The upper air flow will quickly bring a stronger and deeper upper air trough across the region this afternoon and evening. Surface pressure has already started to fall to the west and southeast surface winds have backed across the area and will quickly bring low level moisture back into the region today. A surface area of low pressure is expected to develop across southwestern to near central OK with a cold front extending along the I-44 region by 4pm this afternoon. As the upper air trough draws near the region this afternoon, colder air aloft will begin to rapidly destabilize the atmosphere and storms will form. A few discrete thunderstorms may develop during the first hour of the event, but the upper air flow being nearly parallel to the surface boundary should result in a cluster or a line of thunderstorms moving southeast by later tonight. The tornado threat should be confined to the first hour or so of the event. The last few runs of the Hr3 do suggest some discrete cells developing near northern OK early this afternoon. As the front moves southeast, the updrafts may become elevated on the cool side of the boundary. This would tend to keep any severe threat to some hail and gusty winds directly along the boundary as the event unfolds during the evening hours. The rainfall rates could result in some localized drainage issues in low lying areas.
National Weather Service Flash Flood Watch for Craig, Delaware, Mayes, Nowata, Ottawa and Rogers counties from Wednesday afternoon until Thursday morning.The upper trough should clear the state by 1 am to 6 am Thursday morning from the northwest to southeast. This should cause the precipitation to end from the northwest to southeast by 4 am to 7 am Thursday morning, if not sooner. Only the NAM has hinted at a slower clearing process, and I'll not include this in the Thursday forecast.