Severe Weather Potential - July 9

A complicated forecast is in the works for the next 36 hours, and perhaps even longer, for Iowa and adjacent areas. A strong wave will initiate thunderstorms this afternoon across the western Dakotas and areas of Montana/Wyoming. These storms should develop into a large MCS, possible derecho, during the evening and overnight hours traversing the Dakotas and moving into western Minnesota by sunrise on Thursday. This MCS will likely be making a right turn throughout the night as the low level jet veers, making the projected path perhaps into northern Iowa between 6-10 AM tomorrow. While the severe weather threat would seem minimal, gusty winds nearing severe criteria is a definite possibility.

As this MCS clears, a stable layer will be left over and likely inhibit additional development until the later afternoon hours. With a cold front and strong disturbance coordinate to create sufficient lift to break and inhibition that will be present across northern Iowa and southern Minnesota. With wind fields increasing in strength throughout the lower and mid-levels, expect deep layer shear to be sufficient for supercells as the initial storm mode with damaging winds, large hail, and isoalted tornadoes all being possible. However, with time and more forcing along the cold front it would appear that the growth of another MCS is likely, yielding a damaging wind threat across the central portions of the state. More details into the forecast will be clear tomorrow morning when the extent of the morning MCS is known... Expect an additional update late tonight and early tomorrow as to the possibilities of severe weather across portions of Iowa.