Hurricane Forecast Case
Written on 7:23 PM by Shaun Hutchings
We answered several questions about forecast analysis dealing with flexibility for the Nation Weather Service. We used a simulation they created for their forecast they had for Hurricane Katrina. Here is the link:
National Weather Service Katrina Forecast Simulation
©2010, Shaun Hutchings, All Rights Reserved.
- In the Cone/Warning simulation, what does the white "Potential Track Area" mean? How do you suppose the NWS develops such an area when forecasting?
The ‘Potential Track Area’ is the area where the hurricane could possibly end up. They guess or estimated an exact data point where the hurricane can go but because the forecast is not right they give you that area to show you that hurricane may possible end up anywhere in that area. I think they developed this forecast from past data, or previous hurricanes.
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They have been able to see where the paths of past hurricanes have gone when they were in that exact same spot. They can also see surrounding weather conditions and use their weather knowledge to forecast the location of where the hurricane may go.
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They have been able to see where the paths of past hurricanes have gone when they were in that exact same spot. They can also see surrounding weather conditions and use their weather knowledge to forecast the location of where the hurricane may go.
- How accurate was this "Potential Track Area" as Katrina progressed along its path?
I feel the Track Area was pretty accurate given that the hurricane at one point was headed straight west but they forecasted the hurricane to turn north and head towards land. The hurricane could go anywhere and they forecasted pretty accurate considering that the hurricane could have gone straight or anywhere in a 360 radius. There was some error in the fact that for most of the forecast it predicted that the hurricane was going to hit the pan handle of Florida, but then in one forecast it moved all the way over to New Orleans area. This was a drastic change in forecast but if you think about it, it was only several hundred miles off when it could have been thousands and thousands of miles off in its forecast.
- In the "Strike Probability" simulation, describe in your own words what each of the colors represent. Make your explanation simple enough for a child to understand.
The red shows that the hurricane WILL hit that location. This is so because there is a 100% chance or there is no doubt that the center, or the eye of the hurricane will be within 75 miles of red. Basically that states that the hurricane will pass over that spot. Orange is the next color and that color shows that there is above a 50% chance that the hurricane will be within 75 miles of that location. That means that there is more than 50/50 chance that the hurricane will hit that location. Green says that there is 20% to 49% chance that the hurricane will come within 75 miles. Or in simpler terms the hurricane has less than 50/50 chance of hitting that location. And finally the yellow is showing that there is less than a 20% chance that the hurricane can come within 75 miles. Or stating that there is not a very likely chance that hurricane will hit there but there still is a chance to be somewhat prepared if it does.
- Why would the NWS develop strike probability forecasts? What benefit would such a forecast provide?
They developed it because it shows the likelihood of the hurricane to strike, hit, and pass over or whatever term you would like to use to show that the hurricane will cover a certain location. This predicts or forecast with a probability (percentage of probability) put into it to show this. The benefit of this would be so that they could warn the people or the residents living in certain locations if they are in danger or not. Let’s say you are in the orange level meaning that there is a good possibility that the hurricane would strike there, you can start evacuations or other preparations to survive the hurricane. That also goes with the other colors; if you are in yellow you still need to be cautious and prepared but different levels of emergency are needed for the different colors. This means you do not need to evacuate all of yellow because that is not effective and may cost a lot. If you can forecast like they did with a probability built into it they know better where to focus their attention before and during the emergency.
- As you step through each period of the Strike Probability simulation, how accurate were those strike probability projections? Give detailed explanation.
The strike Probability simulation was really accurate. The orange was almost dead on the entire time. This shows that the hurricane was almost definitely going to hit that location. The green was not as accurate but it still showed a pretty accurate display of where the hurricane was headed and it pretty much showed the path of the hurricane. The only color that was way off was the yellow. The yellow just basically covered their entire basis and showed that the hurricane could move or change at any time so just be prepared. The yellow was not accurate as much as the other colors but it still showed a pretty good representation the path of the hurricane.
- In the "Wind Speeds" simulation, why is NWS providing information other than their expected forecast (shown by the blue line labeled NHC)?
Because there is error in any forecast, so the other information shows that there is possibility that the wind speeds may fall within the other data points. And it also gives the percentile of that range. Towards the NOW part on the graph the other data lines are pretty close because that shows they are better at forecasting the wind speeds in the near future and then as time went on the other data lines got farther and farther away from the forecast. Showing that as time goes on they are not as accurate in their forecast so that there is a larger and higher chance that the wind speed may fall into that range.
- In the "Wind Speed" simulation, describe in your own words what each of the colors represent (yellow and orange). Make your explanation simple enough for a teenager to understand. Hint: The probability shown on the lines do NOT mean that there is that probability that wind speeds will reach that particular level. For example, is it possible for the wind speeds to be somewhere in the black region? (The answer is yes). Explain what the graph is telling us.
The graph shows the forecast which in blue. Then the first color orange shows the probability that the wind speeds may fall in that color with the number listed on it. For instance you have a line above the blue line for the orange and a line below the blue line for the orange and they both have a label of percentages, so you can see for instance a 30%. That means that there is 30% possibility that the speed may lie below the forecast and then another 30% that it could be higher than the forecast. That means 60% chance that the actual speed may lie in the orange. So in simple terms you can say that about a 50/50 chance that the actual speed will lay in the orange. The yellow is very similar with another number and lets say for instance 10%. That means another 10% above and another below adds on to the 60% so it 80% chance that the actual speed will be between the orange and yellow. But just in the yellow there is a 20% probability. In simple terms that means that is a small chance that the actual speed can be in the yellow and then another small chance that it could be in the black.
- How accurate were NWS' "Wind Speed" range projections over time?
The projections were not very good. The speed was actually a lot higher than it was expected. The forecast was way low. It sometimes was within the orange and yellow but some of the time the actual speed was in the black. That means their forecast for the speed was not all too accurate.
- How can a range forecast for hurricanes be helpful in making decisions? For example, if you were the mayor of any city along the gulf coast, would you want range/probability information? How would that influence your decisions about what to do for your city?
If you have a range of forecast for hurricanes it can help you make better decisions on what to do in times of emergency. Like I stated above in one of the questions it’s good to know where to put your focus. For instance it would not be very beneficial to evacuate the entire coast but if you lay within one of the high probability areas then it would be wise to make larger preventive actions than if you are within one of the smaller probability areas or not in one at all. It could make all the decision in the world to either prepare for the worse or be on alert.
©2010, Shaun Hutchings, All Rights Reserved.
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