The Storm Prediction Center this afternoon has upgraded the severe outlook for the state. Much of southwest Iowa is now an enhanced risk of severe weather, with portions of northwest and central Iowa in a slight risk of severe weather.
Looking at the 3pm surface plot, dew points have risen into the mid to upper 60s across southwest and western Iowa. There are a few boundaries that are also in this area, which will help trigger storms later on this afternoon into evening.
Storms will form in northern Kansas and south central Nebraska by this afternoon. Storms initially will will be isolated, so this is where the greatest tornado potential will exist. This is where the Storm Prediction Center has outlined a 5% tornado risk. Southwest Iowa is in a 2% tornado risk this evening, but our tornado potential appears to be low.
This is because storms will begin to line out as the move to the east towards southwest Iowa. By the time they enter into southwest Iowa, the greatest risks will be large hail and damaging winds. However, it is still possible to get embedded tornadoes in a line of storms, so this is why the 2% tornado risk exists.
The models are also depicting an area of storms that will form in northeast Nebraska and southeast South Dakota, and these will slide off to the southeast. Because of these storms, this is why the Storm Prediction Center has shifted the slight risk to now include northwest and central Iowa.
Key timing on these storms will be after dark. Storms will not begin to enter into southwest Iowa until after 9pm. This line of storms will move to the east southeast tonight and will then clear out of the state by sunrise Friday. Once again to recap, the greatest severe weather potential for large hail and damaging winds will be west of interstate 35 and south of interstate 80. We will be here all night tracking the severe weather potential and will update you on any new developments.