OKLAHOMA CITY, OK
(AP)
Tornadoes raked the
southern Plains Wednesday, overturning cars on an Oklahoma City interstate and
destroying dozens of homes.
No deaths were
immediately reported from the tornadoes that hit Oklahoma and rural parts of
Kansas and Nebraska.
The worst damage
seemed to be in the Oklahoma City area. A twister destroyed homes at Bridge
Creek, Amber and Blanchard, southwest of the city, and it appeared another
tornado touched down later Wednesday evening when a second storm came through
the area.
"We have damage
reports, so we do strongly think there was a tornado on the south side of
Oklahoma City," meteorologist Michael Scotten with the National Weather
Service in Norman said after the second storm that hit around 8:40 p.m.
That storm flipped
vehicles on Interstate 35 and left power lines strewn across the roadway,
Scotten said.
It wasn't immediately
clear whether anyone was hurt. The Oklahoma Highway Patrol and an ambulance
company spokeswoman both said emergency personnel were sent to the scene,
though no injuries were immediately reported.
In Grady County,
about 25 miles southwest of Oklahoma City, a zoo was hit by a tornado,
prompting concerns that animals could be on the loose. Alisa Voegeli, a
dispatcher at the sheriff's office, said the zoo's owner and a deputy were on
scene Wednesday night inspecting the damage.
Another threat also
loomed: flooding. The storms dumped up to 6 inches in the southern part of
Oklahoma City, prompting the city to issue a flash flood emergency for the
first time in its history, said city spokeswoman Kristy Yager. Road crews were
waiting for the storms to abate to set up barricades and evaluate trouble
spots.
"They'll
dispatch as soon as the storms end and the weather clears," Yager said.
The Storm Prediction
Center had warned that bad weather would come to Tornado Alley, and more storms
were possible later in the week, with flooding a major concern.
"People just
really need to stay weather aware, have a plan and understand that severe
storms are possible across portions of the southern Plains almost daily through
Saturday," National Weather Service meteorologist Jonathan Kurtz said.
In Oklahoma, Grady
County Emergency Management Director Dale Thompson said about 10 homes were
destroyed in Amber and 25 were destroyed in Bridge Creek. As the storm moved to
the east, forecasters declared a tornado emergency for Moore, where seven
schoolchildren were among 24 people killed in a storm two years ago. When the
first of the storms moved through Wednesday, school districts held their pupils
in safe places.
At Will Rogers World
Airport in Oklahoma City, people were twice evacuated into a tunnel outside the
security zone.
In Nebraska, 10 to 15
homes were damaged near Grand Island, and between Hardy and Ruskin, near the
Kansas line.
At least nine
tornadoes were reported in Kansas, the strongest of them in the sparsely
populated north-central part of the state. That included a large tornado near
the tiny town of Republic just south of the Nebraska state line, where some
homes were damaged. In Harvey County, a tornado destroyed a hog barn and
damaged trees, according to the National Weather Service.
PHOTO of damage in Bridge Creek from @NewsOKPhoto's
Steve Sisney http://t.co/3Krfqvi7TT#okwxpic.twitter.com/EZX6fuR1Bg
—
NewsOK (@NewsOK) May 6, 2015
Screen capture of #tornado warned cell near Oklahoma City. pic.twitter.com/unwRUdeFud
—
Weather Underground (@wunderground) May 6, 2015
LIVE NOW...#tornado on the ground in #Oklahoma
in Caddo County, SW of #OklahomaCity. #OKwxpic.twitter.com/TTn8ayZEYV
—
The Weather Channel (@weatherchannel) May 6, 2015
We continue tracking a tornado on the ground near Lincon Kansas at: https://t.co/wpuVWFj9Ddpic.twitter.com/RGmZm4fADh
—
Iowa Storm Chasing (@IAStormChasing) May 6, 2015
LIVE NOW...#tornado on the ground in #Kansas
just S. of Lincoln; debris in the air...tune in for latest! #KSwxpic.twitter.com/6ZOniaSMGp
—
The Weather Channel (@weatherchannel) May 6, 2015
Lincoln Co, KS #kswxpic.twitter.com/LJKZg4YSAY
—
Matt Unruh (@UnruhMatt) May 6, 2015
Some tree damage in the cemetery on the east side of Lincoln, KS #kswxpic.twitter.com/8oCqUXVD1o
—
Matt Unruh (@UnruhMatt) May 6, 2015
Funnel cloud north of Cyril, OK. Just spun back up. #okwxpic.twitter.com/mIncpcRvDz
—
Colin Deaver (@ColinDeaver) May 6, 2015
A large area in the central/southern Plains is under a #tornado
watch this afternoon. pic.twitter.com/eSNhxJuJ9G
—
USA TODAY Weather (@usatodayweather) May 6, 2015
Source: usatoday.com
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Tornado
Basics
What is a tornado?
A
tornado is a narrow, violently rotating column of air that extends from the
base of a thunderstorm to the ground. Because wind is invisible, it is hard to
see a tornado unless it forms a condensation funnel made up of water droplets,
dust and debris. Tornadoes are the most violent of all atmospheric storms.
Where do tornadoes occur?
Tornadoes
occur in many parts of the world, including Australia, Europe, Africa, Asia,
and South America. Even New Zealand reports about 20 tornadoes each year. Two
of the highest concentrations of tornadoes outside the U.S. are Argentina and
Bangladesh.
How many tornadoes occur in the U.S.
each year?
About
1,200 tornadoes hit the U.S. yearly. Since official tornado records only date
back to 1950, we do not know the actual average number of tornadoes that occur
each year. Plus, tornado spotting and reporting methods have changed a lot over
the last several decades.
Where is tornado alley?
Tornado
Alley is a nickname invented by the media for a broad area of relatively high
tornado occurrence in the central U.S. Various Tornado Alley maps look
different because tornado occurrence can be measured many ways: by all
tornadoes, tornado county-segments, strong and violent tornadoes only, and
databases with different time periods. Please remember, violent or killer
tornadoes do happen outside “Tornado Alley” every year.
When are tornadoes most likely?
Tornado
season usually refers to the time of year the U.S. sees the most tornadoes. The
peak “tornado season” for the Southern Plains is during May into early June. On
the Gulf coast, it is earlier during the spring. In the northern plains and
upper Midwest, tornado season is in June or July. But, remember, tornadoes can
happen at any time of year. Tornadoes can also happen at any time of day or
night, but most tornadoes occur between 4–9 p.m.
What is the difference between a
Tornado WATCH and a Tornado WARNING?
A
Tornado WATCH is issued by the NOAA Storm Prediction Center meteorologists who
watch the weather 24/7 across the entire U.S. for weather conditions that are
favorable for tornadoes. A watch can cover parts of a state or several states.
Watch and prepare for severe weather and stay tuned to NOAA Weather Radio to
know when warnings are issued.
A Tornado WARNING is issued by your local NOAA National Weather Service Forecast Office meteorologists who watch the weather 24/7 over a designated area. This means a tornado has been reported by spotters or indicated by radar and there is a serious threat to life and property to those in the path of the tornado. ACT now to find safe shelter! A warning can cover parts of counties or several counties in the path of danger.
Watch this Youtube video for a great explanation!
A Tornado WARNING is issued by your local NOAA National Weather Service Forecast Office meteorologists who watch the weather 24/7 over a designated area. This means a tornado has been reported by spotters or indicated by radar and there is a serious threat to life and property to those in the path of the tornado. ACT now to find safe shelter! A warning can cover parts of counties or several counties in the path of danger.
Watch this Youtube video for a great explanation!
How is tornado strength rated?
The
most common and practical way to determine the strength of a tornado is to look
at the damage it caused. From the damage, we can estimate the wind speeds. An “Enhanced Fujita Scale” was implemented by the
National Weather Service in 2007 to rate tornadoes in a more consistent and
accurate manner. The EF-Scale takes into account more variables than the
original Fujita Scale (F-Scale) when assigning a wind speed rating to a
tornado, incorporating 28 damage indicators such as building type, structures
and trees. For each damage indicator, there are 8 degrees of damage ranging
from the beginning of visible damage to complete destruction of the damage
indicator. The original F-scale did not take these details into account. The
original F-Scale historical data base will not change. An F5 tornado rated
years ago is still an F5, but the wind speed associated with the tornado may
have been somewhat less than previously estimated. A correlation between the
original F-Scale and the EF-Scale has been developed. This makes it possible to
express ratings in terms of one scale to the other, preserving the historical
database.
How do tornadoes form?
The
truth is that we don't fully understand. The most destructive and deadly
tornadoes occur from supercells, which are rotating thunderstorms with a
well-defined radar circulation called a mesocyclone. (Supercells can also
produce damaging hail, severe non-tornadic winds, unusually frequent lightning,
and flash floods.) Tornado formation is believed to be dictated mainly by
things which happen on the storm scale, in and around the mesocyclone. Recent
theories and results from the VORTEX2
program suggest that once a mesocyclone is underway, tornado development is
related to the temperature differences across the edge of downdraft air
wrapping around the mesocyclone. Mathematical modeling studies of tornado
formation also indicate that it can happen without such temperature patterns;
and in fact, very little temperature variation was observed near some of the
most destructive tornadoes in history on 3
May 1999. We still have lots of work to do.
What do storm spotters look for when
trying to identify a tornado or a dangerous storm?
Inflow bands are ragged bands of low cumulus clouds
extending from the main storm tower usually to the southeast or south. The
presence of inflow bands suggests that the storm is gathering low-level air
from several miles away. If the inflow bands have a spiraling nature to them,
it suggests the presence of rotation.
The beaver's tail is a smooth, flat cloud band extending from the eastern edge of the rain-free base to the east or northeast. It usually skirts around the southern edge of the precipitation area. It also suggests the presence of rotation.
A wall cloud is an isolated cloud lowering attached to the rain-free base of the thunderstorm. The wall cloud is usually to the rear of the visible precipitation area.
A wall cloud that may produce a tornado usually exists for 10–20 minutes before a tornado appears. A wall cloud may also persistently rotate (often visibly), have strong surface winds flowing into it, and may have rapid vertical motion indicated by small cloud elements quickly rising into the rain-free base.
As the storm intensifies, the updraft draws in low-level air from several miles around. Some low-level air is pulled into the updraft from the rain area. This rain-cooled air is very humid; the moisture in the rain-cooled air quickly condenses below the rain-free base to form the wall cloud.
The rear flank downdraft (RFD) is a downward rush of air on the back side of the storm that descends along with the tornado. The RFD looks like a “clear slot” or “bright slot” just to the rear (southwest) of the wall cloud. It can also look like curtains of rain wrapping around the cloud base circulation. The RFD causes gusty surface winds that occasionally have embedded downbursts. The rear flank downdraft is the motion in the storm that causes the hook echo feature on radar.
A condensation funnel is made up of water droplets and extends downward from the base of the thunderstorm. If it is in contact with the ground it is a tornado; otherwise it is a funnel cloud. Dust and debris beneath the condensation funnel confirm a tornado's presence.
The beaver's tail is a smooth, flat cloud band extending from the eastern edge of the rain-free base to the east or northeast. It usually skirts around the southern edge of the precipitation area. It also suggests the presence of rotation.
A wall cloud is an isolated cloud lowering attached to the rain-free base of the thunderstorm. The wall cloud is usually to the rear of the visible precipitation area.
A wall cloud that may produce a tornado usually exists for 10–20 minutes before a tornado appears. A wall cloud may also persistently rotate (often visibly), have strong surface winds flowing into it, and may have rapid vertical motion indicated by small cloud elements quickly rising into the rain-free base.
As the storm intensifies, the updraft draws in low-level air from several miles around. Some low-level air is pulled into the updraft from the rain area. This rain-cooled air is very humid; the moisture in the rain-cooled air quickly condenses below the rain-free base to form the wall cloud.
The rear flank downdraft (RFD) is a downward rush of air on the back side of the storm that descends along with the tornado. The RFD looks like a “clear slot” or “bright slot” just to the rear (southwest) of the wall cloud. It can also look like curtains of rain wrapping around the cloud base circulation. The RFD causes gusty surface winds that occasionally have embedded downbursts. The rear flank downdraft is the motion in the storm that causes the hook echo feature on radar.
A condensation funnel is made up of water droplets and extends downward from the base of the thunderstorm. If it is in contact with the ground it is a tornado; otherwise it is a funnel cloud. Dust and debris beneath the condensation funnel confirm a tornado's presence.
Source: www.nssl.noaa.gov