As I reflect, it was Severe Weather Preparedness Week— March 6-10, 2023. We have already had severe weather this year, but it will become more frequent now that spring is around the corner. Sometimes when thunderstorms are forecast, you will hear weathercasters talking about the atmosphere being very unstable. What does that mean? Rising air cools For thunderstorms to form, air must rise. As air rises, it expands because air at higher elevations has less air pressure. The expansion of rising...

We are bound to have fog from time to time. I still remember when I was in my late teens and insisted on going to see some friends when I could barely see the edge of the road. My parents were not happy. Some areas, such as San Francisco or London, have fog more often. The cause of fog can depend on location. Radiation fog The most common cause of fog in Illinois is when there is a lot of moisture in the air on a clear, calm night. This creates what is known as radiation fog. When you hear...

California has recently been slammed with extreme rainfall and snow in the high elevations, along with high winds. Media have attributed these events to an atmospheric river, but what does that mean? What is an atmospheric river? The ones that affect California occur when the polar jet stream splits over the Pacific Ocean, with part of it diving in a big U-shape down to near Hawaii. The same polar jet stream affects us in Illinois during the winter. As it dives south, huge amounts of water...

You may have heard weathercasters saying that December 1 is the beginning of meteorological winter. However, the calendar says winter starts on December 21. Why are there two dates? Meteorogical vs Astronomical winter December 1 is called the beginning of meteorological winter because we often start experiencing what we think of as winter weather by the beginning of that time. The same goes for spring weather by March 1, summer by June 1, and fall by September 1. Astronomical winter doesn’t...

Winter precipitation is on its way. Rain, snow, sleet, and freezing rain are all potential types of precipitation. Rain is liquid water, while the other three are frozen at the end of their atmospheric journey. So, if snow, sleet, and freezing rain are all frozen water, what’s the difference? What is snow? The first thing to know is that no matter what type of precipitation we end up with at ground level, all precipitation in the middle latitudes starts out as snow. Remember that...

Forecasting day-to-day weather and predicting what climate will be five years or 50 years from now have very different outcomes. Both processes use most of the same land, water, and sea parameters, but the range for climate forecasts can also vary due to human activity. For climate forecasts, scientists may use the word "scenario" instead. In today’s world, predicting temperature and precipitation for a local area is pretty accurate for at least a few days out. However, with any forecast, the...

As we move through August, some folks will reference it as being the “dog days.” What are they talking about? We associate these “dog days” with hot weather. But it does not refer to living dogs being uncomfortable in the heat. Instead, the term is associated with a bright star called Sirius (not the radio platform) that can be seen rising close to the sun. Sirius is one of the brightest stars in the night sky. Because of its brightness, in ancient times it was believed that it added heat when...

We tested your knowledge last month. Did you pass the test? True or False: Due to the Greenhouse Effect, the earth takes in more heat from the sun than it gives off. FALSE: What greenhouse gases do is slow the release of heat. If the earth really took in more heat than it received from the sun, the earth would be much, much hotter.   An increase in temperature the higher you go in the atmosphere is called a (BLANK BLANK).  ANSWER...

It's scorching outside. Stay inside and take our most recent weather quiz.  T or F: Due to the Greenhouse Effect, the Earth takes in more heat from the sun than it gives off. An increase in temperature the higher you go in the atmosphere is called a ____ ____. The eye of a hurricane has calm winds and clear skies because the air is doing what there? T or F: Visible band satellite imagery is equally useful day or night. If the outside temperature is 50 degrees Fahrenheit and the relative...

It’s summer. It’s baseball season. Millions of people attend Major League games, just waiting for their favorite hitter to knock one into the seats. Fans contend with afternoon games that may be hot and muggy or just simply hot. I once went to a Rangers game while attending a conference where the temperature at the start of the game was 103°.  Does it make a difference what the weather is like for hitting home runs? You often hear broadcasters talking about the “heavy air” on a muggy day. Does...

Earth’s atmosphere, while it appears to go forever, is actually a very thin layer of air. Technically the atmosphere reaches out for thousands of miles, but over half of the atmosphere is within 4 miles of the earth’s surface. Think about driving 4 miles- it’s not very far. By the time you’re 16 miles up, 98 percent of the atmosphere is below you. Again, not a big distance. At the upper end of this lies a concentration of a gas that protects life on earth. Without this gas, very little life...

Mississippi and Alabama were recently hammered with severe storms and large-scale tornadoes. The damage that large high-speed tornadoes can cause is phenomenal and life-threatening. Many have heard of the “F-Scale” or “EF-Scale” of tornado intensity. The F stands for Fujita, last name of the scientist that developed the scale. Dr. Tetsuya Theodore “Ted” Fujita developed this scale while serving as a professor at the...

If you ever take a few minutes to watch what happens to clouds in the sky, especially in March, you’ll see many puffy shaped clouds form and fall apart. You’ll see these clouds at other times of the year, but they are around a lot in March and April. What clouds are puffy? Cumulus clouds form within a few hundred to few thousand feet above ground. They form from surface heating of the earth. Imagine a bunch of air bubbles being warmed by the land below them and acting like hot air balloons...

Ominous clouds and an approaching storm may be accompanied by the wail of a community siren. Other times they can be heard in the morning on what may be a nice day. What do the different blasts of the siren mean? Sirens are part of the Public Alert System to let those outdoors be aware of a local or national emergency. Originally designed for civil defense, sirens are also commonly used in the Midwest and other locations to alert people of severe weather. It’s important to realize that sirens...

A large underwater volcano recently erupted in the South Pacific. Volcanoes can send huge amounts of gases and ash into the atmosphere. Very large eruptions can affect the climate. In 1815, one of the most powerful volcanic eruptions in the last several thousand years occurred in the South Pacific. The following year was known as the Year without a Summer in the fledgling nation of the United States. Snow events occurred on the east coast in mid-summer. Western Europe had a very cold summer as...

In December, I provided a weather quiz post, the second one I’ve done. Here are the answers. How did you do this time? Let me know! We’ll try another quiz later in the year.   1. True or False, the United States experiences a monsoon.  True: The southwest part of the United States experiences a monsoon during the summer. Moist air flowing up...

If someone is sad that holiday season is over, here is something to celebrate.  The earth is the closest it will ever be to the sun for the year!  We all know the earth revolves around the sun. It takes about 365.25 days to do this, or one year. However, that revolution (or orbit) is not a perfect circle. Instead, it’s slightly elongated or elliptical, which means the earth is farther from the sun at one time and closer at another. How close is the earth to the sun? It depends There is...

Seeing the tragic consequences of the December tornado outbreak in the Midwest, I’m sure many folks are wondering if there are ways to make homes more resistant to wind damage, whether it’s straight-line winds or tornadoes. The answer is yes. How winds interact with buildings Homes affected by strong winds may be overturned, slide off its foundation, or completely lifted off of the foundation. Winds will be slowed or sped up when coming into contact with buildings, depending on the direction...

A few months ago, I posted a quiz with several weather questions for people to try to answer. It seemed to go over well, so here is round two. I’ll post the answers in a few weeks. True or False, The United States experiences a monsoon.  Freezing rain starts as ______ before it freezes. Seasons are created by changes in ____      ________. Carbon dioxide was discovered to be a...

You’ve probably heard these weather terms many times - El Nino and La Nina. They seem to affect our weather and they come and go. Are they normal to occur? Where do they occur? Why does it affect our weather? What is La Nina? In this post, I’ll focus on La Nina since that is what will likely affect our 2021-22 winter weather. First of all, both La Nina and El Nino are not new.  They have been known for decades, if not hundreds of years particularly along the western coast of South America,...

As I write this, folks just a few miles away are sawing up downed trees and clearing debris from severe wind damage that occurred during a round of thunderstorms passing through the area the night before. No tornado was observed either by eye or on radar, so it appears to have been caused by straight-line winds. However, the worst of the damage was confined to a narrow area and is over a mile long. The relatively small area of damage may have been due to a microburst, a localized area of...

The passage of summer to fall happens this year on September 22, which is called the September or Autumnal Equinox. What is an Equinox and why do we use it? Equinox basically means “equal night.” It comes from a couple of Latin words. We have two equinoxes yearly, one in March (the March or Spring Equinox) and the other one in September. On those two days, the noon sun is directly overhead at the Equator. Well, at least for a moment. Remember the earth is constantly moving around the sun, so...

At the writing of this post on September 2, we are in the average peak week of hurricane activity for the Gulf of Mexico. Remnants of hurricane Ida are drenching the East Coast, and a new hurricane is currently out in the Atlantic. The Earth’s weather is a complex system of winds, moisture, and heat. Hurricanes are a good example of all of these. They move huge amounts of heat from the hot tropics to the milder middle latitudes. What makes them form, and how do they move heat? I’m so glad you...

Growing up, we would listen to the local radio station at breakfast. In addition to the news, they would play songs from the great crooners of the time, including Nat King Cole. One of his songs is The Lazy, Hazy Crazy Days of Summer. As I look out my window, the sky has a milky, hazy appearance. What is haze and why does it happen? What is Haze? Haze is made up of very tiny particles that can be solid, liquid, or a combination. The particles are so small they can stay suspended in...

When I talk to groups about the weather, I usually first open things up for any question someone may have on the subject. A lot of times I get similar questions, so I thought I would address some of those questions in this post. How do landscapes affect storms? One question I get is whether or not rivers, river bluffs or tall hills, which is all we have in Illinois, can affect storms or tornadoes. The answer is no. The processes that are making the storm or tornado occur are up thousands of...

As I write this article, corn has tasseled on about 80% of fields in Central Illinois. Apologies to those with corn pollen allergies! Corn, just like other plants, experiences evapotranspiration (ET). Evapotranspiration is when water is taken up by corn plants, water vapor - the gas form of water - is released into the atmosphere from the leaves while evaporation occurs from the soil, which also adds water vapor to the air.  During the height...

First, thanks for your interest in the How Well Do You Know Weather quiz post from a few weeks ago. Some people sent responses and several said they enjoyed the quiz even if they didn’t send in answers.  Without further ado, here are the questions and answers: 1. Small puffy clouds with flat bases are called ______________ clouds.     Answer: Cumulus. There are...

Tornadoes can form in a few minutes and dissipate just as quickly. However, the conditions that may create a tornado and other severe weather can be seen hours in advance giving forecasters and the public the chance to be vigilant. Tornado Watch vs. Warning Watch: Conditions are right for a future severe thunderstorm or tornado. Watches are issued hours in advance.  Warning: A severe thunderstorm or tornado has been sighted in person or by radar. Seek...

Game shows are on the rebound. Shows that were around in the 1960s and '70s like "To Tell the Truth" and "Match Game" are back on air, along with "Who Wants to be a Millionaire" from the ’90s and the solid, never-went-away "Jeopardy."  Since there seems to be a renewed interest in trivia, this post is a game that anyone can play! The Rules Below are 10 questions. Some will be pretty easy, but a few will test your true weather knowledge. Each is worth 100,000 points - go big or go home!...

If you’ve been outside and experienced those first drops of rain, especially after a dry spell, you know that smell. You might even be able to sense the smell a little before it starts to rain, a signal that rain is coming. Even after a rain, a sweet musty odor will linger for some time. A few years ago, I got to go to Fairbanks at the end of June. As I got off the plane, there had just been a light rain. Departing the airport, the first thing I noticed was an unforgettable sweet smell in the...

Have you ever noticed grass looking greener after a spring rain?  Hold that thought. As you look into how nature works, you see a lot of plant nutrient cycling taking place. Makes sense since the earth isn’t getting any deliveries from Mars. Nitrogen is an essential component of proteins, which all living creatures contain. What does lightning have to do with it?  Lightning plays a part in the cycling of this very vital, life-nutrient. Nitrogen gas (N2) makes up 78% of atmospheric gases. ...

Early spring in Illinois can be a battle between the last of cold winter weather and the mild air of spring. On relatively rare occasions in March, we can experience warm, muggy air that normally doesn’t reach us until April or May. When this occurs early in spring, it’s best to be on guard for severe weather.  Jet streams Jet streams are very fast, high altitude winds that blow from west to east. Illinois is generally influenced by what’s called the polar jet. The polar jet is located about...

Many people have heard of Jim Cantore from The Weather Channel. He is even more of a weather geek than I am. In February 2011, the Midwest was hit with a very strong winter storm, and Cantore was in in Chicago reporting on its effects there. During one of his broadcasts, when it was snowing like crazy, there was a flash of light followed by thunder. Cantore was jumping around like a kid in a candy store and earned made him the title King of...

You’re watching a local weather forecast or checking it online when you notice it says temperatures will be 'above normal or below normal.' But what does this actually mean? Normal is Average In most cases, the word 'normal' is used in place of 'average.' Average Daily Temperature: This is calculated by adding the highest and lowest recorded temperatures and dividing by two. Average Highs and Lows: For an average daily high, all the high temperatures for...

Two words people have learned to dread in the past few years is "polar vortex."  People may not know a lot about what that is, other than it usually means we may be in for some bitterly cold temperatures.  The worst outbreak in my experience was December 23, 1983. I had just finished my graduate work and was beginning to look for weather-related jobs. So, I was living back at home on the farm. The farmhouse was uninsulated, and my bedroom was upstairs with no heat. While I was used to...