Tornado emergency

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Large, violent tornadoes can cause catastrophic damage when striking populated areas.

A tornado emergency is enhanced wording of tornado warnings used by the National Weather Service (NWS) in the United States during significant tornado occurrences in highly populated areas. Although it is not a new warning type from the NWS, issued instead within a severe weather statement (or in rare cases, in the initial tornado warning), a tornado emergency generally means that significant, widespread damage is expected to continue and a high likelihood of numerous fatalities is expected with a large, strong to violent tornado.[1]

Although tornadoes that are classified in damage surveys as "strong" or "violent" (rated EF2-EF5 on the Enhanced Fujita Scale) are capable of significant property damage and loss of life, there have been instances in which these type of tornadoes have resulted in very few to no fatalities; in turn, not all tornadoes of ¼-mile in width or larger produce catastrophic damage (though this is often assumed to be the case). Regardless, people in the path of a large tornado must take immediate safety precautions if they are in or near the projected path of the storm.

History[edit]

First use[edit]

The term was first used during the May 3, 1999 tornado outbreak that spawned an F5 tornado which struck the municipalities of Bridge Creek and Moore, located just south of Oklahoma City. On that day, between 5:30 and 6:30 p.m., David Andra, the Science and Operations Officer at the National Weather Service Weather Forecast Office in Norman watched as the large, destructive tornado approached Oklahoma City. This led to the issuance of the first tornado emergency, which in this instance was released as a standalone weather statement issued separately from the original tornado warning.[2]

"As the large tornado approached western sections of the OKC metro area, we asked ourselves more than once, 'Are we doing all we can do to provide the best warnings and information?' It became apparent that unique and eye-catching phrases needed to be included in the products. At one point we used the phrase 'Tornado Emergency' to paint the picture that a rare and deadly tornado was imminent in the metro area. We hoped that such dire phrases would prompt action from anyone that still had any questions about what was about to happen.[3] "

Text of the Moore Tornado Emergency from May 3, 1999[edit]

...TORNADO EMERGENCY IN SOUTH OKLAHOMA CITY METRO AREA...

AT 6:57 PM CDT...A LARGE TORNADO WAS MOVING ALONG INTERSTATE 44 WEST OF 
NEWCASTLE. ON ITS PRESENT PATH...THIS LARGE DAMAGING TORNADO WILL 
ENTER SOUTHWEST SECTIONS OF THE OKLAHOMA CITY METRO AREA BETWEEN 7:15  
AND 7:30 PM. PERSONS IN MOORE AND SOUTH OKLAHOMA CITY SHOULD TAKE 
IMMEDIATE TORNADO PRECAUTIONS!

THIS IS AN EXTREMELY DANGEROUS AND LIFE THREATENING SITUATION. IF YOU 
ARE IN THE PATH OF THIS LARGE AND DESTRUCTIVE TORNADO...TAKE COVER 
IMMEDIATELY.

DOPPLER RADAR HAS INDICATED THIS STORM MAY CONTAIN DESTRUCTIVE HAIL TO THE 
SIZE OF BASEBALLS...OR LARGER.

Source:[4]

Evolved usage[edit]

At 3:01 p.m. CDT on May 20, 2013, this bulletin was issued by the National Weather Service Norman forecast office confirming that a destructive tornado was on the ground and headed for Moore and southern portions of Oklahoma City, Oklahoma. Note the differences between this bulletin and the first-ever bulletin from 1999. It should also be noted that this was issued during an updated tornado warning and not in a follow-up severe weather statement.

Text of the Moore Tornado Emergency from May 20, 2013[edit]

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE NORMAN OK
301 PM CDT MON MAY 20 2013

THE NATIONAL WEATHER SERVICE IN NORMAN HAS ISSUED A

* TORNADO WARNING FOR...
  NORTHWESTERN MCCLAIN COUNTY IN CENTRAL OKLAHOMA...
  SOUTHERN OKLAHOMA COUNTY IN CENTRAL OKLAHOMA...
  NORTHERN CLEVELAND COUNTY IN CENTRAL OKLAHOMA...

* UNTIL 345 PM CDT

* AT 259 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS AND STORM
  SPOTTERS WERE TRACKING A LARGE AND EXTREMELY DANGEROUS TORNADO NEAR
  NEWCASTLE. DOPPLER RADAR SHOWED THIS TORNADO MOVING NORTHEAST AT 20
  MPH.

THIS IS A TORNADO EMERGENCY FOR MOORE AND SOUTH OKLAHOMA CITY.

IN ADDITION TO A TORNADO...LARGE DESTRUCTIVE HAIL UP TO TENNIS BALL
SIZE IS EXPECTED WITH THIS STORM.

* LOCATIONS IMPACTED INCLUDE...
  MIDWEST CITY...MOORE...NEWCASTLE...STANLEY DRAPER LAKE...TINKER AIR
  FORCE BASE AND VALLEY BROOK.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THIS IS AN EXTREMELY DANGEROUS AND LIFE THREATENING SITUATION. IF YOU
CANNOT GET UNDERGROUND GO TO A STORM SHELTER OR AN INTERIOR ROOM OF A
STURDY BUILDING NOW.

TAKE COVER NOW IN A STORM SHELTER OR AN INTERIOR ROOM OF A STURDY
BUILDING. STAY AWAY FROM DOORS AND WINDOWS.
&&

$$

Source:[5]

Standardization and recent usage[edit]

After the original usage for the May 3, 1999 F5 tornado, the term Tornado Emergency was used by other National Weather Service Weather Forecast Offices (WFOs), although no uniform criteria existed and the issuance was entirely at the discretion of the forecaster issuing the warnings. Usage of the term varied from simply confirmed tornadoes in populated areas to significant, rare tornadoes causing severe damage and injuries. Some NWS forecast offices, such as the one serving the Des Moines, Iowa metropolitan area, have created standardized criteria and purpose for the usages of the heightened wording. Because data about the tornado and its exact path are often ascertained after the initial tornado warning is issued, this designation is usually added to the Severe Weather Statement (SAME code: SVS) that is used to follow-up a tornado warning.

On April 2, 2012, the National Weather Service began an experimental program within its Wichita, Topeka, Springfield, St. Louis and Kansas City/Pleasant Hill offices in Kansas and Missouri called Impact Based Warning, which allows the respective offices to enhance warning information, such as adding tags to the warning messages which signify the potential damage severity. In regards to tornadoes, the creation of this multi-tiered system resulted in the implementation of an intermediate tornado warning product, a Particularly Dangerous Situation Tornado Warning.[6][7]

On April 1, 2013, the IBW experiment expanded to include all National Weather Service WFOs within the Central Region;[8] the IBW experiment will be expanded again to include eight additional offices within the Eastern, Southern and Western Regions in the spring of 2014.[9] Within the span of eleven days, the National Weather Service WFO in Norman issued tornado emergencies for parts of the Oklahoma City metropolitan area and central Oklahoma: first on May 20, 2013 for the EF5 tornado that struck Moore and portions of southern Oklahoma City,[10] and again on May 31, for portions of eastern Canadian County and western sections of the immediate Oklahoma City area.

Criteria[edit]

The National Weather Service Weather Forecast Office in Des Moines is one of the forecast offices to have created a set purpose and criteria for the usage of "tornado emergencies" in tornado warning products, which were made effective on March 12, 2010.[1] According to the Des Moines office, the purpose of the tornado emergency wording is as follows:

  • To motivate and provide a sense of urgency to persons in the path of this storm to take immediate shelter in a reinforced structure that offers maximum protection from destructive winds.
  • To communicate to state, local, and county officials and emergency responders that they should prepare for immediate search and rescue operations.
  • To communicate the need to prepare for immediate medical emergencies, evacuation measures, and emergency sheltering.

And before usage, the following criteria must be met:

  • A large and catastrophic tornado has been confirmed and will continue (a radar signature alone is not sufficient).
  • The tornado will have a high impact and/or affect a highly vulnerable population (estimated to be once every 10 years for central Iowa).
  • The tornado is expected to cause numerous fatalities.

The National Weather Service office in Nashville, Tennessee also created criteria to declare a tornado emergency within a tornado warning statement effective January 1, 2011. It states, "Tornado Emergency can be inserted in the third bulletin of the initial tornado warning (TOR) or in a severe weather statement (SVS)." Before the phrase can be used:

  • a confirmed large tornado must be going through a highly populated area such as Metro Nashville
  • a violent tornado with a significant damage history
  • a confirmed tornado, radar shows evidence of debris
  • the confirmed tornado is expected to cause significant widespread damage and loss of life.

Tornado safety[edit]

It is recommended that people in the path of a large and violent tornado, whether referenced in a tornado warning or a tornado emergency, seek shelter in a basement, cellar or safe room, as stronger tornadoes (particularly those significant enough to warrant the inclusion of a tornado emergency declaration within a tornado warning) pose a significant risk of major injury or death for people above ground level. Those who do not have below-ground shelter are still advised to take cover in a room in the center of the home on the lowest floor, and cover themselves with some type of thick padding (such as mattresses or blankets), to protect against falling debris in the event that the roof and ceiling collapse.[11]

Example of tornado emergency usage[edit]

An example of a tornado emergency issued in Alabama

Problems playing this file? See media help.
SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
1203 PM CDT SAT APR 24 2010

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1230 PM CDT FOR CENTRAL
YAZOO COUNTY...

...THIS IS A TORNADO EMERGENCY FOR THE WARNED AREA...

AT 1203 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS AND STORM
SPOTTERS WERE TRACKING A LARGE AND EXTREMELY DANGEROUS WEDGE
TORNADO.  THIS TORNADO WAS LOCATED 6 MILES NORTH OF SATARTIA MOVING
NORTHEAST AT 60 MPH.

THE TORNADO WILL BE NEAR...
  YAZOO CITY AND LITTLE YAZOO BY 1210 PM CDT...
  MYRLEVILLE BY 1215 PM CDT...
  BENTON AND EDEN BY 1220 PM CDT...
  MIDWAY BY 1225 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WARNING MEANS THAT A TORNADO IS OCCURRING OR IMMINENT. YOU
SHOULD ACTIVATE YOUR TORNADO ACTION PLAN AND TAKE PROTECTIVE ACTION
NOW. SIGNIFICANT DAMAGE HAS OCCURRED WITH THIS SIGNIFICANT TORNADO!

THIS IS AN EXTREMELY DANGEROUS AND SERIOUS LIFE THREATENING
SITUATION. THIS STORM IS CAPABLE OF PRODUCING STRONG TO VIOLENT
TORNADOES. IF YOU ARE IN THE PATH OF THIS TORNADO...TAKE COVER
IMMEDIATELY!

A TORNADO WATCH REMAINS IN EFFECT UNTIL 800 PM CDT SATURDAY EVENING
FOR MISSISSIPPI.

List of tornado emergencies issued[edit]

See also[edit]

References[edit]

  1. ^ a b "Tornado Emergency Media Advisory". NWS - Des Moines, Iowa. March 12, 2010. Retrieved 2010-03-29. 
  2. ^ "Tornado emergency in south oklahoma city metro area". NWS - Norman, Oklahoma. May 3, 1999. Retrieved 2007-08-13. [dead link]
  3. ^ "May 3rd, 1999 from the NWS's Perspective". The Southern Plains Cyclone (National Weather Service) 2 (2). Spring 2004. Archived from the original on 2004-11-08. Retrieved 2008-02-15. 
  4. ^ Mathis, Nancy (2007). "Inside the Bear's Cage". Storm Warning: The Story of a Killer Tornado. Touchstone. p. 129. ISBN 0-7432-8053-9. 
  5. ^ National Weather Service, Norman Weather Forecast Office (2013-05-20). "Tornado Warning". Iowa State University Department of Agronomy. Retrieved 2013-05-24. 
  6. ^ "Impact Based Warning Experimental Product". National Weather Service. Retrieved 2012-04-04. 
  7. ^ Draper, Bill (2012-04-01). "'UNSURVIVABLE!' New Tornado Warnings Aim to Scare". Yahoo! News and the Associated Press. Retrieved 2012-04-04. 
  8. ^ "Impact Based Warning Experimental Product". Crh.noaa.gov. Retrieved 2014-01-22. 
  9. ^ National Weather Service (2014). "Impact Based Warnings". National Oceanic and Atmospheric Administration. Retrieved March 12, 2014. 
  10. ^ Howell, George (2013-05-21). "Okla. Medical Examiner preparing for '40 more bodies' | National News - KCCI Home". Kcci.com. Retrieved 2014-01-22. 
  11. ^ "The Online Tornado FAQ (by Roger Edwards, SPC)". Spc.noaa.gov. Retrieved 2014-01-22.