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May 15-20th Severe Weather Event

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Wednesday looks like the next decent shot at severe for a portion of the sub-forum.

 

Fairly conditional as it looks though, with several potential issues.

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1 hour ago, Chicago Storm said:

Wednesday looks like the next decent shot at severe for a portion of the sub-forum.

 

Fairly conditional as it looks though, with several potential issues.

Degree of destabilization being one.

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I'm certainly impressed with the intensity of the LLJ being forecast across the model suite for Wednesday (in addition to the surface low maintaining around 990 mb). Don't see broad 45-55+ kt LLJs in May very often during the daytime. Morning convection/leftover cloud cover is certainly going to be the biggest concern, although I get the feeling the dynamic support may be able to overcome some of that.

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SPC now has enhanced svr for southern WI and slight extending south to Chi town area.  Did not really expect this for this Monday in the Great Lakes.

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SPC now has enhanced svr for southern WI and slight extending south to Chi town area.  Did not really expect this for this Monday in the Great Lakes.


They're probably going a bit overboard given how things look.

Does look like some agreement on a small bowing MCS moving across N. IL/S. WI later this afternoon and even. Severe threat likely waning with eastward extent though.
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12 hours ago, andyhb said:

I'm certainly impressed with the intensity of the LLJ being forecast across the model suite for Wednesday (in addition to the surface low maintaining around 990 mb). Don't see broad 45-55+ kt LLJs in May very often during the daytime. Morning convection/leftover cloud cover is certainly going to be the biggest concern, although I get the feeling the dynamic support may be able to overcome some of that.

Sort of interesting how the trough is progged to evolve from more of a negative tilt to a positive tilt over time.  Actually, that 500 mb look with broad troughing and sort of a "hangback" feature in the west has caused trouble in this region before.

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7 hours ago, Hoosier said:

Sort of interesting how the trough is progged to evolve from more of a negative tilt to a positive tilt over time.  Actually, that 500 mb look with broad troughing and sort of a "hangback" feature in the west has caused trouble in this region before.

Still trying to understand how on Earth there is not at least a marginal risk out for Wednesday.

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21 minutes ago, andyhb said:

Still trying to understand how on Earth there is not at least a marginal risk out for Wednesday.

Yeah, that is surprising.  Marginal is not much of a bar to reach even with the various uncertainties.  

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You are right. I was focusing so much on tomorrow, I didn't think much about Wednesday. The 18z 3km NAM nearly has a string of pearls of supercells in NW Missouri Wednesday. Northern Missouri to southern Iowa may be an area of significant severe weather.

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Yeah, that is surprising.  Marginal is not much of a bar to reach even with the various uncertainties.  



That's exactly what I was thinking upon seeing the outlook. Pattern recognition alone and pretty decent consistency on the guidance in the track, strength and timing of the synoptic system should enable one to outline a broad area where severe is possible and then fine tune it with subsequent outlooks once trends become more clear. To the less informed user, it appears severe storms are unlikely, whereas at the WFO level we've been mentioning the conditional severe potential for the past few days in AFDs.

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57 minutes ago, RCNYILWX said:

That's exactly what I was thinking upon seeing the outlook. Pattern recognition alone and pretty decent consistency on the guidance in the track, strength and timing of the synoptic system should enable one to outline a broad area where severe is possible and then fine tune it with subsequent outlooks once trends become more clear. To the less informed user, it appears severe storms are unlikely, whereas at the WFO level we've been mentioning the conditional severe potential for the past few days in AFDs.

00z NAM has a 90-100 kt H5 jet streak with this thing at 21z Wed. I can't recall the last time I saw that forecast in May with instability available.

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1 hour ago, RCNYILWX said:

 


That's exactly what I was thinking upon seeing the outlook. Pattern recognition alone and pretty decent consistency on the guidance in the track, strength and timing of the synoptic system should enable one to outline a broad area where severe is possible and then fine tune it with subsequent outlooks once trends become more clear. To the less informed user, it appears severe storms are unlikely, whereas at the WFO level we've been mentioning the conditional severe potential for the past few days in AFDs.

I was floored when I saw no marginal risk let alone a slight. I don't get the reasoning I mean even at conditional standpoint, a marginal would be valid.

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Should be a oozy of a light show here shortly.  Maybe we can pile up some hail. Frozen stuff from the sky is the only thing that really gets my severe attention

One of the Coolest spots in the MW by day, severe by night.

 

Best Climo

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Put your hard hats on from Saukville to UGN... Don't hear that often.

 

Initial wind gust arriving as i type.  Was weak.

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47 minutes ago, HillsdaleMIWeather said:

0Z NAM shows potential for some really violent storms on Wednesday. SPC really dropped the ball on the Day 3.

I actually wasn't really impressed with the NAM overall, but caveat is that I checked quickly. Would like to have more instability to play with in case the NAM is overdone. Anyway, we should be able to manage at least a marginal risk when the day 2 outlook comes out, heh.

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Ended up being a nice little wannabe severe storm.  That's how MKE does severe. These setups from that far out west normally don't deliver by the time they hit the lake shore.  Add in the time of day we're looking at, blah.  I will say this held together a little better than I thought.  

Now to go to sleep to the dripping of the rain through the trees and the low rumbles of the departing "storms"

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The MCS faded as it approached Lake Michigan. CAPE gradient fading with the eastward extent and increasing CIN both didn't help the cause, among other things.

Should note, the 3km NAM and HRRR did horribly today. The 3km didn't have the MCS on any runs today. The HRRR correctly showed how things would play out through the morning runs, then quickly backed off. Heck, several late afternoon runs had absolutely nothing, while the MCS was ongoing over N. IA.

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I am going to be flat out honest, they are really low balling Wednesday, I honestly do not agree with the weak risk being put out. I don't see what they are seeing on this one, every model is showing enough CAPE, good to great shear and convection initiating.

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12 minutes ago, Stebo said:

I am going to be flat out honest, they are really low balling Wednesday, I honestly do not agree with the weak risk being put out. I don't see what they are seeing on this one, every model is showing enough CAPE, good to great shear and convection initiating.

Both of the lowballing outlooks were issued by the same forecaster.

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20 minutes ago, Stebo said:

I am going to be flat out honest, they are really low balling Wednesday, I honestly do not agree with the weak risk being put out. I don't see what they are seeing on this one, every model is showing enough CAPE, good to great shear and convection initiating.

It's somewhat similar to that low-key event we had back on April 10.

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Just now, Powerball said:

It's somewhat similar to that low-key event we had back on April 10.

Yeah I just don't know about this one. Even their SREF tools say they should be slight risk at the very least.

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SPC i think will have Wednesday have an marginal over most Ohio valley with slight or enhanced in where marginal is now on the Day 2. I think there could couple tornadoes over an area. Maybe several isolated supercells

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Regarding Wednesday, I think a slight risk should cover much of the current marginal risk area, and pulled further south into C. MO as well.

I would not go higher than slight risk/30% probs though.

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RC made a good point in the morning discussion.  Given the low level moisture situation tomorrow, we're not going to want too much warming as it could result in relatively high temp/dewpoint spreads for any tornado threat.

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I'm hoping SPC is just a bit gunshy at this point and playing cautious.  Better to up the ante as we get closer than hyping and then retreating as has happened on a number of occasions in outlooks this calendar year across the nation,  some quite embarrassing.

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