1. Wildfires, Tornados, and Avalanches…Oh My!!!
Natural Disaster Week
Wildfires, Tornados, and Avalanches…Oh My!!!

2. Wildfires

3. What Are They?
Wildfires are any non-controlled, non-structured fire that occur in wild lands
They are essential to plant and rehabitation to wild lands
They are also destructive, especially as more and more urban growth moves into these wild lands

4. How Do They Start?
There are many contributing factors to the ignition of a wildfire
Drought
Increasing drought creates dry tinder which is the #1 ignition source
Overgrowth
With more and more environmental restrictions, overgrowth and dead timber are ready sources for ignition
Lightning
#1 cause of wildfires
Humans
Campfires, cigarettes, and other human behavior is the #2 source for wildfires

5. US Danger Zones

6. Global Warming as a Factor?
Many environmentalists are looking at global warming as a contributing factor
We are seeing wildfire seasons getting longer
We are seeing more drought occurring
We are seeing increasing temperatures during summer months
We are seeing decreasing rain and moisture during winter months
This is not just a US problem, but a global problem

8. Yellowstone Fire, Summer of 1988
The largest and most destructive wildfire in US history
Began as small sporadic fires
Lightning
Small fires that put themselves out
By mid-July it began to get out of hand
Quickly spread with fuel and winds
Finally put out with Fall cool air and winter moisture
793,880 acres destroyed
9,000 firefighters and 4,000 military personnel
Wildlife destroyed is to this day immeasurable

9. Old Faithful Complex

17. Rehabilitation
In the 20 years since the fires Yellowstone has shown remarkable regrowth
The ability of nature to heal its wounds has even amazed scientists who believed that the devastation to Yellowstone was “unrecoverable in many areas”

22. Fire Prevention
Though forest fires are a part of nature, human resources have contributed to prevention
More Knowledge
More Technologies
More Understanding
All Contribute to Smokey’s old saying, “Only You Can Prevent Forest Fires”

23. Fun Fact Smokey Bear was created by the US Forest Service in 1944
He and his saying remain one of the most recognized campaigns in US History

24. Tornadoes!

26. What Are They?
Although tornadoes occur in many parts of the world, these destructive forces of nature are found most frequently in the United States east of the Rocky Mountains during the spring and summer months.
In an average year, 800 tornadoes are reported nationwide, resulting in 80 deaths and over 1,500 injuries.
A tornado is defined as a violently rotating column of air extending from a thunderstorm to the ground.
The most violent tornadoes are capable of tremendous destruction with wind speeds of 250 mph or more.
Damage paths can be in excess of one mile wide and 50 miles long.
A Tornado in Broken Bow, Oklahoma, carried a motel sign 30 miles and dropped it in Arkansas!

27. What Causes Tornadoes?
Thunderstorms develop in warm, moist air in advance of eastward-moving cold fronts. These thunderstorms often produce large hail, strong winds, and tornadoes.
Tornadoes in the winter and early spring are often associated with strong, frontal systems that form in the Central States and move east. Occasionally, large outbreaks of tornadoes occur with this type of weather pattern.
Several states may be affected by numerous severe thunderstorms and tornadoes. During the spring in the Central Plains, thunderstorms frequently develop along a "dryline," which separates very warm, moist air to the east from hot, dry air to the west.

28. What Causes Tornadoes Cont’d
Tornado-producing thunderstorms may form as the dryline moves east during the afternoon hours.
Along the front range of the Rocky Mountains, in the Texas panhandle, and in the southern High Plains, thunderstorms frequently form as air near the ground flows "upslope" toward higher terrain. If other favorable conditions exist, these thunderstorms can produce tornadoes.
Tornadoes occasionally accompany tropical storms and hurricanes that move over land. Tornadoes are most common to the right and ahead of the path of the storm center as it comes onshore.

29. Tornado Variations
Some tornadoes may form during the early stages of rapidly developing thunderstorms. This type of tornado is most common along the front range of the Rocky Mountains, the Plains, and the Western States.
Tornadoes may appear nearly transparent until dust and debris are picked up.
Occasionally, two or more tornadoes may occur at the same time.

30. Waterspout Waterspouts are weak tornadoes that form over warm water.
Waterspouts are most common along the Gulf Coast and southeastern states. In the western United States, they occur with cold late fall or late winter storms, during a time when you least expect tornado development.
Waterspouts occasionally move inland becoming tornadoes causing damage and injuries.

31. How Do Tornadoes Form?
Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere.

32. How Do Tornadoes Form?
Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical.

33. How Do Tornadoes Form?
An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.

34. How Do Tornadoes Form?
A lower cloud base in the center of the photograph identifies an area of rotation known as a rotating wall cloud. This area is often nearly rain- free. Note rain in the background.

35. How Do Tornadoes Form?
Moments later a strong tornado develops in this area. Softball-size hail and damaging "straight-line" winds also occurred with this storm.

36. Tornadoes Take Many Shapes and Sizes
Weak Tornadoes
69% of all tornadoes
Less than 5% of tornado deaths
Lifetime minutes
Winds less than 110 mph

37. Tornadoes Take Many Shapes and Sizes
Strong Tornadoes
29% of all tornadoes
Nearly 30% of all tornado deaths
May last 20 minutes or longer
Winds mph

38. Tornadoes Take Many Shapes and Sizes
Violent Tornadoes
Only 2% of all tornadoes
70% of all tornado deaths
Lifetime can exceed 1 hour

39. Tornado Myths
MYTH: Areas near rivers, lakes, and mountains are safe from tornadoes. 
FACT: No place is safe from tornadoes. In the late 1980's, a tornado swept through Yellowstone National Park leaving a path of destruction up and down a 10,000 ft. mountain.
MYTH: The low pressure with a tornado causes buildings to "explode" as the tornado passes overhead.
FACT: Violent winds and debris slamming into buildings cause most structural damage.
MYTH: Windows should be opened before a tornado approaches to equalize pressure and minimize damage.
FACT: Opening windows allows damaging winds to enter the structure. Leave the windows alone; instead, immediately go to a safe place.

40. Tornadoes Occur Anywhere
Carolinas Outbreak:
March 28, 1984, afternoon-evening
22 tornadoes
57 deaths
1,248 injuries
Damage $200 million
37% of fatalities in mobile homes

41. Tornadoes Occur Anywhere
Pennsylvania-Ohio Outbreak:
May 31, 1985, late afternoon-evening
41 tornadoes, including 27 in PA and OH
75 deaths in U.S.
1,025 injuries
Damage $450 million

42. Tornadoes Occur Anywhere
Plains Outbreak
April 26-27, 1991, afternoon of 26th through early morning 27th
54 tornadoes
21 deaths
308 injuries
Damage $277+ million
15 deaths in/near mobile homes, 2 deaths in vehicles

43. Weather Radars
Meteorologists rely on weather radar to provide information on developing storms.
The National Weather Service is strategically locating Doppler radars across the country which can detect air movement toward or away from the radar.
Early detection of increasing rotation aloft within a thunderstorm can allow life- saving warnings to be issued before the tornado forms.

44. Frequency of Tornadoes
Tornadoes can occur at any time!
In the southern states, peak tornado occurrence is in March through May, while peak months in the northern states are during the summer
Tornadoes are most likely to occur between 3 and 9 p.m. but have been known to occur at all hours of the day or night.
The average tornado moves from southwest to northeast, but tornadoes have been known to move in any direction. The average forward speed is 30 mph but may vary from nearly stationary to 70 mph.
The total number of tornadoes is probably higher than indicated in the western states. Sparce population reduces the number reported.

48. Clues A Tornado Is Coming
Look out for:
Dark, often greenish sky
Wall cloud
Large hail
Loud roar; similar to a freight train

49. More Clues
CAUTION!
Some tornadoes appear as a visible funnel extending only partially to the ground. Look for signs of debris below the visible funnel.
Some tornadoes are clearly visible while others are obscured by rain or nearby low- hanging clouds.

51. Windsor Colorado May 22,2008

53. Check out the Hail

54. Some Cool Videos

57. Poor Old People on a Bus

58. Scary…But Oh So Funny!!!

59. Avalanches!

60. What Are They?
An avalanche is an abrupt and rapid flow of snow down a slope, resulting from either natural triggers or human activity.
Typically occurring in mountainous terrain, an avalanche can mix air and water with the descending snow.
Powerful avalanches have the capability to entrain ice, rocks, trees, and other material on the slope; however avalanches are not rock slides!!!

61. What Are They?
Avalanches are classified by their morphological characteristics, and rated by either their destructive potential, or the mass of the downward flowing snow.
Some of the morphological characteristics used to classify avalanches include the type of snow , the nature of the failure, the sliding surface, the propagation mechanism of the failure, the trigger of the avalanche, the slope angle, direction, and elevation.
Avalanche size, mass, and destructive potential are rated on logarithmic magnitude scales, typically made up of 4 to 7 categories, with the precise definition of the categories depending on the observation system or forecast region.

66. What Kinds Of Avalanches Are There?
Loose Snow Avalanche
Occurs in freshly fallen snow on steep slopes
Watch out back country skiers and snowboarders!
Slab Avalanches
Slab avalanches account for around 90% of avalanche-related fatalities, and occur when there is a strong, cohesive layer of snow known as a slab.
These are usually formed when falling snow is deposited by the wind on a lee slope, or when loose ground snow is transported elsewhere.
When there is a failure in a weak layer, a fracture very rapidly propagates so that a large area, that can be hundreds of meters in extent and several meters thick, starts moving almost instantaneously.

67. What Kinds Of Avalanches Are There?
Isothermal Avalanche
Occurs when the snow pack becomes saturated by water. These tend to also start and spread out from a point. When the percentage of water is very high they are known as slush flows and they can move on a very shallow slope
Powder Snow Avalanches
Among the largest and most powerful of avalanches, powder snow avalanches can exceed speeds of 300 km/h, and masses of 10,000,000 tons;
Their flows can travel long distances along flat valley bottoms and even up hill for short distances. A powder snow avalanches is a powder cloud that forms when an avalanche accelerates over an abrupt change in slope, such as a cliff band, causing the snow to mix with air. This turbulent suspension of snow particles then flows as a gravity current.

69. How Are Avalanches Triggered?
Avalanches are always caused by an external stress on the snow pack, they are not random or spontaneous events.
Natural triggers of avalanches include additional precipitation, radiative and convective heating, rock fall, ice fall, and other sudden impacts; however, even a snow pack held at a constant temperature, pressure, and humidity will evolve over time and develop stresses, often from the downslope creep of the snow pack.
Human triggers of avalanches include skiers, snowmobiles, and controlled explosive work. The triggering stress load can be either localized to the failure point, or remote.
Localized triggers of avalanches are typified by point releases from solar heated rocks.
Remotely triggered avalanches occur when a tensile stress wave is transmitted through the slab to the start zone, once the stress wave reaches the start zone a fracture initiates and propagates the failure. Of exceptional note is that avalanches can not only entrain additional snow within the failing slab, but can also, given the sufficient accumulation of overburden due to a smaller avalanche, step down and trigger deeper slab instabilities that would be more resilient against smaller stresses. The triggering of avalanches is an example of critical phenomena.

70. Avalanche Prevention
Ski resorts will use dynamite to create “controlled avalanches”
These controlled avalanches remove build up of large amounts of snow from the top of ski mountains so that avalanches are less likely to be triggered
When skiing, snowboarding, or snowmobiling, always carry a avalanche shovel and beacon in case you are caught in an avalanche!
Beacons- emit a “beep” radio signal that allows rescue workers to find you using probes specially designed to receive the beacon’s signal

71. Avalanche fences in Switzerland

72. Avalanche blasting in France

75. Some Cool Videos
Some swear words…sorry!!!

79. Fun Fact
During WWI approximately 50,000 soldiers died as a result of avalanches during mountain campaigns in the Alps at the Austrian- Italian front, many of which were caused by artillery fire

80. Oh Wait…
Living here in Colorado there is one thing we must be aware of when it comes to mother nature
LIGHTNING!!!
Between
3239 Deaths
9818 Injuries
90 people killed yearly
#1 State for strikes: Florida (Colorado is 24th)
Colorado is ranked 10th when it comes to casualties

82. THE END…