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Major Severe Weather Outbreak November 17


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Which is why I've been riding the frontal placement issues. Either could mean initiation over the metro, or just west.

 

Definitely.  Was just taking a closer look at the 4km NAM.  Looks like it's kicking off initiation right at noon from Dekalb down towards Peoria.  That would give the storms a full 1-2hrs to mature before impacting Chicago if that scenario pans out.  Definitely an interesting/somewhat scary situation for Chicago.

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^ The above map depicting a solid squall line is definitely misleading.  No way will we be seeing a solid line like that with so much shear in place.  I'm not seeing a big dump of cold air immediately following the front either, so undercutting of cold air doesn't seem to factor in.  Forcing is very strong of course, which may try to create more of a line eventually, but even then with so much shear in place the line will be full of "kinks" capable of producing tornadoes.

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Just doing a quick comparison between the 00z GFS and 00Z NAM, and even comparing to the 18Z runs, and not only am I thinking like several people in here that d1 severe may have to go slight risk in an area inside a line containing CID/ISW/GRB/ORD/SPI/STL,

 

but d2 may have to go from ISW to GRB, APN, CYVV, CYOW, ART, ELM, UNV, JST, HTS, JKL, BNA, MEM, ARG, RFD for the slight risk, and moderate risk (wind gusts) for an area contained by a line from EVV, IND, FWA, TOL, DTW, BAX, MBS, RQB, ETB, SPI, MWA. that's just my guess, I'm sure others here have differing opinions, and please feel free to make changes.

 

but if you don't want to go moderate risk for day 2, i could also see a 30% wind prob in place of the mod risk for day 2.

 

thoughts, with SPC coming out in ~ 2 hours with the new d1?

 

that's from my post in the great lakes/ohio valley forum.

 

any thoughts on the risk areas as I see them, as I delineated them (d1 being the 16th, d2 being the 17th)?

 

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So based on that top map St. Louis is in tornado 5 zone! Cool!

STP has advantages and disadvantages. I was in a mesoanalysis max of 5 STP in IA on October 4th and it stayed partly sunny. I think the greatest tornado threat here is further NE across IN and E IL.
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STP has advantages and disadvantages. I was in a mesoanalysis max of 5 STP in IA on October 4th and it stayed partly sunny. I think the greatest tornado threat here is further NE across IN and E IL.

 

Yet it also had a relative maxima in the area that got hit by 2 EF4s...

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STP has advantages and disadvantages. I was in a mesoanalysis max of 5 STP in IA on October 4th and it stayed partly sunny. I think the greatest tornado threat here is further NE across IN and E IL.

 

And up into southern MI.. Incredible set up to say the least.. Not much else to add as it has all been covered well by many here already.

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It will be key to refer to mesoanalyses helicity in terms of "now-casting". Here we're talking about a very broad area with tornado potential. In retrospect, 10/4 was a restively localized (yet powerful) tornado episode near the triple point. While there was an elongated area of high STP's, the greatest helicity was up near Wayne.

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Totally different setup, but since I started working at LOT in July 2010, this is the most legit looking widespread potential for the CWA since 4/10/11. Very concerned for this area because people here already are not prepared for tornadoes, then add to the mix that it's November.

Sent from my SCH-I535 using Tapatalk

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^ The above map depicting a solid squall line is definitely misleading.  No way will we be seeing a solid line like that with so much shear in place.  I'm not seeing a big dump of cold air immediately following the front either, so undercutting of cold air doesn't seem to factor in.  Forcing is very strong of course, which may try to create more of a line eventually, but even then with so much shear in place the line will be full of "kinks" capable of producing tornadoes.

 

So will we probably see scattered cellular activity along the cold front then (a.k.a. hit and miss type)?

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Totally different setup, but since I started working at LOT in July 2010, this is the most legit looking widespread potential for the CWA since 4/10/11. Very concerned for this area because people here already are not prepared for tornadoes, then add to the mix that it's November.

Sent from my SCH-I535

 

Someone mentioned that exact event to me earlier today.  As you know, the main focus with that one ended up being farther north.

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One more thing to add into the mix: given the time of year (fall, where water temps are relatively warm relative to land temps), and given the strong dynamics of this system, the effect of the lake breeze will not be as much as a factor. So that's not going to protect Chicago, if something were to go its way.

 

It's going to be zero factor with these kinds of low level winds.

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Totally different setup, but since I started working at LOT in July 2010, this is the most legit looking widespread potential for the CWA since 4/10/11. Very concerned for this area because people here already are not prepared for tornadoes, then add to the mix that it's November.

Sent from my SCH-I535

 

Someone mentioned that exact event to me earlier today.  As you know, the main focus with that one ended up being farther north.

Yup, and that's highly unlikely to happen this time. The 12z SPC WRF from the day before had a string of supercells moving through the Chicago area.

Sent from my SCH-I535 using Tapatalk

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