Weather Update: Severe Weather Likely Today for Parts of Midwest

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Here is the update for today’s severe weather risk (check out yesterday’s post to see what has evolved). The risk area has shifted a bit, but many large population centers will still be under the gun later this afternoon, evening and into the overnight hours.

First, lets look at the general overview of today’s setup and who has the largest risk. This is the Storm Prediction Center forecast.
-An ENHANCED RISK of Severe Weather is in place south of the Twin Cities area (many southern suburbs) and stretches to the lakeshore in Wisconsin. A sliver of Northern Iowa is also in this risk area (photo below will show cities)
-A SLIGHT RISK of Severe Weather is in place surrounding the Enhanced Risk. This includes the Twin Cities, portions of Iowa, Nebraska & South Dakota. This also stretches into a large part of the Lower Peninsula of Michigan (with lakeshore communities and Grand Rapids being in the risk area). The farthest south extent of this risk approaches the I-94 corridor, with the Kalamazoo/Battle Creek/Portage Metro areas being the farthest south the risk area goes).
-A MARGINAL RISK for severe weather surrounds the slight and stretches from a large majority of the Northern Plains all the way to Central Pennsylvania. This risk area includes South Bend, the Northern Chicago Suburbs, Toledo, Detroit, Omaha and Pittsburgh.

The largest threat, as seen above, will be in the enhanced risk area, which is where the majority of the storms will initiate (Southern Minnesota, with the possibility that some initiation could occur farther west in southeast South Dakota). A very unstable air mass (with large surface based CAPE (Convective Available Potential Energy) values in place) will be in place across this area. A progressive low-amplitude shortwave trough is north along the Canadian Border and very near Lake Superior. This will help influence the development in this area and will also help with progression to the East-Southeast. The action will form ahead of a cold front that will be diving Southeast. Deep-layer winds and vertical shear will be maximized along and north of this front. Initiation in parts of Minnesota and Wisconsin will favor intense supercells that could contain large hail (possible 2 inches in diameter or larger). This will also be where the largest tornado threat will be (though, that threat isn’t as high as a wind/hail threat). These initial supercells, however, will have the possibility of producing tornadoes. As the storms increase and begin to form clusters, they’ll affect areas of Iowa and Southern Wisconsin, with a large severe threat still in place as well as a tornado threat. This is when wind threat will begin to come into play. The storms will then begin to take on a more linear formation and race to the southeast, moving into parts of Southern Lower Michigan by late evening into the overnight hours. The highest risk here will be severe winds (just a few days after the anniversary of the 1998 Derecho that caused widespread destruction in portions of Southwest Lower Michigan). If the storms do bow out more, then expect the winds to intensify. Also, while the tornado threat isn’t high, keep an eye on the line and keep an ear open to your local NWS office. Brief but damaging tornadoes could spin up in portions of lines like these. These “kinks” really can rapidly rotate. Below is the treat for Hail, Wind & Tornadoes as per SPC.

Threat By Area:

Minnesota/Iowa/South Dakota into Eastern Wisconsin: Storms are already forming and intensifying as I type in portions of southern North Dakota, northeastern South Dakota and extreme western Minnesota. This activity will continue to build southeastward through the afternoon. Large hail will be the largest threat in this area, with a bit of a tornado threat and even possible damaging winds. Below is a graphic put together by the NWS Office in the Twin Cities that highlights the areas and threats.

Central Wisconsin: This is the area where the storms will really continue to build and intensify. The strongest storms will be along and south of Highway 29. While the NWS Green Bay graphic below highlights damaging winds & hail, I do not want the tornado threat to be downplayed, especially with initiating supercells (though shear parameters are definitely not favoring significant tornadic development). Hail & wind will be the primary threats though, and a flooding risk does exist (simply based off heavy rain in the thunderstorms).

Southern Wisconsin: This area will see very similar threats to that of the area just north. The graphic below from NWS Milwaukee will help explain it all.

Central and Southern Michigan: By the time the storms arrive in this area, they should already be congealed into a line. This will enhance the damaging wind threat (but still supporting a bit of a hail threat as well as a tornado threat in line kinks). But, we’ll stick with damaging winds in the bowing segments. Many people always believe that the lake will protect them, especially this time of the year with the cold pools in place. However, at this time with this system, we can rule out the lake helping to weaken the storms. Essentially, the convective activity will ride up and over this cold layer because it’ll already be too strong to be affected. It will maintain its intensity as it crosses the cold boundaries of the lake. In addition, lakeshore communities could see an enhanced risk from severe wind as the stroms slope off of the cold dome and come on-shore. The further east the storms move and as we move further from sunset into the overnight, the storms will begin to weaken as they slide southeast. This, of course, is all dependent on how much instability develops. Seeing as this area lies in the later evening area, instability is a major player. Temps and dew points are already climbing across the area and if they build further east, we could really see this line continue to affect even the Detroit/Toledo areas and as far south as Fort Wayne. Moving towards tomorrow, there is a chance that severe weather could form along and south of the I-94 corridor (including the Kalamazoo/Battle Creek/Portage areas). However, this main line of convection plus cloud cover in its wake could inhibit that. Nonetheless, it remains something we should watch. This will be an area really watched on my Twitter (make sure you give a follow for updates) simply due to the possible microscale changes that may have an effect on severe weather later (for better or for worse). Below is the risk graphic from the NWS Office out of the Grand Rapids.

Northern Illinois (including Downtown Chicago): Another area that will vary depending on how the heat and humidity picks up. Right now, the severe risk doesn’t appear that great tonight, but that could change. Tomorrow, the severe risk will shift south of the Chicagoland area. The risk graphic from NWS LOT (NWS Chicago/Romeoville) is included below.

As always, even the day of, threats and microscale changes can change just about anything. Significant updates will be posted BELOW my closing line below. In addition, my Twitter feed (www.twitter.com/universeofadv) will feature updates as well as any watches/major warnings issued. Check that out for a play-by-play.

Stay safe everyone and remember to have a way to get warnings…especially as we shift into the overnight. If you live in one of the areas listed, click the links I included for each area that will take you to your local National Weather Service office. Here is where you can see any warnings issued. I have also included their Twitter Links below.

NWS GRR (Grand Rapids) Twitter
NWS LOT (Chicago) Twitter
NWS GRB (Green Bay) Twitter
NWS MKX (Milwaukee) Twitter
NWS MPX (Twin Cities) Twitter

Follow along with me on Facebook as well to get post updates (www.facebook.com/universeofadventures) and Instagram is a good one too (though I am still building it – www.instagram.com/universeofadventures). Subscribe to the right and you’ll get notified whenever a new post goes up. No spam! Only notifications!

Until tomorrow, “When clouds appear like towers, the Earth is refreshed by frequent showers”

Adventure Brett (or Forecaster Brett?)

P.S. Outside of the severe weather threat, we really need to keep an eye on the HEAT in all of the mentioned areas above. Take heat precautions everyone. Temps will be in the upper 80s and lower 90s for a good majority of the area with high dew points (hence the risk for severe weather). Hydrate and take breaks inside in cooler air.