Tornado warning
From Wikipedia, the free encyclopedia
A tornado warning is issued when:
- a tornado is reported on the ground or is indicated on doppler radar
- a waterspout is headed toward landfall
- a funnel cloud is reported in the sky
- a tropical cyclone is making landfall with winds greater than 115 mph (experimental for 2006, will be renamed "Extreme Wind Warning" if successful)
It is also issued when, depending on the circumstances:
- a thunderstorm with a threshold strong, tight rotation signature is indicated by doppler radar, or
- a rotating wall cloud is reported (in context of all other available information).
The Skywarn program, which teaches lay people how to spot tornadoes, funnel clouds, wall clouds, and other weather phenomena, is offered by the National Weather Service. In tandem with Doppler radar information, eye witness reports can be very helpful for warning the public of an impending tornado, especially when used for ground truthing.
A tornado warning means there is immediate danger for the warned and immediately surrounding area -- if not from the relatively narrow tornado itself, from the severe thunderstorm producing (or likely to produce) it. All in the path of such a storm are urged to take cover immediately, as it is a life-threatening situation. A warning should not be confused with a tornado watch (issued by a national guidance center, the Storm Prediction Center) which only indicates that conditions are favorable for the formation of tornadoes.
In the United States, local offices of the National Weather Service issue warnings for tornadoes and severe thunderstorms on a per-county basis, narrowing down to parts of counties in many cases, and usually with a narrower pathcast of where the tornado(s) is expected to track within the area is mentioned in the warning message.
In Canada, similar criteria are used and warnings are issued by regional offices of the Meteorological Service of Canada of Environment Canada in Vancouver, Edmonton, Toronto, Montreal and Halifax.
Tornado warnings are generated via computer then disseminated through various communication routes accessed by the media and various agencies, on the internet, to NOAA satellites, and on NOAA Weather Radio. Civil defense sirens are also activated for the affected areas if present.
The first tornado warning was issued by the meteorological staff of Tinker Air Force Base in 1947 and was also coincidentally the first successful tornado forecast.
Advances in technology, both in indentifying conditions and in distributing warnings effectively, have been credited with reducing the death toll from tornadoes. The average warning times have increased substantially to about 15 minutes; and in some cases to more than a one hour's warning of impending tornadoes. The U.S. tornado death rate has declined from 1.8 deaths per million people per year in 1925 to only 0.11 per million in 2000. Much of this change is credited to improvements in the tornado warning system.
[edit] Tornado Emergency
Main Article: Tornado Emergency
When a large, extremely violent tornado is about to impact a densely populated area, the Weather Service has the option of issuing a severe weather statement with enhanced wording; this is called a tornado emergency. Such an upgrade has only been used five times in U.S. history[citation needed]: in 1999 for the F5 that hit Moore, Oklahoma, in 2003, for an F4 tornado that again hit Moore, Oklahoma, another F4 Tornado that hit western Oklahoma City the next day, and most recently, in 2007 for the EF5 that hit Greensburg, Kansas.
[edit] Example of a Tornado Warning
TORNADO WARNING
OHC103-092115-
/O.NEW.KCLE.TO.W.0022.070809T2023Z-070809T2115Z/
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE CLEVELAND OH
423 PM EDT THU AUG 9 2007
THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A
* TORNADO WARNING FOR...
MEDINA COUNTY IN NORTHEAST OHIO...
* UNTIL 515 PM EDT
* AT 419 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO 7 MILES WEST OF
LODI...OR ABOUT 15 MILES WEST OF MEDINA...MOVING EAST AT 40 MPH.
* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
WADSWORTH
IF YOU ARE CAUGHT OUTSIDE...SEEK SHELTER IN A NEARBY REINFORCED
BUILDING. AS A LAST RESORT...SEEK SHELTER IN A CULVERT...DITCH OR LOW
SPOT AND COVER YOUR HEAD WITH YOUR HANDS.
THE SAFEST PLACE TO BE DURING A TORNADO IS IN A BASEMENT. GET UNDER A
WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. IF NO BASEMENT IS
AVAILABLE...SEEK SHELTER ON THE LOWEST FLOOR OF THE BUILDING IN AN
INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE BLANKETS OR PILLOWS TO
COVER YOUR BODY AND ALWAYS STAY AWAY FROM WINDOWS.
IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE
NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.
LAT...LON 4100 8217 4114 8216 4114 8207 4117 8206
4116 8169 4099 8168
$$
LAPLANTE
[edit] See also
Severe Weather Watches and Warnings |
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