During Minnesota Severe Weather Awareness Week every April, outdoor warning sirens will be activated twice across Hennepin County for the statewide tornado drill day.

The sirens and their associated equipment are purchased and maintained by cities within Hennepin County. They are activated at the county level, at the recommendation of the National Weather Service.

Sirens are used for severe weather warnings, as well as for other situations when people should take shelter. Weather-related sirens are triggered when the National Weather Service has issued a tornado warning, and/or if there are reports of sustained straight-line winds in excess of 70 mph.

Per Minnesota policy, the sheriff’s communication division tests/activates all sirens in Hennepin County at 1 p.m. on the first Wednesday of each month.

Hennepin County siren coverage map (PDF)

For your safety

• Outdoor warning sirens are meant to be heard outside. The system is not designed to provide notification inside your home or business. When sirens sound, residents should always seek shelter and tune to local weather information on radio, television, or NOAA Weather Radio for more information.
• Hennepin County does not issue an “all-clear” tone from the outdoor sirens. The threat of severe weather does not stop when the sirens stop. Continue to shelter and stay tuned to local weather information on radio, television or NOAA Weather Radios for the duration of the warning period.
• If the siren sounds while you are in your vehicle, seek shelter immediately. The safest place to be is in a sturdy building, on the lowest level away from windows. If there is not a building nearby, and the tornado is approaching quickly, get as far away from the road and cars as possible and lie in a low area covering your head with your arms. Do not go under an overpass; the bridge could collapse or become a wind tunnel with flying debris.

Make a plan

You and your family can create an emergency plan with very little effort. An emergency plan can be vital, because you may not be together when a disaster strikes. It is important to plan in advance how to get to a safe place, how you will meet up together, and how your family will react based on the situation. Your emergency plan should include strategies to keep yourself and your family connected and informed before, during and after an emergency, as well as arrangements for keeping safe. All members of your household should know what to do in an emergency. See the resource list below for some ideas to get started.

Be weather-aware

It's important to check daily weather forecasts and plan accordingly. Know your location at all times. That means, knowing when you've crossed a city border or a county line, so you'll know when you've moved from one weather warning area to another. Understand weather alerts, and the differences between an advisory (severe weather is possible in a few days), a watch (conditions are right for severe weather) and a warning (take cover now.)

One good tool is a NOAA weather radio. You can buy receivers at many retail outlets, including electronics, department, sporting goods, and boat and marine accessory stores and their catalogs. They can also be purchased via the Internet from online retailers or directly from manufacturers. There are many choices of receivers from a number of manufacturers with prices ranging $20 to $100. The price will depend upon its use, handheld or desktop, and its capabilities allowing residents to pick the receiver they find fit best.

Make a disaster supply kit

This is a collection of basic household items you may need in the event of an emergency. Try to assemble your kit well in advance of an emergency as you may need to evacuate at a moment's notice and take essentials with you. The following is a list of recommended basic supplies for your kit:

• Water, one gallon of water per person per day for at least three days, for drinking and sanitation
• Food, at least a three-day supply of non-perishable food
• NOAA Weather Radio with tone alert and extra batteries
• Flashlight and extra batteries
• First aid kit
• Whistle to signal for help
• Dust mask, to help filter contaminated air and plastic sheeting and duct tape to shelter-in-place
• Moist towelettes, garbage bags and plastic ties for personal sanitation
• Wrench or pliers to turn off utilities
• Can opener for food (if kit contains canned food)
• Local maps
• Cell phone with chargers
• A copy of your family emergency plan
• Copies of family documents (i.e., birth certificates, passports)

When emergency hits

Turn on your NOAA Weather Radio and/or a television for information. Follow instructions when advised to evacuate or shelter-in-place. If informed to shelter-in-place stay inside and close all windows and doors. Also, activate your personal/family emergency plan and locate your emergency kit.

Resources

• Plan for your risks
• Plan to protect yourself and your family
• Be ready in any location
• Family emergency plan (PDF)
• Family emergency communication plan wallet cards (PDF)

Hennepin County works with local, state and federal agencies to prepare for situations that could endanger public health, such as infectious diseases, bioterrorism and chemical spills. Learn more about public health emergency preparation.

Pipelines

Transmission pipelines carry large volumes of crude oil or petroleum or product at the bulk supply level. Hennepin County has 104 miles of gas transmission pipelines and 31 miles of liquid transmission pipelines. There are also hundreds of miles of gas distribution main lines and service lines that bring gas to homes and businesses. Since 2002, Hennepin County has had eight significant incidents involving pipelines, resulting in four injuries. Hennepin County is at a greater risk for pipeline incidents than the much of the rest of Minnesota, due to its concentration of these lines.

Aviation

Hennepin County is at a higher risk of significant aviation incidents due to both the number of aircraft operations conducted as well as the higher risk flight modes of approach and departure occurring in the vicinity of the three airports.

Minneapolis-Saint Paul International Airport is the 17th busiest airport in the US with 425,332 takeoffs and landings in 2012.

Flying Cloud (FCM) and Minneapolis Crystal Airport (MIC) are busy general aviation airports also located in Hennepin County.

Energy hazards

Nuclear

The Monticello Nuclear Generating Plant is located 13 miles northwest of Hennepin County borders, and the Prairie Island Nuclear Generating Plant is located 31 miles to the southeast of the county line. Hennepin County is included in the Ingestion Pathway Zone extending 50 miles from both plants.

Hydropower

Hennepin County has three hydropower facilities. A 12-megawatt generator is located at St. Anthony Falls; a 14.4 Megawatt generator is located at Lock and Dam No.1; and a 8.9 Megawatt generator is at the Lower St. Anthony Falls Lock and Dam. Years ago, power was generated at the Coon Rapids Dam at Brooklyn Park, but operations were suspended in 1966 and the dam was donated to the Three Rivers Park District.

Security threats are any incident or action taken by adversarial or criminal elements that threatens public safety and security.

Specific attack methods range from sabotage and cyber attacks, to the use of firearms and explosives, to unconventional attacks using chemical, biological, radiological and even nuclear weapons.

Minnesota and Hennepin County have had past incidents that were tied to both international and domestic terrorism organizations or provided support to the aims of these groups.

The Twin Cities has a similar general risk of security threats or attacks, as does any other major U.S. metropolitan area. Law enforcement and security agencies at all levels are responsible to define, detect and defend against security threats, as led by the Federal Bureau of Investigation.

Earthquake

An earthquake is the sudden release of energy from the Earth’s crust which results in seismic waves that can be destructive. Most earthquakes are associated with particularly active regions of the Earth where huge plates contact each other.

Hennepin County is far from these active regions and is in a relatively stable area of middle North America. However, earthquakes have struck Minnesota and will almost certainly continue to do so in the future. The closest earthquake epicenters to Hennepin County were in Cottage Grove in 1981 (measured 3.6 Richter scale) and in New Prague in 1860 (estimated 4.7 Richter scale). Hennepin County has a much lower risk of earthquakes than most of the rest of the United States.

Landslides

Landslides include any downslope fall or slide of rocks or soils. Changes in local conditions, such as heavy rains or the removal of plant cover can help trigger landslides. Hennepin County is vulnerable to rock falls, along the Mississippi River gorge from Minneapolis south to Fort Snelling. However, light human activity reduces the consequences.

The highest risk of slope failures in Hennepin County is along the steep north valley wall of the Minnesota River Valley in Eden Prairie and Bloomington. Overall, risks of landslides in Hennepin County are low.

Learn more about landslides within Hennepin County.

Sinkholes

Sinkholes form in land that is underlaid by carbonate rock that is dissolving as ground water moves through it or when acidic water moves downward from the surface. Cavities develop in the rock and expand through this process. When the cavity is located close to the surface, a collapse may occur. Another possible emergency is groundwater contamination from toxic compounds on the surface reaching bedrock through these water routes.

Areas where depth to bedrock is 50 feet or less are at the highest risk. In Hennepin County, sinkhole conditions exist in a band from near Crystal southward to the area of the International Airport. The risk of sinkholes developing in Hennepin County is generally low, compared to the more active sinkhole areas in southeastern Minnesota.