June/July 2023 Severe Discussion

[Powerball]

25 minutes ago, cheese007 said:

What might be a good target area?

I'd say Wichita Falls and Lawton (that entire vicinity) for chasing.

18z HRRR was a supercell / tornadic bonanza for DFW proper though.

[Ed, snow and hurricane fan]

2 hours ago, Powerball said:

I'd say Wichita Falls and Lawton (that entire vicinity) for chasing.

18z HRRR was a supercell / tornadic bonanza for DFW proper though.

Cells are starting to grow upscale by the time they reach DFW around 9 pm, but STP of 10, don't see that everyday.  SPS storms happen before dark, however.  If I had to guess where a chaser would want to chase.

[Powerball]

6 hours ago, Ed, snow and hurricane fan said:

Cells are starting to grow upscale by the time they reach DFW around 9 pm, but STP of 10, don't see that everyday.  SPS storms happen before dark, however.  If I had to guess where a chaser would want to chase.

18z HRRR was definitely a worst case scenario for DFW. The 00z and especially the 06z have backed off a fair bit, with somewhat stronger capping and somewhat slower timing

That said, one thing which stands out (and while I'm not entirely convinced on the upscale growth part) is all the drier air above 850mb. This could allow for a few things, which is the cells remaining discrete for a longer period (which would be concerning as low level shear really picks up during the early evening hours), but also for outflow boundaries (with there no longer being a stable surface layer unlike the past 48-72 hours) to either trigger more numerous storms further SE than what the CAMs are currently depicting or cause them to propagate further SE than currently depicted on the CAMs given the negligible capping in place.

[yoda]

 

[cheese007]

D1 Mod risk is a big jump in one go (though with the caveat it is Broyles)

Forecast Discussion

SPC AC 150601 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0101 AM CDT Thu Jun 15 2023 Valid 151200Z - 161200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHWEST KANSAS...WESTERN OKLAHOMA AND THE FAR NORTHEAST TEXAS PANHANDLE... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS AND GULF COAST REGION... ...SUMMARY... Widespread severe storms associated with damaging wind gusts, large hail and a few tornadoes are expected today across parts of the southern and central Plains. Hailstones greater than 2 inches in diameter and wind gusts above 70 knots will be likely along the more intense parts of a fast-moving line of storms. A severe threat is also expected to develop in parts of the Southeast, and in parts of the Ohio Valley. ...Significant Severe Weather Event Expected Today Across Parts of the Southern and Central Plains... ...Southern and Central Plains... A shortwave trough will move into the central U.S. today, as an associated 80 to 95 knot upper-level jet moves into the southern Plains. Ahead of the jet max, a moist and very unstable airmass will be in place from parts of central and north Texas into western Oklahoma and the eastern Texas Panhandle. At the surface, a low will deepen across the southern High Plains as a cold front moves southward through the central High Plains. Ahead of the front, surface heating and increasing low-level convergence will likely result in convective initiation early this afternoon. Storms will rapidly increase in coverage along an axis of strong instability from southwest Kansas south-southeastward across the far northeastern Texas Panhandle and into western Oklahoma. As storms grow upscale, MCS development is expected to occur late this afternoon and be maintained through the evening. By midday, a narrow corridor of maximized low-level moisture is forecast from northwest Texas extending north-northwestward into southwest Kansas. MLCAPE is forecast to reach the 3000 to 4500 J/Kg range by mid afternoon. In addition, RAP forecast soundings have low to mid-level lapse rates approaching 9.0 C/km. This potent thermodynamic environment will be augmented by an increase of deep-layer shear throughout the day, as an upper-level jet moves in from the west-southwest. Upon approach, an increase in large-scale ascent will be coupled with strengthening deep-layer shear. RAP forecast soundings suggest that 0-6 km shear could reach 60 to 70 knots along the instability axis, which will be very favorable for severe storms. The current thinking is that cells will first initiate in the early afternoon, with supercells forming rather quickly. A small cluster is expected to rapidly expand during the mid afternoon, as a line of supercells develops. Hailstones of greater than 2 inches in diameter, along with a tornado threat will be possible with the more intense supercells. As the convective cluster grows upscale in the mid to late afternoon, a Derecho will become possible as an organized severe line segment moves southeastward across the southern Plains. Wind gusts ahead of the more intense parts of the line will likely be greater than 70 knots. A few tornadoes will be possible, along with a continued threat for large hail from late afternoon into the evening. The MCS, associated with a potential for damaging wind gusts, could move into the Ark-La-Tex by mid to late evening, and into parts of the lower Mississippi Valley during the overnight period. ...Southeast... A shortwave trough will move through the central Gulf Coast states today, as a cold front advances southward across toward the central and eastern Gulf Coast. Ahead of the front, surface dewpoints in the lower to mid 70s F, will contribute to strong destabilization by afternoon. MLCAPE is forecast to peak in the 2000 to 3000 J/kg range by afternoon. Thunderstorms are expected to form ahead of the front, and will likely be concentrated along pre-existing outflow boundaries. The greatest coverage could occur from far southern Alabama extending eastward into northern Florida, where strong deep-layer shear is forecast to be strong and low-level lapse rates are forecast to be steep. This should lead to a wind-damage threat in the late morning and early afternoon, as storms gradually intensify. An isolated tornado threat and potential for large hail will also likely exist with the stronger cells. The severe threat should move toward the immediate coastal areas during the afternoon as the cold front advances southward. Further northeast into southeast Georgia and southern South Carolina, moderate instability is forecast to develop by midday. A vorticity maximum is expected to move eastward across southern South Carolina around midday, which should support scattered convective development. Thunderstorms that form within the stronger instability could be associated with isolated damaging wind gusts and hail. ...Ohio... An upper-level trough will move southeastward today across the Great Lakes region, as a cold front advances southeastward into Indiana and Ohio. Ahead of the front, surface dewpoints are forecast to be in the lower 60s F. As surface temperatures warm along the moist axis during the day, a pocket of moderate instability is forecast by early afternoon. Thunderstorms will likely form along and ahead of the front, moving southeastward into the Ohio Valley. RAP forecast soundings near this maximum in instability have MLCAPE peaking in the 1500 to 2000 J/kg range, with 0-3 km lapse rates exceeding 8.0 C/Km. This should be enough for a marginal wind-damage threat with the more intense line segments. A threat for hail will also be possible. ..Broyles/Bentley.. 06/15/2023

[Powerball]

Hmmm, I'm liking the look of the 12z CAMs so far...

[yoda]

SPC moved the ENH and MOD risks further into TX on the 1630z OTLK 

 

Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1130 AM CDT Thu Jun 15 2023

   Valid 151630Z - 161200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
   INTO TONIGHT FROM WESTERN OK AND VICINITY INTO NORTH TX...

   ...SUMMARY...
   Widespread severe storms associated with giant hail (larger than 3-4
   inches in diameter), intense wind damage (greater than 80 mph) and a
   few tornadoes are expected from mid afternoon into tonight across
   western and southern Oklahoma into north and northeast Texas.

   ...Southern Plains this afternoon through tonight...
   A midlevel shortwave trough is moving east-northeastward across
   northern NM as of late morning, and in response to this wave weak
   lee cyclogenesis is underway across northeast NM/southeast CO.  This
   will help draw rich low-level moisture northwestward through the
   afternoon, with mid-upper 60s boundary-layer dewpoints reaching
   western OK/eastern TX Panhandle, and low-mid 70s farther southeast
   into northwest and north TX.  The moistening is occurring beneath
   very steep midlevel lapse rates near 9 C/km, which will contribute
   to extreme buoyancy (MLCAPE in excess of 4000 J/kg) this
   afternoon/evening along the warm front and east of the dryline.

   Severe storm development is expected by early-mid afternoon along
   the dryline from the TX Panhandle into southwest KS, with subsequent
   development on the dryline into northwest TX.  The extreme buoyancy,
   steep lapse rates and very long hodographs will all be quite
   favorable for intense supercells capable of producing giant hail
   (3-4 inches in diameter or greater).  Despite modestly high
   temperature-dewpoint spreads (20 to 25 F) initially, a gradual
   increase in low-level shear/hodograph curvature will support some
   tornado threat late this afternoon/evening.  

   As storms spread eastward this evening, upscale growth into one or
   more clusters appears likely, with an increasing threat for swaths
   of intense gusts in excess of 80 mph.  The corridor of the most
   intense storms is expected across western/southern and parts of
   central OK, as well as north TX.  Thus, the ENH/MDT risk areas have
   been expanded southward and southeastward into TX to reflect both
   the high-end hail threat with the initial supercells, and a high-end
   wind threat with any late evening/overnight storm clusters.

[Powerball]

Today is really escalating quickly.

 

[Powerball]

The parameters over Dallas are already on the extreme end, and we haven't even reached peak heating / shear (not to mentiom, the best surge of moisture is still looming in Central TX).

You can see the old outflow boundary from yesterday on the Satellite marked by a congested billowing CU field, slowly meandering NE, although nothing should come of it for now.

[radarman]

DFW may approach all time record dews of 80F.  It's been hit 5 times, interestingly, twice in 97 (late may, again mid June).

[Quincy]

Looks like we’ll have several intense supercells today. The entire region from North Texas to the OK/TX panhandles looks to have a higher end parameter space. 

I’d suspect storm modes get clustered/linear by early evening across central/northern Oklahoma. More discrete storms appear probable across southern Oklahoma and North Texas  

DFW may be in the cross hairs as a tail end Charlie storm could tap into lower 70s dews and prove to become quite intense.

 

[radarman]

FWD disco casually dropping mentions of Jarrell 97

[Quincy]

40 minutes ago, radarman said:

FWD disco casually dropping mentions of Jarrell 97

Saw that. Was kind of odd. I almost posted an analog (5/15/03), but it shows a regional tornado outbreak and has a few key differences synoptically. 

This is really a unique event given the time of year. I can’t say that there are many analogs that seem to closely match today. You could see mostly hailers with big wind later, given higher LCLs and modest low level shear. On the other hand, you could have a couple of strong/intense tornadoes, IF sustained storms manage to remain at least semi discrete, and can tap into better moisture and low level shear after 23-00z.

[Powerball]

Not sure I've ever seen this wording in a MD...

Mesoscale Discussion 1076
   NWS Storm Prediction Center Norman OK
   0149 PM CDT Thu Jun 15 2023

   Areas affected...Central/Eastern OK Panhandle...Western/Central
   OK...Eastern TX Panhandle...Far Northwest TX

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

   Valid 151849Z - 152045Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Intense supercell thunderstorms capable of all severe
   hazards, including giant hail, hurricane-force wind gusts, and
   tornadoes, are expected across the region this afternoon and
   evening.

   DISCUSSION...Visible satellite imagery currently shows an expanding
   cumulus field from the central/eastern OK Panhandle down through the
   eastern TX Panhandle and into far northwest TX. Thus far, most of
   the cumulus within this field have a relatively flat appearance,
   with only a few pockets with more vertical development (i.e. over
   far southwest OK/far northwest TX and central OK Panhandle). Recent
   mesoanalysis suggests some convective inhibition remains, which is
   verified with the appearance of the cumulus field. 

   Continued air mass destabilization is anticipated, with the limited
   convective inhibition likely eroding over the next hour. This
   erosion of the inhibition coupled with forcing for ascent attendant
   to the approaching shortwave trough, and additional mesoscale ascent
   related to the low-level confluence over the region, will likely
   result in convective initiation by 20Z (perhaps even sooner). 

   The air mass over the region represents a rare combination of
   buoyancy of shear during any time of the year, but particularly mid
   June. Forecast sounding suggest MLCAPE from 3000 to 4000 J/kg  and
   effective bulk shear from 60 to 70 kt when storms initiate. These
   type of environment will result in intense supercells, capable of
   all severe hazards, including giant hail (3"+ in diameter),
   hurricane-force wind gusts, and tornadoes. The tornado potential may
   be mitigated somewhat by the higher LCLs and relatively modest
   low-level shear. However, given the overall character of the
   environment, tornadic supercells cannot be ruled out.

   ..Mosier/Thompson.. 06/15/2023

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

   ATTN...WFO...FWD...OUN...LUB...AMA...

   LAT...LON   36000116 36710153 36990125 36970023 35899812 34249711
               33809804 33989945 34189999 34620034 36000116 

[yoda]

Interested in what kind of watches are issued.  As the MCD says, it will be a tornado watch.  However, with winds likely over 80 mph (I'm guess text will say to 90mph and hail to 4" in diameter)... could they go PDS just to cover everything even though no violent tornadoes are likely?

[Quincy]

8 minutes ago, yoda said:

Interested in what kind of watches are issued.  As the MCD says, it will be a tornado watch.  However, with winds likely over 80 mph (I'm guess text will say to 90mph and hail to 4" in diameter)... could they go PDS just to cover everything even though no violent tornadoes are likely?

Interesting situation. I can’t imagine they’d go with a PDS tornado watch with relatively “low” significant tornado probabilities. Also, if storm mode stays relatively discrete, especially south of I-40, can’t see them going with a severe thunderstorm watch. 

Maybe an initial tornado watch out west and wait for a later watch near I-35?

[Powerball]

A regular Tornado Watch with strong wording for hail/wind is likely the way they'll go.

Looks like some initiation is trying to occur near Altus.

[Powerball]

9 minutes ago, Powerball said:

A regular Tornado Watch with strong wording for hail/wind is likely the way they'll go.

Looks like some initiation is trying to occur near Altus.

And there it is...

 

[Quincy]

95/95 probabilities for large hail/sig hail

[Powerball]

17 minutes ago, Powerball said:

And there it is...

 

 

"Hail Up to DVD Size"

 

[cheese007]

Heading in the direction of Wichita Falls. Depending on how things shake out may end up doubling back to DFW if the "tail end charlie" ends up down here 

[Quincy]

Seceral WoFS members show convective initiation across North Texas by 21-22z. That would not surprise me at all, given recent trends. 

 

[Powerball]

Low level shear is unimpressive (for now), but otherwise, talk about a powder keg...

[Powerball]

 

[Chinook]

Wow, big upgrade from slight risk as of 1730z yesterday

[Powerball]

 

[Chinook]

and so it starts with a couple of supercells jammed together

 

[Powerball]

3 minutes ago, Powerball said:

 

 

And another one with word for DVD sized hail...

 

[Chinook]

Ryan Hall stream says chasers/spotters saw a tornado in Lawton with some buildings damaged

[Chinook]

Lawton tornado several minutes ago. Also, new possible tornado about 20 miles east of Lawton