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Weather

How to Read a Weather Map

You have probably seen weather maps online or on TV. Weather maps are marked with Hs and Ls, which indicate high and low pressure centers. Usually surrounding these “highs” and “lows” are lines called isobars. Isobars are lines that show equal pressure. The boundaries between different air masses are called fronts. Fronts can be found in three different ways. Winds often “converge” or come together at the fronts. Also, temperature differences can be quite noticeable from one side of a front to the other side. Finally, the pressure on either side of a front can vary significantly. There are four different kinds of fronts you may see on a weather map. The most basic ones are the cold and warm fronts. Cold fronts are depicted by a blue line with triangles pointed in the direction of motion. Cold fronts divide the leading edge of a cold air mass replacing a warmer air mass. Cold fronts nearly always extend anywhere from a south direction to a west direction from the center of low pressure areas. A warm front is depicted by a red line with half-moons located on the side of the direction of its motion. A warm front is the leading edge of a relatively warmer air mass replacing a colder air mass. Like a cold front, warm fronts also extend from the center of low pressure areas but nearly always on the east side of the low. If the front is essentially not moving, it is called a stationary front. Stationary fronts are depicted by an alternating red and blue line with a triangle on the blue portion and half-moon on the opposite side of the red portion of the line. Cold fronts typically move faster than warm fronts, so in time they can “catch up” to warm fronts. When they do, the air is colder and denser. This is called an occluded front and they are indicated by a purple line with alternating triangles and half-moons on the side of its motion. Now you know how to read a weather map! Find weather maps and more information on the weather at weather.gov.

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Weather

Seasons change – but why?

Seasons change. But what does that mean? While spring usually signals warmer weather, the change toward spring is the result of how the earth is tilted. On the first day of spring the earth’s axis is not tilted away from or toward the sun. This tilt gives us a nearly equal amount of daylight and darkness across the earth and the sun is directly overhead at noon on the equator. The first day of spring can occur anywhere between March 20 and March 23. As the days transition from spring toward summer, our earth is beginning to tilt toward the sun more each day. On this first day of summer, the sun is at its highest point in the sky, and we have our longest day of the year. The first day of summer can occur anywhere between June 20 and June 23. Slowly through the summer, the tilt of the earth begins to change again, with the earth tilting less and less toward the sun each day. Pay careful attention to the shadows from the sun around your house from trees and buildings. You will notice the shadows getting longer as the sun gets lower in the sky with each passing day. What is the opposite of spring? If you answered fall you are correct! The sun is now lower in the sky than it was over the summer, but at the same height it was on the first day of spring. The first day of fall can occur anywhere between Sept. 20 and Sept. 23. Through late fall the earth begins to tilt away from the sun more each day. On the first day of winter the sun is at its lowest point in the sky and we have our shortest day of the year. The first day of winter can occur anywhere between Dec. 20 and Dec. 23. Now you know how and why the seasons change. It’s due to the tilt of the earth — not the calendar. Watch the sun and the shadows throughout the year to see the passage of the seasons.

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Weather

Stay Safe on Spring Break!

Cabin fever is a real thing. After a long winter, you want to get outside. You want to get rid of your jackets and mittens. You want to go to the beach! Every year, thousands of families head to the beach for spring break. It’s a time to relax with your toes in the sand! Soak up some rays! Have some fun in the sun! But don’t let the good times fool you. The beach is beautiful but also a little bit dangerous, if you’re not careful. Some of the dangers you can find at the beach include heat exhaustion, getting sunburnt and rip currents. What can you do to stay safe on spring break? 1. Only swim at beaches where a lifeguard is present. Lifeguards are there to keep you safe. Never go swimming without a lifeguard. This is the most important safety tip to remember when you go to the beach. 2. Break the grip of the rip! Rip currents are dangerous currents that can pull you out to sea. If caught in the grip of the rip, don’t panic. Try to swim parallel to the shoreline until you can escape the current’s pull. If you can’t reach shore, call or wave for help. Remember: Wave and yell … swim parallel! 3. Drink plenty of water at the beach. If you don’t drink enough water, you could get dehydrated and light-headed. 4. Wear sun protection. Too much time in the sun could lead to a painful sunburn. Make sure to wear sunscreen when at the beach. 5. Stay cool! Overdoing it in the heat and humidity can lead to heat exhaustion, which can make you dangerously sick. Take breaks from the sun in a cool, shaded location.

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Weather

Recognizing Patterns at the Storm Prediction Center

The job of alerting the public about severe weather is performed by NOAA’s Storm Prediction Center (SPC) in Norman, Oklahoma. The SPC is responsible for issuing Tornado and Severe Thunderstorm Watches and provides severe weather forecasts up to eight days in advance of the storms. How can they forecast severe weather so far in advance? SPC has a team of forecasters who specialize in the various types of hazardous weather such as tornadoes and thunderstorms. They use supercomputers and forecast models to understand the state of the atmosphere and what it might do next.The forecasters focus on weather pattern recognition by looking for certain patterns in the models. These patterns often occur in the atmosphere several days in advance of an outbreak of severe weather. Typically, details of potential severe weather become more apparent one or two days out. When forecasters identify potential severe weather they then have a momentous decision to make: whether to issue a Tornado or Severe Thunderstorm Watch. It’s a huge responsibility. Their decision will impact the lives of ordinary people, causing them to change their daily activities. For example, placing New York City or Chicago in a watch puts millions of people on notice about severe weather potential. A watch will put Emergency Operation Centers (EOCs) and other public safety agencies on heightened alert. It is not a decision that can be taken lightly. But that is their job. A forecaster explains, “Knowing the destructive force of a tornado, living in central Oklahoma, and seeing destruction first-hand, you can become overcome by a dreadful feeling of knowing that this will not end well. You know the power of the storms. There is a very eerie feeling that comes over you, especially if storms occur overnight when people are sleeping. You can watch the storms on radar and see the towns the storms are crossing and realize the potential damage. Our role is to protect life and property. I keep that in front of my mind at all times.” Dangerous weather can occur anytime and anywhere. While storm forecasts are not exact yet, they have vastly improved over the past couple of decades due to additional satellites taking weather measurements from space and more computing power. The men and women of NOAA’s Storm Prediction Center use these tools to keep us safe.

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Kids

Buffalo is for Snow-Lovers

If you like snow, then Buffalo is for you. Last winter, this upstate city in New York received more than 100 inches of snow! Over 5 feet of this snow arrived during one storm in November. The storm led to hundreds of major roof collapses and structural failures, thousands of stranded motorists and scattered food and gas shortages due to impassable roads. Numerous trees also gave way due to the weight of the snow, causing isolated power outages. A second storm arrived a couple days later, dropping another 1 to 4 feet of snow. Storm totals from the two storms peaked at nearly 7 feet, with homes submerged in dense snowpack. While Buffalo was swamped in what residents called “a wall of snow,” a few miles inland the snow only amounted to a couple of inches. How come? The reason is the city’s location on the shore of Lake Erie. When really cold air from the north comes down over Lake Erie, the warm lake below acts as a source of energy, producing lake effect snow. The cold air sucks up warmth and moisture from the lake through evaporation. How long the air spends over the lake is called residence time, and how far it travels over the lake is called fetch. Residence time and fetch are very important because if the air doesn’t spend enough time over the lake, it doesn’t get enough energy or moisture to make lake effect snow. The wind must be coming from the right direction over the lake to produce record amounts of snow. When the air reaches the shore, it dumps all of that moisture in snow form. These snow storms form in narrow bands that don’t really move, so five miles away it could be sunny, but in the storm you could get feet of snow. That’s the power of lake effect snow. So, if you like snow, Buffalo is for you!

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Weather

It’s a Bird! It’s a Plane! No! It’s a NOAA Weather Balloon!

In order to predict the weather, you need to observe the weather. But how do you do that? You can look out the window but that only gives you a small look at what’s happening in the earth’s atmosphere. So, how can you find out what’s happening in the sky thousands of feet above you? With a balloon! NOAA’s National Weather Service launches weather balloons twice a day from 102 sites throughout the United States, the Caribbean and the Pacific to help with weather forecasting. Since the late 1930s, the National Weather Service has used balloons to obtain upper air observations. These are not ordinary balloons. Underneath each balloon, hangs a sensor package and a parachute. As the weather balloon rises through the atmosphere, the sensors measure air pressure, temperature, relative humidity, and wind speed and direction. This information is sent back to the surface using radio signals, where it is included as a starting point for weather forecast models. Forecasters then use this information to forecast the weather. That’s right, you can thank a balloon for your weather forecast. A typical weather balloon flight can last more than two hours. In that time, it can rise more than 115,000 feet into the atmosphere. During the flight, the balloon and its sensors are exposed to temperatures as cold as -130oF and an air pressure less than one percent of what is found on the Earth’s surface. If the balloon enters a strong jet stream it can travel at speeds exceeding 250 miles per hour. When the balloon gets to around 20 miles high in the sky, it will pop and the sensors fall to the ground. The parachute will open as it falls so the sensors and popped balloon come back to Earth slowly. It can land in a wide variety of locations, such as in trees, on bridges and in backyards — sometimes more than 200 miles away from where it was launched! Once it lands, if found, it can be returned to the National Weather Service. Each one has its own addressed, postage-paid return mailbag attached to the package. Returning them benefits the environment and saves taxpayer dollars by recycling the units for reuse. So, if a weather balloon lands in your backyard, please return it to the National Weather Service. They’ll be glad to have it back!

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Weather

Snow Day or Snow Way

Winter is here! And with it comes snow, freezing rain and sleet in many parts of the country. These storms can mean school-closing snow days. Or they can mean nothing but rain. How do meteorologists make their forecasts? Almost all of our weather, including winter weather, occurs in the lowest several miles of the atmosphere. Generally how much warm/cold air is in the atmosphere determines whether we’re going to get snow, freezing rain or sleet. The main types of winter precipitation are snow, freezing rain and sleet (also known as ice pellets). Critical ingredients are moisture and very cold (sub-freezing) temperatures. • Snow: Precipitation in the shape of ice crystals, mainly of intricately branched, hexagonal form and often gathered into snowflakes, made directly from the freezing of the water vapor in the air. • Freezing Rain: Rain that falls as a liquid but freezes when it hits the ground, creating a coating of ice on roads, walkways, trees and power lines. • Sleet (also known as ice pellets): Pellets of ice composed of frozen or mostly frozen raindrops or refrozen partially melted snowflakes. These pellets of ice usually bounce after hitting the ground or other hard surfaces. How do snow, freezing rain and sleet form? See the illustration below. A wedge of warm air is depicted by the red area. This air is warmer than freezing (32°F or 0°C). The thicker the wedge of warm air the less frozen/freezing precipitation would be expected. Meanwhile in the picture cold air is represented by the blue area. This air is cooler than freezing. Look at the above illustration again and imagine that you’re a meteorologist. Your forecast decides whether the schools are open or closed in the morning. Do you give the kids a snow day? Or is it just going to rain? To make an accurate prediction, you need an understanding of the amount of warm and cold air and where it is in the atmosphere (along with the necessary moisture). Challenging, isn’t it? A few degrees of temperature can turn your snow forecast into rain. After seeing how snow, freezing rain and sleet form you can understand how difficult they can be to predict. Now you know what it’s like to be a meteorologist facing a tricky winter forecast.

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Weather

Storms from the Sun

What is space weather? Just like the weather you experience on earth, space weather has its calm and stormy periods, too. Space weather is caused by large-scale eruptions on our sun. Those eruptions affect and interact with Earth’s own atmosphere and magnetic field. Solar flares are sudden, explosive releases of energy from active regions on the sun. These active regions have strong magnetic fields and can show up as cooler, darker areas, seen as sunspots. Sunspots are likely areas for these solar eruptions. Solar flares release energy that travels at the speed of light, and light is so fast that it travels all the way around Earth almost eight times in just one second! When strong enough, the solar flare causes problems with radio communications like those used in airplanes flying over the oceans. These eruptions can also accelerate charged particles at the sun, the tiny building blocks that make up every atom, creating what we call a solar radiation storm. These tiny particles can travel near the speed of light and arrive at Earth in tens of minutes to hours. These particles can also affect radio communications near the North and South Poles. Additionally, these tiny particles can pass through satellites causing problems with the satellite’s electronics and sensors that can result in permanent damage. When these radiation storms are strong enough, they can cause an increase in radiation exposure to astronauts in space and to airline passengers in flight near the Earth’s poles. These eruptions may also result in large parts of the sun’s atmosphere being blown into space, called a coronal mass ejection or CME for short. These CMEs can be thought of as clouds of tiny particles that together act as a giant magnet. These clouds can arrive at Earth in as little as 15-16 hours, and when they do, they cause a “jolt” to Earth’s own magnetic field resulting in geomagnetic storming. These geomagnetic storms can cause extra electric currents to flow in large power lines, in extreme cases overloading parts of the power grid and possibly causing power outages or problems. Additionally, some communication and navigation systems may become degraded, affecting things like road-building and airplane traffic. While these storms can create such problems, they are also the driver of the spectacular northern and southern lights, or auroras. The aurora is much like a neon sign where atoms are excited and emit beautiful light. But in the case of the aurora, this sign is much bigger and high in the sky, usually near the North and South Poles. The sun is not just our nearest star and what gives us light. It also produces a wide range of space weather that can impact the technologies we use every day.

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Weather

Blame It on El Nino

You might have heard weather forecasters on TV talking about El Niño. What is El Niño? How will it impact the weather where you live? Can you blame El Niño for snow days and bad weather? El Niño was originally recognized by fishermen off the coast of South America as the appearance of unusually warm water in the Pacific Ocean, occurring near the beginning of the year. El Niño means “the little boy” or “Christ child” in Spanish. This name was used for the tendency of the phenomenon to arrive around Christmas. El Niño doesn’t happen every year. But it’s here in 2015, according to forecasters with NOAA’s Climate Prediction Center. The current El Niño has strengthened over the past few months, with a strong event likely during the late fall and early winter. When an El Niño develops, it can start a chain reaction in the atmosphere influencing the weather in places much farther away from the tropical equatorial Pacific Ocean, including the United States. Just like the tides roll in and out, our climate warms during the summer and cools during the winter. An El Niño is like changing the level of those tides in some places. Perhaps they come in a little higher or earlier now, getting you wet before you have a chance to move your beach blanket to higher ground. Meanwhile, heavy rains in the southern half of the U.S. may lead to flooding causing widespread damage to towns and communities. In addition, El Niño could elevate the risk for severe weather across the Southeast during winter. Above-average late fall to winter temperatures across the northern tier of the U.S. might mean a milder winter. Which might mean fewer snow days, if you live there. Tropical systems in the Atlantic are also suppressed, which means there is less of a chance of a storm hitting the eastern half of the country. It’s important to understand that a strong El Niño only favors these impacts, but doesn’t guarantee they will happen. Not every El Niño event leads to the same climate conditions. So don’t blame El Niño if you don’t like the weather. Bad weather happens every year— El Niño or not. Look at the map above to see how El Niño might impact your weather. It is projected to be warmer in the northern Plains, dryer in the Midwest and wetter in the South. In addition, strong El Niños are often associated with heavy winter rains across California, which could bring much needed moisture to a region devastated by drought. But if the rain comes too quickly and heavily, it could lead to damaging landslides.

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Weather

Back to School: Five Weather Tips to Stay Safe!

Fall is here — it’s time to go back to school! While it’s great to see your friends again, fall is full of weather hazards, including floods, heat, lightning and tornadoes. Don’t let bad weather catch you unprepared. Make sure that you’re ready for the weather before you leave home. Remember these five weather tips to stay safe. Don’t let the weather ruin your day. Be prepared for it! Doing so will keep you and your friends and family safe. Make sure that they know these five tips, too. Want to learn more about the weather? Visit weather.gov/owlie to discover more great weather science and safety information from Owlie Skywarn, the official mascot of the National Weather Service. You can also become a Young Meteorologist, print out Flat Owlie and read Owlie’s journal! Heat: Beat the Heat! It can be hot when the school year starts! When it gets hot, slow down. Drink plenty of water. Stay out of the sun until it cools off. Be smart and beat the heat. Know Before You Go Don’t get caught at the bus stop without an umbrella! Start your morning by checking your local forecast at weather.gov. It will tell you how hot or cold it will be, whether it will rain and other important information. You can check weather.gov on a computer, iPad or even a mobile phone. Know before you go! Tornado: Take Shelter! A tornado watch means that tornadoes are possible. A tornado warning means that a tornado has been sighted — seek shelter in a sturdy building immediately! Make sure that you know where the tornado shelter is in your school. And always follow your teacher’s instructions when it comes time to find shelter. Floods: Turn Around, Don’t Drown! Flooded rivers and roads covered by water are dangerous. Even vehicles as large as a school bus can be swept away in as little as two feet of water. Do not attempt to cross. Turn around, don’t drown! There is no safe place outside when thunderstorms are in the area. If you hear thunder, you are in danger! Whether you’re on the playground or playing an after-school sport, go indoors immediately when you hear thunder or see lightning! When thunder roars, go indoors!

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