Severe weather is likely across Northwest Arkansas and the River Valley starting tomorrow afternoon, with damaging winds and tornadoes possible.
A huge dip in the jet stream, combined with a powerful low pressure system currently positioned in Arizona, will trigger thunderstorm development across Eastern OK and Western AR tomorrow. Strong wind shear ahead of the system will allow for some of the storms to be severe, though the amount of instability, or “thunderstorm fuel”, is still in question.
The latest Day 2 Convective Outlook by The Storm Prediction Center has a level three enhanced risk over southern portions of the River Valley, including Scott, Logan, Sebastian and Le Flore counties in our coverage area. A level two slight risk exists over the remaining counties in Northwest Arkansas, though future outlooks could increase the risk across these areas.
Currently, a medium risk of tornadoes exists across Le Flore, Sebastian and Scott counties in our coverage area, with the threat of significant tornadoes in southern portions of Le Flore county. For the rest of the coverage area, a low risk of tornadoes exists with the latest update. Extremely high wind shear ahead of the front will be the driving force for the tornado risk in this event. There are still questions about the northern extent of the instability, which may limit the tornado risk in Northwest Arkansas. Regardless, this is a very potent system that will have the potential to produce strong tornadoes during the mid-late afternoon hours tomorrow, especially if isolated storms form ahead of the main line. QLCS spin ups are also possible within the main line as it moves through the area tomorrow, which can produce tornadoes in a short period of time.
The greatest risk with this event will be the threat of damaging wind gusts as the main line of storms push through the area tomorrow evening. The latest outlook has a high risk of damaging winds in Scott, Logan, Sebastian and Le Flore counties. The remainder of the KNWA & FOX24 coverage area is under a medium risk at this time. Wind gusts could exceed 80 mph with the strongest storms embedded within the line.
In addition to tornadoes and damaging wind gusts, flash flooding will also be a concern, despite the fast moving nature of this system. Most of the coverage area is currently under a level two slight risk for flash floods tomorrow afternoon-evening. Rainfall totals of 1-3″ are likely across the area, with isolated totals up to 4″ wherever heavier rain bands set up. All of this rain will fall in a span of a few hours, so scattered flash floods are possible as the line of storms moves through Northwest Arkansas.
Showers and thunderstorms could develop as early as 4 PM tomorrow, with isolated supercells capable of all modes of severe weather possible. This is when the tornado risk will be greatest, as these storms will have the best chance to tap into the instability that will be in place. Large hail up to the size of quarters will also be a threat with these initial thunderstorms.
Later in the evening, the main line of thunderstorms will move into the area. The main severe risk with these storms will be damaging wind gusts, however, spin ups within the line are likely as significant wind shear will still be in place. The severe weather risk will gradually taper off once the leading edge of the line moves through the area around midnight, however, rain could continue into early Saturday morning. All of the rain will be well out of the area by Saturday afternoon, with the Razorback game looking dry and cool behind the front.
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