MOBILE, Ala. (WKRG) – The National Weather Service (NWS) in Mobile talked to News 5’s Caroline Carithers about the Chickasaw tornado that occurred Friday and why it was not warned.
A confirmed EF-0 tornado touched down in Chickasaw last Friday. Viewers explained their frustrations that the NWS in Mobile did not issue a tornado warning for this storm.
The Lead Forecaster at the NWS Mobile, John Purdy, explains that forecasters look very closely at the pre-storm environment before severe weather is expected. In this particular instance, the parameters they look at, such as instability and wind shear, did not favor tornadic development. Purdy says the main threat for Friday was “straight line winds because the instability was high” and the wind shear was low.
John Purdy tells of the major challenges the Gulf Coast has with forecasting spin up tornadoes. With these, a lot of times, the tornado occurs between radar scans – every five minutes – and the forecasters do not see it in time to warn on it. This usually occurs with weaker tornadoes, which is what happened in Chickasaw on Friday. Purdy expresses that “by the time we get the warning out, it is gone.”
The NWS also tries not to over-warn viewers on these quick spin-up tornadoes. Purdy explains that if they did warn on every spin up, they could have ten tornado warnings per severe weather day and people would stop taking them seriously. He expresses that it is a delicate balance of over-warning spin up tornadoes and making sure the public takes stronger, life-threatening tornadoes very seriously.
After there is a report of tornado damage, the NWS goes out to survey it and informs the public how strong the tornado was and its track.
The NWS is in charge of issuing watches and warnings during severe weather, while TV stations portray that information to the public once it is issued.
For more on the interview, check out the video!