Weather FAQ & Homework Help

Weather Forecasting
1. Where does your weather information come from?
2. Why does the forecast change everyday?
3. How do you forecast weather?
4. How accurate are your forecasts?
5. What about the five day forecast?
6. Why is Mobile's airport used for an "official" temperature?
7. Where can I get past weather information?
8. How can I become a meteorologist?
9. Where can I get forecasts for other countries?

Weather Team
1. How can I get one of the Storm Team to visit my school or organization?
2. Is it true that there really is no map behind the weathercaster?
3. What do the letters "AMS" or "NWA" mean?
4. How can I get a copy of a WKRG news broadcast?

General Weather
1. What is the difference between relative humidity and dewpoint?
2. What is pressure?
3. How do I set my barometer?
4. How do I convert from Fahrenheit to Celsius?
5. What is the radar?
6. What is the satellite?
7. What is a Sun Dog?
8. What causes tides?
9. What is the heat index?
10. What causes the seasons?
11. Does anything special happen at the equinox or solstices?
12. What is the sea breeze?
13. Where do clouds come from?
14. What is virga?
15. What does zonal mean?
16. What is the jetstream?
17. What is wind shear?
18. What is turbulence?
19. Where can I find highs and lows for a day?
20. Where can I get the pressure or relative humidity?
21. Where can I find tide forecasts or past tide levels?

Severe Weather
1. What is severe weather?
2. When does severe weather happen?
3. How can I know when severe weather is likely?
4. What is a NOAA Weather Radio?
5. What's the difference between a watch and a warning?
6. Is there always a warning before severe weather?
7. Can lightning strike twice?
8. What counties does WKRG cover for watches and warnings?

Gulf Coast Weather
1. Is Gulf Coast weather different from what it was forty years ago?
2. Is there any normal weather?
3. Do we know what Gulf Coast weather was hundreds of years ago?

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Weather Forecasting

1. Where does your weather information come from?
Our weather data is compiled by the National Weather Service in Washington, DC and we receive it by satellite. The data includes readings taken at hundreds of sites each hour in North America and worldwide, along with radar and satellite images updated every few minutes, and information from weather balloons which are launched twice each day.

2. Why does the forecast change everyday?
Weather is always changing and that means every time we get new data we can see something that maybe we didn't see before so we have to update the forecast at least twice a day.

3. How do you forecast weather?
We look for patterns and trends on weather maps, satellite and radar, to tell us how fast a weather system is moving and in what direction. Computer models use math to give us an idea of how the atmosphere is changing and this helps to guide our forecasts. By simply watching the sky and knowing the wind direction we also see signs of changes.

4. How accurate are your forecasts?
This is a tricky question. WKRG broadcasts to hundreds of communities in a large area. We may predict rain that occurs in half of these communities so that half of our viewers would say we were right and the other half might not agree. Or we may predict rain that happens everywhere in the middle of the day when most people are at work or in school and only a few people notice. Each viewer probably has a different way of measuring how accurate we are. For example, if we predict a high temperature of 90 degrees but the official high is 89, would we be wrong? How many degrees off can a forecast be before it is wrong? How do you measure accuracy?

5. What about the five day forecast?
Predictions for five days ahead are better than they were a few years ago but when you look at one, you have to look at the trends, not the exact numbers. The 5 day forecast is really an outlook not a forecast.

6. Why is Mobile's airport used as an "official" temperature?
Mobile's airport has a very complete record of temperature and other weather information. Most local forecasters use it as a standard so that when you hear different forecasts you'll know that they all have the same reference.

7. Where can I get past weather information?
All weather data for the United States is archived at the National Climatic Data Center in Asheville, North Carolina. For local information, one of the easiest ways to find out what the weather was on a certain day is to go to the library and look in the weather section of a newspaper or check the climate section of Mobile's National Weather Service Office. Most major papers have a weather map along with a summary of the previous day's weather.

8. How can I become a meteorologist?
Most meteorologists get a four-year college degree that starts with 3 semesters of calculus, 2 semesters of physics, 2 semesters of chemistry. In the third and fourth year of college the focus is on hydrodynamics, thermodynamics, computer modeling, map-reading, and the various areas of weather. Other meteorologists are trained in the military. The majority of  meteorologists do not work on TV and just because you see someone on TV talking about the weather, it doesn't mean they are fully trained in a traditional college degree program. Those of us on TV have to have a love for weather and a love for communicating. We also have to be willing to give up some of our privacy and be public figures. Meteorologists are also called atmospheric scientists and they work in many areas of society.

9. Where can I get forecasts for other countries?
The World Meteorological Organization has links to weather forecast offices all around the globe.

Weather Team

1. How can I get one of the Storm Team to visit my school or community?
We get dozens of requests for appearances, many of which we are not able to fulfill. Please send a letter or email directly to the weathercaster that you would like to see. Include as much information about your event's, location, time and date as well as information on your organization. Keep in mind that it is difficult to get a team member to come out for an event that will have small attendance or an event that conflicts with our normal on-air schedules.

2. Is it true that there really is no map behind the weathercaster?
Yes! When we deliver the forecast we stand in front of a blank green screen. The maps you see behind us are electronically inserted over the color green. We know what's "behind" us only by looking at TV monitors off to the side of the screen.

3. What do the letters "AMS" or "NWA" mean?
AMS is the American Meteorological Society. NWA is the National Weather Association. The letters mean that the weathercaster went through an application process to earn a certification stating that his or her weathercasts meet a high level of skill in communication and presentation.

4. How can I get a copy of a WKRG news broadcast?
We cannot make copies of past broadcasts but there is a company that makes them available for a fee. Contact Metro Monitoring Service at 1-800-861-5255

General Weather

1. What is the difference between relative humidity and dewpoint?
Both relative humidity and dewpoint measure moisture but they do it in different ways. Relative humidity tells you how much moisture is in the air compared to how much the air can hold (warmer air holds more moisture than colder air). Dewpoint tells you exactly how much moisture is in the air. Think of dewpoint as a shoe size- it's not measured in inches or feet or gallons, it's simply a number. Dewpoint is also the temperature that you cool air down to in order to get dew or condensation. Relative humidity is moisture relative to the air temperature, dewpoint is not.

2. What is pressure?
Pressure is a measurement of how much air there is above us in the atmosphere. We usually don't feel it unless it changes very quickly as it does when you go up or down in an elevator or airplane. Low pressure or falling pressure generally means cloudy, unsettled or wet weather while high pressure or rising pressure means calm and clear weather. People with arthritis are very sensitive to changes in pressure.

3. How do I set my barometer?
There should be a dial on the back or bottom of the barometer that adjusts the current reading. Simply turn the dial until the reading is the same as the current pressure. As the pressure changes throughout the day you'll see the needle or mercury move. Some barometers have a second dial that does not move unless you move it. It is usually controlled from the front of the instrument and it's there for a reference so you can see how much the pressure reading changes. Use a weather radio to give you the current barometer reading.

4. How do I convert from Fahrenheit to Celsius?
Use the formula: C = 5/9 * (F - 32)   or   F = (9/5 * C) + 32. The National Weather Service has an online calculator for other weather parameters.

5. What is the radar?
The radar shows precipitation, which is either rain, snow, sleet or hail. Doppler radar allows us to see if the precipitation is rotating which gives indication of a possible tornado.

6. What is the satellite?
The weather satellite shows clouds.

7. What is a Sun Dog?
A Sun Dog is the nickname for a Parhelia. It is a bright colored area you see in thin high clouds on either side of the sun. It looks like a piece of a rainbow. It's called a Sun Dog because it follows the sun like a dog.

8. What causes tides?
Tides are caused mainly by the gravitational pull of both the sun and the moon.

9. What is the heat index?
The heat index is the warmer temperature we feel when our bodies are unable to cool off through perspiration. When the dewpoint is very high, perspiration does not evaporate and cool us off very well. Our body temperatures can rise to put us in danger.

10. What causes the seasons?
Seasons are caused because the earth's axis is tilted as the earth revolves around the sun. In the winter the North Pole is tilted away from the sun meaning the sun is lower in the sky and the minutes of daylight are short. Six months later, when the earth is on the other side of the sun, the north pole is tilted toward the sun, the days are longer, and the sun is higher in the sky. When the rays are more direct we heat up.

11. Does anything special happen at the equinox or solstices?
No. These points are astronomical reference marks for how the earth is tilted in relation to the sun.

12. What is the sea breeze?
The sea breeze is when the land heats faster than the water and draws air inland during the afternoon.

13. Where do clouds come from?
Clouds form either when moisture is added to the air to make it saturated, or when air is cooled until the moisture is condensed. In some cases, clouds form somewhere else and the wind carries them to you and in other cases clouds form directly overhead.

14. What is virga?
Virga is precipitation, usually rain, that falls from the clouds but evaporates before it hits the ground. From a distance you'll see it as light streaks extending down from the cloud.

15. What does zonal mean?
Zonal is a word that means the winds are moving from west to east.

16. What is the jetstream?
The jetstream is a river of wind far above the ground that guides weather systems. It can be anywhere between 5 to 8 miles up and have winds easily from 100mph up to 200 mph. There can be more than one jetstream above a continent. Jetstreams can also strengthen thunderstorms when they pass over them.

17. What is wind shear?
Wind shear is when two adjacent winds move at different speeds or in different directions or both of the above. In any case the winds are cutting or shearing across each other.

18. What is turbulence?
Turbulence is caused when an airplane passes through a region of wind shear or when a plane passes in and out of a jetstream. It is also common near mountain ranges. Since air is invisible, turbulence is sometimes not known until a plane experiences it. Sometimes turbulence makes it seem as though a plane is falling and this is what many people call an "air pocket." An air pocket is when the plane hits a region of sinking air that causes a rapid loss in altitude.

19. Where can I find highs and lows for a day?
Start in the weather section of your local newspaper. Most daily papers print a summary of the previous day's weather. You can find past highs and lows by going to the library and looking in older newspapers. You can find highs and lows for Mobile or Pensacola by visiting the Climate section of the Mobile National Weather Service.

20. Where can I get the pressure or relative humidity?
Use a weather radio to get pressure, relative humidity, wind, and temperature, updated each hour. Online you can find it in the local weather section of wkrg.com

21. Where can I find tide levels and forecasts?
Local tide forecasts are listed on wkrg.com on the left side of the page. You can get past and future tides for anyplace on Earth here.

Severe Weather

1. What is severe weather?
Severe weather is sudden, violent, hazardous weather that comes from powerful thunderstorms. It could be large hail, flash flooding, extreme winds or tornadoes.

2. When does severe weather happen?
Usually in the warmer seasons but it can happen whenever the temperature and humidity levels are high and a strong jetstream is above us. Severe storms are most likely in the late afternoon but they can happen at any time, day or night.

3. How can I know when severe weather is likely?
Keep up with the weather forecast and get a NOAA Weather Radio.

4. What is a NOAA Weather Radio?
It's a radio that picks up a continuous broadcast from the National Weather Service, 24 hours a day, in most locations in the US. They are inexpensive and sold at most electronics stores. Not only are many portable and battery-operated but some have a built-in alarm that sounds when severe weather is possible.

5. What's the difference between a watch and a warning?
A watch means severe weather is possible. A warning means it's happening. Watches for severe weather last several hours and cover large areas. When they are issued you must watch the sky and stay alert. Warnings tell you to take immediate action to find safety because severe weather is imminent or happening. Warnings cover small areas such as counties and they last for up to an hour (flash flood warnings last several hours).

6. Is there always a warning before severe weather?
No, because sometimes it develops before we can detect it and also because along the Gulf Coast, there is a lot of isolated severe weather. A watch is usually issued first and then a warning before severe weather happens. It's up to you to look out for your own safety.

7. Can lightning strike twice?
Yes, lightning can strike the same spot twice during a storm or on different occasions.

8. What counties does WKRG cover for watches and warnings?
In Mississippi we cover Greene, George, Jackson, and Harrison Counties. In Alabama we cover Mobile, Washington, Clarke, Monroe, Conecuh, and Escambia Counties. In Florida we cover Escambia, Santa Rosa, and Okaloosa Counties. By agreement with TV stations in neighboring areas, they would cover counties outside of this area for watches and warnings. See the map in our Severe Weather article.

Gulf Coast Weather

1. Is Gulf Coast weather different from what it was thirty or forty years ago?
Yes, but that doesn't mean that we won't return to patterns that older people may recall from when they were growing up. Our weather patterns will always change but that does not mean that something is "wrong" with the atmosphere.

2. Is there any normal weather?
Yes and no. Most people use the word "normal" to mean the type of weather that you can expect. Meteorologists use the word "normal" to mean the same thing as average. However, even when you use math to come up with average temperatures or rainfall, for example, weather is rarely close to the average or normal. Normal includes all of the extremes. If the average NBA basketball player is 6 feet, 10 inches tall, the odds are that only a few of the players are exactly that height- half would be shorter and half would be taller.

3. Do we know what Gulf Coast weather was hundreds of years ago?
Not exactly, most weather records start in the mid 1800's. That means whenever we talk about a record, we are only talking about the last 150 years.