The Norman Forecast Office says the tornado potential is not equal in every one of the counties shaded in red. If storms develop, tornadoes are most likely to occur along and north of a line from Arnett to Fairview, to Enid to Ponca City in far northern Oklahoma.
"Areas south of that line, including most of the rest of watch, will likely see severe storms with large hail and damaging winds, but the tornado potential is lower, but not zero!" the NWS says on its Facebook page.
Forecasters say instability and wind shear are forecast to increase Sunday, leading to a "significant severe weather outbreak." But they also say the situation continues to develop, and the exact area where the most severe weather will hit is likely to change.