Severe Weather May 26th- 28th 2021

[weatherextreme]

 

 Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0232 AM CDT Mon May 24 2021

 

 

 

 Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0339 AM CDT Mon May 24 2021

   Valid 271200Z - 011200Z

   ...DISCUSSION...
   Medium-range model guidance is coming into better agreement in the
   depiction of a mid-level shortwave trough over the north-central
   U.S. on Thursday (day 4).  Additionally, it appears that a
   lower-latitude belt of stronger flow will overspread the TX
   Panhandle and OK where a moist/unstable sector will reside.  There
   is uncertainty about the eastern extent of a moist/unstable airmass
   across the mid MS Valley and the probable weakening of an MCS
   Thursday morning.  Nonetheless, it seems prudent to introduce a
   15-percent severe risk for Thursday for much of OK northeast into
   southeast KS and into MO.  Uncertainty increases by Friday (day 5)
   owing to convective influences in the prior days across the central
   U.S.  The upper-air pattern begins to appear less favorable for
   organized severe storms by this weekend but model variability is
   relatively high at this point.

[CheeselandSkies]

Could possibly expand this to include Wednesday, as well. The two days might be a fairly noteworthy event all told. Friday and the weekend are still rather nebulous, a few GFS runs depicted potential huge days in that timeframe (like Plains-wide 3KM EHI ≥10) but it seems to have backed off on that.

[nrgjeff]

Thursday signal has been on the models since the weekend. SPC is right to highlight it. 

First of all I believe the NAM is too veered off, too fast, and overall wrong. At 84 hours that's well beyond it's strength. NAM is good to about 36-48 hours.

GFS has finally found a consistent groove for Thursday. It's barely got enough shear, both speed and directional. Normally I'm bearish cold fronts. However in late May all boundaries are game on. Enough cross boundary flow is forecast aloft. 

ECMWF is a bit east and south too. That may pull back with time. Though the Euro is slower / west Wednesday it wants to push faster east Thursday. Doubtful, even with an MCS.

Bottom line: Thursday should be a good chase day following the Wednesday fun. Friday is up in the air, but a boundary will remain in late May.

[weatherextreme]

9 minutes ago, CheeselandSkies said:

Could possibly expand this to include Wednesday, as well. The two days might be a fairly noteworthy event all told. Friday and the weekend are still rather nebulous, a few GFS runs depicted potential huge days in that timeframe (like Plains-wide 3KM EHI ≥10) but it seems to have backed off on that.

Added.

[StormChazer]

Will definitely be chasing here in OK if Thursday pans out. Haven't had a really good chase day yet here to be honest.

[Chinook]

Here are two cross-sections (colors are total wind speed) across Colorado, Kansas, and Missouri. These show that the low-level southerly jet increases from 34 kt just above the surface (at 00z, not shown) to about 56 kt or 58 kt in a span of 6 hours on Wednesday evening. I have always found it amazing that as the surface temperatures cool, the winds pick up, but above the surface, not at the surface, in these special situations.

 

 

SPC upgraded to 30% for wind on Wednesday

[yoda]

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Tue May 25 2021

   Valid 261200Z - 271200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
   NEBRASKA AND KANSAS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE CENTRAL
   GREAT PLAINS INTO THE TEXAS PANHANDLE AND PARTS OF THE NORTHEAST
   U.S....

   ...SUMMARY...
   Scattered severe thunderstorms are probable over parts of the
   central Great Plains.  Severe gusts, large hail, and a couple of
   tornadoes are possible.

   ...Eastern Wyoming into the lower Missouri Valley...
   A mid-level shortwave trough initially over ID Wednesday morning,
   will move east into the Dakotas during the period.  A lower-latitude
   belt of moderate mid-level flow is forecast to move from NM/CO into
   the TX Panhandle by early evening and strengthen across KS
   overnight.  A surface low is forecast to develop over the
   central High Plains and develop eastward along the KS/NE border
   late.  

   A residual frontal zone over the central Great Plains is forecast to
   advance northward into NE during the day.  Increasing
   south-southeasterly low-level flow will advect moisture into western
   NE/eastern WY by mid afternoon.  Increasing large-scale ascent
   coupled with the diurnal weakening of a capping inversion, will
   support widely scattered thunderstorms by late afternoon.  Large to
   very large hail is possible in addition to severe gusts with
   supercellular activity.  By early evening, additional storms will
   probably develop farther east within the moisture plume over
   west-central NE as a LLJ strengthens and a potential tornado risk
   before upscale growth occurs.  There is high confidence in the
   eventual development of an MCS to move across southern NE and into
   northern KS overnight.  Very steep mid-level lapse rates (8-9 deg
   C/km in the 700-500 mb layer) and richer moisture may aid in the
   development of a mature/severe MCS.  Model run-to-run consistency
   and increased confidence yielded 30-percent wind probabilities this
   outlook update.  Severe gusts, potentially significant, could
   accompany the more pronounced bowing portions of the squall line as
   it moves east into the lower MO Valley late.

   ...Southwest Kansas into west TX...
   A lee trough/dryline is forecast to sharpen during the day as 60s F
   dewpoints are forecast in the High Plains.  Forecast soundings show
   a very unstable airmass developing by late afternoon across the TX
   Panhandle with 3000+ J/kg MLCAPE expected.  Localized erosion of
   CINH will likely lead to widely scattered thunderstorms developing. 
   Effective shear around 40 kt will favor supercells with a threat for
   very large hail and severe gusts.  A tornadic supercell is possible,
   especially where temperature/dewpoint spreads are locally minimized.
    Increasing convective inhibition during the evening will eventually
   lead to a diminished severe risk by late evening.

[yoda]

 

[yoda]

Day 3 looks to be the chase day -- images in this post... disco in the one below

[yoda]

Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0244 AM CDT Tue May 25 2021

   Valid 271200Z - 281200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR MUCH OF
   OKLAHOMA...SOUTHEAST KANSAS...AND A LARGE PART OF MISSOURI...

   ...SUMMARY...
   Scattered severe thunderstorms are likely on Thursday and Thursday
   evening from parts of the southern Great Plains into the Ozarks and
   middle Mississippi Valley.  Very large hail, significant severe
   gusts, and several tornadoes are possible.

   ...Lower MO Valley eastward into the OH Valley...
   Uncertainty remains regarding details on the evolution of an early
   day MCS over the lower MO Valley per recent model guidance. 
   However, models indicate an MCV over the lower MO Valley may aid in
   storms persisting during the morning or possibly developing on the
   outflow and moving east across central MO into the mid MS Valley
   during the day.  Strong potential instability and mid-level flow
   will favor organized storms.  Severe gusts and a few tornadoes may
   be the primary threats with this activity as it eventually moves
   into lower OH Valley late.

   ...KS/OK/eastern TX Panhandle into the Ozarks...
   To the south of morning showers/storms over the lower MO Valley, a
   very moist boundary layer (15-17 g/kg lowest 100 mb mean mixing
   ratios) is forecast to become very to extremely unstable (2500-4500
   J/kg MLCAPE) by mid afternoon south of an outflow boundary and cool
   front.  Strong heating near the front and outflow boundary will
   likely be preferable locations for thunderstorm development by
   mid-late afternoon.  Forecast soundings show ample deep-layer shear
   favoring organized storms (e.g., supercells) with very large CAPE in
   the -10 to -30 deg C layer.  Large to giant hail is possible with
   the early discrete supercell activity.  Although low-level shear is
   modest, a tornado risk may focus near a potential outflow boundary
   or perhaps where SRH may be maximized (per stronger 850-700 mb flow)
   during the early evening over northeast OK into southeast KS and
   southwest MO.  While it is too early in the outlook cycle to have
   much confidence in the potential for a significant tornado, some
   environmental ingredients may overlap.

   By early evening, additional explosive thunderstorm development is
   probable near the front as storms congeal and grow upscale within
   the moist/instability reservoir centered over OK.  A severe-wind
   producing MCS is possible during the evening and perhaps persisting
   into the overnight across OK into the western Ozark Plateau.

   ...TX dryline...
   Strong heating over west and southwest TX will contribute to very
   steep low-level lapse rates beneath an elevated mixed layer.  Models
   show a mid-level disturbance initially over AZ will quickly move
   east into central/eastern NM by late afternoon with an associated
   speed max.  Although most of this region will remain capped,
   weakening convective inhibition and appreciable boundary-layer
   moisture will result in a very unstable airmass (2500-3500 J/kg
   MLCAPE) with 50-kt west-southwesterly 250 mb flow.  A couple of
   widely spaced supercells posing a risk for large to very large hail
   and severe gusts are possible during the late afternoon through
   early evening.

   ..Smith.. 05/25/2021

[CheeselandSkies]

Heading out this afternoon, target for tomorrow still somewhat up in the air. Either south-central NE or western KS. Then I'll be in position for Thursday's action, as well.

[OKTWISTER]

Latest from NWS Tulsa for Thursday. 

 

Hazardous Weather Outlook
National Weather Service Tulsa OK
147 PM CDT Tue May 25 2021

ARZ001-002-010-011-019-020-029-OKZ049-053>076-261045-
Adair OK-Benton AR-Carroll AR-Cherokee OK-Choctaw OK-Craig OK-
Crawford AR-Creek OK-Delaware OK-Franklin AR-Haskell OK-Latimer OK-
Le Flore OK-Madison AR-Mayes OK-McIntosh OK-Muskogee OK-Nowata OK-
Okfuskee OK-Okmulgee OK-Osage OK-Ottawa OK-Pawnee OK-Pittsburg OK-
Pushmataha OK-Rogers OK-Sebastian AR-Sequoyah OK-Tulsa OK-Wagoner OK-
Washington OK-Washington AR-
147 PM CDT Tue May 25 2021

This Outlook is for Northwest and West Central Arkansas as well as
much of Eastern Oklahoma.

.DAY ONE...This Afternoon and Tonight.

SEVERE THUNDERSTORM.
RISK...Limited.
AREA...Far Southeast Oklahoma.
ONSET...Ongoing...ending by early evening.

FLASH FLOOD.
RISK...Limited.
AREA...Southeast Oklahoma; Northwest Arkansas.
ONSET...Ongoing.

HEAVY RAIN.
RISK...Limited.
AREA...Southeast Oklahoma; Northwest Arkansas.
ONSET...Ongoing.

DISCUSSION...

There is a limited severe storm risk mainly across southeast
Oklahoma this afternoon. Damaging winds are the main threat.
Locally heavy rainfall fell across portions of southeast Oklahoma
this afternoon, shifting into northwest Arkansas. Another round of
heavy rain is possible with the afternoon storms over the same
areas. Thus, there is limited flash flood potential thru early
evening.

SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT...
Local Spotter Activation May Be Needed.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
WEDNESDAY...Thunderstorm Potential.
THURSDAY...Severe Thunderstorm Potential...High Wind Potential...Heavy Rain Potential.
FRIDAY thru MONDAY...Thunderstorm Potential.

EXTENDED DISCUSSION...

Storm coverage on Wednesday will be isolated at best and during
the afternoon, mainly across far eastern Oklahoma and western
Arkansas. Severe weather is not expected.

A high impact weather event is expected from Thursday afternoon
and night. Severe storms are expected to form ahead of a cool
front across northeast Oklahoma Thursday afternoon and then grow
into a complex and move into western Arkansas and southeast
Oklahoma Thursday night. The initial storms across northeast
Oklahoma will pose the threat for tornadoes, very large hail to 2
inches in diameter or greater, and damaging winds. Due to the very
unstable airmass expected to be in place, and the potential for a
boundary to be draped across the region, there is potential for a
strong tornado. After storms congeal into a complex, wider swaths
of damaging winds will become the main severe concern. The severe
threat on Friday afternoon will be confined mainly to southeast
Oklahoma ahead of a cool front.

While storm chances remain in the forecast thru the weekend and
into early next week, severe weather is not expected during this
time.

Repeated heavy rainfall on top of saturated soils may lead to
an increasing flood threat later this week in addition to the
severe weather potential.

[OKwx_2001]

1 hour ago, OKTWISTER said:

Latest from NWS Tulsa for Thursday. 

 

Hazardous Weather Outlook
National Weather Service Tulsa OK
147 PM CDT Tue May 25 2021

ARZ001-002-010-011-019-020-029-OKZ049-053>076-261045-
Adair OK-Benton AR-Carroll AR-Cherokee OK-Choctaw OK-Craig OK-
Crawford AR-Creek OK-Delaware OK-Franklin AR-Haskell OK-Latimer OK-
Le Flore OK-Madison AR-Mayes OK-McIntosh OK-Muskogee OK-Nowata OK-
Okfuskee OK-Okmulgee OK-Osage OK-Ottawa OK-Pawnee OK-Pittsburg OK-
Pushmataha OK-Rogers OK-Sebastian AR-Sequoyah OK-Tulsa OK-Wagoner OK-
Washington OK-Washington AR-
147 PM CDT Tue May 25 2021

This Outlook is for Northwest and West Central Arkansas as well as
much of Eastern Oklahoma.

.DAY ONE...This Afternoon and Tonight.

SEVERE THUNDERSTORM.
RISK...Limited.
AREA...Far Southeast Oklahoma.
ONSET...Ongoing...ending by early evening.

FLASH FLOOD.
RISK...Limited.
AREA...Southeast Oklahoma; Northwest Arkansas.
ONSET...Ongoing.

HEAVY RAIN.
RISK...Limited.
AREA...Southeast Oklahoma; Northwest Arkansas.
ONSET...Ongoing.

DISCUSSION...

There is a limited severe storm risk mainly across southeast
Oklahoma this afternoon. Damaging winds are the main threat.
Locally heavy rainfall fell across portions of southeast Oklahoma
this afternoon, shifting into northwest Arkansas. Another round of
heavy rain is possible with the afternoon storms over the same
areas. Thus, there is limited flash flood potential thru early
evening.

SPOTTER AND EMERGENCY MANAGEMENT ACTION STATEMENT...
Local Spotter Activation May Be Needed.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.
WEDNESDAY...Thunderstorm Potential.
THURSDAY...Severe Thunderstorm Potential...High Wind Potential...Heavy Rain Potential.
FRIDAY thru MONDAY...Thunderstorm Potential.

EXTENDED DISCUSSION...

Storm coverage on Wednesday will be isolated at best and during
the afternoon, mainly across far eastern Oklahoma and western
Arkansas. Severe weather is not expected.

A high impact weather event is expected from Thursday afternoon
and night. Severe storms are expected to form ahead of a cool
front across northeast Oklahoma Thursday afternoon and then grow
into a complex and move into western Arkansas and southeast
Oklahoma Thursday night. The initial storms across northeast
Oklahoma will pose the threat for tornadoes, very large hail to 2
inches in diameter or greater, and damaging winds. Due to the very
unstable airmass expected to be in place, and the potential for a
boundary to be draped across the region, there is potential for a
strong tornado. After storms congeal into a complex, wider swaths
of damaging winds will become the main severe concern. The severe
threat on Friday afternoon will be confined mainly to southeast
Oklahoma ahead of a cool front.

While storm chances remain in the forecast thru the weekend and
into early next week, severe weather is not expected during this
time.

Repeated heavy rainfall on top of saturated soils may lead to
an increasing flood threat later this week in addition to the
severe weather potential.

Wow that's one of the more bullish ones I've seen from them at this range. Usually they are a bit more on the conservative side. Definitely concerning and I think we'll see a wind-driven moderate risk (tornado risk might be lower but still significant) by Day 1. 

[stormdragonwx]

Yeah I would think Mod risk with at minimum a 10% hatched for tornadoes. It is May after all.

[OKTWISTER]

Looking at the NWS Tulsa Discussion today I think the better chance of a strong tornado may be SE/SC KS near the boundary.  Will have to see where that is in the afternoon I think with no cap it will line up quickly and become a wind event.  I also hate QLCS tornadoes as they are not going to be easy to see as everything is going to be in heavy precipitation with possible flash flooding issues.  It is almost feeling like Derecho time. 

Tomorrow will finally signify a change in the upper level pattern,
switching from the southerly flow aloft that has been providing a
steady stream of clouds and moisture form the Gulf over a majority 
of the past two weeks. More westerly flow aloft will arrive
Wednesday, which should aid in clearing out some of the clouds and
providing the region with some sunshine. With the sunshine comes
warming temperatures with highs climbing back to near and above
average for the next few days. The main focus in this period
continues to be the threat for some significant severe weather to
affect the area Thursday afternoon and especially into the evening
and overnight hours. Thursday afternoon will be warm and moist
ahead of a frontal boundary that will be draped across southern
Kansas during the afternoon hours. Large instability and little to
no cap could lead to supercell development in the afternoon
across northeast Oklahoma. All hazards would be possible with this
initial development, although it is less certain that storms will
fire in this area with the lack of large scale forcing in place.
More likely is that storms will develop along the boundary in
southern Kansas by late afternoon and grow upscale into a large
convective complex that will then surge south across the area. A
large swath of damaging wind gusts will be possible with this
line. Additionally, low level shear will still be in place ahead
of the line and the possibility for tornadoes to develop along
the leading edge will be possible as well. continue to monitor the
latest forecast updates for more details.

 

[weatherextreme]

Upgrade to moderate for Wednesday

 

45 % sig wind and hail prob

10 % Tor probs

 

Pretty close to a high-risk day probabilities.

 

 

 

 Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1256 AM CDT Wed May 26 2021

   Valid 261200Z - 271200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE CENTRAL PLAINS...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
   MODERATE RISK INTO THE SOUTHERN PLAINS AND ACROSS THE NORTHEASTERN
   US...

   ...SUMMARY...
   Severe thunderstorms will spread across the central Plains during
   the late afternoon and evening with a threat for large and
   destructive hail, very damaging winds, and tornadoes. Scattered
   severe is also expected across the southern High Plains and much of
   the northeastern US where damaging winds are the primary concern.

   ...Central/southern Plains...

   Early this morning a well-defined upper trough was located over
   eastern WA/OR. This feature is forecast to translate into eastern
   MT/WY by 27/00z with diffluent high-level flow expected to spread
   across the northern High Plains region during the afternoon. In
   response, a surface low should develop over southern WY by 18z then
   settle southeast along a frontal zone draped across the central
   Plains. Favorable low-level trajectories across KS/southern NE will
   force higher boundary layer moisture into the NE Panhandle prior to
   forecast maximum temperatures. In fact, isolated supercells will
   likely initiate across parts of eastern WY along the western fringe
   of higher-moisture content where large-scale forcing will be
   maximized. Latest thinking is boundary-layer heating will be most
   intense across southeast WY/southern NE Panhandle, south along the
   NM/TX border region. NAM forecast sounding for BFF at 21z exhibits
   around 3000 J/kg MLCAPE with surface-6km bulk shear on the order of
   40kt. Environmental conditions appear very favorable for discrete
   supercells early in the convective cycle ahead of the surface low
   into northeast CO. With time, numerous supercell structures should
   grow upscale as they mature along/south of the aforementioned
   frontal zone. Very large hail will likely be noted with this early
   activity, and SRH values certainly suggest tornadoes will be a
   threat until storm mergers lead to a potentially significant MCS
   downstream over southern NE/northern KS. If an intense MCS does
   evolve, as seems possible, very damaging winds could be noted along
   the leading edge of this cluster as it surges east-southeast along
   the nose of a pronounced LLJ.

   Isolated severe thunderstorms will also develop south across the
   High Plains into west TX where strong afternoon heating will once
   again allow surface parcels to reach their convective temperatures
   by late afternoon. Modest southwesterly flow aloft will support
   supercells, and large hail/wind are the greatest risks along the
   southern dryline.

   Northeast...

   Moist plume characterized by PW values in excess of 1.5 inches
   currently extends across the lower MS/lower OH Valley into lower MI.
   Deep trajectories appear favorable for some of this moisture to be
   drawn northeast across the OH Valley into southern QC ahead of the
   primary front that will approach the international border by early
   evening. However, strong boundary-layer heating will be observed
   well ahead of the front where moisture content should be slightly
   drier, but noteworthy and sufficient for robust convection. Only
   minor changes have been made to earlier severe probabilities across
   this region and that is to extend the SLGT Risk south into VA where
   higher moisture content/stronger instability will be noted.

   Forecast soundings suggest scattered thunderstorms may develop
   across upstate NY, southwest across western PA into eastern OH by
   16-17z as surface temperatures warm through the 70s to near 80F.
   This activity will then spread/develop east across the Hudson Valley
   into portions of New England. Farther south, surface temperatures
   should warm into the upper 80s across the Delmarva region and this
   higher buoyancy may result in a greater risk of hail from eastern PA
   into northern VA as thunderstorms develop a bit later during the mid
   afternoon. Otherwise, damaging winds will likely be the greatest
   risk with multicellular updrafts that intensify during the heat of
   the day ahead of the short-wave trough.

[mob1]

15 percent hatched tornado contour added to the morning update. 

 

https://www.spc.noaa.gov/products/outlook/day1otlk.html

 

[OKTWISTER]

1 minute ago, mob1 said:

15 percent hatched tornado contour added to the morning update. 

[DanLarsen34]

Just now, OKTWISTER said:

Looks like today has real potential. The new outlook mentions the potential for several long-track, discrete cells that could produce significant tornadoes. Considerable spread remains, though, between models in terms of the exact details regarding convective evolution. Regardless, high-end damaging winds and some strong tornadoes will likely occur today. 

[Quincy]

HRRR shows convection holding off until just about 23-00z, but then erupting into a mixture of discrete and semi-discrete supercells. SPC cautioned that some CAMs show convection initiating several hours sooner. The 12z DDC sounding is cautionary as there isn’t much of a cap and the convective temperature is 80F. HRRR showed temps reaching the 80s by early afternoon. 

I’d think a compromise is probably the most realistic scenario, especially with HRRR having a “late” bias with CI. 

 

[OKTWISTER]

 I think Thursday will be upgraded to a Moderate Risk for S. KS and N. OK.  The upgrade would be for wind and hail but the 10% tornado hatch this morning may also be expanded. 

 

[StormChazer]

9 minutes ago, OKTWISTER said:

 I think Thursday will be upgraded to a Moderate Risk for S. KS and N. OK.  The upgrade would be for wind and hail but the 10% tornado hatch this morning may also be expanded. 

 

I think you're right, we do see a small moderate area, but that 10% tornado section is so dependent on where that boundary sets up tomorrow after tonight's storms. So I don't think we see a moderate risk or any hatched area for strong tornadoes until tomorrow morning's update(unless they throw a mod out sooner for the wind and hail).

Either way, I'll be chasing tomorrow. I'm in north Tulsa, so luckily(or unluckily) I don't have to drive far for a possible strong tornado.

[MUWX]

15 minutes ago, StormChazer said:

I think you're right, we do see a small moderate area, but that 10% tornado section is so dependent on where that boundary sets up tomorrow after tonight's storms. So I don't think we see a moderate risk or any hatched area for strong tornadoes until tomorrow morning's update(unless they throw a mod out sooner for the wind and hail).

Either way, I'll be chasing tomorrow. I'm in north Tulsa, so luckily(or unluckily) I don't have to drive far for a possible strong tornado.

I am thinking we get a moderate for wind or hail with the next update. I wouldn’t be shocked to see hatching added to the tor, but I would be shocked if we see 15% next update. 

[StormChazer]

15 minutes ago, MUWX said:

I am thinking we get a moderate for wind or hail with the next update. I wouldn’t be shocked to see hatching added to the tor, but I would be shocked if we see 15% next update. 

Yeah, this is what I'm thinking. If a cell can stay isolated enough on the boundary, then there is potential for a strong tornado. But I think there's only going to be 1, maaayyybe 2 cells that have that opportunity before they squall out. So I think hatching will be needed, but will stay at 10%.

[MUWX]

4 minutes ago, StormChazer said:

Yeah, this is what I'm thinking. If a cell can stay isolated enough on the boundary, then there is potential for a strong tornado. But I think there's only going to be 1, maaayyybe 2 cells that have that opportunity before they squall out. So I think hatching will be needed, but will stay at 10%.

I could potentially see it getting bumped to 15%, but not until tomorrow, and even then it’s probably a stretch. 

[StormChazer]

Liking the 12Z HRRR.

These would have some good tornado potential as they stay discrete enough for a couple hours.

[nrgjeff]

Today May 26: Parameter space supports SPC 15% hatched. 50kt at 500 mb and 40kt at 850 mb. Turning nearly 90 degrees. CAPE 3,000-4,000 j/kg.

Two boundaries may support cyclical supercells and multiple or long-track tornadoes. WF/OFB lifts north to around I-70. Been a focus of the CAMs for a few runs. Despite slight cluster risk, pattern recognition calls for supercells. 

Second boundary is the quasi-DL coming into southwest Kansas later. Winds remain backed ahead of it with ample moisture. While 700 mb is warm, the cap should bust via explosive development. I believe both targets are fairly equal.

Tomorrow May 27: Depends on overnight MCSs. Boundary should be draped in southern Kansas. While it may behave like a CF early, stalling makes it more OFB. Late May the CF crash risk is low. Terrain is not ideal in northeast Oklahoma; so, one would hope northwest Oklahoma or southeast Kansas. Still just enough cross-boundary upper flow for supercells.

PS Friday May 28, boundary still in West Texas. 

[StormChazer]

1 hour ago, nrgjeff said:

Terrain is not ideal in northeast Oklahoma; so, one would hope northwest Oklahoma or southeast Kansas. Still just enough cross-boundary upper flow for supercells.

 

Honestly, where the 10% tornado patch is, it's not too terribly bad terrain wise, there's a section between Interstate 75 and highway 99 with trees and some hills, but outside of that, it's fairly flat up there all things considered, unlike the stretch of 44 in between OKC and Tulsa as well as East Oklahoma(Yikes).

[OKwx_2001]

I'm in the southern part of the 10% tor risk for tomorrow. We'll see what happens. I've only had 1 severe thunderstorm warning this year so this should break the inactive streak. As long as the tors stay away from my house... And anyone else's 

[OhioWX]

The last few HRRR runs show an interesting trend for tonight. It shows an intense MCS develop and move across much of Nebraska, yet little to no convection across Kansas. With this scenario, a 45% hatched wind probability could easily verify in Nebraska, but the 15% hatched tornado probability would be a bust with minimal storm development in the area. We'll see how it pans out, but something to be wary of, especially for those chasing in Kansas.