Outdoor Warning Siren Activation ProtocalMasterpiece on the Mississippi
TO: The Honorable Mayor and City Council Members
FROM: Michael C. Van Milligen, City Manager
SUBJECT: Siren Activation Protocol
DATE: February 25, 2010
Dubuque
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AIl•AmaicaCity
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Emergency Management Director Tom Berger and Fire Chief Dan Brown are
recommending that the City of Dubuque adopt the Outdoor Warning Siren Activation
Protocol, as established by the Davenport office of the National Weather Service.
Local jurisdictions are encouraged to change policies to allow siren activation for life -
threatening severe storms, in addition to tornadoes. Statistics have shown there is
imminent danger to people outdoors when thunderstorm winds exceed 70 mph and /or
there is golf ball size or larger hail.
I concur with the recommendation and respectfully request Mayor and City Council
approval.
Michael C. Van Milligen
MCVM:jh
Attachment
cc: Barry Lindahl, City Attorney
Cindy Steinhauser, Assistant City Manager
Tom Berger, Emergency Management Director
Dan Brown, Fire Chief
** -■,
r EMERGENCY
�NAGEMENT
DUBUQUE COUNTY
Thomas I. Berger, Director
Willis Wagner, Chairperson
Mike Wuertzer, Vice- Chairperson
Memo
To:
From:
Date:
Subject:
City Manager Mike Van Milligen
Tom Berger 6-K" -
Dan Brown
02 -17 -2010
Siren Activation Protocol
14928 Public Safety Way
Dubuque, IA 52002 -8216
Phone: 563 - 589 -4170
Fax: 563 - 589 -0015
E -Mail: dbqema@yousq.net
The Davenport Office of the National Weather Service has implemented an Outdoor
Warning Siren Activation Protocol for local jurisdictions that enhances when the sirens are
used for weather emergencies. Statistics have shown there is imminent danger to people
outdoors when thunderstorm winds exceed 70 mph and /or there is golf ball size or larger
hail. Activation of the outdoor warning sirens for these types of severe storms may not have
happened in the past. Local jurisdictions are encouraged to change policies to allow siren
activation for life threatening severe storms in addition to tornadoes. The weather service
has developed the criteria in order to provide consistency across the area so the citizens
may take appropriate actions when severe weather threatens. Siren activation for tornado
warnings will remain the same as in the past. The determination that the winds have
reached 70 mph or more and /or hail has reached golf ball sized will be determined by
spotter reports and /or Doppler radar. An initial concern in our meetings was that the sirens
would be over used resulting in a complacency issue. After review of the storms over the
past 15 years, on average it may increase our outdoor warning siren activation 2 -3 times.
We have attached copy of the procedure, adapted for Dubuque County for your review. We
have also attached a copy of statistics for Dubuque County that would indicate how many
times this may affect us along with other pertinent information. This year the Davenport
Office of the NWS Office will be using their public opportunities to educate people about
outdoor warning sirens and it will be a major component of their storm spotter classes for
2010. Chief Brown and I are in favor of adopting the protocol for the City of Dubuque and I
would like to implement that in my budget hearing presentation as well as work with Randy
Gehl to promote it community wide.
Dubuque Area
Outdoor Warning Sirens
Guidance for Testing and Activation
Purpose
The purpose of this document is to establish common guidelines for activation of
outdoor warning sirens throughout the Dubuque area. Activation is the responsibility of
each jurisdiction having control over the outdoor warning sirens and adherence to this
policy is voluntary.
The outdoor warning sirens represent only one part of a broader public emergency
notification system. Other components might include: NOAA Weather Radio All -
hazards, law enforcement, text notification networks, and the media. Sirens are used to
alert citizens who are outdoors of an imminent hazard and prompt them to go indoors
and seek further information.
This document is not intended to relieve, replace, or supersede any authority or
responsibility local jurisdictions might have to protect the citizens of their community.
Background
Confusion hinders public response. Using common guidelines for the outdoor warning
sirens throughout the various jurisdictions of Dubuque County will minimize confusion in
emergency situations. Establishing common guidelines will also enable communities to
partner in an area -wide public education campaign regarding sirens and the overall
public emergency notification system.
These guidelines are based on communication technology and systems available in the
Dubuque County area, and also on the current science of severe weather warnings.
Siren Activation for Imminent Threats
Upon hearing outdoor warning sirens it is important that all persons immediately refer to
local broadcast media (radio, TV, etc.) for additional information!
When activated, the tone should be sounded for 3 -5 minutes, re- sounding for the
duration of the threat (every 10 -15 minutes is recommended). Repeated sounding of
sirens has directly resulted in saved lives in numerous cases, including local examples
such as Granville /Utica (2004) and Iowa City (2006). In both of these cases, the initial
siren tone was not heard, but later tones alerted people to the continuing threat.
If sirens have more than one tone, local officials should pre- determine the tone that is
most discernible and use that tone for all alerts.
February 8 2010
Severe Weather
National Weather Service warnings define the area threatened by the storm and include
information about the history and /or potential of the specific storm. In addition, trained
spotters provide real -time reports of an imminent threat approaching or occurring in the
community. When a warning includes the specific hazards defined below or when
trained spotters report any of these hazards, sirens should be activated for all
jurisdictions in the threatened area.
Tornadoes — Activation recommended for:
• Tornado Warning issued by the National Weather Service and /or
• Tornado or funnel cloud reported by a trained spotter
Severe Thunderstorms — Activation recommended for:
Severe Thunderstorm Warning issued by the National Weather Service or a report
from a trained spotter that includes:
• wind 70 mph* or greater (whole trees blown down), and /or
• golf ball sized hail ** or larger (1.75 inch diameter or greater)
* Most fatalities during tornadoes or severe thunderstorms occur due to falling trees or
large branches. 70 mph is the typical threshold at which large branches and small trees
break. (Additional background for this threshold is available in the engineering
document for the Enhanced Fujita damage scale: www.spc.ncep.noaa.gov /efscale)
** Hail begins to break windows when it reaches or exceeds golf ball size.
Additional considerations:
Although other weather factors pose a risk, community -wide outdoor warning sirens
should NOT be sounded for lightning or flash floods. By its nature, lightning is "self -
alerting" and citizens should go indoors when thunder is heard. Also, because of the
frequency of lightning, sounding sirens could desensitize the public to the sirens.
Although flash floods present a threat, that threat is localized and typically in a known
area. In addition, Flash Flood Warnings are often issued more than one hour before the
flooding occurs, allowing local officials time for mitigation efforts, and eliminating the
usefulness of community -wide sirens in this situation.
Local Life - threateninq Events
Non - weather emergencies (hazmat incident, terrorism, nuclear emergency, etc.) that
pose a threat to those outdoors and require action to protect life, should be alerted via
the outdoor warning sirens by local officials based on existing agreements or local
discretion depending on the emergency. If outdoor warning sirens are activated, the
life- threatening conditions should also be relayed to Quad Cities NWS for broadcast on
NOAA Weather Radio All- hazards.
February 8 2010
All Clear
There will be no "all clear" signal from outdoor warning sirens. Citizens are expected to
be indoors and should monitor local media for additional information.
Testing
Outdoor warning sirens will be tested the first Tuesday of each month at 9:30 a.m.
If a severe weather watch or warning is in effect for our area prior to 9:30 a.m. on a
scheduled test day, the sirens should not be tested that day. Outdoor warning siren
tests will resume on the next scheduled monthly date.
Dubuque Area
Outdoor Warning Sirens
Public Safety Answering Point (PSAP)
Quick Reference Guide for Activation and Testing
Sirens should be sounded for 3 -5 minutes, resounding for the
duration of the threat (every 10 -15 minutes is recommended).
Severe Weather
Tornadoes
• Tornado Warning issued by the National Weather Service and/or
• Tornado or funnel cloud reported by a trained spotter
Severe Thunderstorms
Severe Thunderstorm Warning issued by the National Weather Service or
report received from a trained spotter that includes:
• wind 70 mph or greater (whole trees blown down), and/or
• golf ball sized hail or larger (1.75 inches in diameter or greater)
Local Life - threatening Events
Non - weather emergencies (hazmat incident, terrorism, nuclear emergency, etc.)
that pose a threat to those outdoors and require action to protect life, should be
alerted via the outdoor warning sirens by local officials based on existing
agreements or local discretion depending on the emergency.
All Clear
There will be no "all clear" signal from outdoor warning sirens.
Testing
First Tuesday of each month at 9:30 a.m. If a severe weather watch or warning is
in effect for the Dubuque area prior to 10 a.m. on a scheduled test day, the sirens
should not be tested that day. Outdoor warning siren tests will resume on the next
scheduled monthly date.
February S 2010
Tornado
Severe
Thunderstorm
Wind
Large Hail
Tornado
Thunderstorm Wind
Hail
Total Events
Average per year
Most in one year
Warning Basis
U.S. Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
Dubuque County, Iowa Severe Weather Risk Assessment
Ouicl- Response Severe If calker Threats
In extreme cases, wind speeds can exceed 200 mph; however, 84% have
wind less than 110 mph. Most fatalities occur with the stronger tornadoes.
Recommendation: Seek immediate shelter in a basement without windows.
Severe wind speeds range from near 60 mph (scattered damage, typically
tree branches) to over 120 mph (widespread tornado -like damage).
Recommendation: Seek immediate shelter indoors away from windows.
For winds over 70 mph, seek shelter in a basement without windows.
Can reach the size of softballs.
Recommendation: Seek immediate shelter indoors away from windows.
Severe If calker Injuries 1 atalities in Dubuque ('own), 1 1 .Since 1955
Injuries
1
6
4
Fatalities
0
0 4 hail injuries occurred with tennis ball sized hail.
0
Notes
Severe Heather /'rents in Dubuque County, 1 I ,S'inc'e 1995 (last 15 years)
Hail Hail Wind Wind Wind
(2.1 ') (21.75') (258 mph) (270 mph) (275 mph)
28 13 49 13 5
2 0.9 3.5 0.9 0.3
7 3 7 3 2
Tornado
5
0.4
2
Severe I f cruller I f arltings '. for Dubuque County, 1. 1 1995-200 -
Tornado Warnings Severe Thunderstorm Warnings (Estimated * *)
Tomado indicated by radar Thunderstorm with wind over 58 mph and/or
or trained spotters quarter sized (1 ") hail or larger
Average lead time* 12 minutes 20 minutes
Average per year* 1.3 4.7
Most in one year* 3 14
*Statistics are for guideline purposes, calculated from county -based warnings before storm -based warnings went into effect in Oct. 2007.
**Severe Thunderstorm Warnings were issued under the 3/ " hail threshold. This threshold changed to quarter sized (1'9 hail in April 2009.
Numbers listed here are based on an estimated 30% reduction in the number of warnings due to the change in hail criteria.
Notes
• Hail golf ball sized and larger can break house and car windows.
• Severe thunderstorm wind around 70 mph can down large branches and winds 75 -80 mph begin to fell
whole trees.
• A recent local study suggests wind forecasts in Severe Thunderstorm Warnings are accurate +/- 10 mph.
• The greatest risk factors for tornado fatalities include being outdoors or in a mobile home, overnight
hours, weekends or holidays, and occurrences outside the normal "season ".
Dubuque County, IA Risk Assessment (continued)
Lightning:
• Warnings are not issued for lightning because all thunderstorms produce lightning, and all cloud -to-
ground lightning is potentially fatal.
• When thunder can be heard or lightning seen, the lightning is within
"striking distance ".
Recommendation: Remain indoors during all thunderstorms due to the
lightning threat. Wait 30 minutes after the last thunder is heard before
resuming outdoor activities.
For more information, contact:
Donna Dubberke, Warning Coordination Meteorologist
National Weather Service Quad Cities
9050 Harrison Street
Davenport, IA 52806
(563) 391-7094 x726
donna.dubberke a,noaa.gov
Flash Floods:
• A flash flood occurs within a very short time (generally 6 hours or less) relative to the rainfall.
• Flash Flood Warnings are issued for those storms that produce extreme rainfall rates leading to flash
floods.
• Currently, the average lead time for Flash Flood Warnings is 55 minutes.
Recommendation: Initiate flash flood mitigation measures. Flood prone
streets should be monitored and barricaded as necessary. People living in
flood prone areas should move to higher ground.
National Weather Service
National Storm Event Database www.weather.gov
Storm -Based Warnings www.ncdc.noaa.ov
www. weather.govisbwarnings