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April 13 Severe Threat - TX, OK, LA, ARK, KS, MO, IA


OUGrad05

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Right, though I do wonder if it will get linear before hitting central AK.

 

Edit: Possible PDS tornado watch coming in the area of highest risk: http://www.spc.noaa.gov/products/md/md0238.html

 

Mesoscale Discussion 0238
   NWS Storm Prediction Center Norman OK
   1241 PM CDT Fri Apr 13 2018

   Areas affected...Northeast TX...Northwest LA...Central and Southern
   AR

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

   Valid 131741Z - 131945Z

   Probability of Watch Issuance...95 percent

   SUMMARY...Elevated thunderstorm activity over southeast OK and
   northeast TX may become rooted in the boundary layer by mid
   afternoon.  This will increase the risk of intense storms capable of
   tornadoes, large hail, and damaging winds.  A tornado watch will be
   needed later today.

   DISCUSSION...Radar/satellite imagery shows a band of elevated
   convection extending from Pushmataha/Choctaw counties OK southward
   into Kaufman/Navarro counties TX.  Some increase in intensity has
   been noted in the past hour, although activity remains sub-severe. 
   A substantial capping inversion was in place over this region at
   12z, but the 18z FWD/LZK soundings indicate rapid cooling at the
   base of the EML and a diminishing cap.  Given current trends, the
   thunderstorm activity may become surface-based in the next couple of
   hours.

   Strong low-level wind fields will remain in place ahead of the
   convection, and may increase through early evening.  Local VAD
   profiles already show 0-3 km SRH values of 300-400 m2/s2 with
   forecast soundings suggesting values over 500 m2/s2 this evening. 
   Assuming activity can remain semi-discrete, a few intense supercells
   are likely to evolve.  Parameters appear favorable for the risk of
   strong tornadoes, along with large hail and damaging winds.  PDS
   wording is being considered in the tornado watch for this region.
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SPC considering PDS wording for the watch in Arkansas.

"

SUMMARY...Elevated thunderstorm activity over southeast OK and
   northeast TX may become rooted in the boundary layer by mid
   afternoon.  This will increase the risk of intense storms capable of
   tornadoes, large hail, and damaging winds.  A tornado watch will be
   needed later today.

   DISCUSSION...Radar/satellite imagery shows a band of elevated
   convection extending from Pushmataha/Choctaw counties OK southward
   into Kaufman/Navarro counties TX.  Some increase in intensity has
   been noted in the past hour, although activity remains sub-severe. 
   A substantial capping inversion was in place over this region at
   12z, but the 18z FWD/LZK soundings indicate rapid cooling at the
   base of the EML and a diminishing cap.  Given current trends, the
   thunderstorm activity may become surface-based in the next couple of
   hours.

   Strong low-level wind fields will remain in place ahead of the
   convection, and may increase through early evening.  Local VAD
   profiles already show 0-3 km SRH values of 300-400 m2/s2 with
   forecast soundings suggesting values over 500 m2/s2 this evening. 
   Assuming activity can remain semi-discrete, a few intense supercells
   are likely to evolve.  Parameters appear favorable for the risk of
   strong tornadoes, along with large hail and damaging winds.  PDS
   wording is being considered in the tornado watch for this region."

   ..Hart.. 04/13/2018
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1 hour ago, Chicago Storm said:

Even 10% is too high. Activity down in the vicinity of that 15% tor area will become QLCS-ish fairly quickly. A few tors possibly with that given the environment, but not nearly 15% worthy, or even 10% worthy for that matter.

The enhanced risk further north is probably being over-played a bit as well. 

Hopefully no one chasing tries to make a play on a storm in SE. NE/SW. IA/NW. MO...All of that activity will quickly rocket north of the stalled WF.

SPC considering a PDS watch... lol

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RGENT - IMMEDIATE BROADCAST REQUESTED  
TORNADO WATCH NUMBER 39  
NWS STORM PREDICTION CENTER NORMAN OK  
115 PM CDT FRI APR 13 2018  
  
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
  
* TORNADO WATCH FOR PORTIONS OF   
  NORTHWEST ARKANSAS  
  SOUTHEAST KANSAS  
  SOUTHWEST MISSOURI  
  EASTERN OKLAHOMA  
  NORTH CENTRAL TEXAS  
  
* EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 115 PM UNTIL  
  1000 PM CDT.  
  
* PRIMARY THREATS INCLUDE...  
  A FEW TORNADOES AND A COUPLE INTENSE TORNADOES POSSIBLE  
  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2.5  
    INCHES IN DIAMETER LIKELY  
  SCATTERED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE  
  
SUMMARY...STORMS DEVELOPING ALONG AND AHEAD OF THE DRYLINE ARE  
EXPECTED TO INTENSIFY AND EVOLVE INTO SUPERCELLS CAPABLE OF VERY  
LARGE HAIL, DAMAGING WIND AND A FEW TORNADOES.  
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new storms developing in LLJ axis over NE TX ahead of the older elevated stuff......

 

 

RGENT - IMMEDIATE BROADCAST REQUESTED  
TORNADO WATCH NUMBER 40  
NWS STORM PREDICTION CENTER NORMAN OK  
150 PM CDT FRI APR 13 2018  
  
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
  
* TORNADO WATCH FOR PORTIONS OF   
  MUCH OF ARKANSAS  
  NORTHWEST LOUISIANA  
  SOUTHEAST OKLAHOMA  
  NORTHEAST TEXAS  
  
* EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 150 PM UNTIL  
  1000 PM CDT.  
   
..THIS IS A PARTICULARLY DANGEROUS SITUATION  
  
* PRIMARY THREATS INCLUDE...  
  NUMEROUS TORNADOES EXPECTED WITH A FEW INTENSE TORNADOES LIKELY  
  WIDESPREAD LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2.5  
    INCHES IN DIAMETER LIKELY  
  WIDESPREAD DAMAGING WIND GUSTS TO 70 MPH LIKELY  
  
SUMMARY...INTENSE THUNDERSTORMS ARE EXPECTED TO TRACK ACROSS THE  
WATCH AREA THIS AFTERNOON AND EARLY EVENING, POSING A RISK OF  
TORNADOES, LARGE HAIL AND DAMAGING WINDS.  STRONG TORNADOES ARE  
POSSIBLE.  MULTIPLE ROUNDS OF SEVERE STORMS ARE EXPECTED ACROSS THIS  
REGION.  

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MESOSCALE DISCUSSION 0239  
NWS STORM PREDICTION CENTER NORMAN OK  
0206 PM CDT FRI APR 13 2018  
  
AREAS AFFECTED...EASTERN KANSAS...NORTHWEST MISSOURI...FAR SOUTHEAST  
NEBRASKA...SOUTHERN IOWA  
  
CONCERNING...SEVERE POTENTIAL...WATCH LIKELY   
  
VALID 131906Z - 132130Z  
  
PROBABILITY OF WATCH ISSUANCE...80 PERCENT  
  
SUMMARY...A SEVERE THREAT IS LIKELY TO DEVELOP ACROSS NORTHEAST  
KANSAS, NORTHWEST MISSOURI AND SOUTHERN IOWA OVER THE NEXT COUPLE OF  
HOURS. LARGE HAIL AND WIND DAMAGE WILL BE THE INITIAL THREAT BUT A  
TORNADO THREAT IS EXPECTED TO EVENTUALLY DEVELOP. WEATHER WATCH  
ISSUANCE WILL LIKELY BE NEEDED ACROSS THE REGION THIS AFTERNOON.  
  
DISCUSSION...THE LATEST SURFACE ANALYSIS SHOWS A 991 MB LOW OVER FAR  
SOUTHEAST NEBRASKA WITH A COLD FRONT EXTENDING SOUTH-SOUTHWESTWARD  
FROM THE LOW INTO NORTHEAST AND CENTRAL KANSAS. A DRYLINE BEGINS  
NEAR THE FRONT IN EASTERN KANSAS AND EXTENDS SOUTHWARD INTO NORTHERN  
OKLAHOMA. THUNDERSTORMS ARE DEVELOPING ALONG THE DRYLINE IN  
SOUTHEAST KANSAS WITH OTHER CELLS INITIATING TO THE NORTH OF THE LOW  
IN THE OMAHA AREA. THIS CONVECTION IS EXPECTED TO INCREASE IN  
COVERAGE AS THE CAP WEAKENS OVER THE NEXT HOUR OR SO. THE STORMS  
SHOULD REACH NORTHWEST MISSOURI AND SOUTHWEST IOWA BY MID AFTERNOON.  
  
AHEAD OF THE STORMS, A CORRIDOR OF LOW-LEVEL MOISTURE IS ANALYZED  
FROM FAR SOUTHEAST KANSAS NORTHWARD INTO FAR NORTHWEST MISSOURI  
WHERE SURFACE DEWPOINTS ARE IN THE LOWER TO MID 60S F. THE RAP IS  
SHOWING MLCAPE VALUES FROM EASTERN KANSAS INTO FAR SOUTHWEST IOWA IN  
THE 2000 TO 2500 J/KG RANGE. IN ADDITION, FORECAST SOUNDINGS  
STEADILY INCREASE DEEP-LAYER SHEAR ALONG THE INSTABILITY CORRIDOR  
THROUGH LATE THIS AFTERNOON. 0-6 KM SHEAR SHOULD REACH THE 40 TO 50  
KT RANGE WHICH WILL BE FAVORABLE FOR SUPERCELL DEVELOPMENT. THE  
INSTABILITY, SHEAR AND STEEP MID-LEVEL LAPSE RATES WILL BE SUPPORT  
LARGE HAIL FORMATION WITH THE STRONGER UPDRAFTS. DAMAGING WIND GUSTS  
WILL ALSO BE LIKELY AS STORM ORGANIZE. AS DEEP-LAYER SHEAR AND  
LOW-LEVEL SHEAR INCREASE LATER THIS AFTERNOON, A TORNADO THREAT WILL  
ALSO LIKELY DEVELOP.  
  

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500 mb winds are going to need to veer a bit over the southern part of the risk area.

Also, saying today deserves a 5% is just as comical as the things you claim to be comical are. The low level shear/moisture over the risk area along with storms (regardless of mode) expected within that low level environment portends a higher than 5% tornado risk.

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Just now, andyhb said:

500 mb winds are going to need to veer a bit over the southern part of the risk area.

Also, saying today deserves a 5% is just as comical as the things you claim to be comical are. The low level shear/moisture over the risk area along with storms (regardless of mode) expected within that low level environment portends a higher than 5% tornado risk.

This i agree with. Not sure we need the 15% or the pds watch but this day definitely warrants more than 5% and it also needs to be hatched. It might not verify but the potential is there.  

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2 minutes ago, andyhb said:

500 mb winds are going to need to veer a bit over the southern part of the risk area.

Also, saying today deserves a 5% is just as comical as the things you claim to be comical are. The low level shear/moisture over the risk area along with storms (regardless of mode) expected within that low level environment portends a higher than 5% tornado risk.

Pretty sure I said there would be a few tors in the vicinity of their 15% tor area, but it's just not looking like that sig of an event.

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Just now, Chicago Storm said:

Pretty sure I said there would be a few tors in the vicinity of their 15% tor area, but it's just not looking like that sig of an event.

That's irrelevant to what I said, you said it should be broad-brushed 5% probs earlier.

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2 minutes ago, Chicago Storm said:

Pretty much. Just calling it on how it looks.

You're not just calling it how it looks, you're basically claiming with your language that everyone else is stupid for thinking this has some more significant potential.

Whatever.

I would go 10% hatched/45% hatched hail/30% hatched for the moderate risk.

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First TOR warning of the day:

The National Weather Service in Norman has issued a

* Tornado Warning for...
  Northern Seminole County in east central Oklahoma...

* Until 315 PM CDT
    
* At 225 PM CDT, a severe thunderstorm capable of producing a tornado
  was located near Seminole, moving northeast at 45 mph.

  HAZARD...Tornado and golf ball size hail. 

  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. 

* Locations impacted include...
  Seminole, Cromwell and Little. 
 

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URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 41
   NWS Storm Prediction Center Norman OK
   220 PM CDT Fri Apr 13 2018

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Southern Iowa
     Northeast Kansas
     Northwest Missouri
     Southeast Nebraska

   * Effective this Friday afternoon and evening from 220 PM until
     900 PM CDT.

   * Primary threats include...
     A few tornadoes likely
     Widespread large hail and isolated very large hail events to 2.5
       inches in diameter likely
     Scattered damaging wind gusts to 70 mph likely

   SUMMARY...Thunderstorms developing over eastern Kansas will track
   northeastward across the watch area, while other isolated cells form
   over IA/northern MO.  Supercells capable of large hail and a few
   tornadoes are expected.
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7 minutes ago, andyhb said:

You're not just calling it how it looks, you're basically claiming with your language that everyone else is stupid for thinking this has some more significant potential.

Whatever.

I would go 10% hatched/45% hatched hail/30% hatched for the moderate risk.

Yep those were the risk categories I mentioned last night to you and others. 

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3 minutes ago, Chicago Storm said:

Even the 70% prob tor watch further north in KS/MO/IA might be a stretch.

The 18z TOP sounding was terrible.

dHg1SOC.gif

I don't really consider this a terrible sounding for 18z considering the wind fields downstream are more favorable. Pretty solid thermodynamic profile.

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4 minutes ago, Chicago Storm said:

Even the 70% prob tor watch further north in KS/MO/IA might be a stretch.

The 18z TOP sounding was terrible.

18z OAX sounding, while north of the warm front, was very impressive kinematically.

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23 minutes ago, andyhb said:

You're not just calling it how it looks, you're basically claiming with your language that everyone else is stupid for thinking this has some more significant potential.

Whatever.

I would go 10% hatched/45% hatched hail/30% hatched for the moderate risk.

The same can be said for the opposite.

Agree with hail/wind probs down there. Maybe 45% wind if the QLCS takes off later?

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