Meteorologists use weather radar to get an idea of how intense precipitation is, which way it is moving and how fast it is moving. They radars send an energy wave field into the sky. When the wave field bounces off an object in its path, the energy is reflected back to the radar and computers sort it into different colors that represent different information.
The blue box shows where the radar is located. Pretend you are in the middle of a circle of friends and each of them is shining a flashlight at you. They represent the raindrops.
Pretend you have a mirror. If you spin slowly in your spot, your mirror will receive the energy from each flashlight – just like a radar receives energy reflecting off raindrops! See how it looks like there are spokes in the colors spreading out from the blue box?
These pictures show two important information the radar measures. The left image is known as “reflectivity.” If a lot of energy is reflected back, it means the precipitation is dense – the energy couldn’t make it through the raindrop or hail and was forced back. The scale at the bottom shows cooler colors mean light precipitation, and warmer colors mean heavy precipitation. When you get into pink, purple and light blue, that alerts us to hail and even large hail.
The right image is “velocity.” It shows us how fast the wind is moving toward or away from the radar. Green is toward, red is away. Remember that!
Ok. Now in the left image, that is a SUPERCELL THUNDERSTORM. This one is special because it has a tail. I call it a tail because I am a dog. Meteorologists call this a HOOK ECHO. It really does look like a hook! But this hook means that the precipitation is being pushed around the storm. Hmmm. A clue!
The image on the right, remember, is showing winds. Whenever you see greens and reds right together, like Christmas, it is an even better clue! Find that spot on the picture. Now take your finger and trace from the brightest green to the blue box. Then take another finger and trace from the blue box to the brightest red. Your fingers almost made a tornado! The winds moving toward the radar and away from the radar but right next to each other mean there is rotation. Meteorologists call that a TORNADO VORTEX SIGNATURE, or TVS. This means there might be a tornado. We can’t say for sure from a TVS because radars can’t “see” at the ground.
But wait, what?!?
Why can’t they see at the ground? Well, if it did, it would detect trees and buildings! We have to point the beam up a little to avoid that if we can. And, to make things more tough, the Earth curves! The radar beam is generally more straight, so the farther the beam goes out, the higher it is above the Earth because the Earth curves away.
A funnel has to touch the ground to be a tornado – so now what?
Radars can detect a tornado causing damage if the debris is getting kicked up high enough to hit the beam. Other than that, we can just guess and rely on special storm spotters and law enforcement to confirm a radar on the ground.
Phew! Lots of information, but now you can look at radar for TVS’s!
The Storm Prediction Center launched a brand new site this week!
This is a good place to start your day to pay attention to the weather. My human’s browser is set to open to this page every time she opens a new window. That way she always knows if there is a weather threat.
Look at the big map. You can glance at it and know in a few seconds what areas need to pay attention. In the area inside the brown line, they are expecting possible thunderstorms. Inside the green area, there is a slight risk of these thunderstorms being severe. If there is a yellow area, that is a moderate risk. If you are in this area, you should pay attention to the weather and make sure you have a plan to get safe in severe weather. A red area is rare, but means a high risk of severe weather. This is very serious and if you are in this area, you should pay close attention to the weather all day and have your safety plan ready to start at any time.
Also on this page you can see current severe weather watches and areas they are thinking about issuing watches (those are called mesoscale discussions). You can see in the picture they just issued a severe thunderstorm watch for parts of the Texas panhandle and western Oklahoma. If you want to know more about what concerns them about this area, you can click on the watch and you can read more complicated meteorology terms.
Severe weather climatology at the lower left is interesting to look at. My friends have been working on this for a long time. You should check it out to see what time of year is your biggest risk for different types of severe weather.
Storm report trends are new, but gives you a quick glance at what is going on.
And a great FAQ about the difference between a severe weather watch and a severe weather warning on the lower right.
If you keep scrolling down, you will find even more technical stuff, but important tornado safety tips.
Start your day here to be weather ready!
Today is a special day because it is the first day of Spring! This means at most places in the world, there are 12 hours of daylight, and 12 hours of darkness.
The photo on the left was made with a satellite. Look how you can barely see Greenland at the top, and barely see the tip of Antarctica at the bottom. And look how they have about the same amount of sunlight!
“WorldView+” is a favorite app on my human’s iPhone. This app lets you look at webcams all over the world. We bookmark our favorites. Sometimes when we need a break, we check the weather in different places on Earth. I would download it if you are allowed. It is VERY educational.
We thought it would be cool to compare webcams from the top of the world, and the bottom on a day where they have about the same amount of sunlight!
It’s my favorite week of the year! National Severe Weather Preparedness Week begins TODAY!
All week I will be giving tips about what you can to to be ready for the severe weather season.
Severe weather can happen at all times of the year, but spring is the most common.
Why spring? Because that’s when winter and summer crash into each other! Where they collide is where you will find thunderstorms.
There can be as many as 40,000 thunderstorms each day around the world. They are the most common in the U.S., where they can produce tornadoes, floods, lightning and damaging winds.
Three basic ingredients are needed for a thunderstorm to form: moisture, rising unstable air (air that keeps rising when given a nudge), and something to nudge the air up.
The sun heats the surface of the earth, which warms the air above it. If this warm surface air is forced to rise—hills or mountains, or areas where warm/cold or wet/dry air bump together can cause rising motion—it will continue to rise as long as it weighs less and stays warmer than the air around it.
As the air rises, it transfers heat from the surface of the earth to the upper levels of the atmosphere (the process of convection). The water vapor it contains begins to cool, releases the heat, condenses and forms a cloud. The cloud eventually grows upward into areas where the temperature is below freezing.
As a storm rises into freezing air, different types of ice particles can be created from freezing liquid drops. The ice particles can grow by condensing vapor (like frost) and by collecting smaller liquid drops that haven’t frozen yet (a state called “supercooled”). When two ice particles collide, they usually bounce off each other, but one particle can rip off a little bit of ice from the other one and grab some electric charge. Lots of these collisions build up big regions of electric charges to cause a bolt of lightning, which creates the sound waves we hear as thunder.
Check back with me this week as I highlight a different type of severe weather each day, and talk about ways to be ready for severe weather season.
Being prepared to act quickly during severe weather will help you not be as scared and think more clearly.
I learned about this really cool app that came out from the National Severe Storms Lab and grad students at the University of Oklahoma. My human made everyone in her family download it. It is called “mobile Precipitation Identification Near the Ground” or mPING. The app lets you report whether rain, snow, sleet or freezing rain is hitting the ground at your spot.
But who cares?
Well I do, of course, but research does too!
Radars can’t see right at the ground. They have to point their beam up a little to avoid as many trees and buildings as possible that could block it. So that means if the radar detects a snowflake up high, but it melts into a raindrop by the time it gets to the ground, the radar doesn’t know.
Researchers are working hard on computer programs that make a best guess from the radar data about what is actually falling. But, with mPING, they can see where they are right and where they were wrong!
It is really a cool idea! There have been tons of humans reporting. I’ve seen the reports on my human’s computer screen. It looks like a Christmas tree.
I am sad though, because I can’t use the app.
My paws are too big to click on a button that small. www.nssl.noaa.gov/projects/ping
I have to admit, I think this is one of the most amazing things I have ever seen. It is called the Pont du Gard. They say it was built in two thousand years ago to carry water and people. That is way long ago! And to think something that old has stood up to big floods for thousands of years! They just stopped allowing cars on it about ten years ago!
I found out about it when my human was looking for information about a huge flash flood research project in Europe.
She got distracted.
But the flash flood research project is the biggest field weather project in the history of Europe. Radars on trucks, ships, airplanes, balloons – all of these things will be used to figure out how to forecast flash floods better and save lives.
I think it is important to remember bad weather happens to people all over the world. And, it is good to work together to figure out how to help.
Help your pets keep their cool. It will “feel” as hot for them as it will for you. Do not leave your pets in a closed vehicle. Be sure your animals have access to shade and a water bowl full of cold, clean water. We don’t tolerate heat well because we don’t sweat. Our bodies get hot and stay hot. During summer heat, avoid outdoor games or jogging with your pet. If you would not walk across hot, sunbaked asphalt barefoot, don’t make us walk on it either. (Dogs can also get blisters on their paws from hot pavement. OUCH!)
Tips for people!
- Avoid the Heat. Stay out of the heat and indoors as much as possible. Spend time in an air conditioned space. Only two hours a day in an air-conditioned space can significantly reduce the risk of heat-related illness. Shopping malls offer relief if your home is not air-conditioned. If air conditioning is not available, stay on the lowest floor out of the sunshine. Remember, electric fans do not cool, they just blow hot air around.
- Dress for the heat. Wear loose-fitting clothes that cover as much skin as possible. Lightweight, light-colored clothing that reflects heat and sunlight and helps maintain normal body temperature. Protect your face and head by wearing a wide-brimmed hat. Avoid too much sunshine. Sunburn slows the skin’s ability to cool itself. Use a sunscreen lotion with a high SPF (sun protection factor) rating.
- Drink FOR the Heat. Drink plenty of water and natural juices, even if you don’t feel thirsty. Even under moderately strenuous outdoor activity, the rate your body can absorb fluids is less than the rate it loses water due to perspiration. However, if you have epilepsy or heart, kidney, or liver disease; are on fluid-restrictive diets; or have a problem with fluid retention should consult a doctor before increasing liquid intake.
- Do not drink IN the Heat. Avoid alcoholic beverages and beverages with caffeine, such as coffee, tea, and cola. Alcohol and caffeine constrict blood vessels near the skin reducing the amount of heat the body can release. Although beer and alcohol beverages appear to satisfy thirst, they actually cause further body dehydration.
- Eat for the Heat. Eat small meals more often. Avoid foods that are high in protein because they increase metabolic heat. Avoid using salt tablets, unless directed to do so by a physician.
- Living in the Heat. Slow down. Reduce, eliminate, or reschedule strenuous activities such as running, biking and lawn care work when it heats up. The best times for such activities are during early morning and late evening hours. Take cool baths or showers and use cool, wet towels.
- Learn the symptoms of heat disorders and know how to give first aid.
Thinking About Others
- Do not leave children, pets or elderly friends in a closed vehicle, even for a few minutes. This is a “No-Brainer”. Temperatures inside a closed vehicle can reach 140°F-190°F degrees within 30 minutes on a hot, sunny day. However, despite this common sense rule, deaths from heat occur almost every Summer when someone leaves their child in a closed vehicle.
- When outdoors, protect small children from the sun, their skin is sensitive!
I’ve learned a lot of people don’t understand the difference between a severe thunderstorm or tornado watch, or a severe thunderstorm or tornado warning. This scares me!
Here is how I remember the difference: Watch = WATCH! Watch the weather! Something bad could happen in the next six hours or so! Listen to NOAA Weather Radio. Watch TV for weather updates. Check the Internet! Prepare your emergency action plan! This is the site of the Storm Prediction Center, where a bunch of people watch the weather all the time. They send out a severe thunderstorm watch or a tornado watch when they think weather conditions are right to make a thunderstorm severe or a tornado. When a watch is issued for your area, get ready for bad weather!
Warning = ACT NOW! There is another group of weather people at the National Weather Service watching the weather all the time – right over where you live. When they think a thunderstorm will be severe or a tornado will form in the next 30 minutes or so, they issue a severe thunderstorm or tornado WARNING. Take cover! Get out of a mobile home and into a sturdy building! Go to the basement! Don’t wait for hail to break your windows or for a tornado to tear off your roof. GO NOW.
Another place I check to see if there will be severe weather is also on the Storm Prediction Center site. They issue “Outlooks” that tell us if they think there will be severe weather on any day up to eight days in advance! This is a great site to check often!
Now I hope you are not confused anymore! Watch = Watch the weather. Warning = Act NOW!
It is downslope time where I live! This is the time of year when winds coming from the west bump into the Rocky Mountains, and then fall down to the plains on the other side like a waterfall. Think about how rough the water is at the bottom of the waterfall. In areas near the mountains it can get windy when the air rushes down the slopes of the mountains. Winds can gust to near 100 mph! We call it “downslope,” or “chinook” winds. Chinook is a Native American word that means “snow eater.” The wind is usually dry and warm, and can melt a foot of snow in less than an hour!
Sometimes when we have downslope winds we see clouds that look like spaceships. They are caused by strong waves of air bumping over the mountains. See my picture? It is not the best example, but you get the idea.
Sometimes these winds can cause damage because they are so strong, and some towns even have special building codes to protect people and pets.
Other parts of the world have these winds, but they call them different names. In California, they are called Santa Ana winds, and are a huge fire danger. People in Europe call it the foehn. Argentina in zonda. Halny wiatr in Poland. Koemband in Java.