Chase Day 12 Discussion - Moderate Risk (OK/KS/MO/IL)

[nsrobins]

Hope moderators don't mind me starting this:Another batch of severe wx developing this evening, especially E and NE OK into NW MO and SW IL. My faith in RAP has taken a hit after being too far west with last night's initiation so NAM mainly used to pinpoint McAlester, OK for a target from 20Z.SRH focii of >250 illustrate the substantial shear with height in place by 22Z with a decent LLJ pushing under 60kt 500mb SWlys. Big CAPE again helps to generate in excess of 700 SRH in above area and into C OK. DL however may not be a big player here as it's back in W OK at 22Z although does bulge across the I35 later. It's OFBs and maybe the infamous gravity wave that will lead the initiation IMO.Depsite the strong 500mb flow, storm motions look to be playing ball again with a NE motion at 20mph.

[Tom Lynch]

 

Warts and all

 

Tom

[nsrobins]

I'm wondering if the ppn models have missed a trick here and have gone too early and too far east.Not for the first time this season I'm scatching my head and thinking about going west of the I35 almost toward the I44 around Chickasha, OK for initiation off the DL where inhibition fades at 21Z and still within the juicy stuff.I know I can't be in two places at once so perhaps Norman on the I35 would be a compromise. 

[PolarWarsaw]

Any live feeds today such as Channel 9 news from last night?

[Cookie]

Any live feeds today such as Channel 9 news from last night?

 

Just a case of wait and see how sever things get!

[nsrobins]

Current obs: Duke 81/46 NW 7kts; Altus 85/69 SW 8kts; Lawton 81/72 SSW 7kts; Ardmore 81/68 S 12kts. Diffuse DL into far W OK now and forecast to sharpen around Lawton by 21Z.

 

14Z High res rapid breaks ppn out by 20Z in a line Stillwater/OKC/Lawton. Not a huge fan of it but it's done OK lately. May be another sign that we're edging a tad further West to start the play. 

[NL]

Tornado watch likely to be issued soon. Current MD focus on most of Oklahoma northern Texas and Southern Kansas.

   MESOSCALE DISCUSSION 0726   NWS STORM PREDICTION CENTER NORMAN OK   1226 PM CDT MON MAY 20 2013      AREAS AFFECTED...MUCH OF OK INTO NWRN TX AND SERN KS      CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY       VALID 201726Z - 201930Z      PROBABILITY OF WATCH ISSUANCE...95 PERCENT      SUMMARY...SEVERE STORMS ARE LIKELY TO FORM THIS AFTERNOON WITH A FEW   SIGNIFICANT TORNADOES...EXTREMELY LARGE HAIL...AND DAMAGING WINDS   ALL POSSIBLE. TWO WATCHES WILL BE NEEDED SOON FROM KS INTO N TX.      DISCUSSION...SURFACE MAP SHOWS A QUASI-STATIONARY BOUNDARY FROM SERN   KS INTO NRN OK AND BENDING SWWD W OF THE I-44 CORRIDOR. FARTHER   SW...A WEAK AREA OF LOW PRESSURE WAS NOTED OVER NWRN TX...ON THE   NOSE OF A LOW LEVEL LAPSE RATE PLUME WITH DRYLINE EXTENDING SW   ACROSS W TX.      VISIBLE IMAGERY SHOWS DEEPENING CU ALONG THE BOUNDARY FROM NRN OK   INTO SERN KS WHERE A DEEP MOIST LAYER EXISTS. GIVEN A GRADUAL   INCREASE IN THETA-E AND BREAKS IN THE CLOUDS...THIS AREA COULD BE   WHERE INITIAL DEVELOPMENT OCCURS. LONG HODOGRAPHS AND STEEP MIDLEVEL   LAPSE RATES WILL FAVOR VERY LARGE HAIL...AND LOW LEVEL VEERING WIND   PROFILES WILL BE SUFFICIENT FOR TORNADOES GIVEN AFOREMENTIONED   THERMODYNAMIC FACTORS.      TO THE S...AN EXTREMELY VOLATILE AIR MASS EXISTS WITH AN INCREASING   CU FIELD FROM NWRN TX INTO SWRN OK WHERE STRONG HEATING PERSISTS.   WIND FIELDS ALOFT ARE MORE THAN FAVORABLE FOR SUPERCELLS...WITH VERY   LARGE HAIL LIKELY. ALTHOUGH SHEAR IN THE LOWEST 1-2 KM IS NOT   PARTICULARLY STRONG...VERY LARGE VERTICAL ACCELERATIONS...AS WELL AS   HODOGRAPH AUGMENTATION NEAR THE SFC FRONT WILL AID IN TORNADO   POTENTIAL. HP SUPERCELLS ARE EXPECTED WITH STRONG MESOCYCLONES AND   POSSIBLE RAIN-WRAPPED TORNADOES.      ACTIVITY MAY EVENTUALLY MERGE INTO ONE OR MORE BOWS...AND RAPIDLY   EXPAND NEWD ACROSS ERN OK LATER THIS EVENING PER MULTIPLE CONVECTION   ALLOWING MODELS.

Latest visible satellite image.

 

[Paul]

Team just on the move now, milkshaked up and ready to chase

 

http://www.netweather.tv/index.cgi?action=chaselive;sess=

[Arron]

And we're off! Stream is up and running and trying a new combination so hopefully it'll hold up

[icbinb]

http://www.spc.noaa.gov/products/watch/ww0191.html

 

And there it is!

 

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 191
NWS STORM PREDICTION CENTER NORMAN OK
110 PM CDT MON MAY 20 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF
NORTHWEST ARKANSAS
CENTRAL AND EASTERN OKLAHOMA
NORTHWEST TEXAS

* EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 110 PM UNTIL
1000 PM CDT.

* PRIMARY THREATS INCLUDE...
SEVERAL TORNADOES POSSIBLE
NUMEROUS LARGE HAIL EVENTS LIKELY WITH A FEW VERY LARGE HAIL
EVENTS TO 4 INCHES IN DIAMETER POSSIBLE
NUMEROUS DAMAGING WIND GUSTS TO 70 MPH LIKELY

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 115 STATUTE
MILES EAST AND WEST OF A LINE FROM 30 MILES NORTHWEST OF GROVE
OKLAHOMA TO 40 MILES EAST OF WICHITA FALLS TEXAS. FOR A COMPLETE
DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE
(WOUS64 KWNS WOU1).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 189...WW 190...

DISCUSSION...RAPID INTENSE STORM DEVELOPMENT IS EXPECTED DURING THE
NEXT FEW HOURS...BOTH NEAR A STALLED SURFACE FRONT ROUGHLY WEST OF
THE I-35 CORRIDOR...AND NEAR THE PRE-FRONTAL DRYLINE NOSING
NORTHEASTWARD INTO SOUTH CENTRAL OKLAHOMA BY LATE AFTERNOON.
ISOLATED SUPERCELLS ARE LIKELY ALONG THE DRYLINE...WITH THE MOST
PROMINENT TORNADO THREAT...WHICH PROBABLY WILL INCREASE BY EARLY
EVENING AS THE SOUTHERLY LOW-LEVEL JET STRENGTHENS AND ENLARGES
LOW-LEVEL HODOGRAPHS. ONE OR TWO STRONG TORNADOES MAY NOT BE OUT OF
THE QUESTION. OTHERWISE...LARGE HAIL IS LIKELY...SOME VERY LARGE...
WITH INCREASING DAMAGING WIND POTENTIAL ACROSS EASTERN OKLAHOMA AS
CONVECTION CONSOLIDATES AND EVOLVES INTO AN ORGANIZED CLUSTER.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
600. MEAN STORM MOTION VECTOR 25035.


...KERR

[Boro Snow]

Team just on the move now, milkshaked up and ready to chase

 

http://www.netweather.tv/index.cgi?action=chaselive;sess=

im watching lets hope for a good night plenty of tornados but no injuries, good luck guys

[nsrobins]

Well done HRRR, although this is an early kick-off. First cell off the DL just east of Lawton. Aggitated Cu field extends NEwards up to OKC.

[nsrobins]

And we're off! Stream is up and running and trying a new combination so hopefully it'll hold up

These storms have a few hours to mature before the shear reaches decent tornadic levels - and when it does it could be very fruity with the 22Z sounding for OKC for instance showing a classic figure of eight clockwise looped hodo that should do very nicely.

[Paul]

Hmm, think the stream lasted about 2 mins before bombing, we're really struggling with it this year

[Paul]

Aha, stream back - things developing nicely it looks like..

[Stu Robinson]

Can you ensure that you keep the GPS track up and running? - the stream is OK but not important.

[chionomaniac]

Here we go again. It seems that tonight we have a more SW/NE tilt on initiation compared to yesterday.

[lorenzo]

This virtual chasing is addictive..

[Arron]

Right on the fringe of inet connection here but seems to be holding up

[lorenzo]

Heard them mention Velocity couplets a lot last night on channel 9, no experience spotting these so look forward to your explanation W09.

 

Twitter is simply superb for storm chasing the volume and speed of information going up is amazing, I like those 3D radar renditions of the Supercells, stunning imagery.

[dallas]

Some good footage from reed timer yesterday,

 

http://kfor.com/2013/05/20/reed-timmer-takes-dominator-4-inside-violent-tornado/

[Stu Robinson]

Mid level rotation already on the cell NE of Rush Springs - this is the cell that we can see from the NetWx video stream.

[chionomaniac]

Heard them mention Velocity couplets a lot last night on channel 9, no experience spotting these so look forward to your explanation W09.

 

Twitter is simply superb for storm chasing the volume and speed of information going up is amazing, I like those 3D radar renditions of the Supercells, stunning imagery.

You need to have a doppler radar image to be able to see these- they can be seen on the GRlevel 3 or even the radarscope app. for instance there is a storm currently heading towards Lindsay and when looking at the velocity component we see base velocities around 30mph - effectively all the wind is travelling in the same direction. If any rotation occurs in the cell then we see velocities indicated in different directions right next to each other - hence the GRlevel 3 will pick this up as a rotating storm -and I guess that has started to occur already on the one Stuart has indicated above.

[BlackSkyuk]

Storms starting :-

 

(4News)

http://kfor.com/on-air/live-streaming/ (Just had update from Reed Timmer)

 

(News9)

http://www.news9.com/Global/category.asp?C=207228&BannerId=988

[chionomaniac]

Here is the couplet from last nights Carney tornado.

Massively impressive