Thunderstorm activity is never uniform in coverage. The convective characteristics of thunderstorms make them inherently irregular and random. You might be surprised to learn that the spatial tendency of random is to cluster into blobs as opposed to uniform pattern over time.
Central Wisconsin, upper Michigan (mostly), and even Fargo North Dakota area have been absent of severe thunderstorms this spring. It's normal for southern and western areas to see severe weather before the rest of Wisconsin does. 2018 has been a strange year with late spring, then mid summer heat for Memorial Day weekend. As June arrives expect the trends above to change. June/July are peak season for severe weather statewide. We are trying to avoid complacency.
The last few days reminded me of last winter when all the snow went to the northwest and central Wisconsin missed out. The "days since last winter storm warning" map from March is very similar to the "days since severe storm" map (not shown) at this point with over 320 days since last severe warning for some counties in central Wisconsin. We all know how last winter ended. Perhaps it all comes at once? That's the type of scenario our team is preparing for.
Severe or Tornado warnings do not always equal severity level either with differing warning strategies between offices. The majority of Wisconsin storms have been marginally severe at best so far this year. The image below from May 29, 2018 shows where warnings were issued and where the storm reports (mostly sub-severe level) occurred. Most offices overwarn, some do not.
As you can see, not the best performance in this situation. Severe storms were occurring to the west in Minnesota with 3500 SBCAPE present in northwest Wisconsin so it was an easy mistake to make.
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