Severe Weather 4-4-23 and 4-5-23

[WxSynopsisDavid]

The one good thing here is we have a few fail modes being presented. In all honesty, that is digging for something positive right now because the current fail modes still yield a sizeable outbreak.

[WxSynopsisDavid]

Looking at the GFS, these are high end Supercell Composite values being we are 80hrs out. The size of the warm sector is unreal.

[bdgwx]

4 of the top 5 CIPS analogs were high risk days.

Edit: The other one was a moderate that produced 36 tornado reports.

[largetornado]

0z nam rolling in. Looks like a shift west

[Malacka11]

1 minute ago, largetornado said:

0z nam rolling in. Looks like a shift west

The NAM was massively west with yesterday too if I remember right no?

[WxSynopsisDavid]

1 minute ago, Malacka11 said:

The NAM was massively west with yesterday too if I remember right no?

Yeah, like i said earlier, the NAM suite has been off this storm season. It was horrible with the last 2 outbreaks and outperformed by the other models. Its doing the same thing, like you said, it did with yesterdays outbreak.

[Radtechwxman]

Surprised at the SPC outlook. It was tamer than I imagined. Talked about possible moisture issues which I find odd because dew points look better imo than compared to Friday's setup. However, if we get deep mixing could see some issues. They mentioned moisture depth could be shallower. Also mentioned capping concerns and absence of lift. I think there will be ample forcing to overcome that imo. 

[Powerball]

Based on the Day 4 SPC outlook for MI/OH/IN, this thread should be expanded to 4/5.

[cheese007]

13 minutes ago, Powerball said:

Based on the Day 4 SPC outlook for MI/OH/IN, this thread should be expanded to 4/5.

Wild how fast threats surrounding the 4th have escalated

[largetornado]

MUCAPE of 4500 per nam 3k at 18z tuesday. Lmao

[andyhb]

5 hours ago, Powerball said:

Based on the Day 4 SPC outlook for MI/OH/IN, this thread should be expanded to 4/5.

Wednesday has potential to be significant in the Lakes if there’s enough destabilization, 500 mb setup is consistent with some of the bigger early season events in the area.

[cyclone77]

The Euro has been very consistent in developing convection across northeast MO and the eastern 1/3 of IA mid-late afternoon for many consecutive runs.  This then moves across northern IL/southern WI during the evening.  This is all well out ahead of the cold front in the open warm sector.  Winds look to stay fairly backed, even well south of the warm front during the afternoon/evening.  Looks like a nice little mid-level speed max arrives by late afternoon per Euro.

[andyhb]

 

That is classic for a significant Great Lakes severe event. Timing/destabilization pending of course.

[MidwestChaser]

Izzi didn’t seem too impressed per the last AFD.


.

[andyhb]

4 minutes ago, MidwestChaser said:

Izzi didn’t seem too impressed per the last AFD.


.

Think this one is off timed for the Chicago area. Biggest threat is west on Tuesday, east on Wednesday.

[WxSynopsisDavid]

10 minutes ago, andyhb said:

 

That is classic for a significant Great Lakes severe event. Timing/destabilization pending of course.

There is a few noticeable trends I'm seeing leaning towards the prospective of a more significant threat. Previous NAM runs struggled to present any sort of mechanism to fire convection east of the dryline. NAM seems to be more vigorous with the surface low coming out of the southern plains and has it deepening to 988mb. The pivot of the low cutting north is timed right when the trough orients negative. Convection looks to fire around sunset or after along the dryline. Not liking the timing of that because it suggest bulk of convection holds off until near sunset when the cap is breached, when the LLJ cranks. Though there will be convection across the lakes on Tuesday, it looks as if this is becoming more of a Wednesday event.

[Paulie21]

FWIW the 21Z RAP is basically just last Friday lol. Stronger LLJ remains in W IL but the sfc flow is far better in E IA. Gonna be another split between everyone sitting in Galesburg vs Iowa City. Pick your poison. 

 

 

 

[Malacka11]

How are storm motions looking right now for this threat? Are they going to be as wack as Friday or even a little bit slower? I know people were saying that it was gonna be shit again for chasing but 

[WxSynopsisDavid]

5 minutes ago, Paulie21 said:

FWIW the 21Z RAP is basically just last Friday lol. Stronger LLJ remains in W IL but the sfc flow is far better in E IA. Gonna be another split between everyone sitting in Galesburg vs Iowa City. Pick your poison. 

 

 

 

Big tick upwards in parameters on the RAP. NAM seems to be trending to that scenario but still holds convection off until around sunset like the HRRR. This is a promising "potential" trend by the RAP.

[RCNYILWX]

Think this one is off timed for the Chicago area. Biggest threat is west on Tuesday, east on Wednesday.

*If* the cap breaks as the Euro is showing, the parameter space is high end. For those who recall the wind blown sig hail event on 4/7/20, it had CI pegged for that setup from 6 days out and locked in. It's recently been the most robust with the 500 mb short wave and speed max, enough for CI between 21z and 00z.

Because the cap is rather stout, I wouldn't lock in the Euro depiction playing out, but it's interesting that's it's latched onto that scenario. If I were drawing up the outlook for the DVN, LOT, MKX CWA border region and points east, would probably go 15% hatched hail, 15% wind and 2-5% tor. Conditional, but potentially higher end setup late Tuesday afternoon into Tuesday evening, in the 21-03z timeframe.

LCLs look a bit marginal for higher tornado probs, but warm front proximity suggests anything close to the front would have that potential if a couple storms go.

Edit: Added a gif showing the last several runs of ECMWF 6-hour lightning density valid 06z Wednesday.

Edit 2: Added 500 mb heights and vorticity loop from the last several ECMWF runs valid 00z Wednesday

[i was on a spring break ski trip last week, though I'll be around and working day shifts this week to add to the discussion. Last Friday was one of the few significant severe events in the LOT cwa that I've missed since I've been out here.]

[WxSynopsisDavid]

6 minutes ago, RCNYILWX said:

*If* the cap breaks as the Euro is showing, the parameter space is high end. For those who recall the wind blown sig hail event on 4/7/20, it had CI pegged for that setup from 6 days out and locked in. It's recently been the most robust with the 500 mb short wave and speed max, enough for CI between 21z and 00z.

Because the cap is rather stout, I wouldn't lock in the Euro depiction playing out, but it's interesting that's it's latched onto that scenario. If I were drawing up the outlook for the DVN, LOT, MKX CWA border region and points east, would probably go 15% hatched hail, 15% wind and 2-5% tor. Conditional, but potentially higher end setup late Tuesday afternoon into Tuesday evening, in the 21-03z timeframe.

LCLs look a bit marginal for higher tornado probs, but warm front proximity suggests anything close to the front would have that potential if a couple storms go.

[i was on a spring break ski trip last week, though I'll be around and working day shifts this week to add to the discussion. Last Friday was one of the few significant severe events in the LOT cwa that I've missed since I've been out here.]

 

Main issue the models been struggling with is the cap. Some models like the RAP now showing the cap being breached hours before sunset. EURO been showing this however. Others like the NAM and HRRR breach the cap at or just after sunset. Interesting to point out, both the EURO and RAP are different in how the cap breaches.

[frostfern]

So if I chase it's looking like Northern Illinois will be entirely after dark?     I can get to Iowa after spending Monday night somewhere well south of Chicago, but it will be a long drive back to Michigan once it's over.  Could be difficult driving in heavy rain too.  I have obligations Wednesday.  I will have to keep watching trends tomorrow morning.  If the initiation is going to trend later in the evening and farther west than Eastern Iowa I might just forget it.  

[WxSynopsisDavid]

Here's another potential thing to think about. The "fly in the ointment" was tonight's event when models started to show a much more significant event for today they backed off for Tuesday. Considering tonight's event underperformed, I wonder if the models will start to go back to a more high end solution for Tuesday with these capping issues and mixing/lcl issues resolved.

[RCNYILWX]

Main issue the models been struggling with is the cap. Some models like the RAP now showing the cap being breached hours before sunset. EURO been showing this however. Others like the NAM and HRRR breach the cap at or just after sunset. Interesting to point out, both the EURO and RAP are different in how the cap breaches.

I wouldn't necessarily call it struggling with the cap. It basically underscores the conditional nature of the threat with eastward extent in the late afternoon and early evening. There's good agreement on a fairly strong cap, but variance on whether there's a wave to break the cap. Without a short-wave, the convergence along the warm front alone likely wouldn't be enough to overcome the minimal forcing and height rises. We won't hit convective T with an EML that stout.

The fact the Euro has shown a short-wave and CI multiple runs in a row has my attention though.

[WxSynopsisDavid]

2 minutes ago, RCNYILWX said:

I wouldn't necessarily call it struggling with the cap. It basically underscores the conditional nature of the threat with eastward extent in the late afternoon and early evening. There's good agreement on a fairly strong cap, but variance on whether there's a wave to break the cap. Without a short-wave, the convergence along the warm front alone likely wouldn't be enough to overcome the minimal forcing and height rises. We won't hit convective T with an EML that stout.

The fact the Euro has shown a short-wave and CI multiple runs in a row has my attention though.

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I should of chose better terminology when I said struggling. My apologies, but yes I am in agreement with that. Correct me if I'm wrong but the more high-end, severe outbreaks we seen in years past always featured a short wave out ahead of the dryline, early day surface low or mcs, to help breach the cap and lay down boundaries to set off convection.

[largetornado]

HRRR isn’t shy

[WxSynopsisDavid]

Just now, largetornado said:

HRRR isn’t shy

That's a substantial trend higher with STP compared to previous runs. Seems like the CAM is having a better handle/grasp on Tuesday now that tonight's event is wrapping up.

[RCNYILWX]

I should of chose better terminology when I said struggling. My apologies, but yes I am in agreement with that. Correct me if I'm wrong but the more high-end, severe outbreaks we seen in years past always featured a short wave out ahead of the dryline, early day surface low or mcs, to help breach the cap and lay down boundaries to set off convection.

I had a feeling that's what you meant, but wanted to clarify for those following the discussion. It's definitely a colloquial thing to call variance in the guidance on capping issues "struggling".

Regarding your second point, I'd say that it's fair to say higher end events likely had a strong EML and therefore needed some sort of wave to help break the cap if the large scale synoptic forcing (such as height falls) was lacking.

I've brought up April 7, 2020 because of how that event hinged on the cap breaking and there was decided variance on whether the cap would break and coverage of storms.
SPC outlooks seemed to largely discount the ECMWF for that event interestingly enough.

While Tuesday is not similar synoptically to that 2020 event, time of year, strong EML, and consistency of the ECMWF depiction are interesting parallels.

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[andyhb]

HRRR has problems with LCL heights early in MO, highlighting the concern with mixing (although it tends to be too aggressive with that).

[WxSynopsisDavid]

6 minutes ago, RCNYILWX said:

I had a feeling that's what you meant, but wanted to clarify for those following the discussion. It's definitely a colloquial thing to call variance in the guidance on capping issues "struggling".

Regarding your second point, I'd say that it's fair to say higher end events likely had a strong EML and therefore needed some sort of wave to help break the cap if the large scale synoptic forcing (such as height falls) was lacking.

I've brought up April 7, 2020 because of how that event hinged on the cap breaking and there was decided variance on whether the cap would break and coverage of storms.
SPC outlooks seemed to largely discount the ECMWF for that event interestingly enough.

While Tuesday is not similar synoptically to that 2020 event, time of year, strong EML, and consistency of the ECMWF depiction are interesting parallels.

Sent from my SM-G998U using Tapatalk
 

Great analysis and comparison there. With the fail modes in place, April 7 2020 could be the floor. I still believe tonight's event was the "fly in the ointment" that caused the CAM to back off a tad with concerns to Tuesday. Interesting to note, the EURO stuck to the scenario and the RAP and now the HRRR are caving towards the EURO scenario. Will be interesting to see how tomorrow's convection impacts the environment for Tuesday.