Severe Weather Threat - May 6, 2024

[KevinH]

First Fred mentioned he expects a broad highlight for D6 from the SPC D4-8 this morning and sure enough, the SPC highlighted D6.


Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0403 AM CDT Wed May 01 2024

Valid 041200Z - 091200Z

...DISCUSSION.
For Saturday/D4 to Sunday/D5, scattered to perhaps numerous thunderstorms are possible over a large section of the CONUS from the southern Plains into the Southeast. Mid 60s F to lower 70s F will be common across the entire area, aided by southerly surface winds around an East Coast high. Aloft, generally weak flow will exist over the same areas, well east of a developing western upper trough. As such, the weak shear will likely minimize overall severe potential through Sunday/D5.

For Monday/D6, models have shown increased run-to-run consistency in depicting a deep upper trough developing over the Great Basin and emerging into the Plains. Rich low-level moisture will be in place ahead of this system, which is forecast to enter the central Plains with a negative tilt and strong shear. While minor trough-geometry differences exist amongst the models, the combination of strengthening shear, a potentially deep surface low and ample moisture and instability necessitate introducing severe probabilities for parts of the Plains on Monday. All facets of severe appear possible with such a system, including supercells, squall lines, tornadoes, damaging winds and large hail.

 

[Fred Gossage]

Last night's data looked a bit meaner than today's cycle, but it still appears to be a potentially significant severe/tornado threat across a large geographic area of the classic Great Plains, and if data nudges back in the direction of last night's GFS/Euro solution, the system would have a rather high ceiling (and probably a pretty high floor too). Having said that, even with good general model agreement, the exact magnitude of the threat will be very fickle to the very specific geometry and timing of the shortwave embedded within the larger scale longwave trough. In a lot of ways, synoptically evident outbreaks on the Plains are much more tricky than in Dixie. They are much more reliant on exact timing of shortwave ejection, exact low-level wind trajectories, and other things that are a little more flexible in Dixie events because of our west-to-east geometry versus theirs, our proximity to the Gulf vs the EML source region, and how hard it is for them to sustain higher-end tornado potential deep into the overnight unlike here.

 

[Maxis_s]

The day after that also looks pretty significant, somewhat surprised they haven't outlined an area for that too but I assume they will on the next D6 or D5.

 

[Fred Gossage]

Too much inconsistency with the way the energy is handled in the trough beyond Monday. It's looked anywhere from being strung out and shifting north with time on some model runs to next Tuesday-Wednesday being somewhat reminiscent of 4/15-16/1998 from the Ozarks to KY/TN/MS/AL on last night's 00z GFS. Way more questions than answers beyond Monday on even the basic things.

 

[Wind Driven Coconut]

Surprised by how quiet this thread is considering how strongly worded this morning’s SPC extended forecast was. Sounds like another multi day severe storm outbreak is inbound next week. The discussion mentioned upgrading for Tuesday and adding outlooks for Wednesday through Friday as far east as MS.

 

[jiharris0220]

Surprised by how quiet this thread is considering how strongly worded this morning’s SPC extended forecast was. Sounds like another multi day severe storm outbreak is inbound next week. The discussion mentioned upgrading for Tuesday and adding outlooks for Wednesday through Friday as far east as MS.

Perhaps the hunger for action has been quenched since tornadoes have been touching down practically everyday since the 26th of April.

 

[Casuarina Head]

I know that the SPC seems more bullish, but re: Monday: doesn’t the trough appear to be less broad-based (read: potentially messier wind-profiles) on the latest EPS vs. a few days earlier? If so, wouldn’t this potentially limit the ceiling for discrete-based EF2+ tornado coverage and/or quantity, regardless of timing? (Just posing a question here.) I do think the potential for significant severe is there, nevertheless.

 

[Maxis_s]

Surprised by how quiet this thread is considering how strongly worded this morning’s SPC extended forecast was. Sounds like another multi day severe storm outbreak is inbound next week. The discussion mentioned upgrading for Tuesday and adding outlooks for Wednesday through Friday as far east as MS.

Absolutely. Day 6 also looks very interesting, with them mentioning that significant severe weather potential is likely for a very broad area.

 

[KevinH]

Surprised by how quiet this thread is considering how strongly worded this morning’s SPC extended forecast was. Sounds like another multi day severe storm outbreak is inbound next week. The discussion mentioned upgrading for Tuesday and adding outlooks for Wednesday through Friday as far east as MS.

Updated the title of the thread due to the D5 wording of today’s D4-8 (below). Added a question mark to the title bc the SPC did not highlight any areas for D6-8 (yet), but said highlights are likely in future outlooks.

Day 4-8 Convective Outlook
NWS Storm Prediction Center Norman OK
0316 AM CDT Thu May 02 2024

Valid 051200Z - 101200Z

...DISCUSSION...
A large upper trough with a strong embedded shortwave will develop across the western CONUS on Sunday/D4, with an 80 kt 500 mb speed max forecast over CO and NM by 12Z Monday. This trough will progressively become negatively tilted, moving quickly across the central and northern Plains during the day on Monday/D5. Even with the leading wave moving northeast, height falls will persist as far south as northern TX as a secondary speed max noses into CO/NM through Tuesday/D6 morning.

Although model differences exist regarding the timing of the strong lead wave, the combination of a deepening surface low, strong large-scale ascent and moderate to strong instability will support scattered to perhaps widespread severe storms on Monday. Low-level moisture return will increase Sunday/D4 night as a southerl low-level jet develops. During the day on Monday/D5, models show low to mid 60s F dewpoints as far north as I-80 in NE/IA, with upper 60s to lower 70s F from OK into TX. The end result will be 2000 to perhaps 3000 J/kg MUCAPE across the warm sector, with strengthening shear. The strong wind fields and progressive nature of trough will lead to an eastward expansion of steep low-level lapse rates across most of NE, KS, and into central OK by late afternoon, aiding surface-based storms including supercells, tornadoes, particularly damaging winds and very large hail. If slower solutions such as the ECMWF verify, the severe risk could last well into the evening across eastern KS, OK, and western MO.

Given the aforementioned timing and positioning differences with the parent trough and cold front/dryline, will maintain a broad 15% risk area, with upgrades in later outlooks as predictability increases.

For the Tuesday/D6 through Thursday/D8 period, significant severe weather potential is likely primarily from parts of TX, OK, and AR, and eventually LA and MS as strengthening zonal flow will be possible across the region. A moist and unstable air mass beneath such a flow regime (moderate west/southwest flow with subtle disturbances) would lead to an eastward expansion of the EML, with not only a tornado risk but very large hail. Additional severe outlooks are likely as these details become more predictable.

..Jewell.. 05/02/2024

 

[jiharris0220]

Gfs is quite bullish on the kinematic environment in Kansas.

 

[Clancy]

CIPS supporting robust potential from D5 all the way through D8. CSU probs reflect this as well.

 

[KevinH]

CIPS supporting robust potential from D5 all the way through D8. CSU probs reflect this as well.
View attachment 26207View attachment 26208View attachment 26209View attachment 26210View attachment 26211

Good grief man… SMH

 

[cincywx]

CIPS supporting robust potential from D5 all the way through D8. CSU probs reflect this as well.

Looks like Ohio is trying to re-enter the ring after a month-long breather. Plenty of time for things to change but 5/8 has my ears perked up at the moment.

 

[JPWX]

Yeah next week looks interesting

 

[andyhb]

Some really major events popping up in the CIPS for the Plains on Monday. The setup on the 12z guidance is dangerous and would suggest the potential for an outbreak of severe storms across KS into N OK potentially, timing/amplitude tbd.

 

[notsoencrypted]

Surprised by how quiet this thread is considering how strongly worded this morning’s SPC extended forecast was.

When an event is still 5+ days away, there's not a lot of discussion that can happen. Waiting and watching are the name of the game until things get closer. I'm actually surprised by how much there is in this thread already!

 

[Wind Driven Coconut]

I suppose you’re correct, but that Day 4-8 this morning was sculpted in Broylesspeak, definitely got my attention.

 

[CheeselandSkies]

When an event is still 5+ days away, there's not a lot of discussion that can happen. Waiting and watching are the name of the game until things get closer. I'm actually surprised by how much there is in this thread already!

Absolutely. I think at this point we've collectively seen enough setups that looked "huge"/"slam-dunk outbreak" across multiple runs of multiple models outside of Day 5 only to downtrend inside that range and vice versa, to know not to put too much stock into them one way or the other.

 

[TornadoFan]

SPC added a 30% risk area for Monday

 

[warneagle]

I suppose you’re correct, but that Day 4-8 this morning was sculpted in Broylesspeak, definitely got my attention.

Yeah the wording was strong enough that I got about halfway through reading D4 and was like “waiiit a minute” and scrolled down to see who wrote it lol

Surprisingly not Broyles, so I don’t get to post the meme