Severe weather threat continues over northern Plains and Great Lakes region!
Thunderstorms are expected to be widespread over the northern half of the U.S. this afternoon into the evening, with all modes of severe weather possible. Extremely large hail and widespread damaging winds would appear to pose the greatest threat, but there is an increased threat for tornadoes in areas where low-level shear is maximized, and as long as any cells can remain relatively isolated. With that said, wind profiles for later this evening suggest that storms may organize into one or more Mesoscale Convective Systems, or, possibly even a derecho overnight, impacting an area from northern Iowa to lower Lake Michigan. The threat for extremely damaging winds will be greatest with any of these systems that are able to sustain themselves for any length of time, and will continue into tomorrow across lower Michigan and surrounding areas. (Of note, the 18z NAM shows what appears to be a derecho racing across Iowa later tonight and slamming into southern WI and Lake Michigan by early tomorrow morning...) Multiple rounds of severe weather will be possible for tomorrow over eastern Wisconsin, northern Illinois, Indiana and Ohio as well as Michigan, where the Storm Prediction Center has issued a rare Day-2 moderate risk for this region. After the possible derecho overnight, the area is expected to recover enough instability-wise for at least one more round of intense weather, again likely culminating with another strong MCS or derecho. Before that, though, the strong wind shear that will be in place over this area appears to be favorable for cells to remain discrete for at least a short time over lower Michigan tomorrow afternoon, and will pose a more significant threat for tornadoes. Tomorrow's weather set-up is of particular concern given the highly populated area which could be impacted. It's likely that at least several chasers will be streaming this event live both tonight and tomorrow, so as always be sure to check the
Live page for a look at what's happening in real-time.
http://www.tornadovideos.net/component/content/article/1-latest-news/1242-severe-weather-threat-continues-over-northern-plains-and-great-lakes-region
