Weather 4 Kids
CBS4 meteorologist Dave Aguilera has lots of helpful information for children who have an interest in the weather.
What Is Meteorology?
If you didn't know better you might think meteorology might just be the study of "meteorites". But, that would not be correct. Meteorology is the study of things in the earth's atmosphere, especially those dealing with weather. So simply put meteorology is the study of weather.
To find out what meteorology means we have to go way back to ancient Greece. Back then the word meteor would be any object that might be in the sky, it could be rain, snow, rainbows, or yes, even outer space rocks falling through our atmosphere.
Over time the word meteorology came to be known as the study of things in our atmosphere and the study of meteorites fell under the study of astronomy, (which is the study of things beyond earth and its atmosphere.).
What makes Colorado weather special?
If you live in Colorado you will most likely encounter almost any type of weather phenomena, it could be wild or it could be mild. The most important geographical feature that affects our weather is the mountains.
When a storm system hits the Rocky Mountains it can do any number of things. Blast right over the mountains, through the mountains, around the mountain or just be a lazy storm and linger over the High Country.
Breaking Down The Colorado Lingo
Have you ever wondered about why different parts of town and different parts of Colorado have the nicknames names they do? CBS4 meteorologist Dave Aguilera took some time to explain it -- for newcomers and natives alike.
Aguilera was inspired to do this after Michael Walters of Arvada posed a great question to cbs4denver.com about the lingo used to describe areas in Colorado.
We are new to the Denver Metro Area. We watch your station as I like it the best. However, I get confused about what is the Foothills, Flat Range, upper this, lower that. Call me stupid but what seperates the foothills from the flat range? Can you tell me what all of the reference definitions are or, where I may be able to find this on the Web?
Get all of Aguilera's answers in the story Aguilera Breaks Down Some Colorado Geology Lingo.
What makes the weather?
If you picture the Earth's atmosphere as a big pot of soup, the "Spoon" that stirs up that soup, is the Sun.
The Sun will heat different air masses around the Earth to different temperatures, depending upon the season. Some of these air masses may be cold. Some of these air masses may be warm.
What Is Climate And What Is Weather?
Both of these terms describe what you might see outside. The difference is one is long term and one is short term.
Weather is the way our atmosphere is behaving right now, tonight, tomorrow and the next day. That's the short term. Climate is the way our atmosphere behaves over a long period of time, years even decades.
Another way to look at these to words is this way. Climate is what we expect. Weather is what we get.
Colorado thunderstorms can produce a variety of dangerous weather!
In our state it is possible to have a thunderstorm in any month of the year; however, the peak season for Colorado thunderstorms is during the summer months. Severe weather season here typically gets up and running in May and runs through August. With that said, it is important to remember that the big month for severe weather is June. On average, over 40 percent of tornadoes reported in our state have happened in June.
What is severe weather?
The National Weather Service definition for a severe thunderstorm is a storm that produces 58 mph winds or greater or hail 3/4 inch diameter or larger. These strong storms could also, produce flooding rains, dangerous lightning and even tornadoes.
What is a thunderstorm?
A simple explaination is a thunderstorm is any storm that produces thunder. But, it is much more than that.
Thunderstorms are a complicated mix of water, ice, wind and heat. There are several ingredients that a thunderstorm needs to develop.
Moisture- to form clouds and rain
Unstable air- warm air that can rise rapidly through cooler air in the atmosphere
Lift- this could be mountains, heating from the sun, or cold or warm fronts
Some meteorologist, look at thunderstorms as a cooling engine for the earth. The thinking is that a thunderstorm is a huge natural pump. Think of it this way, high up in the atmosphere say 30, 40 or 50 thousand feet up, close to the top of some of these storms, the air can be as cold as 90 to 100 degrees below zero! That's cold! At the same time, especially on a hot summer day, temperatures here on the ground can be 90 to 100 degrees above zero. Thunderstorms can move this heat on the surface of the earth up into the upper levels of the atmosphere quickly. This is called "convective heat transport". Without thunderstorms some scientists and meteorologist estimate that the mean temperature of the earth could rise as much as 20 degrees. That would make it impossible to live in certain areas of our planet.
What is Thunder?
Lightning causes thunder. It is estimated that a bolt of lightning can be as hot as 50,000 degrees Fahrenheit! That is about 5 times hotter that the surface of the sun. As a result of this tremendous heat, the air along and in the channel that lightning creates expands. This rapidly expanding air creates the sound we call thunder.
Lightning
All thunderstorms contain lightning. In Colorado, lightning is awesome to look at and photograph. But, it is also, very dangerous! The National Weather Service refers to lightning as the "Underrated Killer". Believe it or not, lightning is the top life threatening weather hazard in our state!
How is lightning formed?
Simply put lightning is a huge spark that occurs during a thunderstorm. The reason for this electrical discharge is the attraction of positive and negative electrons. Here's what happens.
The friction caused by the strong updrafts and downdrafts moving particles inside of a thunderstorm help to create an electrical charge. During this process positive charges (protons) build up in the top of the thunderstorm (cumulonimbus cloud). At the same time negative charges (electrons) gather at the bottom of the thunderstorm. Then, these negative charges are attracted to positive charges that are coming together on the ground.
When the negative charges meet the positive charges, bingo, you have lightning.
Have you ever been shocked by a tiny spark when you touch a doorknob or another person? That is somewhat the way lightning is formed. Think about it this way. When you walk across a carpet you create friction and attract negative charges. Then when you touch a doorknob, the negative charges are attracted to the positive charges in the doorknob and that creates a small spark.
What are the main forms of lightning?
There are several different forms of lightning, all depending upon where the bolt starts and finishes.
Forms of Lightning
Cloud -to-ground (CG)
Cloud-to-cloud (CC)
In cloud IC
Cloud to air (CA)
There are also a few other forms that are very rare.
What makes up a lightning bolt?
When you see a stroke of lightning it may look like one big bolt. But, believe it or not, you may be looking several different strokes in the same spot going both up and down. Each one of these strokes is extremely fast. Some can be measured in millionths of a second! Each one of these strokes has a specific name. The electrical charge coming from the cloud is called "the stepped leader". The charge coming from the ground is "an upward streamer" this comes from the object that is about to be struck. When these two leaders meet, that creates a path for the electricity to pass from the cloud to the ground, and the ground to the cloud.
How do you know if lightning is close?
If you can here thunder that means lightning is close. Even if the thunderstorm is not directly overhead that does NOT mean you are safe. Lightning can occasionally strike as far as 10 or more miles from the storm it started from. That is why it is very important to get indoors when you hear thunder outside.
One good way to estimate how far away lightning is, is to use the sound of the thunder. The next time you hear thunder start counting until you see the lightning. The number of seconds that pass between the sound and the sight of a lightning bolt will give you a good indication as to how far away the thunderstorm is.
Here's how you do it: Take the number of seconds that pass between the sounds of thunder and see the lightning and divide by 5. For example if you counted 5 seconds and divide by 5 that equals 1. That means the storm is about one mile away. 5/5=1. If you counted to 10 and divide by 5, that means the lightning is 2 miles away. 10/5=2.
Know when to take cover: the difference between a tornado watch and a tornado warning
Tornado Watch: Is issued when conditions are just right for tornadoes to develop. It does not mean tornadoes are imminent, just that you should be aware that the possibility is there. When you hear or see that a watch is in effect, you should keep an eye and ear tuned to television or radio so you know what is going on with the weather.
Tornado Warning: Is issued when a tornado has been spotted, or indicated on Doppler radar. When a tornado warning is issued for your town or county you should take immediate safety precautions.
What is a Tornado?
A tornado is a rapidly rotating column of air dropping from a strong thunderstorm to the ground. That thunderstorm cloud is known as a cumulonimbus cloud.
What causes a Tornado?
Inside a cumulonimbus cloud or thunderstorm, you have updrafts and downdrafts. Warm rises up into the thunderstorm and cold air sinks down in the thunderstorm.
Now all air masses have a certain amount of spin, but, the updrafts and downdrafts in a thunderstorm increase that spin inside the storm. This motion creates a horizontal rotating column of air. The rising and dropping air tilt that column vertically and if that column of air extends to touch the ground, Bingo, you have a tornado!
The technical term for this process is called "Conservation of Angular Momentum." Have you ever seen an ice skater doing spins on the ice? When the skater pulls their arms in close to their body, they can spin faster and faster.
With a thunderstorm, the tighter the spinning air goes, the stronger the rotating column of air gets.
How long can a tornado last?
Some twisters may last only for a couple of minutes and are on the ground for a few feet to a few miles. While some can last several minutes to several hours and travel from a few miles to more than a hundred miles. A few of these huge tornadoes may have paths of destruction that are a mile wide.
When do tornadoes occur?
In Colorado, primetime for tornadoes is from mid May through mid August. Colorado twisters have been reported in 9 out of 12 months of the year.
The big month for tornadoes is June. Through the years most of the recorded tornadoes in our state have popped up in the month of June.
Most of our tornadoes happen between 1pm and 9 pm. In fact, 88 percent of them occur during this time period. And over half of all twisters threaten between 3pm and 6 pm.
If you break it down by county, Weld County in Northeast Colorado is the big winner or loser (depending on how you look at it) in number of tornadoes. In fact, Weld County on average has one of the biggest numbers of tornadoes across the country! The reason for that is primarily due to Weld counties size. It is 2 to 3 times larger than most counties in the United States.
Where are Tornadoes most likely to form?
Tornadoes can occur anywhere in the state of Colorado, but, most of them develop in Eastern Colorado. Most of those occur east of Interstate 25.
Twisters have been reported in every state in the United States. But, if we look at the nation as a whole, the bulk of tornado producing thunderstorms hit an area that meteorologist call "Tornado Alley." This is an area of land in the nation's midsection that is clobbered by more tornadoes than anyplace else in the world!
This area runs from North Texas through Oklahoma, Kansas, Missouri, and Ohio. That's not to say all tornadoes occur in this area. But, a large number of them do. Other areas that pick up a lot of tornadoes include many southern states like Mississippi, Alabama, Georgia and Florida.
How is the Strength of a Tornado measured?
Meteorologists use a scale called the "Enhanced F-scale" to measure the power of a tornado. It is a scale that is based upon how much damage any given tornado produces.
*** Important note about F-scale winds: These precise wind speed numbers are actually guesses and have never been scientifically verified. Different wind speeds may cause similar looking damage from place to place. Even from building to building. A new "Enhanced F-scale" will be implemented in February 2007.
The Enhanced F-scale replaced the old Fujita scale, (F-scale), which is named after Professor T. Theodore Fujita, a pioneer in the study fo tornadoes. The new Enhanced F-scale gives more detailed information about damage and winds.
Click here to see the Fujita Scale.
What is "Virga"?
This is a word used by weathercasters a lot, especially, during the summertime but, it can happen any time of the year. In meteorology, the word is used to describe precipitation that falls from a cloud but, evaporates before it reaches the ground. Virga looks like a ragged or torn bottom edge of a cloud. Kind of like a wispy, curtain hanging from the bottom of a cloud, but, not making it all the way to the ground.
The word itself is actually an acronym (an abbreviation of several words in such a way that the abbreviation itself forms a word.)
V I R G A = Variable Intensity Rain Gradient Aloft
Virga can cause lots of weather effects, because as rain or snow changes from liquid or solid to vapor, it takes heat from the air and cools that air. This colder air starts to sink at a faster rate and can produce powerful winds on the ground. These powerful winds are sometimes called microbursts.
What is the North American Monsoon?
During the month of July you might start hearing talk about the "monsoon." But, do you really know what it is?
The North American Monsoon provides summer thunderstorms from California to Colorado and from Mexico to Montana. The area of coverage is basically, the southwestern U.S. and Northwest Mexico. It is sometimes referred to as, the Southwest monsoon or the Mexican Monsoon.
The word monsoon simply means a wind that reverses direction. A lot of people when they hear the word "monsoon" tend to think about the torrential flooding rains that typically occur in India and Southeast Asia.
Our summer monsoon is not quite that dramatic. But, it does provide lots of moisture during what is often the hottest part of our summer. And can sometimes produce flooding rains with slow moving thunderstorms.
Typically, somewhere around the 2nd or 3rd week of July, the wind reverses direction and can provide an open pipeline to move moisture up into Colorado.
Some of the Front Range's biggest floods have happened during the summer monsoon. Such as the deadly Big Thompson Flood in 1976 and the devastating Spring Creek flood of 97, that produced a one day record for rainfall for Fort Collins.
How Does The Southwest Monsoon Work?
Here are the basic mechanics of the Southwest monsoon.
When summer begins High Pressure moves in and centers over the four corners area. This High may hover around the Colorado down into the Southwestern U.S. This can produce dry and hot conditions in June and the early part of July. As the summer moves on this area of High Pressure typically, starts to move to the east. This helps to shift the overall wind flow pattern to a more southerly direction.
This opens the door for moisture to flow northward from the Pacific Ocean and the Gulf of Mexico. As a result Colorado sees a rise in daily afternoon and evening showers and thunderstorms.
What is wind?
Wind is air moving over the earth's surface. Air is all around us all of the time. Air gets moving in two ways from the uneven heating of the earth by the sun and differences in air pressure.
As the sun warms the earth, the heating is uneven, meaning some parts of the earth get heated up more than others. Such as land and water being heated and holding heat at different rates. Other areas may receive direct sunlight at certain times and indirect sunlight at other times. So with that said, across the earth we have warm air and cool air. Warm air weighs less than cold air and tends to rise up into the atmosphere. Cool air will then sink in and replace that rising warm air. This movement of air masses helps to make the wind blow.
Wind is also caused by differences in air pressure within our atmosphere. Air flows from high pressure to low pressure. The speed of the wind is faster if the difference between the high pressure and low pressure is larger. Greater the difference = Faster the wind.
What's the fastest wind ever recorded?
We may have two winners for this one.
Wind speed is typically, recorded with an instrument called an Anemometer. The fastest wind ever recorded with an anemometer, was on top of Mount Washington, New Hampshire. In the spring of 1934 an anemometer recorded a wind speed of 231 miles per hour!
In, 1999, a wind speed of 318 miles per hour was estimated with Doppler radar in an Oklahoma tornado. That's over three times faster than the fastest baseball pitch in the major leagues!
How To Read A TV Weather Map
There are a few things to remember when you are watching the weather on CBS4. When you watch the weather forecast on TV you might hear and see the weather forecaster talk about cold fronts, warm fronts, high pressure, low pressure or many other different things that are going to affect our weather. See a special slideshow that shows how each of these graphics look.
What types of clouds are there?
You may have noticed clouds come in endless shapes and sizes, but, they are classified in ten different types. These types may seem pretty complicated, but, when you group them into different levels of the atmosphere, remembering the different types does become easier.
Believe it or not if you know what cloud types to look for you can actually, predict your own local weather if you know what to look for.
Cloud types are put into groups by how they look to a person on the ground. The ten types of clouds are put into four different categories and separated by using Latin words to identify what they look like.
The first category is the High Clouds. High clouds use the prefix Cirro or Cirrus and are made up of mostly ice crystals. These feathery looking clouds normally float above 20 thousand feet in the atmosphere.
High Clouds:
• Cirrus (see image)
• Cirrocumulus (see image)
• Cirrostratus (see image)
The second category is Middle Clouds. Middle clouds use the prefix Alto and can roam between 6,500 feet up to 20,000 feet. These clouds contain mostly water droplets, because they are at a lower level. Some of them however, can contain ice crystals if the temperatures are cold enough.
Middle Clouds:
• Altocumulus (see image)
• Altostratus (see image)
The 3rd category is Low Clouds. Low clouds can have two different prefixes attached to them. They are Cumulus (which are rising puffy, cotton ball looking clouds or Stratus which are layered clouds. These clouds can have bases from the surface to 6,500 feet, but, we can see there tops rise higher than that.
Low Clouds:
• Cumulus (see image)
• Stratocumulus (see image)
• Nimbostratus (see image)
• Stratus (see image)
The 4th category is Clouds of Great Vertical Development. These are true thunderstorm clouds. These clouds are produced through thermal convection or frontal lifting and can grow over 40 thousand feet tall!
These clouds can make heavy rain, snow, hail, lightning and even tornadoes.
Clouds of Great Vertical Development:
• Cumulonimbus (see image)
There is also, a special group of cloud types that you might see while you are looking at the sky here in Colorado. These clouds don't fit into the previous four categories but, by watching these clouds you can also, describe and predict what type of weather is going on.
These other types are Fog, Contrails, Mammatus (see image), and orographic(mountain wave).
Fog is a cloud in contact with the ground. It is made up of billions of tiny water droplets floating in the air. Fog is different from other clouds only because it touches the earths surface.
Contrails are made at high altitudes where very cold temperatures freeze water in just a few seconds before it can drop or evaporate. The word Contrail is short for condensation trail. This happens when water vapor is put into the air from the exhaust fumes of a jet engine.
Mammatus clouds can sometimes look scary. These clouds look like lots of dark sinking pouches. These clouds are formed with thunderstorms and hang from the bottom of a storm looking like they are bulging down from the bottom of a cumulonimbus cloud.
Orographic clouds have many descriptive names here in Colorado. These tend to appear along the Colorado Front Range when we have strong winds in the upper levels of the atmosphere. These form when air is forced up into the atmosphere by the mountains. Sometimes these are called mountain wave clouds. If the clouds are thin, lens-like looking or flying saucer looking, they are called lenticular clouds.
What is a cloud?
A cloud is a group many small drops of water and/or ice crystals, so tiny that they can float in the air!
All clouds are made up of water. In fact, clouds, snow and rain are all some form of water. Clouds are droplets of water and/or ice crystals, rain are liquid water and snow is a group of many ice crystals.
Water existing as a gas in the air is called water vapor.
Clouds form through a process called "condensation." This happens when warm air rises. As this air expands, it cools. This cooling and expanding process forces the water vapor in the air to become a liquid droplet that will stick to tiny dust particles or ice crystals floating in the air.
It takes billions of these tiny droplets to stick together and become a cloud.
Anatomy Of An Avalanche
It's a great name for a hockey team, but, a real avalanche is one of the most dangerous things you can encounter in the Colorado mountains.
Thousands of avalanches happen every year in our mountains, with most of them happening during or right after a big mountain snowstorm. On average 6 people die in Colorado avalanches every year. Avalanche experts advise skiers, boarders, hikers and snowmobilers to wait at least 36 hours after a big snowstorm before going out in backcountry areas. This may allow a weak spot to stabilize after a time.
An avalanche is a huge sliding mass of snow. Sometimes this river of flowing snow may contain ice, dirt, rocks and even uprooted trees. These things may have been pulled up into tons of snow flowing down the slide.
Avalanches typically happen on slopes greater than 30 degrees. If you're a skier that's about the steepness of a Black Diamond run at a ski resort. And while ski areas prepare there slopes so avalanches do not occur, its areas out of bounds and in the backcountry areas where people tend to get into trouble.
Here's how avalanches form.
Snow accumulates on mountain slopes in layers, one snowstorm at a time. And if it is wind-driven snow, that makes the slabs even weaker.
Another factor in creating these weak slabs of snow is the temperature. Relatively warm days and cold nights create a melting and refreezing cycle hardening old layers into ice and the new snow has a hard time sticking and bonding to the old layers. This can create cracks in the snow layer where avalanches may be more prone to occur. Then when a skier, boarder or snowmobiler rides through a weak spot an avalanche may occur. In some cases just the weight of the top layers may be enough to break free and flow down the mountain.
Here are a few tips from the National Weather Service to stay safe in avalanche prone areas:
- Never travel alone. Always have one or more companions. Even small avalanches can be fatal. If you are alone and get trapped, you may not be found until spring.
- If crossing a slope that may be prone to avalanches, do it one person at a time. You want to minimize the impact on your party if an avalanche is accidentally released.
- In avalanche country all members of your party should carry avalanche rescue equipment, including an avalanche beacon, shovel and probe pole. This increases your chances of affecting a successful rescue and finding your friends alive.
What Is Snow?
Snow is a type of frozen precipitation. Typical snowflakes are made up of ice crystals that can form in certain storms that have the right temperature and moisture. Snow forms mainly when water vapor in the atmosphere changes into ice, without becoming a liquid, at a temperature that is typically less than 32 degrees high above the ground.
Snowflakes form when water vapor freezes into ice crystals that stick to tiny bits of dirt that are floating in a storm. One snowflake can be made up of hundreds of small ice crystals!
Because each snowflake follows a different path in a storm, no snowflakes look alike. Each snowflake however, has six sides, because of the way ice crystals begin, each snowflakes start with a hexagonal (six sided), ice crystal and as more and more ice crystals are made the snowflake keeps its hexagonal formation.
Because of gravity, as the snow crystals get bigger and bigger, they eventually get heavy enough to fall to the ground.
How Does A Forecast Get Put Together?
Dave Aguilera explains in this special video clip how a meteorologist like him puts together a forecast.
What is upslope?
One of the main producers of heavy snowfall along the Front Range is something called "upslope flow." A simple definition of upslope is when moist winds blow from east to west across the Front Range.
In, the winter, as cool moist air rises in elevation, clouds and precipitation can form and can produce rain or snow. If the temperature is cold enough and the upslope strong enough this can produce heavy snow.
For example, Denver, sits at an elevation of 5,280 feet, that's 1 mile above sea level. That's why Denver is called "The Mile High City". As you travel east into Western Kansas and Nebraska you drop down to around 3,000 feet above sea level. So when moist air rises from 3,000 feet up to 5,280 feet this increase in elevation is enough to make clouds and precipitation and sometimes that precipitation could be heavy snow.
What is an advisory?
Advisories are issued by the National Weather Service for winter season weather that may not be as extreme as those conditions that require a Warning.
A Snow Advisory is issued when general snow accumulations are expected:
• Between 4-8 inches in 12 hours in the mountains
• Between 3-6 inches in 12 hours at lower elevations
A Snow and Blowing Snow Advisory is issued when falling snow is accompanied by blowing snow. This may cause travel problems due to lower visibilities and drifting snow.
A Blowing Snow Advisory is issued when wind blown snow will occasionally reduce visibilities and create a hazard for travelers.
A Dense Fog Advisory is issued when widespread fog will reduce visibilities to ¼ mile or less.
A Wind Chill Advisory is issued when wind and temperature combine to produce wind chill values of 18 degrees below zero to 25 degrees below zero.
A Winter Weather Advisory is issued for freezing drizzle or a mix of precipitation types (such as snow and sleet) that will impact travel conditions.
A Sleet Advisory is issued when sleet accumulates to a quarter to a half inch.
A Frost Advisory is issued during the growing season when temperatures are expected to drop to between 32 and 35 degrees on clear, calm nights.
A Blowing Dust Advisory is issued when blowing dust reduces visibilities to between a quarter of a mile and a mile.
What's The Difference between Winter Watches and Warnings?
During the winter season, you may hear terms like these on Television or Radio: "There's a Winter Storm Watch in effect through Tomorrow" or "There's a Heavy Snow Warning in effect through the weekend". Would you know the difference between a watch and a warning if you heard or saw it today? These watches and warnings are issued by the National Weather Service.
Maybe this list will help you out:
• A Winter Storm Watch is issued when winter storm conditions are possible within the next 12 to 36 hours, but the timing, intensity or occurrence may still be uncertain.
• A Winter Storm Warning is issued when heavy snow is occurring or will develop in the next 12 to 36 hours. As will winds greater than 15 mph and blowing snow.
• A Heavy Snow Warning is issued when heavy snow is occurring or will develop within the next 18 hours. The winds however are expected to be less than 15 mph.
A Blizzard Watch is issued when blizzard conditions are possible in the next 12-18 hours.
A Blizzard Warning is issued when the following conditions are possible in the next 12-18 hours:
• Sustained winds of 35 mph or greater
• Considerable falling and/or drifting snow lowering visibilities to less than ¼ mile.
• A Wind Chill Watch is issued when wind chill warning criteria are possible in the next 12 to 18 hours.
• A Wind Chill Warning is issued for wind chills of at least -25 degrees on the plains and -35 degrees in the mountains.
• A Freeze Watch is issued when freeze conditions are possible in the next 12 to 24 hours.
• A Freeze Warning is issued during the growing season when widespread temperatures are expected to drop below 32 degrees.
• A High Wind Watch is issued when high wind conditions are expected to develop in the next 12 to 36 hours.
• A High Wind Warning is issued for the following conditions: sustained winds of 50 mph for at least 1 hour or gusts to 75 mph for any duration in the mountains and foothills. Or sustained winds of 40 mph for at least 1hour and/or gusts to 58 mph for any duration at lower elevations away from the foothills.
Winter Weather
Colorado's winter season can beautiful and brutal all at the same time. So it is very important for you to know when to expect snow and how much.
The Front Range of the state can and has seen some tremendous snowstorms over the years. Some of these storms have been strong enough to produce full blown blizzards.
One example, of a big blizzard in Colorado happened in 1997, at that time it had been a while since Eastern Colorado had a real blizzard producing storm. Many people had a tough time believing that a real blizzard was on the way. Several people ignored warnings about the storm that was heading in. Tragically, several people died after getting caught out in the storm. That storm dumped around two to three feet of snow along the Front Range.
A few more heavy snow producing blizzards have happened since then. One storm in 2003 pounded the Denver area with about three feet of snow. Some of the mountain areas picked up 80 to 100 inches of snow with that one. That blizzard was forecast days in advance and many people that time around paid more attention to the warnings. So although the storm did cause a lot of damage, fewer people ended up getting caught out in the big snowstorm.
When the Front Range receives a big snowfall, we usually receive what Meteorologists call an "Upslope." That occurs when air pushes in from the plains up against the mountains, that air rises in elevation and cools. Cooler air holds less moisture than warm air.
So, more often than not if we do have an Upslope that produces low clouds and precipitation. In the winter that could mean snow, in the summer that could mean rain. In the greater Denver metro area and upslope condition typically exists with an East or Northeast wind.