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Christmas outbreak?

Tallis Rockwell

By Tallis Rockwell,
in Central/Western States

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Tallis Rockwell

Tallis Rockwell

Posted
Posted

Some decent instability and modest shear are going to meet in Southeast Texas and Louisiana next week. 


 ZCZC SPCSWOD48 ALL
   ACUS48 KWNS 200818
   SPC AC 200818

   Day 4-8 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0218 AM CST Thu Dec 20 2018

   Valid 231200Z - 281200Z

   ...DISCUSSION...
   High-PW air mass will be shunted off the Atlantic coast during the
   day2 period. Current medium-range model guidance suggest numerous
   fast-moving short waves will traverse the CONUS such that
   moisture/instability will struggle to return north until Christmas
   day when a significant moisture surge is expected across the western
   Gulf basin into TX. This moisture surge will be induced by a
   significant trough that will progress across the southwestern
   US/southern Rockies region. While models agree broadly that
   destabilization should occur across the southern Plains, timing of
   the ejecting trough may greatly influence potential severe threat
   with this feature. Will not introduce severe probs at this time but
   organized convection may ultimately evolve during the day7/8 time
   frame.

   ..Darrow.. 12/20/2018

image.thumb.png.d702e8148874a1e152311c27accbcfcf.png

Could this be a significant event?

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Tallis Rockwell

Tallis Rockwell

Posted
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Posted

NAM is starting to put in a much more interesting mode over Houston and Central TX

2018122412_NAM_069_30.53,-95.8_severe_ml.png

day3otlk_0830.gif?1545664013274

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0212 AM CST Mon Dec 24 2018

   Valid 261200Z - 271200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
   CENTRAL TEXAS IN THE EVENING AND INTO SOUTHEAST TEXAS OVERNIGHT
   WEDNESDAY...

   ...SUMMARY...
   Scattered severe thunderstorms are possible Wednesday over portions
   of central Texas during the evening and moving into southeast Texas
   overnight.

   ...Synopsis...
   A lower-latitude, mid-level shortwave trough will eject east into
   the central-southern High Plains from the southern Rockies with a
   closed mid-level circulation evolving Wednesday night over southwest
   KS.  A broad belt of strong, cyclonic mid-level flow will overspread
   a destabilizing moist sector located over TX/OK.  In the low levels,
   a surface cyclone will develop northeastward from the TX/NM border
   across the TX/OK Panhandles and into north-central KS by early
   Thursday morning.  A north-south dryline is forecast from the
   eastern TX Panhandle into southwest TX and a Pacific cold front will
   overtake the aforementioned boundary and accelerate east across much
   of central TX late.

   ...TX Panhandle/far western OK into northwest TX...
   A seemingly conditional risk for severe thunderstorms will probably
   unfold beginning by the early-mid afternoon through the evening over
   this region.  Strong low-level moisture transport will occur to the
   southeast of a deepening surface low, in a warm sector with an
   increasingly narrow moist/unstable airmass with northwest extent,
   from western north-central TX northwestward into the eastern TX
   Panhandle.  Despite boundary-layer dewpoints only in the mid to
   upper 50s, very cool 500mb temperatures (-17 to -18 degrees C) may
   yield SBCAPE in the 250-750 J/kg range.  However, strong DCVA (and
   120m/12hr 500mb height falls over the South Plains between 12z-00z)
   may promote an early convective initiation (CI) during the morning
   over West TX.  The early CI scenario is possible and would have
   deleterious effects on the development of buoyancy.  As it stands
   currently, a marginal risk for severe gusts and perhaps a tornado
   seem to be a sufficient highlight.  But...if the early CI scenario
   does not occur and a brief window (1-2 hour) of cloud breaks and
   heating can occur, a greater risk for supercells with an attendant
   tornado/wind risk would develop. 

   ...Central into eastern TX...
   A moist airmass, characterized by lower to middle 60s degree F
   dewpoints, will gradually destabilize during the day as stronger
   deep-layer forcing for ascent remains to the west and northwest of
   the region.  Strong south-southeasterly low-level winds veering to
   the southwest in the mid levels will result in a wind profile
   supporting thunderstorm organization.  By the late afternoon/early
   evening, thunderstorms are forecast to develop over the Concho
   Valley with thunderstorm coverage expected to increase as this
   activity moves into richer low-level moisture near I-35.  Severe
   gusts and the possibility for a few tornadoes may accompany a band
   of thunderstorms as it grows upscale and moves east reaching the
   Upper Coast of TX during the midnight-6am CST period.  Farther north
   over northeast TX, weaker instability may result in a lower risk for
   wind damage as thunderstorms move through the area overnight.
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Sydney Claridge

Sydney Claridge

Posted
Posted

And we now have an enhanced risk (with 10% tornado risk/30% severe wind risk) including Austin and the NW suburbs of Houston, with the slight risk extending northwards to DFW.  I'm a little skeptical of severe in DFW given that most of the models tend to keep them in the lower-to-mid-60s for temperatures (with dew points a few degrees lower) along with what appears to be multiple rounds of convective precipitation, though the shear seems good, and the models have at least trended a little bit upwards on moisture return.

The presence of isolated thunderstorms in a high-shear environment on the HRRR and NAM 3k does have me a bit intrigued, though much of this appears to be elevated convection ahead of the main line.  With such a slow year for severe thunderstorms it has been at least it is something.  Hopefully 2019 will have some more interesting setups to look forward to.

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Sydney Claridge

Sydney Claridge

Posted
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Winds are picking up here in Fort Worth.  Also, SPC has expanded the Enhanced risk zone further west and northwards, now including Abilene and reaching just south of DFW.  Slight risk now goes up to the Red River and even includes a little bit of southern OK.  Definitely seems that the SPC is hinting towards stronger moisture return further north, as the tornado risk has also shifted northwards too.

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Jebman

Jebman

Posted
Posted
11 hours ago, BrandonC_TX said:

And we now have an enhanced risk (with 10% tornado risk/30% severe wind risk) including Austin and the NW suburbs of Houston, with the slight risk extending northwards to DFW.  I'm a little skeptical of severe in DFW given that most of the models tend to keep them in the lower-to-mid-60s for temperatures (with dew points a few degrees lower) along with what appears to be multiple rounds of convective precipitation, though the shear seems good, and the models have at least trended a little bit upwards on moisture return.

The presence of isolated thunderstorms in a high-shear environment on the HRRR and NAM 3k does have me a bit intrigued, though much of this appears to be elevated convection ahead of the main line.  With such a slow year for severe thunderstorms it has been at least it is something.  Hopefully 2019 will have some more interesting setups to look forward to.

I sure hope not. I really do NOT want a tornado in North Buda near the county line where I now reside.

It only takes one tornado to ruin your day.

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Tallis Rockwell

Tallis Rockwell

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First warning 

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service San Angelo TX
445 PM CST WED DEC 26 2018

The National Weather Service in San Angelo has issued a

* Tornado Warning for...
  Northern Callahan County in west central Texas...

* Until 530 PM CST.

* At 445 PM CST, a severe thunderstorm capable of producing a tornado
  was located over Eula, or near Clyde, moving east at 35 mph.

  HAZARD...Tornado.

  SOURCE...Radar indicated rotation.

  IMPACT...Flying debris will be dangerous to those caught without
           shelter. Mobile homes will be damaged or destroyed.
           Damage to roofs, windows, and vehicles will occur.  Tree
           damage is likely.

* This dangerous storm will be near...
  Baird around 500 PM CST.
  Putnam around 520 PM CST.

Other locations impacted by this tornadic thunderstorm include
Admiral and I-20 Near The Callahan-Eastland County Line.

This includes Interstate 20 between Mile Markers 295 and 323.
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mayjawintastawm

mayjawintastawm

Posted
Posted

And they canceled the Cotton Bowl!?! BC was in for the first time since Doug Flutie (remember him?) was QB and my sister was a freshman way back in 1985. I was looking for a zillion LSRs today and found basically none in the Metroplex area near the time of the game. Guessing too much CIN and cloud debris to get things going. Of course, lightning alone can ruin your day, but still. What happened?

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