Storm Prediction Center Moves The Severe Weather Risk Into Our Area!
The Storm Prediction Center has moved the severe weather risk into our area in their latest update. This is a sharp change from what we saw earlier, so I wanted to give you the latest info.
SPC Severe Weather Risk Today/Tonight
Earlier today, the slight risk was placed to our west and did not include any part of our area. In their latest update, they made a move that places our area now in the severe weather risk.
SPC Categorical Severe Weather Risk Today/Tonight
Notice the slight risk now includes our northwest counties including parts of Washington, Orange, Dubois, Lawrence, and Jackson counties in Indiana.
SPC Hail Risk Today/Tonight
Notice the hail threat is up to 15% in the northwest part of our area.
SPC Damaging Wind Risk Today/Tonight
Notice the slight risk area also includes at 15% chance of damaging winds.
SPC Tornado Risk Today/Tonight
Notice SPC has now placed the northwestern part of our area in a 5% chance of tornadoes.
Severe Weather Discussion
Let's jump right in and take a look at the parameters present this afternoon. Keep in mind we look for wind energy, instability, and forcing as necessary ingredients for organized severe weather.
I am going to run through this quickly so I can get you caught up quickly this afternoon. The latest data does show sufficient wind energy for severe weather and it has all week. This is the NAM computer model's forecast for "rotation" potential in storms this evening. Notice it has solid values for central IL through southern/central Indiana.
If wind energy alone was enough, then I would be concerned. We know that wind energy alone is not enough and we need fuel / instability to support organized severe weather. Here is the latest instability for our area and it quickly becomes obvious that there is nothing.
The question is can this instability increase? All the data says a definitive "no" including the latest update from the very reliable HRRR computer model. Notice the instability values by mid evening are only in southern IL and remain near zero in our area.
I can tell you that the forcing is really not good at all on this setup either. Let's put this all together.
My Thoughts On Our Severe Weather Risk Tonight
SPC made a bold move this afternoon to move the slight risk of severe weather into our area. They did this despite the fact that there is zero instability in our area and despite the fact that computer models forecast next to no instability. The wind energy is definitely supportive of organized severe weather and even isolated tornadoes, but the instability is nothing less than pathetic. On top of this, the forcing to generate storms in our area is not very strong at all with the front moving through on Saturday. Based on the latest data, I think forecasting an organized severe weather threat for our area just seems aggressive. If I was placing the slight risk, I would include central Illinois through west central Indiana. The window is rather narrow, but Illinois certainly should be under the slight risk. I think a few isolated tornadoes could occur in those areas. StormView3D shows this area has the best coverage of storms is only in Illinois right now.
AdvanceTrak shows the storms are more intense over Illinois, then weakening quickly as they move toward our area that has next to now instability. Keep in mind, the timestamp is on the top right part of each image.
The bottom line is the wind energy is actually supportive of severe weather this evening, but the instability is not even close. While I cannot rule out a rogue severe weather report in the northwest part of our area, it doesn't look like a widespread organized severe weather threat.
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