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May 15-20 Severe Threat

MattPetrulli

By MattPetrulli,
in Central/Western States

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rolltide_130

rolltide_130

Posted
Posted
3 minutes ago, andyhb said:

81/67 at CDS and 80/69 upstream at ABI. The forecast parameter space later on towards 23-01z is among the most robust I've ever seen in this portion of the country.

Not gonna lie I'm getting some 6/8/95 vibes in terms of the potential ceiling for this event today.. whether it pans out that way remains to be seen though.

Actually seeing mesoscale details fall into place as event time nears.. haven't had that in a while.  

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jojo762

jojo762

Posted
Posted

Mid-level rotation is definitely starting to get going on the Beaver Co. Supercell, evident by the structural changes on radar. Per various area VWPs, conditions really are not that favorable for sustained low-level rotation yet - especially up into Kansas.

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andyhb

andyhb

Posted
Posted

Posting this for posterity because I'm pretty sure I've never seen a more strongly worded AFD from AMA.

Quote 

Area Forecast Discussion
National Weather Service Amarillo TX
128 PM CDT Tue May 16 2017

.MESOSCALE UPDATE...
...Severe weather outbreak likely today...

* Overview/Bottom Line: This has the makings of a pretty
  significant severe weather outbreak and as much we dug for a
  reason it may not happen, there are few to point to. Everyone
  stay safe and weather aware today!

* Synoptic Overview: A synoptically evident severe weather outbreak
  pattern has set up with pretty much all the boxes checked and also
  verified by observational data. In short, an upper low analyzed
  near Las Vegas this morning will open as it bottoms out over srn
  NM this afternoon before lifting and deepening again as it ejects
  over us tonight. Though the best height falls will occur this
  evening, modest height falls and the approach of a lead shortwave
  will be able to easily overcome a weak EML with storms all but
  guaranteed to form this afternoon.

* Mesoscale: A dryline is slowly mixing east early this afternoon
  and with the more significant synoptic forcing hanging back and
  fairly meridional flow aloft, think dryline progression will
  continue to be slow early this afternoon. Mid to upper 60s dewpts
  are present over the eastern half of the Panhandles and with the
  exception of the very western edge of the deep sfc moisture, these
  dewpts should not mix out much through the day. Unlike many severe
  weather days around here, this one won`t require sunshine and
  strong daytime heating as forecast soundings indicate 76/68 will
  yield upwards of 3500 J/kg MLCAPE in the east. Even if
  temperatures rise to the mid 80s...mixing of dewpts into the low
  to mid 60s that would occur simultaneously would probably keep
  CAPE values in the same range as they would be with 76/68. These
  T/Td trends will be monitored closely though for tornado potential
  this afternoon as more limited mixing could actually somewhat
  counter-intuitively increase the tornado threat by keeping LCLs
  lower. In addition to expecting MLCAPE values to push 3500-4000
  J/kg, a good deal of 0-3km MLCAPE should be noted with values
  pushing 150 J/kg this afternoon. CAPE in the hail growth zone will
  be near or surpass 1000 J/kg as well, so thermodynamically this
  event is on point.  If that wasn`t quite exciting (or scary)
  enough for you, kinematically this event may be better. After a
  period of veer-back-veer profiles early this afternoon (seen on
  the 18z KAMA special sounding), expected veering flow around h6
  will put the last piece of the puzzle in place to create uber-
  favorable shear profiles. These forecast profiles feature veering
  and mostly strengthening flow with height through the entire
  atmosphere and effective and 0-8km bulk shears of 60-70 kts.
  Initially weak low level shear/helicity will increase rapidly late
  this afternoon, especially in the eastern 2 tiers of Panhandle
  counties.

* Threats and Timing: Storms may struggle a bit intially due to the
  VBV profile and a bit of remaining CINH, but won`t take long to
  get going in earnest and this is an "all-threats" kind of day,
  though fast storm motions could keep the flash flood threat on the
  lower side. The biggest concerns are tornadoes and large to giant
  hail given supercell storm mode and the aforementioned CAPE/shear
  combo. Some hail could get as big as softballs.  The tornado
  threat is pretty concerning late this afternoon/early evening as 0-
  1 SRH values increase to nearly 300 m2/s2 by 23Z in the southeast
  TX Panhandle and over 200 m2/s2 further north. Given this and
  expected discrete or quasi-discrete supercell storm mode, concern
  certainly exists for a strong tornado or two.  The best tornado
  threat will be 20Z-01Z in the eastern half of the combined
  Panhandles with the first round of storms, though another tornado
  threat cannot be ruled out in the far east with a possible second
  round later this evening. This second round of storms will be
  conditional on the first round, but the stronger dynamics as the
  main upr wave crosses should help make up for any lacking
  thermodynamics in the wake of the first round.

* Location: As has been mentioned, the eastern half of the
  Panhandles looks the best.  Right now it looks like the western
  edge of the severe threat will be bounded by a Canyon to Amarillo
  to Stinnett to Spearman to Liberal line.  None of these
  aforementioned locations are free from a severe threat though the
  tornado threat on the western edge is certainly lower than it is
  further east.  If a second round materializes, it should occur
  after 9 PM and be confined to areas east of a Clarendon to Pampa
  to Perryton line.

 

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rolltide_130

rolltide_130

Posted
Posted
1 minute ago, MUWX said:

Does anyone think the spc will be more aggressive with the next update? 

Because of how small the MDT is I don't forsee an upgrade to high unless they essentially just scratch the MDT altogether and go straight high. That's happened before but it's extremely rare. (The last one was 5/3/99 I believe) 

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jojo762

jojo762

Posted
Posted
3 minutes ago, Upper Level LOL said:

In what way? They already have a moderate and a PDS TOR watch out. They'll only go high if the forecast warrants it, if there is a higher probability of sig hail (which there very well may be).

Can't get a high risk for significant severe hail. You can get 60% hail probabilities but those don't equal a high risk. Only a 30+% hatched TOR or 60% hatched damaging wind risk can = high risk. Area seems too small to me, but it could probably verify if they pulled the trigger.

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Disc

Disc

Posted
Posted

Along with the tornado potential the hail potential looks crazy today too. Check out the huge amount of CAPE in the hail growth region between -10 and -30C. Also couple that with a lapse rate nearing 8C/km at 700-500mb. You need around 7C/km to start seeing a threat for giant hail. Of course with the other kinematics in place (shear, helicity etc.) we won't have a problem seeing rotating updrafts as well, which will allow hail to reside within the hail growth zone longer.

 

39150291fa3045b49fd0f968e7556f2a.png

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Amped

Amped

Posted
Posted
2 minutes ago, SmokeEater said:

Storm structure looks amazing already, not a good sign.

Sent from my SM-G950U using Tapatalk
 

The cells just now forming east of Amarillo are the ones that are supposed to have the most potential.

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jojo762

jojo762

Posted
Posted

I have a feeling this is gonna be a big day... Surprised to see a supercell look as good structurally as the Beaver Co. one does this early. Can't imagine what the primetime supercells will look like later on the DL bulge when the LLJ starts cranking. Hansford/Ochiltree Co. supercell also has good structure indicative of strong mid-level rotation.

 

Appears there may have been a brief tornado on the Beaver Co. storm.

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jojo762

jojo762

Posted
Posted

ICT for thursday... wow...

Quote

ATTENTION THEN TURNS TO SEVERE THUNDERSTORM POTENTIAL THURSDAY   
LATE AFTERNOON AND EVENING ACROSS CENTRAL AND SOUTH-CENTRAL KS, AS  
A DRYLINE/FRONTAL ZONE COMBO TIGHTEN UP AHEAD OF ANOTHER POWERFUL  
SHORTWAVE APPROACHING FROM THE SOUTHWEST. ONCE AGAIN, STRONG   
INSTABILITY IN CONCERT WITH 40-50 KTS DEEP LAYER SHEAR WILL   
SUPPORT SEVERE STORMS CAPABLE OF LARGE HAIL AND DAMAGING WINDS.   
DEEP LAYER SHEAR AND UPPER FLOW VECTORS DO NOT DISPLAY A HUGE   
ANGLE ACROSS THE DRYLINE, WHICH COULD TEND TO FAVOR MORE OF A   
MIXED STORM MODE, POSSIBLY LESSENING THE TORNADO POTENTIAL.   
HOWEVER, LOW-LEVEL SHEAR IS IMPRESSIVE OWING TO A STRONG LOW-LEVEL  
JET AND BACKED SURFACE FLOW, SO ANY DISCRETE STORMS AND/OR TAIL   
END CHARLIE STORMS WOULD HAVE TORNADO POTENTIAL WELL INTO THURSDAY  
EVENING, SOME OF WHICH COULD BE ON THE STRONG/VIOLENT SIDE. WILL   
CONTINUE TO MONITOR.  
  
FINALLY, WE TURN TO STORM POTENTIAL FRIDAY AFTERNOON-EVENING   
ACROSS GENERALLY THE EASTERN HALF OF KS, AS THE PARENT SHORTWAVE   
TROUGH FINALLY BEGINS TO EJECT NORTHEAST ACROSS THE PLAINS. STORM   
POTENTIAL WILL LIKELY BE HIGHLY CONTINGENT ON EXTENT OF THURSDAY   
NIGHT STORMS. IF THURSDAY NIGHT STORMS DEVELOP A LARGE COMPLEX AND  
ASSOCIATED COLD POOL, EFFECTIVELY SCOURING-OUT THE AIRMASS (I.E.   
12Z NAM SOLUTION), FRIDAY SEVERE WEATHER POTENTIAL WILL PROBABLY   
BE LESS. HOWEVER, IF THURSDAY NIGHT COMPLEX DOES NOT DEVELOP A   
MASSIVE COLD POOL, SEVERE WEATHER POTENTIAL WILL BE HIGHER FRIDAY.  
WILL CONTINUE TO MONITOR TRENDS. 

 

 

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jojo762

jojo762

Posted
Posted
2 minutes ago, pbrussell said:

Looks like the main players for today's event are really starting to blow up around KAMA. 

Believe the more intense storms will still develop a bit further south, these certainly will be capable of tornadoes as well though.

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Calderon

Calderon

Posted
Posted
1 minute ago, andyhb said:

Storm that crossed into the OK Panhandle near Perryton has some very strong rotation aloft from both KAMA and KDDC.

Was just noticing that. The previous cell put out a boundary and this cell is ingesting it and looking mighty healthy.

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