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Hoosier

2017 Short/Medium Range Severe Thread

470 posts in this topic

Although not a proficient producer, I got a little lightning action on 11/5 while chasing the IN/OH EF-2.  I'm always game for some boomers.

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SPC shifted the marginal area north some especially for IN/W OH.

Quote

   Day 2 Convective Outlook 
   NWS Storm Prediction Center Norman OK
   1103 AM CST Fri Nov 17 2017

   Valid 181200Z - 191200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE MID
   MISSISSIPPI INTO THE OHIO VALLEY...

   ...SUMMARY...
   A few strong to severe storms capable of marginal hail or damaging
   wind gusts will be possible Saturday mainly over the Ohio Valley
   region.

   ...Synopsis...
   A strong shortwave trough will move from the Plains to the MS Valley
   during the day, with a deepening surface low moving from St. Louis
   to Lake Erie. A rapid increase of winds aloft will occur with a 100
   kt midlevel jet into the OH Valley by 00Z. A strong cold front will
   sweep eastward with southwesterly surface winds bringing a narrow
   plume of mid 50s to lower 60s dewpoints northward into IL and IN.
   Warm air advection in the low-levels will further be augmented by a
   50-60 kt low-level jet. Despite the favorable synoptic scale setup,
   instability will be minimal, with only a few marginally severe
   storms expected during the day.

   ...Mid MS into the OH Valleys...
   An area of mainly elevated thunderstorms is expected to occur early
   in the day, perhaps across eastern MO, and then developing eastward
   across IL and IN, with lift aided by warm air advection. Forecast
   soundings show sufficient instability for marginally severe hail.
   Other activity, perhaps surface based, will occur near the low, and
   southward along the cold front. The main detriment to a more
   substantial severe wind event appears to be the lack of heating,
   with weak low-level lapse rates. This should keep warm sector
   activity immediately along the front. Strong wind gusts will occur
   with the frontal passage, and some of this could be convectively
   enhanced.

   Farther south into TN, MS, and AL, instability will be even less,
   with a capping inversion preceding the front. Here too, some
   convectively augmented wind gusts will be possible during the
   afternoon and early evening.

   ..Jewell.. 11/17/2017

 

day2otlk_1730.gif

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Probably safe to have the broad marginal risk. One can envision a way this exceeds expectations (if a well organized line were to move through with that strong ambient flow and not much stability in the low levels) but it's such a fine line in these setups.

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I'm not extremely optimistic for surface based storms or a severe threat this far north, but can't help but get a bit excited about the potential for some training storms on the nose of the very strong LLJ.  With that said, models often seem to underdo the temps in the warm sector during the cold season when there's strong WAA, and some of the shorter range guidance suggests surface based instability and much less of an inversion as far north as I-70 or so in IN and OH, so it wouldn't surprise me if some areas see some damaging winds with any storms into central and southern IN and OH.  The HRRR also shows some modest rotating storms north of the warm front, so if the mid-level lapse rates aren't completely overturned the threat for some marginal hail could be there a little farther north...though I'm not extremely impressed looking at some of the forecast soundings north of the warm front.  

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1 minute ago, Indystorm said:

Also possible damage to the high school there in Frankfort on the east side.

I wasn't monitoring as it was happening but looking at that line, wonder if there was an embedded tor.

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6 minutes ago, Hoosier said:

I wasn't monitoring as it was happening but looking at that line, wonder if there was an embedded tor.

Reflectivity did look more cellular at the time, but I did not look at velocity.  Am more concerned in near term for se IL and sw IN with breaks in a QLCS line approaching the area.

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Looks like Frankfort will be surveyed tomorrow.  From the limited number of pics I saw, some of the damage characteristics were more typical of what you'd see in a tornado (projectile 2x4 through a car window, debris wrapped around power lines, etc.) but that stuff is not really conclusive so we'll see how they characterize it.

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The tornado in Indiana has not been added to this map for some reason, but all in all, it seems like the southern end of this (like TN/AL) overperformed the most.  

171118_rpts_filtered.gif.f72a79c5247d192a7ebb8e263b8b760c.gif

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