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2015 Short Term Severe Weather Discussion


Hoosier

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If the NAM is to be believed, I think that southern Lower Michigan, northern Indiana and northwestern Ohio are going to be in the sweet spot. (SPC already hinted at upgrading this area to SLGT with the next Day 1 outlook) Best overlap of moderate instability and supercell-supportive shear in excess of 30 knots. On the nose of a 50-70 knot upper level jet and even though surface winds may only be S or even SSW, W to WNW flow at 500mb supports decent crossovers. Any additional localized backing in the wind fields would be helpful in ramping up the 0-1km SRH. 

 

Note that although winds backed to the SE tonight, all guidance has that shifting around toward the S by mid to late morning.

 

Minimal capping means storms have no problem firing, but hopefully the storm mode won't be as junky as Saturday night was. The 4km NAM simulated radar looks decent with several semi-discrete to discrete cells, but this should be taken with a grain of salt after today's convective evolution.

 

RGEM isn't too enthused, which is a little bit of a red flag, but we'll see.

 

I'll probably be taking my weekend (Sun/Mon) up north to give this setup a shot. 

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Although on the fringe of this sub, anyone care to explain theories on the huge bust today in IA/MN/KS? 10% TOR completely busted with 0 reports and all 3 watches with >95%, 90%, 80% 10+ wind reports busted with only 3 reports. Only a handful of hail reports in Kansas...I didn't follow the event today, was a strength-limiting cap the culprit? The shear and instability was certainly there.

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Although on the fringe of this sub, anyone care to explain theories on the huge bust today in IA/MN/KS? 10% TOR completely busted with 0 reports and all 3 watches with >95%, 90%, 80% 10+ wind reports busted with only 3 reports. Only a handful of hail reports in Kansas...I didn't follow the event today, was a strength-limiting cap the culprit? The shear and instability was certainly there.

Probably a lot of opinions and factors on this.

 

I believe that convective evolution was the most problematic. Storms were merging into lines left and right, but even the dominant line that the models had - there wasn't much room for discrete cells, really. Nothing out in front and just a cell or two on the tail end in southeastern Nebraska.

 

Further west, on the western fringe of the initial watches, a plume of higher mid-level temperatures kept capping in place.

 

Shear was decent, but the mesoanalysis was showing bulk shear hovering just around 30 knots for a lot of the area. Sure, SRHs were elevated into tor-favorability, but shear in terms of speed wasn't particularly impressive. Speaking of that, I also noted a lot of veering of the wind profiles, predominantly just ahead of the cold front and behind the front-end line that took charge.

 

Note that the HRRR was pretty close to being spot on with storm mode. It showed the setup going from nothing to a massive line of junk in a matter of 1-2 hours.

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Not expecting much but wouldn't be surprised to see a storm or two go tornado tomorrow where ever winds can locally back a bit more at the surface. Problem is the moisture/instability axis along the front looks like its gonna be pretty narrow, so it'll be a timing game to get it to coincide with the shear increase from the jet max moving through.

mxuphl_ne_f20.gif

mxuphl_ne_f23.gif

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If the NAM is to be believed, I think that southern Lower Michigan, northern Indiana and northwestern Ohio are going to be in the sweet spot. (SPC already hinted at upgrading this area to SLGT with the next Day 1 outlook) Best overlap of moderate instability and supercell-supportive shear in excess of 30 knots. On the nose of a 50-70 knot upper level jet and even though surface winds may only be S or even SSW, W to WNW flow at 500mb supports decent crossovers. Any additional localized backing in the wind fields would be helpful in ramping up the 0-1km SRH. 

 

Note that although winds backed to the SE tonight, all guidance has that shifting around toward the S by mid to late morning.

 

Minimal capping means storms have no problem firing, but hopefully the storm mode won't be as junky as Saturday night was. The 4km NAM simulated radar looks decent with several semi-discrete to discrete cells, but this should be taken with a grain of salt after today's convective evolution.

 

RGEM isn't too enthused, which is a little bit of a red flag, but we'll see.

 

I'll probably be taking my weekend (Sun/Mon) up north to give this setup a shot. 

 

As has been the case this entire season up this way, the problem will be the poor mid-level lapse rates.

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Nice round of crapvection moving into western MI. #bust

Sent from my GT-N8010

 

The activity over Lake Michigan is expected to morph into the "main show."

 

That (Lake Michigan) is about where you want activity to be at this time of day, especially when we have nearly full sunshine ahead of it.

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Zzzzz. I should check out mesoanalysis though.

Sent from my GT-N8010

Modestly backed low-level winds and 100-200 m2/s2 0-1km SRH across western lower Michigan. This should advect east and with lower LCLs, could support an isolated tornado.
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Modestly backed low-level winds and 100-200 m2/s2 0-1km SRH across western lower Michigan. This should advect east and with lower LCLs, could support an isolated tornado.

 

Still not impressed by the instability values to get too hyped up about the potential (even with the strong daytime heating).

 

The higher potential will probably exist in the Saginaw Valley (higher elevation / closer to better dynamics) and along the OH/IN border (closer to the higher moisture / instability values)

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The activity over Lake Michigan is expected to morph into the main show.

That's about where you want activity to be at this time of day, especially when we have nearly full sunshine.

Yeah, we definitely got some nice clearing ahead of the crapvection across SEMI and also imby.

Modestly backed low-level winds and 100-200 m2/s2 0-1km SRH across western lower Michigan. This should advect east and with lower LCLs, could support an isolated tornado.

Alright.

Sent from my GT-N8010 using Tapatalk

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