Multiple tornadoes touched down in southwest Wisconsin on Tuesday and early estimates suggest there could be more than 4 weak twisters. The National Weather Service will be out surveying the damage today after which we will have more details. This post is mostly about the meteorology of the event.
Here are some observations:
1. Tornado/funnel clouds Only
There was one Severe Thunderstorm Warning near Beloit where models had been forecasting the strongest storm would occur. I find it interesting that the Wisconsin, Iowa, northern Illinois region was dominated by tornado and funnel cloud reports with no other severe weather of note (Heavy Rain
is not considered in the same context). This contrasts with the severe weather event across Missouri and Kentucky where watches were issued, severe wind gusts were present, and spatial coverage was far better.
This lines up with my statement on the forecast that morning where I suggested "...weak tornadoes are possible and could actually be the most common form of severe weather today". That's a tough message to convey.
This fact demonstrates that tornadoes can occur in average thunderstorms. They can occur without watch, warning, or SPC outlook (the SPC did pretty good with this event). Tornadoes are localized phenomenon so the overall widespread impact is very narrow & concentrated. I felt communication of the event before it happened was right on target. I'm questioning the warning strategy of the event.
2. Unwarned Tornadoes
These were spotter confirmed tornadoes. The trend with Milwaukee NWS specifically has been not toissue tornado warnings for spotter confirmed, active tornadoes. They were criticized for this for the June 16, 2018 tornado. I understand the statistics of reducing false detection rates. The strategy is disconnected from the purpose of the NWS, to warn the public. If you are going to stop warning tornadoes at least tell us why.
Tornado is happening now. Warn people!
It's a bad look. The after-taste sucks. Storm chasers and spotters (who are critical to the warning process) now have reason to question whether to report severe weather? I know the NWS is confident in their radar technology. I wonder if they are getting ready to ditch spotters all together? I wonder how the general public feels knowing they can't count on the NWS, especially after neighbors tornado reports are ignored? These are the type of questions this strategy creates and all for a few percentage points?
The NWS warned storms further east near Blanchardville and New Glarus closer to the radar, still awaiting official tornado confirmation of the New Glarus storm. What changed between the Grant county tornadoes and this? The radar scan height? Listen to spotters. Do your job. "Easy for you to say, you try warning storms for a day!" Yes please! Email me. I am waiting.
3. Ambient Rotation and Veered Wind Profile
The 18ZRAP sounding from the tornado area yesterday is interesting. From 850mb up wind flow was unidirectional (according to the sounding). 850mb and below was heavily veered. Thermodynamics were average at best but balanced well with shear magnitudes. The setup overall was well balanced.
In addition to directional wind shear, I always look at the synoptic (ambient) rotation. The sounding suggests unidirectional flow, but this image shows 850mb wind pattern but from top to bottom was a carousel. Plenty of energy that can be focused into the lower 0-1KM for tornadoes. It's rare to see this setup in summer especially at upper levels. Pretty effective tornado producer I guess.
4. CIPS Analog Similarities
Tuesday for the most part was unique historically. The June 22, 2010 Eagle Tornado was a close analog. We knew this coming in but wasn't exactly sure how things would play out seeing that this event was not as clear as the 2010 event. The bulk of severe weather stayed south like CIPS suggested. It were the details that mattered most and if you weren't looking for them, you would have dismissed this one all-together.
It was an otherwise uneventful day across Wisconsin as shown by the 24 GIF loop.
With what we've learned today, we will be better prepared for future events of this character!
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