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June 22-23 Severe Weather Outbreak


Stebo

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Main cool front is just now entering western IA.  Plenty of destabilization taking place ahead of that.  The east/west OFB along I-80 is lifting north west of the eastern IA action, and is sort of losing it's definition.  Makes sense given the strong mixing taking place out that way.  Main storms will probably fire along the cool front later this afternoon around, or just after it crosses I-35.  Plenty of time for destabilization out ahead of that over southern WI/northern IL.  Will take far less time to re-destabilize due to the strong daytime LLJ accompanied by unaltered lapse rates waiting upstream.

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Little bit of a chaotic wind field in northern IL but southerly flow trying to reestablish

 

Feel like after the OFB washes out (if it does) that those southerly and SSE'ly winds will veer back to SSW/SW...

EDIT: Unless you brought that up talking about moisture return. In which case I see your point.

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It looks to me that the "main show" gets fired up in south-central to east-central Iowa later this afternoon. The upstream environment includes strong instability (3000-4000 J/kg MLCAPE), great theta-e advection and lies on the fringe of steep mid-level lapse rates. As mentioned, winds are locally backed near and just south of I-80 in the eastern half of Iowa. An outflow boundary is somewhere in the vicinity of I-80, roughly. Latest HRRR guidance supports thunderstorm development in the southeastern third of Iowa by mid to late afternoon, with the threat shifting east into northwestern Illinois.

 

There should be solid air-mass recovery across much of southern Iowa, barring some sort of premature convective explosion. Capping may help stop that from happening. I think if you want tornadoes, it will be in southeastern Iowa and may extend into northwestern Illinois. If the flow also remains at least somewhat backed, we may sustain supercells for several hours and see the threat of a strong tornado.

 

That's my thinking based off of the latest obs and trends.

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Well, if you look at the latest visible satellite loop is appears that clouds have been clearing gradually for a bit, and in the last 30 minutes or so at a bit of a faster clip... at least some clearing is occurring over SE IA and E IL attm with temps ranging in the upper 70's to low 80's across this area as well as C IL, and that should translate north and east some over the next hour or two.

Ceilings are coming up quick now. Still solid mid level clouds.

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Wouldn't sleep on areas generally south of GRR-Lansing-Flint in MI either. The MCS is becoming ill-defined on its southern flank and there should be at least decent destabilization through the afternoon, in addition to near-surface flow that might stay backed for longer.

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Wouldn't sleep on areas generally south of GRR-Lansing-Flint in MI either. The MCS is becoming ill-defined on its southern flank and there should be at least decent destabilization through the afternoon, in addition to near-surface flow that might stay backed for longer.

Kinematically, have to like that area on the nose of the right-front quadrant of the upper level jet.

post-533-0-34377000-1434997765_thumb.gif

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nice that expands pretty far south in to parts of N MO/W central IL

Capping and further displacement from the best upper level forcing is a concern down in this mentioned area, although strong instability and still favorable bulk shear are evident in the latest mesoanalysis.

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It looks to me that the "main show" gets fired up in south-central to east-central Iowa later this afternoon. The upstream environment includes strong instability (3000-4000 J/kg MLCAPE), great theta-e advection and lies on the fringe of steep mid-level lapse rates. As mentioned, winds are locally backed near and just south of I-80 in the eastern half of Iowa. An outflow boundary is somewhere in the vicinity of I-80, roughly. Latest HRRR guidance supports thunderstorm development in the southeastern third of Iowa by mid to late afternoon, with the threat shifting east into northwestern Illinois.

 

There should be solid air-mass recovery across much of southern Iowa, barring some sort of premature convective explosion. Capping may help stop that from happening. I think if you want tornadoes, it will be in southeastern Iowa and may extend into northwestern Illinois. If the flow also remains at least somewhat backed, we may sustain supercells for several hours and see the threat of a strong tornado.

 

That's my thinking based off of the latest obs and trends.

There already is air mass recovery and destabilization across S IA attm. SBCAPE of 2000-4000J/KG, MUCAPE 2000-3000J/KG... everything else is  on track and agreeable. S IA will only further destabilize, possibly to extreme levels.

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There already is air mass recovery and destabilization across S IA attm. SBCAPE of 2000-4000J/KG, MUCAPE 2000-3000J/KG... everything else is  on track and agreeable. S IA will only further destabilize, possibly to extreme levels.

Turning around quick from even just the prior hour's analysis. A good sign if you want severe in S IA.

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Sucks for the WI crew....  Yesterday's focus was up there, and it was sort of a shift south (as figured) and now nothin'....  sucks guys

 

But keep the Spotted Cow coming....

 

I guess wisconsinwx is going to find another hobby.

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It's almost full daylight in LaGrange.. ALEK appears to be a little incorrect in terms of the cover disappearing.

Not quite full daylight.  Still plenty of clouds, but markedly brighter than it was an hour ago.  

If anything happens this afternoon, I will be surprised.  The remaining showers that are sinking SE through the LOT CWA seem to be

taking on a more eastward shift, and there is a long tail of showers and storms all the back to east-central Iowa.  I don't think LOT CWA sees any clearing......but, then, that is just my opinion. 

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Not quite full daylight.  Still plenty of clouds, but markedly brighter than it was an hour ago.  

If anything happens this afternoon, I will be surprised.  The remaining showers that are sinking SE through the LOT CWA seem to be

taking on a more eastward shift, and there is a long tail of showers and storms all the back to east-central Iowa.  I don't think LOT CWA sees any clearing......but, then, that is just my opinion. 

I give it about 60-90 minutes - it is shifting S/SE ward.  I can see blue breaks in the distance from my office in the burbs

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