February 26-27, 2023 | Severe Storms

[Iceresistance]

8 minutes ago, Neoncyclone said:

Speaking of, the new outlook is out now lol. 10% hatched maintained and very very slightly expanded to the east, don't think it expanded north much at all. 

They've mentioned the serious possibility of a Derecho with winds up to 110 mph, how is this not a High Risk? Too much uncertainty?

[Neoncyclone]

2 minutes ago, Iceresistance said:

They've mentioned the serious possibility of a Derecho with winds up to 110 mph, how is this not a High Risk? Too much uncertainty?

Wind-driven high risks are very rare, and like @ClicheVortex2014 said, none of the most notable derechos in like the last 15 years have been high-risk.

Generally it seems that high-risk days are reserved for tornado-driven events, which is important because when those days do happen people need to take it very seriously.

[Iceresistance]

2 minutes ago, Neoncyclone said:

Wind-driven high risks are very rare, and like @ClicheVortex2014 said, none of the most notable derechos in like the last 15 years have been high-risk.

Generally it seems that high-risk days are reserved for tornado-driven events, which is important because when those days do happen people need to take it very seriously.

Today also needs to be taken very seriously as well, this could be literally a giant EF-0 to EF-1 Tornado with more Embedded EF-2 strength that screams to the east from the Texas Panhandle to Missouri and Arkansas. This could be similar to the 2020 Iowa Derecho in terms of intensity.

Edited February 26, 2023 by Iceresistance

[Iceresistance]

Strong wording from the SPC

Spoiler

Just-in-time moisture return from the western Gulf is still
   anticipated ahead of a powerful shortwave trough ejecting from the
   Southwest to the Lower MO Valley. 60+ F surface dew points remain
   confined from the Piney Woods of east TX to the Concho Valley and
   Edwards Plateau of west TX as of 16Z. Guidance continues to differ
   with the northern extent of this richer moisture by evening in KS/OK
   beneath a stout elevated mixed layer. Widespread cloudiness is also
   evident over much of the southern Great Plains, although clearing
   should occur from west to east across the High Plains. The net
   result should be a narrow plume of surface-based instability along
   the dryline from southwest KS to west TX between 21-00Z. 

   Scattered convection will break out after 21Z along the dryline and
   become supercellular towards 00Z given very favorably enlarged low
   to mid-level hodographs. Further moistening into the evening should
   result in the most favorable potential for supercell tornadoes in
   southwest OK between 00-03Z, in addition to very large hail.
   Convection will likely grow quickly upscale into a solid QLCS,
   accelerating east-northeast with embedded supercells and
   mesovortices. Extreme low-level shear profiles in conjunction with
   strengthening of 700-mb winds to around 90 kts behind the line
   should result in widespread severe wind gusts. Embedded swaths of
   80-110 mph winds both straightline and rotating are likely, with
   stronger speeds into the EF2 range possible, until the QLCS outpaces
   the richer moisture in the OK/KS/MO border area overnight. Scattered
   damaging winds from strong to severe gusts may linger through the
   early morning across MO towards the Mid-MS Valley, despite little to
   no buoyancy, given the intense low-level wind fields.

 

[Neoncyclone]

5 minutes ago, Iceresistance said:

Today also needs to be taken very seriously as well, this could be literally a giant EF-0 to EF-1 Tornado that screams to the east from the Texas Panhandle to Missouri and Arkansas. This could be similar to the 2020 Iowa Derecho in terms of intensity.

https://www.spc.noaa.gov/products/outlook/archive/2020/day1otlk_20200810_1630.html

This is the Day 1 outlook for the August 10, 2020 Derecho. It's a moderate risk.

A moderate risk should be taken very seriously. Not every high-impact event should have a high risk slapped on it, it's reserved for top tier events that pose seriously significant threat to life and property.

Should be a very impressive derecho regardless, everyone in the risk area should definitely be paying attention this afternoon. 

 

Edited February 26, 2023 by Neoncyclone

[Iceresistance]

1 minute ago, Neoncyclone said:

https://www.spc.noaa.gov/products/outlook/archive/2020/day1otlk_20200810_1630.html

This is the Day 1 outlook for the August 10, 2020 Derecho. It's a moderate risk.

A moderate risk should be taken very seriously. Not every high-impact event should have a high risk slapped on it, it's reserved for top tier events that pose seriously significant threat to life and property. 

 

I suppose you're right on this one, I think the only time there is a High Risk for wind is if there are extreme parameters in place for a destructive wind event (Derecho) that has very strong model consistency to it. This event has lower instability because of a "Just-in-time" moisture return. I think that the only time they will even consider a High Risk for destructive winds is when the moisture return is stronger than expected, the shear is stronger than expected, or the storms are further to the east than originally thought.

 

My Storm Shelter is ready.

[Neoncyclone]

2 minutes ago, Iceresistance said:

I suppose you're right on this one, I think the only time there is a High Risk for wind is if there are extreme parameters in place for a destructive wind event (Derecho) that has very strong model consistency to it. This event has lower instability because of a "Just-in-time" moisture return. I think that the only time they will even consider a High Risk for destructive winds is when the moisture return is stronger than expected, the shear is stronger than expected, or the storms are further to the east than originally thought.

 

My Storm Shelter is ready.

You're right about the moisture situation, but even then, it's really hard to justify a wind-driven high risk unless it's being shared with at the very least a moderate risk of tornadoes. Straight-line winds (especially in excess of 100MPH) are incredibly destructive to property, but generally the threat to life is low. 

Edited February 26, 2023 by Neoncyclone

[ClicheVortex2014]

9 minutes ago, Iceresistance said:

I suppose you're right on this one, I think the only time there is a High Risk for wind is if there are extreme parameters in place for a destructive wind event (Derecho) that has very strong model consistency to it. This event has lower instability because of a "Just-in-time" moisture return. I think that the only time they will even consider a High Risk for destructive winds is when the moisture return is stronger than expected, the shear is stronger than expected, or the storms are further to the east than originally thought.

 

My Storm Shelter is ready.

There's been better candidates for a wind-driven high risk than today but they remained a moderate risk. The bar is just set super high... as it should be. 

I would say focus on the wording, not the category. A derecho is expected to happen with 80-110 mph winds. As long as convection is surface-based, there'll be a threat for tornadoes within the line

Edited February 26, 2023 by ClicheVortex2014

[Iceresistance]

Dew Point has been increasing by 2°F every hour. It's now close to 50°F DP.

[Iceresistance]

SREF has strong parameters for a Derecho across Oklahoma, and the STP is 30%, Supercell Composite is also at a higher parameter as well.

 

GEFS has a mean Supercell Composite of 10, this is going to be ugly.

Edited February 26, 2023 by Iceresistance

[StormfanaticInd]

This could be bad

[snowlover2]

Slight risk expanded in the OV on updated day 2.

Quote

Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1105 AM CST Sun Feb 26 2023

   Valid 271200Z - 281200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS DURING THE DAY
   FROM ILLINOIS INTO OHIO...

   ...SUMMARY...
   Thunderstorms may produce a few damaging gusts or brief tornadoes
   Monday from parts of Illinois into Ohio and far northern Kentucky.

   ...Synopsis and Discussion...
   A potent shortwave trough will move from MO Monday morning toward
   Lower MI by 00Z, as a surface low occludes from IA toward Lake MI.
   The occluded front will translate east from IL into IN and OH, with
   a warm front moving from northern KY into central OH. 

   The most favorable instability will be associated with the midlevel
   cold pocket, with up to 500 J/kg MLCAPE possible over IL and IN
   through 18Z. After this time, CAPE values will generally remain
   below 250 J/kg near the warm front with mid 50s F dewpoints common.
   An expansive area of strong shear will exist over the entire region,
   with 850 mb winds around 60 kt aiding strong SRH values.

   An arcing line of storms is expected to be ongoing ahead of the vort
   max across central IL early Monday, and is forecast to move into IN
   by 18Z. This activity may produce damaging winds or brief tornadoes
   given sufficient low-level instability and strong shear. Storm mode
   may remain linear, as these storms will be tied to the midlevel
   cooling.

   Farther east, additional cells may develop where heating occurs and
   into the warm advection zone from KY into OH. Isolated supercells
   may occur here, on the southern fringe of the midlevel vort max and
   near the warm front where shear will be strong. Degree of
   destabilization will be the main mitigating factor regarding tornado
   threat.

   ..Jewell.. 02/26/2023

 

[Iceresistance]

There could be a possibility that the Moderate risk is expanded further south to accommodate the high Derecho Parameters.

[ClicheVortex2014]

A book was written by the AMA midnight shift

.SHORT TERM ...
(Today through tonight)
Issued at 356 AM CST Sun Feb 26 2023

It would not be the Texas and Oklahoma Panhandles without having
non-convective winds up to 75 mph, fire weather conditions, areas
of blowing dust, and severe thunderstorms with the potential for
large hail up to ping pong ball size, convective winds up to 80
mph, and potential for tornadoes...all in the same day. Oh and
some areas may start with some fog this morning. Welcome to the
Panhandles.

Lets start with this morning. Latest 08Z observations this
morning shows southerly to southwesterly winds beginning to advect
LL moisture towards the Panhandles with low clouds and some fog
being reported across portions of the south Texas Plains. Current
hi- res model trends are in agreement with some patchy to areas of
fog and/or drizzle for portions of the southern TX Panhandle,
perhaps as far north as the Canadian River valley through about
14-16Z this morning before conditions improve.

We continue to watch the main H500 low pressure move east across
portions of southern California this morning. The main UL low is
still expected to move east across all of the Panhandle and exit
the Panhandles region by 01-03Z Monday. H850/700/500
corresponding jet streaks will intensify as they move east into
the Texas Panhandle and Texas South Plains along and just
downstream of the main H500 low pressure system going into this
afternoon. Closer to the surface as we go into the early afternoon
hours, the potential for cloud cover will still be a concern,
especially for areas in the central and eastern Panhandles. This
should make it quite difficult to have convection initiation early
on in the afternoon as surface heating will be impacted. Back
towards the western Panhandles, the main Pacific front should
enter the western areas sometime between 17-19Z. As it does so,
any residual clouds should clear out quickly. Timing the
progression with the better H850-700 (320+)K theta-e advection
right ahead of the main front along with very good bulk shear of
30-40 kts and a cold column aloft with MLCAPE as high as 750-1250
J/kg, with forcing from the Pacific front, convection should
quickly develop somewhere within the central combined Panhandles.
With the slightly slower progression of the main upper level low
than the previous models eluded to, some scenarios point out to
convection developing as far west as the US-385 corridor. But
forward propagation of the Pacific front along with the better
low level theta-e advection favors areas just east of a line from
Amarillo to Guymon as the potential for the furthest west
convection development. With lowest level shear at an acute angle
to the main Pacific front, if convection development is not
explosive all at once with some domain of separation, very early
on, discrete supercells will be likely. Depending how erect the
main lone updrafts can tap into the colder airmass aloft with
favorable, large hail up to ping pong ball size, along with
damaging wind gusts and even a tornado cannot be ruled out. This
window of discrete cells should be rather brief.

Going past 21Z through 00-01Z Monday, the main mode of convection
will shift to linear as widespread lift from the Pacific front and
now the main vort max rounding the base of the neutral-negative
tilted H5000 trough. Damaging wind threat will be the main
concern moving forward across the eastern Panhandles. Lower LCL
values as low as sub 700m across the far eastern TX Panhandle with
continued good LL directional shear may help to develop kinks in
the main line of thunderstorms where QLCS tornadoes(s) cannot be
completely ruled out. Storm motion along and just ahead of the
line will be very quickly to the east between 50-60 mph. Deeper
convection along the line tapping into the stronger winds aloft
mixing down gusts of 80 mph within the convection will be the
higher probability of severe thunderstorms threats followed by
QLCS tornado at a lower probability, but one to note. The last of
the precipitation should exit the Panhandles between 01-03Z before
the severe thunderstorm threat comes to an end.

But this will not be the last of the active weather for today into
tonight. Back tracking a bit, in the wake of the Pacific front
as it enters the combined Panhandles from NM, any clouds leftover
should clear out quickly as downslope WSW flow and lowering Td
values will move in from west to east. Winds along the NM state
line, in particular for the Texas counties may experience the
strongest sustained winds and peak gusts with gusts as high as 75
mph with 60 to 70 mph with the remainder of the TX Panhandle
along with the central and western OK Panhandle. Areas that do not
see rain today may also have the highest probabilities to contend
with areas of blowing dust. Winds should finally subside by early
morning hours on Monday.

 

[ClicheVortex2014]

Special 18z soundings. Strong cap at AMA.

 

Upstream low-level airmass

[Iceresistance]

5 minutes ago, ClicheVortex2014 said:

Special 18z soundings. Strong cap at AMA.

 

Upstream low-level airmass

Supercell Composite is increasing near Lubbock, TX per College of DuPage Satellite.

[ClicheVortex2014]

Well, about time to join the madness at work. Should be quite a day.

[Ingyball]

Don't like how much sun we're getting here. Thought we would be clouded (and possibly fogged) in all day. The airport is up to 61 already, gonna bust our high forecast lol. I'll be heading into work in a little while so won't be able to chat here. Should be a fun night though. 

[Iceresistance]

Moderate risk slightly larger in the 2 PM Update

[snowlover2]

9 minutes ago, Iceresistance said:

Moderate risk slightly larger in the 2 PM Update

10% tornado area expanded NE some too.

Quote

  Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0155 PM CST Sun Feb 26 2023

   Valid 262000Z - 271200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM THE EASTERN
   TEXAS PANHANDLE ACROSS MUCH OF OKLAHOMA...

   ...SUMMARY...
   A derecho is forecast with widespread damaging winds and embedded
   swaths of significant severe gusts from 80-110 mph, centered on
   parts of Oklahoma this evening into tonight. Embedded tornadoes are
   anticipated as well, with the greatest potential for strong
   (EF2-EF3) tornadoes across southwest Oklahoma this evening.

   ...20Z Update...
   Primary minor changes to the outlook include expanding the
   significant tornado probabilities a bit northeast toward
   north-central Oklahoma, and to include an additional portion of the
   far eastern Texas Panhandle in the Moderate Risk area.

   Visible imagery as well as surface observations indicate rapid
   changes are underway across the region with continued
   thinning/erosion of the low-level clouds over northwest Texas and
   southwest Oklahoma, and widespread severe wind gusts across New
   Mexico ahead of the upper trough.

   Initial storms are likely to form from southwest Kansas into the
   Texas Panhandle between 21-00Z, with damaging winds, large hail, and
   tornadoes as dewpoints rise further. Cells will likely merge into a
   linear MCS/Derecho, producing gusts over 80 mph and isolated
   tornadoes across Oklahoma this evening. Strong forcing along the
   front should counteract convective inhibition, with severe wind both
   within the line and possibly behind it as post-frontal
   boundary-layer mixing persists.

   ..Jewell.. 02/26/2023

 

[Iceresistance]

16 minutes ago, Ingyball said:

Don't like how much sun we're getting here. Thought we would be clouded (and possibly fogged) in all day. The airport is up to 61 already, gonna bust our high forecast lol. I'll be heading into work in a little while so won't be able to chat here. Should be a fun night though. 

It's going to be a crazy one, Dew Point is 54°F at my location.

[snowlover2]

Here we go.

Quote

  Mesoscale Discussion 0189
   NWS Storm Prediction Center Norman OK
   0236 PM CST Sun Feb 26 2023

   Areas affected...Southwest KS...Eastern TX/OK Panhandles...Western
   OK

   Concerning...Severe potential...Tornado Watch likely 

   Valid 262036Z - 262230Z

   CORRECTED TO INCREASE WATCH PROBABILITY

   Probability of Watch Issuance...95 percent

   SUMMARY...Fast-moving supercells capable of all severe hazards,
   including significant wind gusts over 80 mph, very large hail
   greater than 2 inches in diameter, and tornadoes, are expected to
   develop across the region this afternoon and evening. A Tornado
   Watch will be needed within the next hour or two.

   DISCUSSION...Significant air mass modification continues across the
   southern Plains ahead of an intense upper low moving out of the
   Southwest. Much of the eastern TX and OK Panhandles and western OK
   have experienced dewpoint increases of 4 to 8 deg F over the past 3
   hours. This modification is expected to continue as large-scale
   forcing for ascent attendant to the approaching low increases,
   likely resulting in thunderstorm initiation during the next hour or
   two from southwest KS across the eastern OK and TX Panhandles and
   into northwest TX. 

   Wind fields, which are already quite strong, are expected to further
   strengthen as the system approaches. Current mesoanalysis estimates
   the 0-6 km shear is already 70 kt, with forecast soundings
   suggesting an increase to 85-90 kt is anticipated by 00Z. Forecast
   hodographs also show robust low veering with height, supported by
   50-60 kt flow around 1 km. Forecast soundings show surface to 500 m
   storm-relative helicity is over 300 m2/s2 across the eastern TX and
   OK Panhandles at 00Z.

   These environmental conditions are very supportive of supercells
   capable of all severe hazards, including significant wind gusts over
   80 mph, very large hail greater than 2 inches in diameter, and
   tornadoes. Upscale growth into a linear convective line is
   anticipated, with strong wind gusts and embedded tornadoes possible
   once this transition occurs. A Tornado Watch will be needed in the
   next hour or two to cover this potential.

   ..Mosier/Grams.. 02/26/2023

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...OUN...DDC...LUB...AMA...

 

[Iceresistance]

Mesoscale Discussion has a "SEVERE THUNDERSTORM WATCH LIKELY" for Southern Kansas

[snowlover2]

17 minutes ago, Iceresistance said:

Mesoscale Discussion has a "SEVERE THUNDERSTORM WATCH LIKELY" for Southern Kansas

Quote

 URGENT - IMMEDIATE BROADCAST REQUESTED
   Severe Thunderstorm Watch Number 42
   NWS Storm Prediction Center Norman OK
   320 PM CST Sun Feb 26 2023

   The NWS Storm Prediction Center has issued a

   * Severe Thunderstorm Watch for portions of 
     Southwest Kansas

   * Effective this Sunday afternoon and evening from 320 PM until
     800 PM CST.

   * Primary threats include...
     Scattered damaging winds and isolated significant gusts to 80
       mph possible
     A tornado or two possible

   SUMMARY...High-based thunderstorms will spread rapidly northeast
   across southwest Kansas. Initially well-mixed thermodynamic profiles
   will support severe wind gusts as the primary hazard.

   The severe thunderstorm watch area is approximately along and 60
   statute miles east and west of a line from 75 miles north northeast
   of Dodge City KS to 25 miles south southwest of Dodge City KS. For a
   complete depiction of the watch see the associated watch outline
   update (WOUS64 KWNS WOU2).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A Severe Thunderstorm Watch means conditions are
   favorable for severe thunderstorms in and close to the watch area.
   Persons in these areas should be on the lookout for threatening
   weather conditions and listen for later statements and possible
   warnings. Severe thunderstorms can and occasionally do produce
   tornadoes.

   &&

   AVIATION...A few severe thunderstorms with hail surface and aloft to
   1.5 inches. Extreme turbulence and surface wind gusts to 70 knots. A
   few cumulonimbi with maximum tops to 400. Mean storm motion vector
   22050.

   ...Grams

 

[ElectricStorm]

Tornado watch is up now, 60/40 tor probs, 90/90 wind