2020 Short/Medium Range Severe Thread

[CheeselandSkies]

Clouds have come back in force this afternoon.

[Hoosier]

HRRR has consistently been less bullish than the 3 km NAM on westward extent of convective development.  

[Chicago Storm]

About as DOA as DOA can get.


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[Hoosier]

I don't use the Euro as much when we get into CAM range, but it does convect in WI/IL later.

[Indystorm]

80/66 at Lansing.  I'm going to be an optimist here and still follow SPC's afternoon slight outlook.  Severe meso parameters continue to increase and a cap of 10-12 at 700 mb can be breakable.  At least it's not thermonuclear.

[hlcater]

1 minute ago, Indystorm said:

80/66 at Lansing.  I'm going to be an optimist here and still follow SPC's afternoon slight outlook.  Severe meso parameters continue to increase and a cap of 10-12 at 700 mb can be breakable.  At least it's not thermonuclear.

I wish it was. At least then we wouldn’t be having this discussion.

[Chicago Storm]

80/66 at Lansing.  I'm going to be an optimist here and still follow SPC's afternoon slight outlook.  Severe meso parameters continue to increase and a cap of 10-12 at 700 mb can be breakable.  At least it's not thermonuclear.

10-15C at 700mb is just about as bad as it gets.

There will probably be some t’storms that develop, as cooling occurs aloft... But any severe threat will probably be confined to a small portion of WI/MI, and remain relatively minor.


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[hlcater]

Imagine wasting hodographs like these because 700mb temps are 2 degrees too warm.

[A-L-E-K]

Zzzz

[Indystorm]

From LOT's afternoon discussion with hours of concern from 7 to midnight central time..highlights what we have been discussing

Putting this altogether, a highly conditional severe thunderstorm
threat exists after 00Z/7pm through the evening hours roughly
around and north of the Kankakee river Valley westward toward
Peoria. The most significant limiting factor will be the ability
for incoming forcing to erode enough of the substantial low-level
cap currently in place. If sustained deep updrafts can develop,
the environment is favorable for semi-discrete linear segments
with embedded supercell structures capable of producing damaging
wind gusts and large hail. Additionally, a conditional QLCS
tornado/mesovortex threat exists within any convection given
impressively curved low-level hodographs producing effective SRH
values possibly to 500 m2/s2 early to mid- evening. Marginal low-
level CAPE values will be a major detriment to this potential,
with a low-level warm nose below 700 hPa limiting low-level vortex
stretching. Will still need to closely monitor the fine details
of the thermo environment this evening as a kinematic environment
like this that is highly supportive for tornadoes leaves some
concern.

[CheeselandSkies]

1 hour ago, hlcater said:

Imagine wasting hodographs like these because 700mb temps are 2 degrees too warm.

Plains chasers are used to it, as I said earlier it's usually the opposite problem in this neck of the woods because of our distance from the EML source region. Maddening, especially this year.

[Indystorm]

Wagons north according to SPC current meso discussion.

[Hoosier]

New LOT mesoscale disco is worth a read.  To summarize, considerable negatives with a highly conditional threat.  Better shot at convective development after 11 pm or so.

[Indystorm]

Convection blossoming in lower MI, especially just north of Grand Rapids......oh, well.... and SPC maintains slight risk tonight with a 5% tor risk smack dab over Chicago.

[Hoosier]

12 minutes ago, Indystorm said:

Convection blossoming in lower MI, especially just north of Grand Rapids......oh, well.... and SPC maintains slight risk tonight with a 5% tor risk smack dab over Chicago.

Personally I would have removed the 5%.  Could even make a case for removing the 2%... at least part of it.  Though the kinematic environment is very impressive and if anything can manage to be sfc based, it would have a shot to produce.

[Indystorm]

New SPC meso discussion indicates 40% chance of a svr t storm watch being issued for northern IL and Chicago.  700 mb cap is weakening in far northern IL.

[Hoosier]

Modest development underway in IL.

[Roger Smith]

Looking more severe as the front enters southwestern ON, could be some storm damage west of London and also around Cambridge ON recently based on radar, and the front is going to hit the Toronto area around 0500h to 0600h EDT. Came on looking for any reports, I guess it's sleep time there but people will be waking up to vigorous thunderstorms soon. 

[Powerball]

8 minutes ago, Roger Smith said:

Looking more severe as the front enters southwestern ON, could be some storm damage west of London and also around Cambridge ON recently based on radar, and the front is going to hit the Toronto area around 0500h to 0600h EDT. Came on looking for any reports, I guess it's sleep time there but people will be waking up to vigorous thunderstorms soon. 

Nothing severe here, although looking at the radar, the line of storms definitely exploded SW-ward like ripping off a band-aid.

[CheeselandSkies]

[Kitchener poster]

Nothing severe here. But the most spectacular light show of the year for us. 

[purduewx80]

Think there is at least a marginal risk for severe hail across the region overnight as the 850 warm front lifts into northern IL. Mid-level flow is strongest near and north of the IL/WI border. Lapse rates are steep and there is a decent amount of both directional and speed shear such that some transient supercell structures are probable. 12Z NAM for ORD valid at 09Z below:

 

[Hoosier]

2 hours ago, purduewx80 said:

Think there is at least a marginal risk for severe hail across the region overnight as the 850 warm front lifts into northern IL. Mid-level flow is strongest near and north of the IL/WI border. Lapse rates are steep and there is a decent amount of both directional and speed shear such that some transient supercell structures are probable. 12Z NAM for ORD valid at 09Z below:

 

Decent sounding there with a good amount of elevated CAPE.  A bit surprised that SPC doesn't have the 5% hail area extending farther north, but we'll see if that changes on the 1630z update.

[Chicago Storm]

Decent sounding there with a good amount of elevated CAPE.  A bit surprised that SPC doesn't have the 5% hail area extending farther north, but we'll see if that changes on the 1630z update.

Are you really surprised with them?


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[cyclone77]

30 minutes ago, Hoosier said:

Decent sounding there with a good amount of elevated CAPE.  A bit surprised that SPC doesn't have the 5% hail area extending farther north, but we'll see if that changes on the 1630z update.

Nope, copy and paste.

[Hoosier]

Hail area was expanded north on the new update, but only through the I-80 corridor.

[Hoosier]

5 minutes ago, cyclone77 said:

Nope, copy and paste.

It is about 25-30 miles farther north this way, but yeah, no change farther west.

[cyclone77]

4 hours ago, Hoosier said:

It is about 25-30 miles farther north this way, but yeah, no change farther west.

New guy came in at 20z and was like nah, and hacked 100 miles of the north section off out your way.  

[Hoosier]

4 minutes ago, cyclone77 said:

New guy came in at 20z and was like nah, and hacked 100 miles of the north section off out your way.  

Saw that.  Still seems like an environment that could support isolated severe criteria hail, but I can only put so much energy into discussing a 5% hail area.  

[Sydney Claridge]

Not even a 2% tornado risk today but yet we are currently seeing tornado warnings north of Columbus, OH.   This does include Franklin County, generally the northeastern part around New Albany.  It surprised me when I noticed said warnings.