance time, you can determine when an evacuation should be called for to be most effective.
Once you understand your local potential vulnerability to storm surge and have determined appropriate evacuation zones, you can then use a scenario-based approach to determine evacuation clearance times. The purpose is to get the at-risk population out of vulnerable areas before tropical storm winds reach the coast and weather and roadway conditions become unsafe.
How do evacuation clearance times work? The clearance time duration is calculated using a transportation model. By knowing the arrival time of the tropical storm force winds (based on the current forecast issued by NHC), you can reach a suggested Evacuation Decision Time. Other community-specific factors, such as time of day, number of residents to be evacuated, the expected behavior of those residents, roadway network characteristics, hurricane shelter availability, etc. must be included in the evacuation decision in order to be effective. The HURREVAC program (discussed later in this section) computes this automatically and displays the information as a graphical decision arc.
Clearance times can be used to assist evacuation decision-making and present timing options for emergency managers when faced with a potential tropical cyclone. Using current forecast products and information compared to pre-coordinated scenarios for categories of storms, an evacuation clearance time can be a valuable aid to assist with decision-making.
Post-Storm Assessments

After a significant storm hits an area, Post-Storm Assessments serve as an important way to reflect on the success and usefulness of their decision-support tools and HES components and gather lessons learned. Typically, the findings of these studies show that tools are not used to fullest extent, training is needed in many areas, and that attitudes of the public may have shifted compared to expected behaviors. The Post-Storm Assessment provides direction for future initiatives and improvements to the HES.
Local and State interviews are conducted by the HES program partners to verify product use and accuracy of data and information in the HES, such as:
- Evacuation clearance times
- Evacuation timing, issues, success
- Shelter availability
- Behavior of residents
Additional analyses are conducted to determine:
- Specific weather hazards from the storm (surge, tornadoes, inland flooding, high wind)
- What evacuations were called and the corresponding response on the roadway networks
- How citizens reacted, who evacuated, how they made their decisions, and where they went
- Shelter utilization by evacuating citizens and neighboring counties
- Storm data collection
- HURREVAC: performance, training, usefulness
- SLOSH: performance, usefulness
Based on these general findings, recommendations can be made to help guide future evacuations.
Lessons Learned
Recent Post-Storm Assessments have gathered valuable "rules of thumb" to help inform the evacuation planning and decision-making process. For example, one of the survey questions in the assessments asks residents where they heard the evacuation order. The results can help the emergency manager plan and develop public outreach/messaging plans for calling for evacuations:

Hurricane Lili (2002) Post-Storm Assessment Behavioral Survey
Some examples of best practices include:
- Communication: Clear messages, communicated to the public early have the most success
- "Mandatory" vs. "Voluntary" evacuations will have different results from residents.
- Evacuation Best Practices: "Phased" evacuations, where most vulnerable populations are evacuated first, are safest and most efficient
- Coordination: Evacuation messages should be coordinated with neighboring counties, states, military bases, universities, etc.
HURREVAC

HURREVAC ("Hurricane + Evacuation") is a software program designed by Sea Island Software for FEMA to help visualize evacuation timing. HURREVAC automatically gathers HES data, NHC and local weather information, and forecast tracks; calculates evacuation times based on storm speed and intensity; and displays the results graphically.

HURREVAC graphic for Opal Advisory 29
The program is intended to assist with analysis by allowing users to cross reference forecast information (such as tropical storm force wind speed, rainfall forecasts, forecast cone of uncertainty) with certain timing features that may be important in making decisions about who is at risk and vulnerable, when decisions need to be made to ensure safety, and how the risk is changing based on the dynamics of the forecasts.
This valuable decision aid can provide information such as:
- How much time there is before a decision has to be made
- How large an area and which areas need to be evacuated depending on the storm characteristics
- How long it will take for an evacuation
- What shelters are available
HURREVAC is not a model! The forecasts displayed are the official NHC forecasts. The analyses in each community's HES (such as evacuation clearance times, transportation modeling, and behavioral assessments) serve as the foundation for many of the features available in HURREVAC.
HURREVAC can be used as a "what-if" tool to help emergency managers determine courses of action if the storm characteristics change. It is also useful as a planning, training, and exercise tool. Note, however, the technical data in the HES and the HURREVAC outputs are decision aids only and must be balanced with information about current conditions.
The program began when it was developed by John Townsend, a NWS meteorologist. Recognizing the need to analyze NHC forecast information from the emergency management perspective, HURREVAC was initially designed to help visually display forecast information for better planning purposes. Since then, the program has evolved based on input and feedback from FEMA, the U.S. Army Corps of Engineers, and the over 10,000 registered users across the country.
Who Should Use HURREVAC?
HURREVAC is provided free of charge to the emergency management community. Anyone involved in emergency management decision-making, not just evacuation decisions, may find certain aspects of the program useful as a "one stop shop" for a variety of analysis products.
The program is designed to be user-friendly, but in-depth training is available for users who would like to become proficient in using HURREVAC. For more information about HURREVAC or to discuss training opportunities, please contact your FEMA Regional Hurricane Program Manager or visit www.hurrevac.com for more information.
Users should register at http://www.hurrevac.com/register.php. This ensures you receive important product updates, new versions, software enhancements, etc. This is also how you will receive instructions to download and setup the program.
Tracking Current Storms

The above example HURREVAC image shows the:
- Forecast track (black squares, 1 per hour)
- Wind ranges (colored rings: blue = 39 mph/Tropical storm force, yellow = 58 mph, red = 74 mph/Hurricane force )
- Average track error swath (translucent white), and
- Wind probabilities (blue, yellow, red rectangle flags, same wind speeds as ranges)
Real-time monitoring and storm tracking is central to HURREVAC. The program’s primary data sources are the three U.S. government-based forecast centers that together cover tropical cyclone activity worldwide:
- National Hurricane Center (NHC): Responsible for the Atlantic Basin (including the Caribbean and Gulf of Mexico) and the East Pacific basin that extends westward to 140° longitude
- Central Pacific Hurricane Center (CPHC): Responsible for the Central Pacific basin from 140 to 180° west
- Joint Typhoon Warning Center (JTWC): Responsible for the large area that includes the West Pacific and North Indian Ocean, plus the South Pacific and South Indian Ocean
Whenever there is an active tropical cyclone, the responsible forecast center produces sequentially numbered advisories at 6-hour intervals. Issuance times are 03, 09, 15, and 21 Zulu (which translates to 11 pm, 5 am, 11 am, and 5 pm Eastern Daylight Time). These advisories are automatically ingested into HURREVAC so that emergency managers have updated visual representations of the forecast.
In the next pages we will show some of the features of HURREVAC, and one of the displays will be used in the Decision Making section. However, the purpose of this module is not to train you in the use of HURREVAC.
Viewing Forecasts

HURREVAC Screen Display
HURREVAC 2010’s default view is dominated by a large tracking map. Additional "Tabs" are available for displaying:
- Currently displayed storm advisory
- Tropical Weather Outlook
- Various reports generated upon request
Storm Features
Storm Features are options for how forecast information associated with a particular storm advisory is displayed on the map. Wind ranges, wind swath, and error swath (formerly discrete "display modes" in HURREVAC 2000) can now be shown in combination as storm features. Additional forecast attributes such as watches and warnings and wind probabilities also appear under the STORM FEATURES heading of the Toolbox.

Output from HURREVAC for Hurricane Isabel (2003). The colored rings are wind speed ranges corresponding to 39 mph (34 kt, blue), 58 mph (50 kt wind speed, yellow), and 74 mph (64 kt, pink) at the current location of the tropical cyclone. On the coastline, the blue and pink swaths correspond to tropical storm and hurricane warnings. The white dot on land shows the county selected for evacuation purposes. Surrounding the white dot is a larger, black circle which is the decision arc based on the HES data for that county. The decision arc helps visualize when to evacuate citizens (discussed in more detail on the next page).
Decision Arcs
HURREVAC can be used to calculate and visually display when the different bands of winds will move across your community. It also plots the decision arc, a boundary that helps determine when you should make the decision to evacuate. This boundary, based on data in the HES, relates the time required to evacuate vulnerable areas to the size, intensity, and forward speed of the hurricane. In general, the decision arc will get larger if the hurricane’s intensity increases because most communities have to evacuate more people for stronger storms (and therefore will need more time).
The predicted time when 39-mph winds will intersect the decision arc is a good indicator of when you should have your evacuation plans ready to implement. Generally, evacuations should be underway by the time the 39-mph winds of a powerful hurricane intersect the decision arc and completed by the time these tropical storm-force winds have come ashore. However, there is other information that goes into making the decision to evacuate, such as:
- Special community events
- Roads or bridges under construction
- The amount of remaining daylight
- The number of tourists in the area
- The probability of a hurricane strike
- Information from the local weather forecast office about expected local weather and hazards

Output from HURREVAC for Hurricane Isabel (2003).
In the above example, note that the tropical storm force winds (the blue ring) have intersected the decision arc, so emergency management officials would likely begin the evacuation at this point (although they might have begun it earlier if they had special circumstances). Prior to this time, they would have been preparing for the evacuation decision.
It is important to be well prepared in case the storm characteristics change and an updated advisory suddenly:
- Increases the wind range
- Speeds up the storm, or
- Increases the storm category (max wind) resulting in a longer evacuation clearance time and wider decision arc
If that happens, emergency managers may find that the blue ring is already within the Decision Arc, and decision time "cushion" has already passed.
In addition to the decision arc graphic, HURREVAC provides a table (shown below) that indicates the number of hours before certain events are expected to take place (such as the onset of tropical storm force winds) as well as calculations of the distance to set hurricane features.

HURREVAC evacuation timing table for Chesapeake, VA during Hurricane Isabelle
There are manual methods for computing decision arcs which you can learn about in FEMA and NWS courses. In this exercise, we will depend on the decision arc calculations of HURREVAC.
Dealing with Uncertainty
In a perfect world, emergency managers would have 100% accurate hurricane forecasts at least 72 hours before landfall. However, that simply isn’t realistic. As we saw in the Forecasting section, there are errors in both track and intensity, and these get larger when the forecast is for times farther out in the future. Part of the reason for these errors is due to too few observations, as well as observations that may not be perfectly accurate. Part is due to our incomplete understanding of atmospheric physics, which means that atmospheric processes are not perfectly represented in computer models. One result of all this is that the NHC must place larger areas under hurricane watches and warnings than will actually experience winds that high.
Hurricane Watch and Warning Statistics (2000-2008) |
|
Average storm-total watch length | 477 miles |
Average storm-total length with hurricane winds for cases when watch issued |
89 miles |
Probability of hurricane winds at point under watch | 19% |
Average storm-total warning length | 403 miles |
Average storm-total length with hurricane winds for cases when warning issued |
99 miles |
Probability of hurricane winds at warned point | 25% |
Nonetheless, you will likely need to make decisions when the probability of being hit is still relatively small. For example, note in the graphic below that the chances of hurricane-force winds at Tampa Bay and Port Charlotte are both around 30%. The important point here is that seemingly small probabilities may still be quite significant, particularly for communities with long evacuation times. The wind speed probabilities graphics (discussed in the Forecasting section) can help you understand forecast uncertainties.

Wind speed probability graphic, Hurricane Charley (2004)
Another point is made by the next graphic, which illustrates that impacts from a storm can be felt well outside the track error cone. It is crucial to make proper preparations when a watch or warning is issued for your area, even if the exact track forecast does not go over your area.

Example of a track error cone for a very large, fast-moving hurricane overlain with the wind speed probabilities graph
Since the ultimate goal is to save lives, the best course of action is to act conservatively and take into account the uncertainties to determine what the worst-case situation might be and what measures are appropriate. More times than not, the preparations will have been unnecessary (in hindsight) because the hurricane will probably miss you more often than it will hit you. But that one time when the hurricane comes right to your front door, these precautions will have been worth it many times over.
Questions
Question 1
What do you think are some considerations, other than storm surge, that a community might take into account when creating evacuation zones? (Type your response in the box below.)
Community landmarks, geographical features, traffic patterns, political issues, wind impacts, riverine flooding are some of the major local considerations. It is important to create zones that are easy to communicate, so zones must be broad enough to be easily understood (not too specific or cross county lines, for instance).
Question 2
What are some ways of publicizing evacuation zones? (Type your response in the box below.)
Some communities include evacuation maps in public utilities bills or publish them in phone books. Other methods include providing handouts at public events such as community fairs or at locations such as libraries and senior citizen centers and posting copies on community or TV station websites. Some communities also post signs in vulnerable areas. The important thing to remember is that multiple methods will be needed to get the message across.
Question 3
It is important to note that the hazard analysis is based on NOT real-time forecast data or individual forecast "model runs." Can you think of why this is the case? (Type your response in the box below.)
Because forecasts are constantly changing, even a small difference in the intensity, timing, or track could have a big effect on the eventual impact of the storm at a particular location. The hazard analysis allows for planning and contingency planning, but will not necessarily represent the same scenario posed by actual storms. Each hurricane is unique!
Question 4
The data from Hurricane Opal for type of refuge by risk area (see table below) suggests that only 3-8% of residents went to a public shelter. How do you think that compares with the findings from most Hurricane Evacuation Studies? (Choose the best answer)
Type of Refuge in Opal by Risk Area (percent) | |||
Beaches | Mainland Surge | Non-Surge | |
Evacuate to Public Shelter | 4 | 8 | 3 |
Stay with Friend or Relatives | 58 | 55 | 68 |
Go to a Hotel or Motel | 26 | 18 | 17 |
Other (such as churches or work place) | 12 | 20 | 12 |
The correct answer is c.
This is a consistent finding from the Hurricane Evacuation Studies. Residents much prefer to stay at hotels, with friends and relatives, or anywhere other than public shelters. This data can be used to help with shelter planning.
Question 5
The number one factor affecting how much time is needed to complete an evacuation is: (Choose the best answer)
The correct answer is d.
The number of tourists who need to be evacuated is the primary factor, followed by the intensity of the storm, which also affects the size of the area that needs to be evacuated. Certainly the other two answers can also be factors, along with many others, such as the speed of the storm, whether major roads have lanes blocked due to constructions, etc.
Question 6
HURREVAC is a modeling tool that forecasts when a hurricane will make landfall. (True/False)
The correct answer is False.
HURREVAC does not give forecasts itself. It ingests NHC forecast data to help emergency managers make decisions about who to evacuate and when based on the official forecasts and community characteristics as determined by the HES.
Question 7
The main purpose of a Post-Storm Analysis is to: (Choose the best answer.)
The correct answer is a.
Post-Storm Analyses are important in helping emergency managers learn the lessons that can improve decision-making and implementation in future public emergencies of all types.