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March 15/16 Severe Wx


kystormspotter

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Somebody...maybe IND...used to mention that as a general rule, you need at least 24 and preferably 36 hours to get 60 degree dews from the area they are now into our area.  If that were to hold, it would make it tough for the NAM output to verify.  If I had to bet on it, I'd go lower than the NAM, but I do think there's a good chance we will get 60 degree dewpoints into part of the risk area. 

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12z ECMWF continues to be farther south with the surface low and thus the focus of the threat area, but fwiw max dewpoints on this run did increase a few degrees vs. 00z run. Upper 50s dewpoints get to Galesburg to Lacon to just south of PNT.

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EURO gets a tongue of 55° dewpoints up to De Kalb, but that's it. 60s stay south of I-70.

CAPE values fail to crack 1000 north of I-70.

 

It's highlighting west central IL for severe weather and then dying back as you go into the night. and towards eastern IN.

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Yeah the Euro seems to have a good handle on dews currently.  NAM is definitely looking overdone, which isn't surprising.  Question is whether 57-59 dews will be enough for tornadic potiential?  Hail threat still looks really good of course.  Thinking the upper 50 dews should be good for a few tors, but maybe not as many as what could have been if the NAM was correct.  

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12z ECMWF continues to be farther south with the surface low and thus the focus of the threat area, but fwiw max dewpoints on this run did increase a few degrees vs. 00z run. Upper 50s dewpoints get to Galesburg to Lacon to just south of PNT.

Sent from my SM-G900V using Tapatalk

 

 

Surface low deepens pretty fast on there, especially later tomorrow.

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Yeah the Euro seems to have a good handle on dews currently.  NAM is definitely looking overdone, which isn't surprising.  Question is whether 57-59 dews will be enough for tornadic potiential?  Hail threat still looks really good of course.  Thinking the upper 50 dews should be good for a few tors, but maybe not as many as what could have been if the NAM was correct.  

 

 

I agree that upper 50s dewpoints should be good enough for some tors...steep lapse rates will help instability values and temps don't look to get out of hand and result in high LCLs.

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I agree that upper 50s dewpoints should be good enough for some tors...steep lapse rates will help instability values and temps don't look to get out of hand and result in high LCLs.

 

Yeah that's a key right there.  Upper 50s should be okay given that temps shouldn't be well into the 70s, at least further north.  There should hopefully be a sweet spot somewhere over north-central IL where LCLs are low enough, and instability is just enough.  Better SRH up in that area as well.  We also have that fairly strong vort rolling in from upstream at the base of that negative tilt axis which should also help.  

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Euro CAPE values at 21z, 00z, 03z

 

 

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attachicon.gif3.png

 

I think the Euro is a tad stingy on cape, as it has had a history of being that way.  Not sure if it underestimates lapse rates or what, but for some reason it's usually a little low.  Not saying it won't be right in this case, but I'd bet there will be slightly higher cape than what's shown in the main instability axis.  Of course this is the brand new Euro, so who knows lol.  If I were a gambling man I'd wager we'll see a tongue of 1000-1500j/kg along the spine of IL by late afternoon/early evening.  

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Yeah that's a key right there.  Upper 50s should be okay given that temps shouldn't be well into the 70s, at least further north.  There should hopefully be a sweet spot somewhere over north-central IL where LCLs are low enough, and instability is just enough.  Better SRH up in that area as well.  We also have that fairly strong vort rolling in from upstream at the base of that negative tilt axis which should also help.  

 

Here's a NAM sounding south of RFD at 00z...using 62/59 and still manages to generate SBCAPE exceeding 1000.  I'm not so much focused on the precise location as I am in the environment...a 62/59 type environment could be good enough

 

 

post-14-0-15675500-1457984904_thumb.png

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Were you chasing?

What if anything did you witness?

Yes. A slowly rotating wall cloud went from KDAY to downtown Troy. I then went west of Covington, and had an awesome clearing. There was a rapidly rotating wall cloud ~8miles to my WSW. Produced multiple funnels and then a larger one that lasted about 30-45 seconds that was well below the tree line and was most likely on the ground.

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