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wximpact Denver, CO

Page history last edited by hosea@... 12 years, 6 months ago

Welcome to Denver, Colorado!

Denver is the capital of Colorado as well as its largest city with 557,478 people, about twelve percent of the entire state's population











Denver Colorado
Land Area (Sq. Mile) 153 103,718
Population 557,478
Persons per Sq. Mile 3,616.8 41.5
Male %
 50.5% 50.4%
Female %
 49.5% 49.6%

Median Income


% pop. that has High School Diploma, Age 25+ 78.9% 86.9%
% pop. that have Bachelor's or higher, Age 25+ 34.5% 32.7%


 Denver City and County Flag








    Denver’s most famous geographic feature is its elevation. The city is known as the mile high city because its elevation is almost exactly one mile above sea level.
  • This elevation is due to Denver’s location in the high plains at the eastern edge of the Rocky Mountains.

  • These mountains are the most dominant feature of the area.

  • The South Platte River runs through the middle of the city. This river allows for many small creeks and lakes throughout the area.

  • Only 1.6 sq. miles of water in city of Denver

  • On the picture to the right, the smaller foothills are located approximately 15 miles from the base of the foothills

  • Lowest Elevation in Denver is 5,140 ft

  • Highest Elevation is 5,672 ft


    39°45’ N 105°0’W



*Courtesty of NSGS









Denver's known for being located just east of the Southern Rocky Mountains.  The city lies on the high plains in the South Platte River Valley.  Denver is home to many small animals as well such as raccoons, squirrels, opossums, snakes, bats and rats. 
  www.biology-blog.com/images www.aaanimalcontrol.com/Professional-Trapper/wildlife/CO-Denver-Wildlife

Due to the little amounts of rain and higher elevations, evergreen trees mark the terrain.  The area is home to protected bison and elk herds.  The Denver area is also near the grasslands of the Plains.

www.northrup.org www.devergov.org  





Being located around 40° N, the climate in Denver can be considered that of a highland or mountain climate in a continental location.  Because of the high elevation and thinner atmosphere, there is a larger amount of solar radiation which results in nice temperatures, even if there is a large amount of snow present.    There is little humidity in Denver which allows for a comfortable environment even with hot temperatures in summer months. 1  

The weather in Denver is similar both in Spring and Fall.  With mild and dry weather, you are able to experience warm, sunny days and cool evenings.  Temperatures may drop in the mountains, but they are still comfortable.  In the summer, there are countless warm, sunny days.  Typically, Denver has more than 300 sunny days per year.  If you are visiting Denver, you may experience a sudden thunderstorm during a summer afternoon.  Winter days are sunny just like summer days.  The temperatures may vary greatly during winter days, ranging from below freezing temperatures all the way up to 60°F.  While Denver does get snowfall in the winter, the actual amounts are lower than many people imagine.2 


1 http://www.wrcc.dri.edu/narratives/COLORADO.htm





Average Snowfall

Average Precipitation 





As shown by the charts above, the majority of snowfall in Denver occurs in November and March. While many may believe Denver receives an immense

amount of snowfall each year, they typically only receive around 60 inches of snow annually. In regards to rainfall, the majority of rainfall occurs in

the summer months, with the most average rainfall occuring in July.



Key Industry


The Metro Denver Economic Development Corporation, which is affiliated with the Denver Chamber of Commerce, is an organization focused on creating a competitive environment while further expanding on the interests of the area. Overall, it consists of seven counties in the Metro of Denver and two counties in the Northern Colorado region. In 2004, the BreakThrough! Denver campaign was initiated and raised over $13.3 million to reestablish the economic strength of the region after 9/11. Creating 100,000 new jobs by 2008 was the main goal.  There are nine key industries in the Metro Denver region according to the Executive Summary of “Key Industry Clusters” obtained from MetroDenver.org. To be classified as a key industry, the industry’s employment concentration must be greater than the national economy’s and must create a substantial amount of wealth for the region.  What aids these industries the most is the talent that Metro Denver supplies as well as the supreme Universities that aid in that development of talent.  Also, reasonable operating costs and tax policies allow industries to do more business.  Last, but not least, the beautiful Colorado atmosphere gives an overall better quality to life that allow people to enjoy their careers.


Rank Industry # Employees Description
1 Aerospace 20,500 Colorado has the 2nd-largest Aerospace program when include the nine counties that metro Colorado makes up.  Just recently, the United Launch Alliance was created between Lockhead and Boeing's rocket launch divisions.
2 Aviation 14,230 The Denver International Airport, along with 3 other airports, aids in making the aviation industry top for metro Denver.
3 BioScience 15,500 470 bioscience companies have emerged.  11 high education institutions have bioscience programs and lead in research assistance.
4 Energy 28,510 As Colorado has many fossil fuels, renewable energy, and energy research resources, the Energy industry is growing with 2,180 companies.
5 Financial Services 10,310 Many associations and firms allow for the financial services of Metro Denver to be a key industry as well.  There are 10,310 companies in Metro Denver.
6 Information-Technology Software N/A According to the American Electronics Association's Cyberstates 2007 report, Colorado ranks third in the highest workers per capita in the Information Technology - Software industry.
7 Production of Beverages 6,750 Metro Colorado also ranks 3rd out of 50 metropolitan areas for the production of beverages.
8 Broadcasting and Telecommunications 40,750 The broadcasting and telecommunications industry also ranks 3rd.
9 Information Technology - Hardware 12,530 The Information Technology - Hardware industry accounts for 55% of Colorado's exports.  That is 3 times the national average!!


The Denver International Airport  




Land Use


Land use of the 153 square miles in Denver, Colorado ranges from business to nature.

Denver's zoning districts include areas for residential, business, industrial, commercial, and open land use

In these areas, there are buildings ranging from skyscrapers to single family houses, international airports to sporting venues, and museums to parks.

Here, you can find a list of the zoning districts in Denver.



The overall land uses for the state of Colorado is the following:



Denver houses many large skysrapers and many buildings

Denver's land use also includes a large airport that was designed to resemble the snow caps of the mountains.

Also Denver is home to over 200 different parks.

46th & Pecos Park
51st & Zuni Park
Alamo Placita Park
Argo Park
Ash Grove Park
Aspgren Park
Athmar Park
Aztlan Park
Babi-Yar Park
Barnum East Park
Barnum North Park
Barnum Park
Bates-Hobart Park
Bear Creek Park
Bear Valley Park
Berkeley Park
Bezoff Park
Bible Park
Bonnie Brae Park
Burns Park
Centennial Flower Gardens Park
Chaffee Park

Cheesman Park
Ciancio Park
City of Axum Park
City of Brest Park
City of Cuernavaca Park
City of Karmiel Park
City of Madras Park
City of Nairobi Park
City of Potenza Park
City of Takayama Park
City Park
Civic Center Park
Columbus Park
Commons Park
Confluence Park
Congress Park
Cook Park
Cranmer Park

Ruby Hill Park

Crescent Park
Crestmoor Park
Dailey Park
Deboer Park
Denison Park
North Harvard Gulch Park
Dunham Park
Eastmoor Park
Eisenhower Park
Elmendorf Park
Falcon Park
Ferguson Park
Fishback-Landing Park
Flores(Hector M.) Park
Fred N. Thomas Memorial Park
Fuller Park
Garfield Lake Park
Garland & Saratoga Park
Garland Park
Gates-Crescent Park
Globeville Park
Godsman Park


Hampden Heights Park
Harvard Gulch Park
Harvey Park
High Line Canal Park
Highland Park
Hirshorn Park
Huston Lake Park
Hutchinson Park
Inspiration Point Park
Irondale Gulch Park
Jackie Robinson Complex Park
Jacobs(Frances Wisebart)Park
Jefferson Park
Jefferson Square Parks

Platt (James H.) Park
Pulaski Park
Robinson Park
Rocky Mountain Lake Park

Kennedy Park
Kittredge Park
Lawson Park
Lincoln Park
Lindsley Park
Loretto Heights Park
Magna Carta Park
Martin Luther King Park
Martinez Park
Mayfair Park
McNichols Park
McWilliams Park
Mestizo-Curtis Park
Montbello Central Park
Montclair Park
Montclair Reservoir Park
Northside Park
Observatory Park
Pferdesteller Park
Pinecrest Village Park
Pinehurst Park

Rude Park
Sanchez Park
Sanderson Gulch Park
Schafer Park
Silverman Park
Skyland Park
Skyline Park
Sloan's Lake Park
Southmoor Park
Southwest Auto Park
St. Charles Park
Sunken Gardens Park
Swansea Park
Valverde Park
Vanderbilt Park
Verbena Park
Veterans Park
Viking Park
Village Place Park
Wallace Park
Washington Park
West-Bar-Val-Wood Park
Westwood Park
Zeckendorf Place Park







Denver International Airport



By Air







The primary airport in Denver is Denver International Airport (DEN).
It is the 5th busiest airport in the United States and the 10th busiest airport in the world.
However, it is also ranked as one of the least-delayed airports in the US.
A list of airlines that fly out of DEN is included below, along with the links to their websites.



By Car


Here is a chart that includes travel times to Denver from some major cities in the US.




Road Conditions


Follow this link to get a complete update on the weather

and road closures for the state of Colorado.

Current Weather and Road Conditions




including Denver Yellow Cab, Metro Taxi, and Mile High Pedicabs.  Their websites are included below.
For a good car rental while you are in Denver, please contact one of these resources:
All transportation information taken from www.denver.org.  Visit the website for more in-depth information.



Getting Around Denver


Here is a list of travel agencies recognized by the city of Denver as the

best choices for setting up your trip.


AAA Auto Club--Denver

Akwaaba Travel Agency

Polk Majestic Travel

Travel Organizers




The best way to travel around the Denver metro area is by using the Regional Transit District (RTD).  It provides bus and light rail service to the entire Denver area.  Fares are set at $1.75.  Passes can be purchased for individuals or large groups.  Below is a picture of all the places the RTD services.  If you go to http://www.rtd-denver.com/ and click on “System Maps”, you can view the same map and be able to zoom in on every single bus stop and rail station.











Denver Fun Facts

Denver's Population has increased 29.8% since 1990

Denver is the most educated city in the US
Not actually in the mountains, 15 miles east of the foothills
15 steps west of the Capitol building is exactly 1 mile in elevation
2nd closest metropolitan area to the exact center of the continental United States
Made aviation history is 1997 when they opened their $4.3 billion dollar international airport
Average winter temperatures are warmer than cities such as New York, Chicago, and St. Louis
Record low temp. -29 F and record high 112 F
Average about 300 days of sunshine per year
Has one of the US coin mints
Home to the Coors Brewing company
Brewery for Anheuser-Busch and other "micro-brews"
Has 8 professional sports teams in six different sports: Broncos (NFL), Crush (AFL), Rockies (MLB), Avalanche (NHL), Nuggets (NBA), Rapids (MLS), Mammoth (NLL), Outlaws (MLL)




Meteorological Information



Hail: (Bailey Hatch, hatch2)






Denver, Colorado lies in what is known that “Hail Alley,” a region that includes Texas up through North Dakota ("Severe and Hazardous Weather: An Introduction to High Impact Meterology" by Robert M. Rauber, John E. Walsh, Donna J. Charlevoix) and experiences the highest occurrence of large hailstorms. The hail season in Colorado is generally between March and October while June has the highest frequency of hail producing storms(http://www.rmiia.org/Catastrophes_and_Statistics/Hail.htm). In 2007 there were 406 reports of large hail throughout the state (http://www.spc.noaa.gov/).


A Visual of "Hail Alley"






Hail Formation





The damage caused by hail in the United States generally falls into two categories; agricultural and structural. As Denver is an urban area, most of the damage from hail happens to buildings, aircraft, and other expensive vehicles (Rauber, Walsh, Charlevoix). As of February 2007, the seven costliest hail storms in Colorado occurred in Denver. The most expensive occurred on July 11, 1990 and caused $625.0 million worth of damage (which equates to $996.0 million readjusted for inflation). Over the past 10 years hailstorms are attributed to nearly$2 billion in insured damage for all of Colorado. This means that up to ½ of homeowner’s insurance premium is solely to cover damage from hail and wind! (http://www.rmiia.org/Catastrophes_and_Statistics/Hail.htm)



A Hail Storm in Colorado









Lightning: by Alex Diehl--adiehl2






Lightning can occur within clouds, between clouds, or between a cloud and the ground.  When talking about the effects of lightning on a city, we will be mostly concerned with cloud to ground lightning strikes.  Lightning occurs during thunderstorms because of the accumulation of charge.  Positive charge accumulates near the top of the storm while negative charge accumulates in the bottom.  There are several mechanisms through which this accumulation of charge may occur.  The most commonly accepted method involves small, light ice particles receiving positive charge and being swept upwards while larger, heavier ice molecules receive negative charge and travel downwards.  A cloud to ground lightning strike occurs when the local electric field in the cloud reaches about 3 million volts/meter.  At this strength, air no longer serves as an insulator and electrons, or negatively charged particles, begin to move.  The electrons surge towards the ground in the stepped leader, taking the path of least resistance.  When the stepped leader nears the ground, the electric field between the ground and the stepped leader increases so much that the positive charges on the ground jump up to meet the leader.  When the positive charge meets the descending negative charge, a channel for the flow of electron opens and the return stroke occurs.  During the return stroke, the lightning flash that is visible to the eye occurs.  With this flash, the molecules in the path are ionized.  The flash and the current are actually directed upwards from the ground towards the cloud base (Rauber).


Rauber, Robert M., John E. Walsh, and Donna J. Charlevoix. Severe and Hazardous Weather. Dubuque: Kendall/Hunt, 2005.




As in most areas, lightning is most likely to effect Denver during the summer months, particularly July and August.   On any given day in August, 4215 lightning flashes occur in the state of Colorado. These lightning flashes are at a minimum around 8 am Denver time and around a maximum at 4 pm Denver time. Denver, however, is not located in one of Colorado’s hotspots for lightning, which generally occur where mountains and plains intersect.  Denver is located at the southern edge of a minimum for lightning in Colorado.  This minimum is caused by a phenomenon called the Denver Convergence Vorticity Zone or DCVZ.  This zone forms when low level southeasterly flows form over the Colorado Plains.  This zone is a favorable area for thunderstorm formation.  Once the storms are formed, they are carried off to the east causing a lack of lightning activity in this zone.  Although this zone causes a lack of lightning to occur to the north of Denver, the zone may actually cause an increase in lightning activity to the south of Denver.  Therefore, one must be more cautious of lightning if they are in the southern portions of the city.  The table to the right shows all lightning related deaths and injuries that have occurred within Denver County since 1982.  It is interesting to note that although July and August see the highest incidence of lightning, lightning is most likely to harm someone in Denver during the month of June.  Overall, as Denver is a city that sees more sunny days that most other cities in America, the frequency of lightning is not particularly great, especially when compared to cities located on the Great Plains and in the Midwest.  However, the fatalities due to lightning in the areas around Denver are relatively high considering the amount of lightning.  This is in part due to the dangers of “dry lightning”, which is common in the area.  “Dry lightning” is produced by storms that produce very little rainfall.  Because of the lack of rainfall, people do not think that there is as much of a danger and do not seek shelter, therefore, increasing their risk of being struck by lightning.  In other parts of Colorado near Denver, the effects of “dry lightning” have resulted in dangerous wildfires. 






Tornadoes by Todd Laesch--tlaesch2

·Denver Specific Meteorology


Time Frame/Location

In Colorado, the main threat of tornadoes occurs from May through Early August.  June is the most active month.  Nearly 90% of the tornadoes statewide occur between 1pm and 9pm, but can happen at any hour of the day.  The majority develop in the Eastern Colorado plains to the east of interstate 25[i].  The picture below shows the total number of tornadoes reported statewide between 1950 and 2003.  The counties in Eastern Colorado are located in the plains and have reported more tornadoes than the mountain areas of the state.






Why Form in the plains?


The topography of Colorado plays a key role in the formation of severe storms and tornadoes.  During the summer months, there usually is a large temperature spread between the mountains and the plains.  Along with the variations in topography, these factors can lead to an outburst of tornadoes. 


While tornadoes usually do not form over metropolitan areas, Denver has grown drastically over a relatively short period, and tornadoes used to strike quite frequently over the now heavily populated Denver area[ii].


While usually not associated with supercell storms, meteorologists have discovered that tornadoes are able to spawn along Colorado’s front range by a mesoscale phenomenon known as “The Denver Cyclone” later renamed to the Denver Convergence-Vorticity Zone (DCVZ)[iii].


 The Denver Convergence-Vorticity Zone


The DCVZ is an area of 50-100 km in length that has convergent winds[iv].  On the map to the right, the blue line represents the DCVZ.  The Red arrows represent the winds that converge to form the DCVZ just east of Denver.  The main ingredient is the Palmer Ridge that juts out just south of Denver, where the elevation on the ridge is nearly 1,000 ft. higher than Denver’s elevation.  The moist Gulf of Mexico air mass is lifted over the ridge and converges with the northwesterly wind coming off the foothills, to create the zone of convergence where small-scale tornadoes can occur[v].


Data from the 1980’s shows that when a well-formed DCVZ is present in June, there is a 70% chance of a tornado developing somewhere in or around the zone[vi].  On June 3, 1981 two F2 tornadoes moved through the Denver area, which formed as a direct result of a strong DCVZ.  






Source 2: http://ams.confex.com/ams/pdfpapers/115160.pdf












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Drought: (Jamie Dalin- jdalin2)




Drought is a tricky weather condition, as there is no specific definition of a drought though it is usually associated with water shortages and a lack of precipitation.  A simplistic way to look at it is drought occurs when demand of water exceeds supply.1 While this weather phenomenon cannot be easily defined, it has more fatalities associated with it than any other type of weather phenomenon. 4  On average, the state of Colorado only receives 17 inches of precipitation annually.  However, in the mountainous regions, the annual average is around 25 inches with 50 inches in a few high-elevation areas.  Colorado gets its water from five primary sources: snowpack, streamflow, reservoir water, soil moisture, and groundwater.  This water supply has multiple uses for many industries in Colorado including: agriculture; municipal and industrial water supplies; recreation, including mountain snow making; forests and environmental uses, including supporting endangered species; and hydroelectric power.  There are no major rivers that flow into Colorado, so they are unable to gain additional water from rivers.1




Each region of the United States experiences droughts at different times, as precipitation seasons vary among regions.  In the western United States, where Denver is located, most precipitation falls between October and April, the heaviest of which falling between December and March.  The precipitation that falls as snow represents much of the water supply in this area.  Therefore, if Denver does not receive a sufficient amount of precipitation during these months, it is likely to cause a short-term drought during that time.  Most short-term droughts occur in the winter months, however, if dry conditions persist, droughts can last multiple years.4 



A main cause of drought in Colorado and surrounding areas is the persistent ridge in the jetstream that runs over the west coast.  Typically, a center of high pressure resides over this area that has accompanying southeasterly surface winds which enhance the dryness.  There have been several major droughts that have occurred in the western United States.  In the winter of 1976-77, there was a persistent ridge over the western U.S. which led to a very small amount of precipitation.  Only half of the usually amount of precipitation fell that winter.4 Colorado experiences short-term droughts very frequently.  While drought rarely encompasses the entire state, it is present at some place almost every year.  However, multi-year droughts are infrequent in Colorado.1



Drought has a large impact on the people of Denver.  For example, droughts hurt the farming industry in the area.  Crops are not able to grow in such dry conditions.  Also, the tourism industry suffers from drought.  Denver attracts many visitors for its highly reputable ski slopes.  This area suffers without enough precipitation but also initiated the introduction of snow making equipment.  Lastly, droughts in Denver can lead to huge wildfires.  The worst wildfire season in Colorado’s history occurred in 2002 because of the dryness and lack of precipitation After the drought in 1980-81, the state developed the “Colorado Drought Response Plan” to establish “clear mechanisms for monitoring drought conditions and impacts, and communicate water supply and drought impact information to decision makers.”2




It is hard to pinpoint the exact beginning or end of a drought, as there is no clear definition for a drought.  In response, to the lack of definition, there have been several indices that have been developed to help rate droughts.  The Palmer Index is helpful for tracking long-term droughts; however, it does not help with short-term changes.  The Palmer Index is customized to a particular location, so it can consistently reflect drought in multiple different climates.  In addition to the Palmer Index, the Crop Moisture Index can be used to reflect short-term drought.3




4Rauber, Robert M., John E. Walsh, and Donna J. Charlevoix. Severe and Hazardous Weather. Dubuque: Kendall/Hunt, 2005.


CASE STUDY: WILDFIRES - Jamie Dalin (jdalin2)




In 2002, Denver and the rest of Colorado experienced a severe drought.  June of that year was the seventh consecutive month that Colorado experienced well-below normal levels of precipitation.  From May 2001- June 2002, each season held records for being the driest ever up-to-date.  It is said that this short-term drought was comparable to the worst droughts in the 1930s.1 



This drought led to multiple severe conditions, one of which being dangerous wildfires that spread throughout the state.  While wildfires typically occur during the summer months in Colorado, the abnormally dry conditions created more potential for more dangerous fires than usual.  The largest of the fires was the Hayman fire that was started by a group of campers as a campfire.  Strong winds, low humidity, and plenty of fuel from dead underbrush allowed this fire to extend through 120 square miles of forest land, only 50 miles from metropolitan Denver. Winds have caused large problems with wildfires in Colorado.  In the 1994 Storm King fire, 14 firefighters were killed when winds changed the direction of the fire, trapping them inside.2


As the fire was unexpectedly started by a camper, it was not well-forecasted.  However, once it began spreading, it was watched closely.  The Rocky Mountain Area Coordination Center keeps a close eye on these fires.  Typically, warm and dry conditions help fuel these fires; however, fires in the 2002 season came earlier than expected.  Some of the dry conditions were attributed to the lack of snow for the year.  That year, the snowpack in the Rocky Mountains disappeared two months earlier than usual.1




In order for a wildfire to continue to expand, it must have heat, fuel and oxygen.  Additionally, wind, temperature, and humidity influence wildfires.  Strong winds carry the fires upward in addition to creating “spot fires” when they move burning embers and sparks.  During the day, the sunlight heats the surface and the warm air rises, allowing a fire to travel up the slopes if the topography consists of mountainous features.  This was the case in Colorado, where the mountains allowed for the rapid expansion of the Hayman fire as well as others.  Humidity helps stop the spreading of wildfires.  However, in June of 2002, there was very little humidity. Therefore, the fire continued to spread.  Fires can also create their own winds, some of which up to 120 mph like hurricanes.2 Wildfires spread at their travel along the small branches and underbrush in the forests.  As a result of the drought, there was little or no moisture in this fuel for the fire and it could continually enlarge.





The Hayman fire, in particular, had many effects on the area surrounding Denver.  Authorities had to draw up evacuation plans for over 40,000 people in anticipation of the fire spreading.  People were evacuated in Park, Jefferson, and Douglas counties and the authorities planned for additional evacuations.  Additionally, this particular fire was hard for firefighters to get in front of to contain it.2 One danger of these fires is that they can burn down multiple residential homes.  If this occurs, people lose everything: valuables, clothing, furniture, etc. 



















Mountain Windstorms, also called katabatic winds, occur all over the world but commonly go by different names depending on where they happen.  When they occur on the eastern side of the Rocky Mountains, they are called Chinook Winds.  In the United States, the most likely time for them to occur is late fall and winter.  In the U.S., the biggest metropolitan area where these winds occur spans from Fort Collins, CO to Colorado Springs, CO which also includes the cities of Denver and Boulder.

                These winds originate over the Pacific Ocean and start off very warm and moist.  When they reach the Rocky Mountains, they are forced to go up.  As they rise over the Rocky Mountains, they cool off and they lose their moisture.  When they reach the crest of the mountains, they start to go back down the eastern side.  As they descend, they increase in speed and they also begin to warm up.  The winds warm due to the increase in air pressure from the top of the mountains to the bottom of the mountains.  In Colorado they have been known to increase the temperature as much as 25-35 degrees in as short as a few hours.

                It is possible for the winds to have gusts that go over 100 mph and have sustained of over 50 mph.  These Chinook winds can have very adverse affects on the areas they occur.  They have been known to cause damage to agriculture and buildings, as well as cause severe wildfires due to the increase temperatures and decrease in humidity which makes the soil lose its moisture.  The severe and sudden temperature changes can kill some trees and other vegetation that is not used to a big temperature fluctuation. In Boulder, CO, which experiences the worst Chinook winds in Colorado, they experience an estimated $1 million per year damage to property.

To help cope with the strong winds, the Colorado Department of Transportation maintains over 100 weather stations that monitor wind speed and direction.  This helps them issue warnings for taller vehicles that might be affected by higher winds.  Also in some cities, they have adjusted building codes that are similar to those in areas that experience hurricanes so the buildings can deal with the strong wind.






Floods: Rick Moy (rcmoy2)


Colorado suffers from flooding and flash flooding. These floods happen mostly around the time of year when thunderstorms and rain move into the area after the winter time. What happens is when it rains, the snow around the region begins to melt and enter the streams and rivers. This causes the banks of the streams and rivers to raise causing floods in those areas. Flash flooding in the Denver area can happen when the dams or levees fail, river ice jams, and from heavy rain fall. The damage caused by floods is from the rapid water movements. The rapid waters tend to wash away boulders, trees, and other debris which can cause damage to buildings, bridges, and roadways. Also during the time of heavy rains, mud slides may occur from the soil being weakened. Denver is currently under a flood/flash flood warning until April 17th.


Source: http://www.crh.noaa.gov/bou/?n=svr_floods




El Niño- Felicia Braude (fbraude2)



Denver has an interesting relationship with El Niño. El Niño is an oscillation of the ocean-atmosphere system in the tropical Pacific Ocean.1 In general, El Niño impacts the globe in many ways. El Niño happens when the trade winds weaken and allow warmer water flow from the Western Pacific to the east.5 For example, the Southern US has increased rainfall. As a result of this, moisture reaches historically drier areas more frequently. The oceanic changes also affect the atmosphere and produces changes in the weather. Clouds shift toward the east and bring rainstorms to other areas that may have been experiencing a drought. Trade winds are relaxed in the central and western Pacific Ocean and the winds blow westward. Also, El Niño affects the monthly sea surface temperatures in the tropical Pacific Ocean. El Niño is the oscillation between normal and warmer than normal SST’s in the equatorial Pacific. It is easy to gauge the effects of El Niño because of the temperature changes in the ocean. El Niño’s can last for a year before the weather patterns return back to normal. The pattern of when El Niño occurs is irregular, but it is said that our world experiences an El Niño every three to seven years.6  




MID EL NIÑO in 2006  



One of the best ways to describe El Niño’s impact on the city of Denver, Colorado is to investigate the weather lapse in 2006 and 2007. On December 7th, 2007, an article was published on Denver Weather Channel that discussed El Niño and how its past occurrences with Denver related to the current conditions. Klaus Wolter, University of Colorado and National Oceanic and Atmospheric Administration scientist, gave his thoughts on El Niño. He explained how El Niño steered warm, dry weather across Colorado.2  Scientists were expecting several weeks where nothing happened, based on past years. Klaus Wolter explained how there was a dry winter before March 2003, but the snow in March fell thirty inches. In an article published on December 20th, predictions changed.





December 21st, 2006


Denver Knee-Deep in Snow  



Rocky Mountain News attributed effects of El Niño to the watery Christmas season. This was important because El Niño helped hydrate the northeastern plains. The plains had severe, lingering drought conditions in the past, but El Niño saved the drought by creating a moist environment.3 The storms were juicier and pulled moisture from the Gulf of Mexico and the Pacific Ocean. Therefore, the weather center predicted a successful snow on Christmas.


Prior to the storm in December 2006, 22% of Colorado suffered from moderate to severe drought.3 Not only did the storm help rescue Denver from drought conditions, but also it brought extra moisture because El Niño has that particular effect on storm situations. It is interesting to know that the two biggest December snowstorms, 1982 and 1987, were storms that occurred during El Niño. 


In conclusion, 2006 was the warmest year ever recorded in the USA. El Niño was classified as a “long-term warming trend” of climate change and El Niño combined.  According to USA Today, it is clear that El Niño also helped bring strong snowstorms to Denver, even in the month of March. Interestingly enough, temperatures that were above normal in Colorado helped decrease the demand for heating for October-December. The city’s average reading for December was 1.4 degrees Celsius warmer than usual, and consequently the demand for heating was 13.5% lower than normal.4 Therefore, the effects of El Niño reached Denver on many levels. Not only did El Niño help produce great amounts of snowfall in Denver, it also contributed to an increase in temperature and a decrease in the demand for heating. Because of the events of 2006, it was the first time the climate center mentioned climate change as a cause. 



(2) http://www.thedenverchannel.com/weather/10481032/detail.html


(4) http://www.usatoday.com/weather/climate/2007-01-09-warmest-year_x.htm








MOUNTAIN SNOWSTORMS: by Brad Beebe (bbeebe2)





Mountain snowstorms that affect Denver originate from upslope storms.  An upslope storm is a winter storm producing enormous amounts of snow from moisture carried from the Gulf of Mexico.  The Great Plains slope down from about 5,000 feet in elevation near Denver to sea level by the Mississippi River.  Therefore, Denver lies on the highest point of the Plains near the very steep elevations of the Rocky Mountains.  This means that westerly air flows up about 5,000 feet from the Mississippi to reach Denver.  When this air is full of moisture, the rising causes cooling of the moisture.  Condensation then occurs as the air reaches the the Rocky Mountains and decompresses.  The air pressure can drop about 300 mb from the Mississippi without ever leaving the ground.  This can cause heavy cloud formation and consequently mountain snowstorms for Denver.
These easterly winds causing upslope mountain snowstorms are caused by 2 pressure patterns that can act dependently or individually.  Smaller mountain snowstorms occur when a high-pressure center is located in the northern parts of Colorado sending cold artic air to Denver from Canada.  This polar air lacks a moisture source to be a significant source of snowfall for Denver.  However, when a low-pressure center is located south of Colorado, moist air is drawn from the Gulf of Mexico.  This is known as a Four Corners Low because that is generally where the low-pressure center is located to produce this type of upslope storm for Denver.  As the air rises up the plains, it cools and condensces, then when it hits the Rockies, Denver is pounded for up to 2 feet of snow.  When both pressure patterns occur concurrently, large mountain snowstorms dump feet of snow on Denver.
Denver's snowfall during a mountain snowstorm from an easterly wind can be enhanced when the air crosses over the Palmer Lake Divide.  When air flows north of this low-point, it rises rapidly, and therefore condenses rapidly as it reaches Denver.
Mountain snowstorms occur every few years in Denver due to the need of rare easterly winds.  However, when they do occur, large amounts of snow falls causing traffic stoppages.  While this snow does make Denver a premiere skiing area, these snowstorms put a stop to all transportation systems for days.
Rauber, Robert M., John E. Walsh, and Donna J. Charlevoix. Severe and Hazardous Weather. Dubuque: Kendall/Hunt, 2005

Cold Waves








What is a cold wave?


          When cold air from the north moves into the middle or lower latitudes, it is called a cold wave.  They are normally spread over a very large region, such as the Central US.  Any c


old wave has the potential to kill with it’s extremely cold temperatures and to cause great economic distress as it cuts through agricultural regions, such as the South.  During the Winter, a cold air mass begins as a strong high pressure center.  As the high pressure grows, it causes a dip in the jet stream, so that it tracks from the arctic, down the Rocky Mountains, and into the Central US.  Eventually, steering winds, caused by a passing extratropical cyclone or the cold-air pool of the Rocky Mountains, bring the cold air mass into the US.




Example of a cold wave once it has been driven south by steering winds.





What do Cold Waves have to do with Denver?


          Due to the Rocky Mountains, the warm, moist air of the Pacific is not able to penetrate directly into the central US.  Because of this, there is a cold air “pool” to the East of the Rockies, right on top of Denver.  Most often, a cold wave will hit Colorado first, before it progresses to sweep across the nation.  Normally, the cold wave will not last very long, but it will gain strength as it passes over Denver.




What else is interesting about Cold Waves?


Coldest temperature ever recorded in Denver


-29° F (-34° C)


Animation of the development of a Cold Wave




Animation showing the “steering winds” that move a Cold Wave across the country




Animation showing the motion of a Cold Wave across the country








Charlevoix, Rauber, and Walsh, Severe and Hazardous Weather, Kendall Hunt Publishing Company, 2005














Case Study: The Cold Wave of 1888


          After the infamous Children’s Blizzard passed, the resulting jet stream brought an extremely cold high pressure system in from the North.  Even though this is the normal way that a Cold Wave descends into southern latitudes, the resulting wave of brutally cold weather was incredible.  Beginning in Montana on the 12th of January, eventually the cold wave would stretch across the entire country, and hit Denver hard on the 14th.


Weather map showing the conditions when the cold wave hit Denver.  Notice the strong winds that propel the cold wave into the Central US.





On the 13th, Denver recorded a temperature of 12°F.  24 hours later, the temperature had dropped to -16°F.  While this was actually warmer than most of the rest of the country, it was, at this time, the most severe cold wave to ever hit Denver.  When it was all over, there had been a 95°F drop over the course of the month, and a maximum one-day drop of 60°F.  There was also a 95 degree drop in Fort Laramie, Wyoming and North Platte, Nebraska.







BLIZZARDS: by Kim Elsey

           Blizzards form within the NorthWestern part of two types of extra–tropical cyclones, the Alberta Clipper and the Colorado Low.  They have winds exceeding 35 MPH, snowfall and extreme cold temperatures dipping lower than 20۫ F. The Colorado Lows form just east of the Rockies, near Denver, and reach their greatest strength in the plains where the winds are strong enough to form Blizzard conditions.  The Colorado Low is the only Cyclone that forms blizzards in Denver; the Colorado Lows also form the worst blizzards because they form deeper low pressure systems then the Alberta clippers. The cold air necessary for blizzards in Denver comes down from the Canadian Plains before the cyclone forms just east of the Rockies.  Denver Blizzards form when warm moist air from the Pacific rises over the Rocky Mountains and collides with the cold Arctic air that is coming down from Canada.[1]


 Denver is one of the farthest western cities to experience a high probability of experiencing a blizzard in a given year with a 38%-49% probability and an average of about 0.7 blizzards per year for the years 1959-2000 [2]. With recorded snow accumulations in Denver from September through May, it is possible for a blizzard to occur nine months out of the year. This is because Colorado lows form just east of the Rocky Mountains, right over Denver.




Blizzards may not seem like they may cause a lot of damage but, they can have a lasting detrimental effect on a city appear within hours without much warning.  Blizzards cause dangerous driving conditions.  It is very difficult to see because of the blowing snow, and turn the roads into icy accident traps.  The blizzard conditions also foster an environment prone to hypothermia.  With a blizzards high winds, extreme low temperatures and snow as you can see in the chart below it can cause a person to experience hypothermia in a matter of minutes.




[2]Rauber, Robert M., John E. Walsh, and Donna J. Charlevoix. Severe and Hazardous Weather. Dubuque: Kendall/Hunt, 2005.




[4] http://www.nws.noaa.gov/om/windchill/index.shtml


Case Study by Kim Elsey


Colorado Blizzard of March 2003




Called the “Storm of the Century” by Denver’s own mayor, this slow moving Blizzard broke more than one meteorological record in Denver. Denver had not seen anywhere near this much snow in 90 years, when its largest recorded snowfall hit the city. Officials at Denver’s airport were preparing for at most two feet of snow to fall.  But, as the second largest snowfall dropping 35 inches of snow on the city over its duration of 44 hours, the forecast didn’t foresee how heavy this snow would be.


While this may seem like a lot of snow, this Blizzard dropped 87.5 inches of snow in other areas of Colorado. The blizzard started late at night on March 17, 2003 and ending near dusk on March 19.  The State Capitol had their first snow day in recorded history because of the snow.  The Denver International airport, which is known for its high on-time percentage, at 87% in 2003, closed for thirty-two hours, stranding four thousand travelers [3]. A forty-foot gash was cut in the tent-like roof at the airport by the weight of the snow causing a terminal to be closed [4]. 




This storm was also the most costly blizzard in Denver causing more than $93 million dollars worth of damage, nine times more than the second most costly snowstorm that occurred only five years earlier.  The storm caused damage to 258 structures in the city, causing several roofs to collapse injuring two people. Several roads were closed for multiple days due to avalanches, which also caused 270 people to be trapped at a ski resort.  135,000 people lost power throughout the snowfall.  The storm claimed two lives when both people suffered from a heart attack while shoveling the snow.  While it may seem that this blizzard caused only hardships for the residents of Denver, it did bring an end to 19 months of below average precipitation in the area.



[1] http://www.ucar.edu/communications/newsreleases/2004/blizzard.html

[2] http://www.cnn.com/2003/WEATHER/03/20/snowstorm.ap/index.html

[3] http://www.transtats.bts.gov/HomeDrillChart.asp?URL_SelectMonth=2&URL_SelectYear=2008


[4] http://www.flydenver.com/pr/DIAPR_030401_2.pdf


[5] http://www.crh.noaa.gov/bou/?n=denstorm_031703


















Comments (1)

snodgrss@... said

at 1:33 pm on Mar 5, 2008

Great Start! keep it up.

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