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April 23-May 5, 2024 | Multi-Day Severe Weather/Tornado Outbreak


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We are approaching the heart of the 2024 season and right on cue Broyles is back at it again with another Day 7 15% ūüôā¬†

Looking at models, the potential for a multi-day severe event is there but at this range it's really just speculation. Something to watch as we get closer though. 

day7prob.thumb.gif.f4f5e906b1e4baff1311d11ef6cb3d77.gif

 

Edited by ElectricStorm
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Now a broad Day 7 15% added for next Friday. I think the trough will probably slow down a bit like usual, so I'm thinking Thursday might end up being a little more west, while Friday/Saturday and maybe Sunday could be bigger events further east. A week out though so a lot can and will change. 

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1 hour ago, ElectricStorm said:

Now a broad Day 7 15% added for next Friday. I think the trough will probably slow down a bit like usual, so I'm thinking Thursday might end up being a little more west, while Friday/Saturday and maybe Sunday could be bigger events further east. A week out though so a lot can and will change. 

I hope 4.27 isn't the crazy day for Oklahoma

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  • Meteorologist

The multi-day aspect of this sequence is what has me concerned. We've seem some of the worst tornadoes to hit the Plains and Mississippi Valley come from these. Obviously analogs aren't the end all be all (as we have seen). But the analogs for 4/27 has both multiple heavy hitters and plenty of  moderate risk worthy outbreaks to go with it as well. 

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The GFS and NAM have a great dryline for Thursday. Right now the NAM has some capping, but I expect several severe storms in the southern Plains. As of recently, the southern Plains has had some capping issues. I'm sure the Day-3 discussion written tonight will have lots of insights.

 

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  • The title was changed to April 23-?, 2024 | Multi-Day Severe Weather Event
8 hours ago, Ingyball said:

The multi-day aspect of this sequence is what has me concerned. We've seem some of the worst tornadoes to hit the Plains and Mississippi Valley come from these. Obviously analogs aren't the end all be all (as we have seen). But the analogs for 4/27 has both multiple heavy hitters and plenty of  moderate risk worthy outbreaks to go with it as well. 

I'm pretty certain there is going to be some moderate risks in this setup. We are getting close to May which usually means look out

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Spc just upgraded day 3 to enhanced with some decent wording. 

NWS Storm Prediction Center Norman OK

   0131 PM CDT Tue Apr 23 2024

 

   Valid 251200Z - 261200Z

 

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE

   EASTERN TX PANHANDLE AND WESTERN OK INTO SOUTHWEST/SOUTH-CENTRAL

   KS...

 

   AMENDED TO UPDATE FORECAST

 

   ...SUMMARY...

   Severe thunderstorms are likely from late Thursday afternoon into

   Thursday night across parts of the central and southern Great

   Plains. Very large hail, severe wind gusts, and strong tornadoes

   will all be possible.

 

   Guidance continues to suggest strong buoyancy will be in place ahead

   of a negatively tilted shortwave trough ejecting across the southern

   High Plains. General forecast expressed in the previous outlook

   remains valid, but confidence in an area of greater severe-weather

   potential has become more apparent with the most recent guidance.

   Late afternoon development is anticipated across the TX Panhandle,

   with these storms quickly becoming severe and capable of large to

   very large hail up to 3" in diameter. Low-level moisture may be

   later to arrive in west-central/southwest KS, delaying convective

   initiation to a few hours later than farther south. Large to very

   large hail is anticipated with initial development across

   west-central/southwest KS as well.

 

   In both of these areas, storms are expected to move

   east-northeastward off the dryline, encountering strengthening

   low-level southerly flow and environment that is increasingly

   favorable for tornadoes. Low-level shear will continue to

   strengthening into the early evening, and the overall environment

   supports the potential for strong to intense tornadoes if a discrete

   mode can be maintained.

Edited by StormfanaticInd
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I'm still wondering if the cap will be breakable on Thursday or not, especially with how dry the EML source region has been lately. Most CAMs seem to fire at least a few storms but most of them don't really seem Day 3 enhanced worthy quite yet, although CAMs can be a little questionable at this range. I think the initial slight risk for Day 3 was just fine. Not sold yet on a major outbreak but anything that does end up breaking the cap it would probably be a strong tornado producer. 

I think Saturday could end up being a pretty big event but there could be some morning convection issues so we'll see when we get closer how potent it ends up being. 

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This is only 12z NAM but if it somehow verified this would be one of the hands down largest warm sectors i've ever seen for the plains, and it's not even close tbh.

Luckily it's just the NAM so no need to worry too much yet.

This is for Saturday btw.

Screenshot_20240424_131749_X.thumb.jpg.3882646397cabadf7644183c7237defd.jpg

 

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16 hours ago, ElectricStorm said:

I'm still wondering if the cap will be breakable on Thursday or not, especially with how dry the EML source region has been lately. Most CAMs seem to fire at least a few storms but most of them don't really seem Day 3 enhanced worthy quite yet, although CAMs can be a little questionable at this range. I think the initial slight risk for Day 3 was just fine. Not sold yet on a major outbreak but anything that does end up breaking the cap it would probably be a strong tornado producer. 

I think Saturday could end up being a pretty big event but there could be some morning convection issues so we'll see when we get closer how potent it ends up being. 

The 18z HRRR is finally deciding to bust out some isolated storms near the dryline tomorrow. The CAMs have not given me a lot of confidence in the Enhanced risk forecast given by the SPC tomorrow. Certainly there could be 2" hail and tornadoes where storms happen tomorrow. Who am I to say, though? Maybe the SPC will be on target. For Friday, there looks like a great low-level jet or wind speeds or whatever you call it. Several areas severe storms could be (as mentioned in a previous post) occurring in an extensive warm sector.

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  • Meteorologist

Right now I think tomorrow is the day before the bigger days. That doesn't mean a big tor can't happen tho, we've seen those days produce devastating tornadoes before. 

 

I am a little hesitant with the orientation of the upper jet on 4/27, I think it could lead to some messy storm mode. But, with there likely being some sort of capping just due to the region it's in, it could also be a dangerous combo. The more meridional upper flow supports hodographs where the 3 to 6km winds curve upward. This favors Supercells with forward flank downdrafts well out ahead of the rear flank down drafts, which favors long track supercells. The question will be if there's enough space for these storms to go, or of storms will be merging constantly.

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Posted (edited)

Here's my writeup for tomorrow for the Panhandles. Lots of "if"s regarding convective initiation, but bets are off if we get a sustained updraft.

Morning clouds are lingering this afternoon and should, for the most
part, linger throughout the night as well... though some breaks in
the clouds are possible this afternoon. Temperatures will remain in
the 60s for much of the area except for the southwest, where 70s are
possible. A surge of mid-level theta-e advection is expected this
evening in the southeastern half of the Panhandles which may be
enough to kick off some showers generally off the caprock. Previous
model suites suggested that portions of this area may be uncapped
which would support a threat for elevated strong to severe
thunderstorms, but latest models now suggest that the cap may be too
strong for updrafts to overcome. Can`t entirely rule out a strong to
severe thunderstorm in the SE TX Panhandle as that area has the
weakest cap, but it is generally not looking as favorable for strong
to severe thunderstorms tonight.

Clouds will linger into Thursday morning for much of the area,
perhaps with some showers and isolated thunderstorms in the east.
Meanwhile, the upper-level trough begins to take a negative tilt
with the upper-level jet streak approaching the CWA. By 12z
Thursday, the dryline is favored to be in the vicinity of the
Texas/New Mexico border, with low-60 dew points in the southeast and
low-50 dew points as far west as Dalhart and Boise City. Most model
guidance begins to clear the clouds from west to east from the mid
to late morning hours through the afternoon, allowing for
temperatures to warm and the dryline to move eastward and gradually
sharpen as it encounters the deeper moisture present in the east. It
is worth noting that the 12km and 3km NAM keep low clouds lingering
all day in the east, keeping temperatures in the 60s and 70s. This
would most likely negate any severe thunderstorm concerns as the cap
would be too strong to support convective initiation. However, it is
a known bias in those products to keep cool temperatures wedged in
and weaken mixing during the day. Given their known bias and that
those products are currently the outliers, will not be giving much
credence to the idea that clouds linger in the east all day at this
time.

The more favored solution is that the clouds clear out in the
afternoon and destabilization occurs in the central and east
Panhandles. Models suggest a robust cap will be in place prior to
destabilization occurring, with the warmest temperature in the
inversion around 11C to 13C, but this cap should weaken with daytime
mixing. By the mid to late afternoon hours, the dryline is most
favored to set up in the central combined Panhandles, aligned in a
north-south fashion from the vicinity of Guymon to Amarillo, perhaps
slightly further east. Significant uncertainties exist about the
environment at that time such as:

1) How much will the cap be weakened? Most guidance that isn`t the
3km or 12km NAM has MLCIN ranging from near-0 J/kg to -75 J/kg,
suggesting no cap to a moderate cap. This will depend on the actual
strength of the inversion and when the morning clouds clear out.

2) A lead wave with some mid to upper-level forcing is expected to
swing through the Panhandles in the afternoon, but the timing will
be important. If it arrives too early, the cap may still be too
strong for thunderstorms to develop. If it arrives too late in the
afternoon or early evening when temperatures are beginning to cool,
the cap may once again be too strong for thunderstorms to develop.

3) Some CAMs suggest that there may be a dryline bulge which may be
a cause for enhanced surface wind and moisture convergence. This may
aid in convective initiation.

Current thinking is if there was a more favorable corridor for
thunderstorms to develop, it would be in the northern TX Panhandles
or eastern half of the OK Panhandle as that area is currently
favored to clear out first, and is in a more favorable position for
upper-level divergence should the timing be favorable as well.
Regardless, if a thunderstorm is indeed able to develop anywhere
along the dryline, models suggest 1500-2500 J/kg of MLCAPE,
potentially as much as 3000 J/kg along with 45-55 kts of effective
shear. Storm relative helicity (SRH) values are favored to be
between 50-150 m2/s2 between 0-1km, and 100-200 m2/s2 between 0-3km.
If there is a sustained updraft, all of these factors suggest that a
supercell would quickly develop with all severe hazards possible,
and a splitting supercell would be possible given a long and fairly
straight hodograph in the afternoon. Baseball hail (2.75") would be
possible, if not larger if the higher end of the range of
instability verifies. Damaging winds and tornadoes would be possible
as well. A strong tornado (EF2+) would be possible given the low-
level shear, low-level instability, and LCLs between 1000m to 1250m
(not great but not necessarily unfavorable), with a peak timing
window in the late afternoon/early evening when the LLJ strengthens.
 Any thunderstorm would continue through the evening but presumably
weaken as convective inhibition increases. A Pacific front will
overtake the dryline Thursday night and push all moisture out of the
Panhandles.

Vanden Bosch

 

Edited by ClicheVortex2014
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Not quite sold on a major tornado outbreak Saturday yet. Will probably end up with morning convection and the next wave could end up firing too early. That being said though the setup is there if the morning wave can move out quick enough. Won't know for sure the threat level until the day of. 

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0z HRRR has a significant tornado outbreak for IA/NE on Friday which is certainly concerning. Of course 48hr HRRR isn't the best but I'd expect a 10# tornado area to be added at the upcoming Day 2 outlook. 

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