This week will bring a return to severe weather across portions of the Midwest and Great Lakes regions. It begins today with a "Slight Risk" of severe weather in North Dakota and Minnesota (yellow shade on map). Then, there is a much broader "Marginal Risk" for severe weather from Minnesota to South Dakota. That is the lowest severe weather risk category. Tuesday through Friday will feature a few boundaries setting up across the Midwest with several disturbances riding along them. Those will be the focal points of showers and storms throughout the week.
Figuring out exactly where these thunderstorm complexes develop and move is extremely difficult at this juncture beyond the likely thunderstorm threat late Tuesday night into Wednesday morning. However, if we do see storms roll through this week, there will be decent severe weather parameters in place to support strong or perhaps severe weather. This will get a little more in-depth to look at what meteorologists look for to determine if severe weather is a real threat. First, we look at wind energy aloft. Namely, the low-level jet, or the winds at the 850mb level in the atmosphere. They will be quite strong late Tuesday int Wednesday, which will help keep thunderstorms together as they track into the region from Minnesota and Iowa. Secondly, we analyze the instability, or energy, in the atmosphere. That is measured using CAPE (Convective Available Potential Energy). When sufficient CAPE is in place, thunderstorms essentially have "food" to feed off of and can maintain their strength and severity. Values by late Tuesday night will be quite supportive of stronger storms as they exceed 2,000-3,000 J/kg. Typically we look for CAPE values in excess of 500-1,000 J/kg for the
possibility of severe weather. Several other factors go into forecasting severe thunderstorms, and many are at least modestly conducive of supporting stronger storms. The radar may look something like this image late Tuesday night. You can see a complex of showers and storms working its way into the area between 3am and 10am Wednesday morning. Those storms do pose a severe weather threat, but the overall threat doesn't look extremely high locally. The zone of higher severe weather probabilities will exist to our northwest across Minnesota, Iowa,
and Wisconsin. That is where storms will likely fire initially on Tuesday evening, posing a damaging wind, hail, and tornado threat. By the time the storms make their way towards northern Illinois and southern Wisconsin, they will be decaying and weakening, which lowers our overall severe weather threat. It's something we will continue to monitor!
Figuring out exactly where these thunderstorm complexes develop and move is extremely difficult at this juncture beyond the likely thunderstorm threat late Tuesday night into Wednesday morning. However, if we do see storms roll through this week, there will be decent severe weather parameters in place to support strong or perhaps severe weather. This will get a little more in-depth to look at what meteorologists look for to determine if severe weather is a real threat. First, we look at wind energy aloft. Namely, the low-level jet, or the winds at the 850mb level in the atmosphere. They will be quite strong late Tuesday int Wednesday, which will help keep thunderstorms together as they track into the region from Minnesota and Iowa. Secondly, we analyze the instability, or energy, in the atmosphere. That is measured using CAPE (Convective Available Potential Energy). When sufficient CAPE is in place, thunderstorms essentially have "food" to feed off of and can maintain their strength and severity. Values by late Tuesday night will be quite supportive of stronger storms as they exceed 2,000-3,000 J/kg. Typically we look for CAPE values in excess of 500-1,000 J/kg for the 
possibility of severe weather. Several other factors go into forecasting severe thunderstorms, and many are at least modestly conducive of supporting stronger storms. The radar may look something like this image late Tuesday night. You can see a complex of showers and storms working its way into the area between 3am and 10am Wednesday morning. Those storms do pose a severe weather threat, but the overall threat doesn't look extremely high locally. The zone of higher severe weather probabilities will exist to our northwest across Minnesota, Iowa, 
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