Transcript Tornado alley - NWACC

WHY DOES NW ARKANSAS HAVE SO
MANY TORNADOES?
BY
CLAIRE SMITH
EAST/EMPACTS INDEPENDENT STUDY
C. Dianne Phillips, EAST/EMPACTS Facilitator
INTRODUCTION
• Northwest Arkansas is in a section of the Southern
region of the United States known for frequent tornado
activity, tornado alley.
The local topography, in
association with
unstable air masses,
fuels super-cell
thunderstorms which
have the potential for
the formation of
tornadoes.
Community Aspect
There is a need to provide information to the
public . An informational Power Point is
provided to raise awareness about the
frequency and distribution of tornadoes.
Course Content Objectives
To learn..
• Why tornadoes occur in NW Arkansas
• What factors contribute to the formation of
tornadoes
• Determine the location of tornado alley and
the mechanisms that lead to it’s location.
TORNADO ALLEY
What makes Arkansas
a good conductor for
severe tornado
activity?
Meteorology Terms Remember:
• Subtropical Climate- Climate zone with hot humid summers
and chilly mild winters. Significant amounts of precipitation
occur during all seasons, sometimes in excessive quantities.
• Humid Continental Climate- A zone located in the mid
latitudes where there is conflict between polar and tropical
air masses
• Supercells- Storm cells which may produce rain, hail,
lightning, and dangerous bursts of wind. Rotating wind rises
into the storm creating a mesocyclone and the ability for
supercells to travel along the ground for long periods of
time.
• Updraft- Air rising up into a thunderstorm
3 conditions required for a
tornado
1. Moisture in the lower to mid
levels of the atmosphere.
2. Unstable air, which is air that
rises from the ground and does
not stop.
3. A lifting force such as the
unstable air if it is warm. Cooler
air forces the warm air upwards
and triggers thunderstorms.
Conductors
• Arkansas shares a border with 6 states; the eastern boarder
primarily made up of the Mississippi river. Its unique
geography makes up the United States interior highlands.
• The unique geography also creates a collision of several
different air masses from surrounding areas and mountain
regions such as the Ozarks, Ouachita’s, the Gulf of Mexico, as
well as the Mississippi river.
• This creates a big conflict between subtropical climate and
continental climate especially in spring like weather
conditions.
• Arkansas main weather conductor is the warm Gulf of
Mexico.
Conductors
• Although far enough away from the coast to be hit
directly by a hurricane Arkansas gets the aftermath
of a tropical system.
• Tropical systems come with very large amounts of
rain in a short period of time sometimes causing
massive floods.
• Tropical systems are also known for spawning
smaller but dangerous tornadoes which travel up
the coast line to what is known as tornado alley.
Step by Step Formation of a Tornado
1.
2.
3.
Plenty of hot, humid air trapped
beneath cold, dry air.
The "cap," (the stable layer of
air between the hot and cold
air) is disturbed. The
disturbance can be caused by
an upper-level air disturbance,
or the arrival of a front
As the lower-level air rises, it
expands in the reduced air
pressure aloft (air pressure
drops as altitude increases), and
it cools. Eventually, the cooling
causes the moisture to
condense
4. Condensation releases latent
heat, warming the air, making it
buoyant, and causing it to rise
quickly (at speeds up to 150
mph). By now, the cloud
has formed into a thunderstorm.
Upper-level winds tilt the
thunderhead to create the anvil
at the top.
5. The thunderstorm may die out in intense
rain and/or hail. Or it may spawn
a tornado.
Step by Step Formation of a Tornado
6. Interactions between air at various
altitudes, humidity's and
temperatures causes rain,
lightning, air circulation and an
intensification of the
rotating updraft, called a
"mesocyclone." Low-level wind
helps cause this rotation, which is
almost always counter-clockwise
7. A tornado may form below the
mesocyclone. As the spinning
column of air narrows, it rotates
faster and extends higher into the
storm.
http://video.google.com/videoplay?d
ocid=4070406632797901470&q=mesoc
yclone%20and%20tornado%20for
mation&hl=en
The Impact of a Natural Disaster
Can Be Devastating!
Headlines, News Stories, & Records
The town of Dumas, Arkansas is a disaster zone tonight. Power
is out in the city and rescuers have been working for hours to
get people help.
Feb. 24th 2007
Powerful Wind Storms, Tornado Wounds
40, Destroys Over 90 Homes in Arkansas
Mountain View, AR
• http://www.youtube.com/watch?v=uG82kA5J
D4M
• http://www.youtube.com/watch?v=uEVmCvA
6ujc&feature=related
F5 Tornadoes, Moore, OK, 1999
• http://www.youtube.com/watch?v=4pbqGsS5
iB4
Tornado Record Broken 1999
there were 56 tornadoes produced statewide...a record for one
outbreak. The previous record was 34 tornadoes on June 5, 1916. It
must be said that 56 tornadoes is incredible considering that Arkansas is
normally affected by 21 tornadoes per year!
The late Dr. Fujita’s Tornado Scale of Damage ranked tornadoes according to the damage they
left behind- F0:least damage to F5:greatest
damage.
Skills Developed
• Technology
– Microsoft Suite, Word, Power Point, Front Page
– Internet, uTube videos
• Time Management
– Organization
– Planning
• Presentation
– Power point design
• Research
– library, internet, national weather service in Tulsa,
40/29 meteorology archives.
Acknowledgements/References
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40/29 News, Steve Gibbs
National Weather Service in Tulsa, OK
Mountain View, AR Survivors
Dumas Morning News
Dr. Fugita
C. Dianne Phillips, EAST/EMPACTS Facilitator