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Mid to Late May 2019 Severe Threats


Quincy
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Let's look at the 00z sounding from DDC, a lucky RAOB very close to where a tornadic supercell formed just a short time later.

Note the enlarged low-level hodograph. The vast majority of the SRH was contained in the lowest 0-1km. Even though wind fields look unidirectional above 700mb, it's really all about the lower level wind fields. 32 knots of 0-1km shear and >300 m2/s2 0-1km SRH and I'm sure that only increased leading up to the cyclic supercell. Of course, there was large buoyancy, relatively steep lapse rates and more than adequate deep layer shear as well. 
DDC_RAOB_19051800.thumb.png.b3d18336d5ed853b555e1cc468166b9c.png

A faint convective signal along the dryline in the models can end up going big one way or the other (blue sky bust vs. intense supercell). In this case, there was more than ample large scale forcing and substantial height falls impinging on western Kansas was enough. I will admit that I wasn't overly focused on this event since I was not chasing, but I would have favored the southern target (Southwest Texas) due to the questions regarding convective initiation.

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2 hours ago, Indystorm said:

OKC discussion expects that a MCS will affect the southern half of the state overnight tonight and then emphasizes that recovery might take place Sat. afternoon.   No sign of such a system on radar as of yet.  If it does not form tomorrow may be significantly enhanced more than originally expected even though eyes are presently on Monday.

SPC just issued a MD for W into north central TX... 60 percent chance of a STW

https://www.spc.noaa.gov/products/md/md0663.html

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45 minutes ago, yoda said:

Why is DDC putting "this is an emergency situation" at the end of their warning again?  Shouldn't it be at the beginning?

DDC will respond with the information at hand and balance it with the utmost consideration for human life and not based on the observances of a radar warrior

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5 minutes ago, METALSTORM said:

DDC will respond with the information at hand and balance it with the utmost consideration for human life and not based on the observances of a radar warrior

I'm not being a radar warrior... I am just asking a simple question of why they did that.  Usually, if it's an emergency situation as it said in the warning with regards to a confirmed large and dangerous tornado on the ground, then it would be at the very start of the warning.  I'm just wondering, that's all.  Not trying to call out DDC at all

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4 minutes ago, yoda said:

I'm not being a radar warrior... I am just asking a simple question of why they did that.  Usually, if it's an emergency situation as it said in the warning with regards to a confirmed large and dangerous tornado on the ground, then it would be at the very start of the warning.  I'm just wondering, that's all.  Not trying to call out DDC at all

The radar warrior part was me being a lousy poster. Sorry, I'm hammered and just got uppity about defending their wording. I assume somtimes they add things on the fly during a fast changing situation. I was a d##k in my statement and I do apologize

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44 minutes ago, METALSTORM said:

The radar warrior part was me being a lousy poster. Sorry, I'm hammered and just got uppity about defending their wording. I assume somtimes they add things on the fly during a fast changing situation. I was a d##k in my statement and I do apologize

That's alright :) No problem... hope you have a good night

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16 minutes ago, Chinook said:

45% counts as moderate risk, but the graphics and discussion only say enhanced risk. 

Do you really think that a 30-45% risk will be realized over 107,996 square miles??

 

45% hatched constitutes a moderate risk, otherwise 45% wind is enhanced, it's just very uncommon to see a 45% non-hatched wind outlook. 

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Here comes the MCS or combo of MCS and supercells

https://www.spc.noaa.gov/products/md/md0664.html

Mesoscale Discussion 0664
   NWS Storm Prediction Center Norman OK
   0135 AM CDT Sat May 18 2019

   Areas affected...west-central into north Texas...southern Oklahoma

   Concerning...Severe potential...Watch likely 

   Valid 180635Z - 180900Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Severe storms are expected to develop and organize across
   west Texas, and rapidly develop northeastward across northwest Texas
   into southern Oklahoma. Significant damaging winds and a few
   tornadoes are possible.

   DISCUSSION...Substantial moisture and strong instability are already
   in place across much of TX, with persistent south/southwest 850 mb
   low-level jet of 40 kt. This will maintain an unstable and
   relatively uncapped air mass in place as height falls with the upper
   trough occur throughout the night. While isolated severe storms
   currently exist over parts of southwest TX, a marked increase in
   development is expected in the 07-09Z time frame, with upscale
   organization likely. A few supercells are possible given substantial
   veering winds with height and strong instability with steep lapse
   rates aloft, although there is a veer-back signal above 700 mb.
   Therefore, a mixed storm mode is expected, with a threat of both
   widespread damaging winds with bows and with a few embedded/brief
   tornadoes. This threat will accelerate northeast into southern OK by
   12-15Z, and toward the Dallas/Ft. Worth area shortly thereafter with
   a continued severe threat to the east.

   ..Jewell/Bunting.. 05/18/2019

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

   ATTN...WFO...FWD...OUN...SJT...LUB...MAF...
 
   

mcd0664.gif

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10 minutes ago, yoda said:

Now that's got to be rare... day 3 moderate risk issued

Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0230 AM CDT Sat May 18 2019

   Valid 201200Z - 211200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS THE
   EASTERN TX PANHANDLE...NORTHWEST TX...WESTERN/CENTRAL OK...AND FAR
   SOUTH-CENTRAL KS...

   ...SUMMARY...
   Severe thunderstorms capable of all severe hazards, including strong
   tornadoes, are expected across portions of the southern Plains on
   Monday.

   ...SIGNIFICANT SEVERE WEATHER EVENT POSSIBLE ACROSS THE SOUTHERN
   PLAINS ON MONDAY...

   ...Synopsis...
   Active upper pattern will continue on Monday as one shortwave trough
   progresses through the Northeast while another ejects through the
   base of the deep upper trough over the western CONUS late in the
   period.

   Subtropical ridging will remain in place over the Gulf of Mexico and
   Southeast, resulting in the development of strong southwesterly flow
   aloft ahead of the western CONUS shortwave. This strong flow will
   remain in place throughout the day, likely increasing to near 100 kt
   at 500 mb early Tuesday morning. 

   Surface pattern will feature a deepening lee cyclone over the
   central High Plains with a dryline extending southward across the
   eastern TX Panhandle and a warm front quickly moving northward
   through OK. 

   ...Southern Plains...
   Guidance is in good agreement that the ingredients are in place for
   a potentially significant severe weather event on Monday. A sharp
   warm front is expected to move northward throughout the day,
   starting from an early day position near the River Red and reaching
   the OK/KS border by 00Z. Air mass south of this warm front will be
   very moist (i.e. dewpoints in the upper 60s/low 70s) and unstable.
   Consequently, moderate to strong instability will likely to develop
   across the eastern TX Panhandle, northwest TX and much of OK, even
   if strong diurnal heating does not occur. Current expectation is for
   temperatures in this region to reach the low/mid 70s by late
   morning/early afternoon with some areas farther east reaching
   mid/upper 70s.

   Kinematic environment is even more impressive than the thermodynamic
   environment. 60-70 kt of southwesterly 500 mb flow will gradually
   spread eastward/northward across the TX Panhandle and into OK and
   KS. At same time, a strong and persistent low-level jet will be in
   place, with 40+ kt at 850 mb throughout the period. Surface winds
   within the warm sector will likely be southeasterly at 15 to 20 kt.
   All of these factors result in wind profiles very favorable for
   discrete supercells capable of all severe hazards, including
   significant tornadoes. 

   Given that overall large-scale forcing for ascent is minimal
   throughout much of the day, much of the afternoon and evening
   activity is currently expected to initiate along the dryline and
   within the warm sector, with a discrete storm mode favored. As the
   shortwave ejects out later in the period, a more linear MCS may
   develop, resulting in a second round of severe thunderstorms Monday
   night into Tuesday morning.

   ..Mosier.. 05/18/2019
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26 minutes ago, yoda said:

Now that's got to be rare... day 3 moderate risk issued

ETA: looks like this would be around the 15th time ever looking at some sites online and trying to search the Google 

I found 15th time ever as well and first in four years (since 5/9/2015)?

And they don't ever go higher than a 45% hatched area for day 3, so that entire area is the most significant they will go on Day 3.

 

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And while we're at it, there is a tornado warning ongoing in San Angelo, TX right now.  Surprised no one has mentioned this given the potential impacts to a major population center should a tornado touch down.

EDIT: and now there's a tornado warning for Abilene, TX as well with the storm moving into that area, so now another major population center is under a tornado warning.
 

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I chased the SW target yesterday, and decided to get a hotel in Abilene to set up for today. Woke up to the tornado warning on my phone and after looking at radar, I quickly decided to get dressed and chase. While putting my shoes on, the lights cut out. Absolutely terrifying. Ultimately, the tornado passed just north of my hotel and did some slight (EF-1) damage to a neighborhood and then some heavier damage to a commercial business along I-20.

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