Weather Notification Systems

On the heels of the storm last night and more possibly expected tonight, we are sharing information regarding weather notification systems and sirens from the Delaware County Office of Homeland Security and Emergency Management. The Ostrander siren was repaired several years ago and was sounded last night.

  • Outdoor warning sirens are designed to be heard by people outdoors and are a signal that they should seek shelter indoors immediately. They are NOT designed to be heard inside buildings.
  • In Delaware County, there are a total of 16 outdoor warning sirens. Four of them have been built in the two state parks and are maintained by Delaware County Emergency Management Agency. The other 12 are owned and maintained by various local governments.
  • The sirens are activated when a decision to do so is made by the Delaware County EMA staff. They can also be activated by staff at the Delaware County 9-1-1 Center. Sirens are activated manually, NOT automatically.
  • When a decision is made to activate the sirens, all 16 of them are activated, even if they are activated in an area for which a warning has not been issued by the National Weather Service (NWS).
  • Outdoor warning sirens and warnings from systems like DelCo Alerts, NOAA weather radio and even the ones you receive from TV stations do NOT work in sync. The alerts sent by the warning systems are generated automatically when the NWS sends out watches or warnings for severe weather.
  • A watch generally affects a larger area than a warning. A watch means conditions are ripe for a severe weather event to occur. A warning means a severe weather event is occurring. It is possible to receive a watch, but not a warning, even if a warning is issued for locations within Delaware County.
  • Both watch and warning alerts sent out automatically by these systems that are targeted at defined geographic areas called “polygons.” If you have opted to receive an email warning, you willalways receive an email for the address you have provided, no matter where you are physically located. If you have opted to receive a text warning, notification is based on the registered account address.
  • It is recommended that people rely on more than one source of information about severe weather. They can sign up for DelCo Alerts at  Local TV stations have online sign- up forms for their warning systems. People can purchase NOAA Weather Radios on Amazon or at big box stores like Walmart, Home Depot and Best Buy. They cost about $30 each.
  • A Delaware County tax-levy question in 2009 to fund the construction of a countywide outdoor warning siren system was defeated. It is therefore up to local jurisdictions (townships and municipalities) to fund, build and maintain outdoor warning sirens.
  • More information about outdoor warning sirens is available at (scroll down to the bottom of the page).
  • If a member of the public is experiencing a crisis during a severe weather event, they should call 9-1-1. If they have a question or comment that is not an emergency, they should wait until the event has passed and they can then contact Delaware County EMA at 740-833-2180 during normal business hours, Monday-Friday 8 a.m.-4:30 p.m.