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

[WxSynopsisDavid]

9 minutes ago, andyhb said:

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

I remember leading up to this past Friday, the HRRR had a few runs where it did that early on but corrected within 18hrs to the start of convection. Also not the first time I've seen the HRRR do this, seems to be a typical bias of the model.

[brianc33710]

Check out some of these STPs. I thought the max was 20!

https://twitter.com/realStarInBox/status/1642715078809067521/photo/1

OK so this may or may not work.....

EDIT The link opens. I just couldn't share the photo itself.

EDIT 2: I had shared a hodograph using the above given STPs but didn't want to use someone else's work from another forum. So I deleted the follow up message.

[CheeselandSkies]

2 minutes ago, brianc33710 said:

This combines a hodagraph & the above given STPs.

Holy hell. Nearly 5,000 j/kg of SBCAPE in early April...and nearly 300 j/kg 3CAPE. This is just east of Iowa City. Continues to look highly likely I'll be retracing my steps from Friday.

[CheeselandSkies]

12 minutes ago, brianc33710 said:

Check out some of these STPs. I thought the max was 20!

https://twitter.com/realStarInBox/status/1642715078809067521/photo/1

OK so this may or may not work.....

EDIT The link opens. I just couldn't share the photo itself.

The max I do see is 20...right on the Mississippi near Le Claire, IA.

[cyclone77]

1 minute ago, CheeselandSkies said:

Holy hell. Nearly 5,000 j/kg of SBCAPE in early April...and nearly 300 j/kg 3CAPE. This is just east of Iowa City. Continues to look highly likely I'll be retracing my steps from Friday.

Around these parts it seems quite hard to get good synoptic setups without morning crapvection screwing things up.  Nice to see both last Friday's and Tuesday's setups free of that.  

 

[brianc33710]

6 minutes ago, CheeselandSkies said:

The max I do see is 20...right on the Mississippi near Le Claire, IA.

IF you look at the "max" in the bottom right corner it's 25.47. Look closely cause it's not on the picture itself. I just messaged you too. Please read it when you get a chance. 

[hlcater]

Concerned that the trough is too slow to eject and the prospect that the EML does not fully erode during daylight.

[Radtechwxman]

Definitely worried about a cap bust. Timing of wave isn't super ideal and not sure we will get a lead wave like Fri. If not then storms will probably be tied mostly to cf and fire late. Would be a shame to waste this pristine environment. Of course naturally when I'm off and can chase get a strong cap with nothing to break it and on Friday had to work at 7pm so had to chase local and couldn't go to Iowa and it goes nuts. Never fails. Obviously not hoping for destruction like we saw Fri. Don't need anymore lives lost or homes damaged but give me a nice tornado out in a field please. 

[largetornado]

NAM has some ridiculous 850 temps. In my untrained eye, NAM favors cap bust. Nam 3km points to a cap bust/nocturnal threat, as someone pointed out HRRR is trending towards mixing issues. 

[frostfern]

I'm thinking it might end up more localized.  The CAPE / shear combo is impressive, but if the warm sector is really that hot the greatest risk will be relegated to near the warm front.  It's still a scary setup as the potential for an EF3 or EF4 happening somewhere is still significant.  The southern zone over AR could be active again too.

[yoda]

 

 

[yoda]

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1203 AM CDT Mon Apr 03 2023

   Valid 041200Z - 051200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS LATE TUESDAY
   AFTERNOON AND EVENING ACROSS PARTS OF NORTHEASTERN MISSOURI INTO
   SOUTHEASTERN IOWA...NORTHWESTERN AND WEST CENTRAL ILLINOIS...

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   MODERATE RISK ACROSS MUCH OF NORTHERN MISSOURI....CENTRAL AND
   EASTERN IOWA...NORTHWESTERN AND CENTRAL ILLINOIS...AS WELL AS PARTS
   OF NORTHEASTERN TEXAS...SOUTHEASTERN OKLAHOMA...MUCH OF
   ARKANSAS...INTO SOUTHERN MISSOURI...

   ...SUMMARY...
   Severe thunderstorms appear likely to develop late Tuesday afternoon
   into Tuesday night across the lower Missouri Valley into southern
   portions of the Upper Midwest, and across parts of the southeastern
   Great Plains into portions of the Mid South.  These could pose a
   risk for a few strong tornadoes, large hail and damaging wind gusts.

   ...Synopsis...
   As initially amplified mid-level ridging over the mid-latitude
   eastern Pacific gradually becomes suppressed, models indicate that
   downstream troughing will broaden from the Great Basin into the
   Mississippi Valley.  This will be lead by a vigorous short wave
   trough, which is forecast to be accompanied by continuing strong
   surface cyclogenesis from the central Great Plains into the Upper
   Midwest, and building downstream mid-level ridging across the Upper
   Ohio Valley into Ontario, as well as across the northeastern Gulf of
   Mexico into Southeast.

   An intensifying southwesterly mid/upper jet streak (including speeds
   in excess of 100 kt at 500 mb) nosing across the central Great
   Plains through Upper Midwest will contribute to strong deep-layer
   shear within the warm sector of the cyclone.  At the same time,
   intensification of southerly lower-level flow (to 50-70+ kt around
   850 mb) likely will contribute to large clockwise-curved low-level
   hodographs.  This could potentially contribute to an environment
   conducive to supercells and organizing lines or clusters capable of
   producing strong tornadoes and damaging winds, where large-scale
   forcing for ascent and thermodynamic profiles can become favorable.

   However, among a number of substantive lingering uncertainties, the
   quality of the boundary-layer moisture return from the Gulf of
   Mexico remains in question.  Due to (at least initially) relatively
   shallow boundary-layer depth, downward mixing of drier air might
   impact sizable pockets of the potentially broad warm sector through
   the day, based on model output.  Also, ahead of the mid/upper
   troughing, destabilization associated with large-scale ascent and an
   influx of high-level moisture from the subtropical Pacific may
   contribute to convective development which tends to saturate and
   stabilize lapse rates down into the mid-levels, across much of the
   Ozark Plateau into middle Mississippi Valley.  While it appears that
   this will not completely erode the capping elevated mixed-layer air,
   thickening cloud cover aloft may inhibit surface heating and
   suppress potential thunderstorm development in the absence of lift
   to overcome the inhibition.

   ...Great Plains into the Mississippi Valley...
   Both the latest NAM and Rapid Refresh appear increasingly suggestive
   that the dryline could surge east-northeastward across southwestern
   Iowa and northwestern/west central Missouri, at least above the
   surface, by mid to late afternoon, in response to the progression of
   at least one speed maximum within the mid-level flow.  Model output
   generally indicates that largest CAPE will become focused ahead of
   this feature, and south of the warm front advancing northward across
   central Iowa/northern Illinois during the late afternoon.  And the
   dryline might provide a focus for sustained discrete supercell
   development with the potential to produce strong tornadoes while 
   propagating northeastward across northeastern Missouri and
   southeastern Iowa into northwestern and west central Illinois
   through early evening.

   In the wake of this activity, as the cold front begins to overtake
   the dryline and advance southeastward, various model output
   continues to suggest that the evolution of an organizing line or
   cluster of storms is possible.  This may pose a risk for large hail,
   damaging wind gusts, and perhaps a few tornadoes while propagating
   east-southeastward across the lower Missouri/middle Mississippi
   Valley vicinity into Tuesday night.

   Farther south, developments initially along the dryline and then
   ahead of the southeastward advancing cold front remain a bit more
   unclear.  However, there has been a persistent signal within the
   model output that a narrow corridor of more substantive
   boundary-layer moistening could provide a focus for enhanced severe
   weather potential by Tuesday evening.  It is possible that
   associated destabilization may become aligned with the strong
   deep-layer mean flow, possibly allowing for the evolution of one or
   two long track supercells, ahead of a developing squall line.

   ..Kerr.. 04/03/2023

[andyhb]

Remains a strong convective signal on the Euro roughly encompassing the current D2 MDT zone, in a highly favorable parameter space.

[Roger Smith]

Perhaps obvious but there seems to be high potential for this outbreak to continue most of the night 4th-5th across IL, IN, w OH and s MI, pause slightly and redevelop in OH-KY-TN on Wed 5th..It doesn't look a lot different from 4-4-74 to me.  (the dynamics with this one are somewhat further north)

[Jackstraw]

4 hours ago, Roger Smith said:

Perhaps obvious but there seems to be high potential for this outbreak to continue most of the night 4th-5th across IL, IN, w OH and s MI, pause slightly and redevelop in OH-KY-TN on Wed 5th..It doesn't look a lot different from 4-4-74 to me.  (the dynamics with this one are somewhat further north)

I respect your posts RS but the 74 Big Dog?  Oh my you have my ears definitely perked sir!

[KokomoWX]

1 hour ago, Jackstraw said:

I respect your posts RS but the 74 Big Dog?  Oh my you have my ears definitely perked sir!

That day started with an earthquake in Indiana and the local radio station (WILO-AM Frankfort) was talking about that and then boom!

[bdgwx]

CIPS analogs are not as bullish for this event as they were the last couple of days. And based on model runs yesterday and the first ones trickling in this morning (9Z SREF and 12Z HRRR) there seems to be a de-escalation of the severe threat tomorrow IMHO. There are some significant dewpoint depressions (> 12 C) in the current risk area especially in the southern part of it with only isolated elevated 0-3 km CAPE values. With the presence of a strong cap and weak forcing I don't think it is unreasonable at this point to argue in favor of the position that the convection may be sparse and isolated. I realize the severe risk of any hypothetical supercell that does manage to mature could be high, but just how many of them will there be? I have to be honest. I'm even questioning the moderate risk at this point. I'm not saying the SPC is wrong. I'm just starting to think a bit. I want to see if the 12Z ECMWF holds firm with it's more bullish signal on convection.

[purduewx80]

The deep layer of dry air that may cause LCL/capping/moisture issues is clearly evident on 12Z soundings over the Plains this morning, where Gulf return moisture looks great at first glance.

[Santa Clause]

Warm front is what to look at.

[largetornado]

1 hour ago, Wmsptwx said:

Warm front is what to look at.

Yep. Warm front or very close to the triple point. Unless some subtle forcing mechanism occurs in the warm sector, it looks like it will be capped. 

[Chicago916]

Very late day 2 convective outlook.

[sbnwx85]

Locally, it looks like we're going to be sitting on a powder keg tomorrow according to the HRRR...even this far to the east. But it doesn't look like there will be a match to set off the explosion. The RAP and NAM keep the squall line from coming through here until early Wednesday afternoon. That would be enough time to create enough instability to get some severe weather.

[CheeselandSkies]

17 minutes ago, Chicago916 said:

Very late day 2 convective outlook.

Out now...very interesting and rather ominous wording for both ends of the setup (southern one also upgraded to tornado-driven MDT).

[Malacka11]

How's the new Euro looking then? 

[brianc33710]

3 hours ago, bdgwx said:

CIPS analogs are not as bullish for this event as they were the last couple of days. And based on model runs yesterday and the first ones trickling in this morning (9Z SREF and 12Z HRRR) there seems to be a de-escalation of the severe threat tomorrow IMHO. There are some significant dewpoint depressions (> 12 C) in the current risk area especially in the southern part of it with only isolated elevated 0-3 km CAPE values. With the presence of a strong cap and weak forcing I don't think it is unreasonable at this point to argue in favor of the position that the convection may be sparse and isolated. I realize the severe risk of any hypothetical supercell that does manage to mature could be high, but just how many of them will there be? I have to be honest. I'm even questioning the moderate risk at this point. I'm not saying the SPC is wrong. I'm just starting to think a bit. I want to see if the 12Z ECMWF holds firm with it's more bullish signal on convection.

I remember at least 2 2022 severe weather events in AL that were expected to be fairly extensive, 3(E)-4(W)/5 threats. The models showed a warm & humid influx of air from the Gulf. While the warm air mass arrived the humidity didn't. We had 80s/30C temps with >50 mph/80 kmph wind gusts but dewpoints held in the low 50s/10s in Bham & not much higher in Tuscaloosa which is almost always more humid than Bham. Usually the baseline dewpoints here for severe weather weather is 55F/12.5C. As a result we actually had a number of wildfires because of downed powerlines in advance of the delayed rain. But instead of a tornado outbreak we had less severe straight line winds. The dewpoints finally reached 60F/15.5C when the rain arrived but not before. 

[hlcater]

3 hours ago, purduewx80 said:

The deep layer of dry air that may cause LCL/capping/moisture issues is clearly evident on 12Z soundings over the Plains this morning, where Gulf return moisture looks great at first glance.

The one thing making me feel better about that is that it was forecast.

[bdgwx]

12Z GFS isn't exactly what I'd call bullish with convection in SE IA, but it isn't devoid of it either.

The 12Z UKMET, OTOH, is actually pretty bullish with convection more so even than the 0Z cycle. 

And the 12Z ECMWF continues to be bullish in this region.

I think given that I can't justify an argument against a moderate risk in the IA/IL border area.

[largetornado]

19 minutes ago, bdgwx said:

12Z GFS isn't exactly what I'd call bullish with convection in SE IA, but it isn't devoid of it either.

The 12Z UKMET, OTOH, is actually pretty bullish with convection more so even than the 0Z cycle. 

And the 12Z ECMWF continues to be bullish in this region.

I think given that I can't justify an argument against a moderate risk in the IA/IL border area.

FWIW, the HREF has a pretty bullish convective signal for Iowa/mo/ill area. Secondary, hinting at some early activity in Indiana south of i70

[SolidIcewx]

Temps going into the Mid 70s now north of DTW where I live. Hump day looks to be a thump day

[brianc33710]

21 minutes ago, bdgwx said:

12Z GFS isn't exactly what I'd call bullish with convection in SE IA, but it isn't devoid of it either.

The 12Z UKMET, OTOH, is actually pretty bullish with convection more so even than the 0Z cycle. 

And the 12Z ECMWF continues to be bullish in this region.

I think given that I can't justify an argument against a moderate risk in the IA/IL border area.

The SPC didn't mention the possible inhibiting factors they mentioned in previous update. That concerns me.