“Warnings are just the beginning. We have to have public education. We have to have people understand what warnings are. What watches are.”Ron Morales, National Weather Service North Charleston
He brings up a great point so let’s break down the difference between a watch vs a warning! To do that, let’s head to the kitchen! To make some cookies!
The oven is preheated, I’ve got the cookie dough right here- all the ingredients and components to make cookies are right here, we just haven’t done it. This is our watch- the atmosphere is all set for severe storms to form, but they haven’t yet- so we have to be prepared. This does not mean that severe storms WILL occur- I could just as easily turn off the oven and put the dough in the fridge for another day, but it is likely- why would we stop if we came this far?
Once they’re in, and we can observe the cookies forming- we got our warning which means we have to immediately take action as we can observe cookies (or severe storms via radar).
According to Morales, these warnings come with at least an 80% confidence that severe weather is occurring- it doesn’t get to 100% until they get confirmation from damage reports. For our cookies- confirmation comes when we can finally try them.
That’s enough food analogies for now- as there is a difference how watches and warnings are issued.
Watches, both severe thunderstorm and tornado, are not issued by your local National Weather Service office- rather by the Storm Prediction Center in Norman, OK. The SPC watches areas for severe storm development on a national lev el, days before the event, and day of.
“They’ll propose a watch area. They will contact the local NWS offices in that area, a coordination will occur via a conference call, of which counties to keep in or add or take out,” Morales says.
Once that is finalized, the watch will go out. The NWS office is then able to adjust that watch as the day goes on- removing areas early as storms clear the area, or by canceling the watch early.
Until then, the local NWS office has their work cut out for them- determining which storms are or will become severe. This is not an easy task as they monitor storms, sometimes many, minute by minute- watching for signs and signals from radar. Once a decision is made- a rapid process begins to draw the warning polygon, include what hazards are in those storms- whether it’s severe wind gusts, large damaging hail, or a tornado, and push that out to everyone via the emergency alert service or EAS.
I hope this trip behind the scenes helped clear up any confusion with where these alerts come from and what they entail. However this is just the start, have some way to receive these alerts no matter where you are and have a plan in place to act quickly.
Storm Team 2 Meteorologist David Dickson