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Tim from Springfield (IL)

March 26-28 Severe Threat

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Going to start a separate thread for the current end-of-week severe threats, especially what may be the big show in IL on Saturday (after the rare Day 3 afternoon update):

https://www.spc.noaa.gov/products/outlook/day3otlk.html

 

Also, the 2:49 CDT Day 1 now has a slight entering the STL Metro East area in IL, with a narrow hatched hail area from E KS to E MO:

https://www.spc.noaa.gov/products/outlook/day1otlk.html

 

Most of the sub is in Marginal for Day 2 at this time:

https://www.spc.noaa.gov/products/outlook/day2otlk.html

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Well, Tim, I'll bite to help get your thread started.  What with elevated hailers tonight, (St Louis talking about baseball size hail in mid MO along the I-70 corridor) and Friday and then a possible significant event on Saturday and a shelter in place warning I'm going to be spending my time watching models and radars the next two days.  Have to admit the SPC day 3 update spooked me a bit because of its rarity.  Have to admit that 93 degree reading in Tulsa earlier today also surprises me.

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The Northern IL Severe Weather blog's take on Saturday, including an interesting map:

https://nilsevereweather.weebly.com/blogs-weather-updates/severe-weather-threat-increasing-across-illinois-on-saturday-all-hazards-possible-nisw?fbclid=IwAR3Fl2HpqFhOeBgOlPMxSpq_jdqNQJaRwm5oWerPGRYns_cBgLWV7S-s_ag

The blogger also linked to the following SPC map image, including a radar image of long-tracked cells tracking straight northeast west and north of Peoria.  With a serious-looking long-tracked cell shown from west of Canton to LaSalle-Peru.  Plus some nasty cells over and just northeast of PIA:

Picture

 

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Regarding the 3 km NAM, I will eat my hat if it is 65-68˚ in the warm sector at 21z Saturday. Those temps look way too low.

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15 minutes ago, andyhb said:

Regarding the 3 km NAM, I will eat my hat if it is 65-68˚ in the warm sector at 21z Saturday. Those temps look way too low.

Lol all models are advertising here's to hoping dynamics will be able to compensate which appear impressive thus far.

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19 minutes ago, It's Always Sunny said:

Lol all models are advertising here's to hoping dynamics will be able to compensate which appear impressive thus far.

Advertising warmer?

Even the GFS has temps in the low-mid 70s at 21z Saturday. Would make a big difference thermo wise, especially with seasonably high levels of moisture. If we can get the LLJ to be at least SSW by go time, that will yield shear profiles more typical with significant tornado events in this region.

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Just now, andyhb said:

Advertising warmer?

Even the GFS has temps in the low-mid 70s at 21z Saturday. Would make a big difference thermo wise, especially with seasonably high levels of moisture. If we can get the LLJ to be at least SSW by go time, that will yield shear profiles more typical with significant tornado events in this region.

Advertising what you said above (mid-upper 60's) and yeah totally agree even a few degrees warmer can make such a difference.  Still got a couple days to see how temps trend.

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17 minutes ago, It's Always Sunny said:

Advertising what you said above (mid-upper 60's) and yeah totally agree even a few degrees warmer can make such a difference.  Still got a couple days to see how temps trend.

Every other model has temps above 70 over most of the IL warm sector at 21z.

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It won't be in the mid to upper 60s in the warm sector, hell the dews might be that high. 

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22 minutes ago, It's Always Sunny said:

Advertising what you said above (mid-upper 60's) and yeah totally agree even a few degrees warmer can make such a difference.  Still got a couple days to see how temps trend.

With mid-to-high 90s verifying in Oklahoma and Texas in the last couple of days, you really don't need to wait around to figure that it's going to be warmer than typical.

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Haven't looked at parameters yet but I am wondering about similarities between this set up for Sat, and the April 9, 2015 Rochelle-Fairdale IL EF-4.  Both had a positively tilted trough.

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17 minutes ago, Indystorm said:

Haven't looked at parameters yet but I am wondering about similarities between this set up for Sat, and the April 9, 2015 Rochelle-Fairdale IL EF-4.  Both had a positively tilted trough.

I was thinking that to. That day overall had veered sfc flow. I think that storm was a mesoscale accident. Hit an ofb from previous storms. Wf was well north of it. It was also in that sweet spot just se of a rapidly deepening sfc low

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1 minute ago, StormChaser4Life said:

I was thinking that to. That day overall had veered sfc flow. I think that storm was a mesoscale accident. Hit an ofb from previous storms. Wf was well north of it. It was also in that sweet spot just se of a rapidly deepening sfc low

Moisture pooling and locally backed winds are not a "mesoscale accident" lol

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11 minutes ago, Bob's Burgers said:

WRF firing up quite a few cells as well

0z WRF-ARW also fires up cells along the warm front in central Ohio as well, including a decent looking cell in the vicinity of the Columbus area around 20z Saturday.  While I do expect the main tornado threat to be in Illinois, if this verifies there might be severe thunderstorms (and perhaps tornadoes) further east as well, but the WRF-ARW is definitely an outlier here by showing storms along the warm front. 

I'm not sure what to think about comparisons with April 9, 2015 yet.  Some of the models showing broken cells in Illinois and a possible precipitation shield along the lower MS/OH valleys (eg. NAM) remind me of the radar returns on November 17, 2013, but that was a major tornado outbreak (though I think that precipitation shield, as it moved northeast, helped to reduce the severity of storms in the eastern half of the high-risk area in IN/W OH).   I do not wish to compare with 11/17/13 though since this does not seem to be that type of event.

There is a question of model accuracy though, given the reduction in commercial flights to take weather data that can be fed into the computer models.

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8 minutes ago, BrandonC_TX said:

There is a question of model accuracy though, given the reduction in commercial flights to take weather data that can be fed into the computer models.

I honestly thought most wx data came from wx balloons which were released but I have seen your concern raised elsewhere.

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I do think this setup has the potential to be pretty clean. Certainly cleaner than 11/17 ended up verifying as. This doesn't mean this setup is superior to 11/17(because it isnt) but as far as storms themselves go, I think they're gonna be more isolated. The only things I'm worried about from a setup perspective are the critical angles/linear hodographs(see below) and the fairly limited residence time storms will have on the axis of best parameters before flying out of the warm sector at light speed. Storms, especially those at the triple point, may only have 2 hours or so before they go stable. With all this being said, even some small modification to the 0-3km hodograph yields pretty big changes and a much higher caliber of a setup.

Whether or not this can be successfully chased remains to be seen.

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5ddb57fc4d5e2ff69451c674ede49660.png

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7 minutes ago, Indystorm said:

I honestly thought most wx data came from wx balloons which were released but I have seen your concern raised elsewhere.

Most weather data comes from satellites these days 

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1 hour ago, sdantwx said:

Moisture pooling and locally backed winds are not a "mesoscale accident" lol

Well I referenced it was it that sweet spot to se of sfc low so kind of inferring that. Lol. But pretty sure I read somewhere it interacted with an ofb as well

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Just now, StormChaser4Life said:

Well I referenced it was it that sweet spot to se of sfc low so kind of inferring that. Lol. But pretty sure I read somewhere it interacted with an ofb as well

Don't know about the Rochelle tornado but I do know that the Plainfield F5 tornado did interact with a lake outflow boundary as it moved se.

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23 minutes ago, Indystorm said:

Don't know about the Rochelle tornado but I do know that the Plainfield F5 tornado did interact with a lake outflow boundary as it moved se.

Not to get off topic but the parent sup that spawned the infamous Fairdale tor had nice rotation not too long after it initiated, and was cranking quite nicely aloft before it dropped the tor out near Ashton.  

The main sup that we chased that day started way out by Ottumwa, and followed it up to near Clinton when it finally produced.

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Moderate risk coming for eastern DVN, western LOT and northwest ILX CWA with day 2 outlook.

Sent from my SM-G965U using Tapatalk

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1 minute ago, RCNYILWX said:

Moderate risk coming for eastern DVN, western LOT and northwest ILX CWA with day 2 outlook.

Sent from my SM-G965U using Tapatalk
 

Thanks for the heads up.  I've been on frequent refresh for the last 10 mins or so.

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2 minutes ago, RCNYILWX said:

Moderate risk coming for eastern DVN, western LOT and northwest ILX CWA with day 2 outlook.

Sent from my SM-G965U using Tapatalk
 

Wow

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