NWS Lincoln to issue enhanced severe weather warnings beginning
April 1
Enhanced
wording to highlight dangers in severe weather warnings
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[March 21, 2013]
The United States was ravaged by
tornadoes two years ago. Record numbers of tornadoes occurred in
many areas of the country -- and several of them were deadly. More
than 550 people were killed by tornadoes, including 158 in Joplin,
Mo., alone. Nearly all of the deadly tornadoes in 2011 were preceded
by tornado warnings from the National Weather Service -- some with
20 to 30 minutes of advance notice or more. However, the death tolls
were extremely high, despite warnings being issued through multiple
communications methods.
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To address various questions and findings in the wake of the Joplin
tornado, the National Weather Service offices in Kansas and Missouri
experimented with enhancing severe weather warnings in 2012. The
2012 experiment yielded some successful results; however, due to
widespread drought, there were a limited number of cases. The
decision was made to expand this experiment to all the weather
service offices in its Central Region of the United States --
including the office in Lincoln -- starting April 1. The
"enhanced" severe weather warnings -- or impact-based warnings --
are intended to provide more information about the severe weather
threat to the public, emergency managers who activate outdoor
warning sirens, and the broadcast media. Tornado and severe
thunderstorm warnings from the National Weather Service will look
similar; however, the information will be streamlined, including the
addition of a new "Impacts" section. That portion of the warning is
intended to describe what type of damage can be expected from the
warned storm.
The intended outcomes of providing extra information in the
impact-based warnings are to improve communication of critical
information by the National Weather Service, to make warnings easier
to read, to identify the most important information, to highlight
storms that are particularly dangerous, to provide different levels
of potential storm impacts within the same product, and to enable
people to prioritize warnings in or near their areas of interest.
The impact-based tornado warnings will be sent from the National
Weather Service in the same manner as in the past, so no changes are
needed to weather alert radios or computers and mobile devices
programmed to receive these messages. The information within the
warning, though, will look and sound a bit different.
With respect to tornado warnings, there are three possible
impacts that will be communicated:
In
this case, the duration of the tornado is generally expected to be
short-lived. (Based on the tornado climatology of central and
eastern Illinois, nearly 75 to 80 percent of our tornado warnings
will be like this.)
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Credible evidence from trained storm spotters and radar indicates
that considerable tornado damage is imminent or ongoing, and the
tornado duration is expected to be long-lived. (These are fairly
rare in central and eastern Illinois, occurring with about 20
percent of our tornadoes.)
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Catastrophic damage from a tornado is occurring, there is a
severe threat to human life, and the tornado duration is expected to
be long-lived. This will be exceedingly rare -- and used only
when reliable sources confirm a violent tornado. (This type of
tornado has occurred only eight times in central and eastern
Illinois in the past 63 years and is very rare.)
In addition, severe thunderstorm warnings will be enhanced in the
impact-based warnings experiment. With many severe thunderstorm
warnings, the primary threat is damaging straight-line wind, severe
wind from a downburst or very large hail. However, sometimes,
short-lived tornadoes can rapidly develop and cause enhanced damage
within an area of high wind. In this case, the severe thunderstorm
warning will indicate that there is some potential for a short-lived
tornado by stating a tornado is "possible." This will be used when
the available radar and storm spotter information does not indicate
a widespread, long track tornado threat, and if a brief tornado
touchdown may occur.
For more information about the impact-based warnings, visit
http://www.crh.noaa.gov/
crh/?n=2013_ibw_info.
The mission of the National Weather Service is to provide
weather, hydrologic and climate forecasts and warnings for the
United States, its territories, adjacent waters and ocean areas, for
the protection of life and property and to enhance the national
economy. The National Weather Service is the sole United States'
official voice for issuing warnings during life-threatening weather
situations.
[Text from National Weather Service,
Lincoln office] |