The Johnston Brief
Iowa storms have a way of showing up right at dinnertime, and the first spring after you move here, that first siren is genuinely startling. So here is the whole thing in plain English: what the sirens mean, when they are just a test, how to get the warning on your phone, and where to actually go when it counts.
Do two things now, before the next storm: sign up for Polk County Alert Iowa at smart911.com (free warnings by text or call), and keep Wireless Emergency Alerts on for your phone. When a siren sounds and it is not the noon-on-the-first-Saturday test, go inside and get low. The sirens are for people caught outdoors; do not rely on hearing one from inside your house.
Johnston is in Polk County, so the town is covered by the Polk County outdoor warning siren system - the same countywide system as Des Moines, Ankeny, and the rest of the metro. It is an outdoor, all-hazards system, and it goes off for two things:
They sound in cycles of 3 to 5 minutes, then a break, repeated for as long as the warning is active. There is no all-clear siren, so silence does not mean it is over. When you hear them, act, then get your details from a weather app, local TV or radio, or a NOAA Weather Radio.
Polk County tests the whole siren system at noon on the first Saturday of every month, unless storms are expected that day (then they skip it). A siren at noon on the first Saturday is routine. A siren at any other time is not, so treat it as real.
Often no, and that is the piece worth burning into memory: the sirens are designed to warn people who are outside, at a ballfield, on the Trestle-to-Neal-Smith trails, in a parking lot. They were never meant to be heard clearly inside a modern, well-insulated house, especially over a TV or an AC unit, or while you are asleep. If your plan is "we'll hear the siren," you do not have a plan. Get the warning on your phone instead, so it reaches you indoors and overnight.
The Johnston Brief runs a free weekly email and a daily homepage update, and when a real severe-weather day is coming, we say so. Local, useful, no fear-mongering.
People mix these up constantly, and the difference is the whole ballgame:
The goal is to put as many walls between you and the outside as possible, on the lowest level:
Water is Johnston's other everyday risk. Beaver Creek winds through town, the Des Moines River and Saylorville Lake sit right along the north and west edges, and those heavy summer rain events flood low streets and underpasses fast. The rule that saves lives is simple: Turn Around, Don't Drown. It takes only a foot of moving water to float a car, and you cannot see whether the road under it has washed out. Never drive around a barricade or through a flooded street. When the reservoir is high, the Corps' releases raise the river downstream, so watch official gauges rather than eyeballing it.
When the National Weather Service issues a Tornado Warning for Polk County, or a Severe Thunderstorm Warning with winds of 70 mph or more. They cycle 3 to 5 minutes at a time through the warning, with no all-clear siren.
At noon on the first Saturday of each month, unless storms are expected that day. A test at that time is routine.
If it is not the scheduled test, go indoors, get to a basement or the lowest interior room away from windows, and check a weather app, local media, or NOAA Weather Radio. The sirens are for people outdoors, so do not wait to hear one from inside.
Register for Polk County Alert Iowa at smart911.com (free, by text or call), keep Wireless Emergency Alerts on for your phone, and consider a NOAA Weather Radio for overnight storms.
No. Polk County does not sound an all-clear. The sirens may cycle on and off during a warning, so silence does not mean the danger has passed. Wait for the National Weather Service to cancel or let the warning expire, and confirm on a weather app, local media, or NOAA Weather Radio before you come out.
Go to the lowest floor and get into a small interior room with no windows, such as a bathroom, closet, or center hallway, putting as many walls between you and the outside as possible. Cover up with a mattress, cushions, or a bike or sports helmet. If you live in a mobile or manufactured home, leave before the storm and get to a sturdy building.