May 2 - 16, 2023 | Severe Weather Sequence

[Iceresistance]

Another legit signal from the GEFS, the SPC does have this, even though the predictability is currently too low.

   Predictability regarding the surface and upper pattern decreases by
   D7/Thursday into D8/Friday, but continued low-level moistening and
   the potential for some stronger mid/upper-level flow to spread east
   of the Rockies could support an increasing severe-thunderstorm
   threat across parts of the central/southern Plains into the lower MS
   Valley by the end of the week.

 

[ClicheVortex2014]

Going forward... definitely starting to see the focus of severe weather shift west out here to the Plains as you'd expect for late April/early May. 12z Euro was very excited about this.

[Ingyball]

12 minutes ago, ClicheVortex2014 said:

Going forward... definitely starting to see the focus of severe weather shift west out here to the Plains as you'd expect for late April/early May. 12z Euro was very excited about this.

I'm ready for MCS season and just about guaranteed heavy rain. Personally I've had enough Supercell action for 1 spring. 

[ClicheVortex2014]

14 minutes ago, Ingyball said:

I'm ready for MCS season and just about guaranteed heavy rain. Personally I've had enough Supercell action for 1 spring. 

That's a luxury I won't have here. I've experienced enough MCSs in my lifetime but this area does need that rain.

[Iceresistance]

Still too much uncertainty, but it is there.

By D6/Thursday into next weekend, continued low-level moistening and
   the potential for somewhat stronger deep-layer flow/shear to spread
   east of the Rockies may support an increasing severe-thunderstorm
   threat across parts of the southern Plains into the lower MS Valley,
   though predictability remains low regarding the timing and location
   of any such threat.

 

[ElectricStorm]

Something to watch for sure. Models seem to be going back and forth on location and magnitude but it certainly seems like there should be severe weather somewhere. Doesn't really look like a major event right now, but at the same time it'll be May, so it won't take much for it to potentially become a dangerous day. 

[Iceresistance]

1 hour ago, ElectricStorm said:

Something to watch for sure. Models seem to be going back and forth on location and magnitude but it certainly seems like there should be severe weather somewhere. Doesn't really look like a major event right now, but at the same time it'll be May, so it won't take much for it to potentially become a dangerous day. 

Even the ensembles are having some trouble too, but in May, it does not take much to become nasty.

[ClicheVortex2014]

Looking like a string of marginal/slight risks next week with the limiting factor being shear because these shortwaves just aren't that strong. But we'll definitely take any rain these thunderstorms give us. Looks like PWATs will be around an inch which is really good for this time of year here.

Start to get some stronger shortwaves/more favorable upper-level pattern next weekend. 

Edited April 30, 2023 by ClicheVortex2014

[Iceresistance]

Interesting discussion from the SPC

...D4/Wednesday - Far West TX into the southern High Plains...
   A similar regime to D3/Tuesday is expected from far west TX into the
   southern High Plains on Wednesday, though some increase in buoyancy
   is possible, as modestly moist southeasterly low-level flow is
   maintained across the region. There is some indication that
   mid/upper-level flow may increase slightly as well, though
   predictability remains low in that regard. With favorably veered
   wind profiles, any increase in mid/upper-level wind speeds may
   result in sufficient deep-layer shear for organized multicells and
   perhaps a supercell or two.  

   ...D5/Thursday - Southern/central Plains...
   Guidance generally agrees that a midlevel shortwave trough and
   associated jet maximum will emerge from the subtropical Pacific, in
   advance of the persistent West Coast longwave trough. This feature
   will move over portions of the southern and possibly central Plains,
   strengthening deep-layer shear across the region, along with the
   potential for organized convection. However, guidance also generally
   agrees that the surface cyclone development in the lee of the
   Rockies will be relatively weak, limiting the potential for
   northward moisture transport to some extent. Depending on the extent
   that stronger deep-layer flow/shear overlaps more favorable
   instability, some organized severe-thunderstorm threat appears
   possible Thursday afternoon and evening somewhere across the
   southern and/or central Plains.

   ...D6/Friday - D8/Sunday - Southern/central Plains into the lower MS
   Valley...
   Predictability regarding the evolution of the upper-level pattern
   begins to wane by the end of the week. In general, guidance suggests
   that the persistent upper-level trough over the western CONUS will
   finally eject eastward into the Great Plains, though likely in a
   notably weakened state. This may increase the potential for a
   favorable overlap of moderate-to-strong buoyancy and sufficient
   deep-layer shear somewhere across the central/southern Plains (and
   possibly into the lower MS Valley), though uncertainty remains high
   regarding the details of any such threat.

 

[Ingyball]

I do like the wavy pattern that some of the models are showing. No incredibly strong jet-streaks being shown right now, but the GFS does hint towards some good orientation with the upper trough, especially with the first wave or 2. Although a jet streak is great, we've seen the Plains cash in with weak upper flow quite a few times with the most recent being April 19th. We're usually able to make up for it by being close to the surface low and having backed winds at the surface elongate hodographs. 

[Iceresistance]

NWS-Norman has already tagged Thursday for the possibility of Severe Storms.

[Iceresistance]

Should the UKMET Model be trusted for severe weather chances? It has a outbreak signal for May 4th.

[ClicheVortex2014]

2 hours ago, Iceresistance said:

Should the UKMET Model be trusted for severe weather chances? It has a outbreak signal for May 4th.

In general, not if it's by itself. Also not sure about an outbreak on UKMET. Maybe some supercells in Texas but nothing out of the usual

[Iceresistance]

Skinny area

[Iceresistance]

Also, this long discussion

Spoiler

...DISCUSSION...
   ...D4/Thursday: Southern/central Plains...
   A mid/upper-level shortwave trough is forecast to move across parts
   of the southern Plains on Thursday. This wave will likely deamplify
   as it crests a shortwave ridge, but moderate mid/upper-level flow is
   expected to overspread an increasingly moist and unstable airmass
   across the southern Plains during the afternoon. Scattered
   thunderstorm development is expected along the dryline, with
   moderate buoyancy and increasingly favorable deep-layer shear
   supporting the potential for organized clusters and a few
   supercells, with an attendant threat of large hail and localized
   severe gusts. A 15% area has been added where confidence is
   currently greatest in organized convection during the late afternoon
   and early evening, with some future adjustments likely based on
   dryline position and northern extent of stronger deep-layer
   flow/shear. 

   ...D5/Friday and beyond...
   Predictability begins to wane as soon as D5/Friday with regard to
   organized severe-thunderstorm potential. The mid/upper-level low
   that will persist near the Pacific Coast for much of the week is
   forecast to begin ejecting northeastward on Thursday, weakening as
   it does so. The remnant mid/upper-level trough will then gradually
   move across parts of the Great Plains, though there is considerable
   spread regarding the timing, location, and intensity of this trough
   into the coming weekend. There will be some potential for stronger
   mid/upper-level flow and favorable deep-layer shear to impinge upon
   an expanding reservoir of moderate to locally strong buoyancy across
   the central/southern Plains into the lower/mid MS Valley, but
   details regarding the severe-thunderstorm threat on any particular
   day remain very uncertain at this time.

 

[FortySixAnd32]

https://www.foxweather.com/weather-news/blocking-forecast-april-may-pattern?dicbo=v2-WuiAaYh

 

Cool stuff....

 

[Iceresistance]

This is the 12z GFS for May 4th, sounding is basically just to my south, yikes.

[Chinook]

6 hours ago, Iceresistance said:

This is the 12z GFS for May 4th, sounding is basically just to my south, yikes.

It is that time of year when the GFS can pick out the mostly right synoptic setup, and underestimate the CAPE. And it's also about the time to start checking the NAM.

[Iceresistance]

1 hour ago, Chinook said:

It is that time of year when the GFS can pick out the mostly right synoptic setup, and underestimate the CAPE. And it's also about the time to start checking the NAM.

NAM is currently west, and only has one storm in Oklahoma

 

EDIT: And the SREF

Edited May 2, 2023 by Iceresistance

[Iceresistance]

15z SREF already has a 15% STI in SW Oklahoma for 5/4/2023

[Iceresistance]

This could turn into a loose sequence

[ElectricStorm]

0z HRRR fires multiple supercells over western OK for Thursday. Need to watch for some potential morning convection/cloud cover issues but it may not be a big deal as it looks to clear out of the area relatively early. 48hr HRRR isn't the most reliable, so we'll see what it does over the next several runs. I think we could see an upgrade to enhanced at some point. 

[ElectricStorm]

Next interesting day for the southern plains after Thursday could be Sunday. There's a decent amount of uncertainty in the models for now, but I think we could see a highlighted area from SPC sometime over the next few outlooks. 
 

This will probably change but early CIPS runs are bullish 

https://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=GP&fhr=F120&rundt=2023050300&map=thbSVR

[Ingyball]

4 hours ago, ElectricStorm said:

Next interesting day for the southern plains after Thursday could be Sunday. There's a decent amount of uncertainty in the models for now, but I think we could see a highlighted area from SPC sometime over the next few outlooks. 
 

This will probably change but early CIPS runs are bullish 

https://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=GP&fhr=F120&rundt=2023050300&map=thbSVR

I like seeing quite a few ENSO+ years in that list with us being in warm neutral. I'm going to be doing some research into how important it is for analogs to match the current ENSO skill-wise. 

Edited May 3, 2023 by Ingyball

[Iceresistance]

5 hours ago, ElectricStorm said:

Next interesting day for the southern plains after Thursday could be Sunday. There's a decent amount of uncertainty in the models for now, but I think we could see a highlighted area from SPC sometime over the next few outlooks. 
 

This will probably change but early CIPS runs are bullish 

https://www.eas.slu.edu/CIPS/ANALOG/DFHR.php?reg=GP&fhr=F120&rundt=2023050300&map=thbSVR

Yeah, this weekend looks conditional, but the instability (CAPE over 3000) is insane. Any storm that develops in that kind of area will literally explode.