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Plains tornado threat Mon 5/27-Fri 5/31


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Did SPC or any other outfit predict an outbreak?  The guidance seems to be suggesting probability of severe, with the potential for a few tornadoes. 

 

TWC has been using the word outbreak pretty much all week.

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Considering that the current SPC outlook isn't even on the upper boundary of a moderate risk, the discussion of upgrade to high risk is quite pointless.

 

They're watching you... and trolling you. :lol:

 

GIVEN THESE PARAMETERS...IT APPEARS THE THREAT OF A FEW  STRONG/VIOLENT TORNADOES ARE IN PLACE.  HAVE INCREASED SEVERE  PROBABILITIES OVER THIS REGION...AND PORTIONS OF CENTRAL/EASTERN OK  WILL BE CONSIDERED FOR AN UPGRADE TO HIGH RISK AT 20Z IF  SHORTER-TERM MESOSCALE MODELS MAINTAIN THIS SCENARIO.  
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Considering that the current SPC outlook isn't even on the upper boundary of a moderate risk, the discussion of upgrade to high risk is quite pointless.

 

Oh the irony! 

 

:P

 

 

HAVE INCREASED SEVERE

PROBABILITIES OVER THIS REGION...AND PORTIONS OF CENTRAL/EASTERN OK

WILL BE CONSIDERED FOR AN UPGRADE TO HIGH RISK AT 20Z IF

SHORTER-TERM MESOSCALE MODELS MAINTAIN THIS SCENARIO.

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Oh the irony!

:P

HAVE INCREASED SEVERE

PROBABILITIES OVER THIS REGION...AND PORTIONS OF CENTRAL/EASTERN OK

WILL BE CONSIDERED FOR AN UPGRADE TO HIGH RISK AT 20Z IF

SHORTER-TERM MESOSCALE MODELS MAINTAIN THIS SCENARIO.

And I thought we were going to have no high risk this year.

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Oh the irony! 

 

:P

 

 

HAVE INCREASED SEVERE

PROBABILITIES OVER THIS REGION...AND PORTIONS OF CENTRAL/EASTERN OK

WILL BE CONSIDERED FOR AN UPGRADE TO HIGH RISK AT 20Z IF

SHORTER-TERM MESOSCALE MODELS MAINTAIN THIS SCENARIO.

 

Heh

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Incredible.  If something doesn't change drastically between now and 20z, we're seeing a high risk.

 

Eh... probably, I'm just not sure it will be warranted. That type of UH signature existed over C OK yesterday, too. To me, the consensus of the current convection-allowing models suggests storm coverage may be more numerous than is ideal for a violent outbreak in OK. I certainly see the high ceiling today, though; just seems it's a lot more conditional than a 5/24/11 or 5/10/10.

 

Great, now I have to pack up the important stuff in the apartment again. 

 

It's convenient in that that I forgot to get the important stuff out of my bag when I got home last night, though.

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If nothing changes by 20z, I fear that we have a significant outbreak of strong tornadoes in store for the OKC metro area and portions of MO.

 

This could be an extremely dangerous situation. 

 

:yikes:

 

4km NAM/12km NAM/WRF-ARW/WRF-NMM/NSSL WRF/HRRR/RAP all depict an extremely dangerous situation, 

 

 

 

RAP

 

 

 

4km WRF 

 

 

WRF ARW

 

 

WRF NMM

 

 

 

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AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE TULSA OK

1153 AM CDT FRI MAY 31 2013

..SIGNIFICANT SEVERE WEATHER AND FLOODING EXPECTED LATE

THIS AFTERNOON INTO TONIGHT...

.DISCUSSION...

ANOTHER ROUND OF SIGNIFICANT SEVERE WEATHER IS IN THE OFFING

FOR EASTERN OKLAHOMA AND NORTHWEST ARKANSAS LATER THIS AFTERNOON

AND INTO TONIGHT. HEAVY RAIN THAT COULD PRODUCE LIFE THREATENING

FLOOD WILL RAMP UP TONIGHT AND CONTINUE INTO SATURDAY.

THUNDERSTORMS ARE EXPECTED TO DEVELOP LATE THIS AFTERNOON IN

THE VICINITY OF A QUASI-STATIONARY FRONT AND DRY LINE TO THE

WEST OF THE AREA AND BECOME RAPIDLY SEVERE. AT THIS TIME...THE

STATIONARY FRONT IS LOCATED NEAR A KTOP-KICT-KGAG LINE. THE DRY

LINE IS WORKING INTO SOUTHWEST OKLAHOMA CURRENTLY. THE FRONT WILL

ONLY BE MAKING SLOW PROGRESS TO THE SOUTHEAST DURING THE DAY WHILE

THE DRYLINE WORKS WEST. THE AIRMASS IN ADVANCE OF THESE BOUNDARIES

IS EXTREMELY MOIST AND UNSTABLE WITH ABUNDANT DEEP LAYER SHEAR IN

PLACE ACROSS THE AREA. DISCRETE SUPERCELLS ARE EXPECTED TO DEVELOP

NEAR THESE BOUNDARIES LATE THIS AFTERNOON AS THE STRONG CAP ERODES.

THESE SUPERCELLS ARE EXPECTED TO MOVE INTO EASTERN OKLAHOMA DURING

THE LATE AFTERNOON/EVENING HOURS. THESE SUPERCELLS WILL BE CAPABLE

OF PRODUCING VIOLENT LONG TRACK TORNADOES...HAIL TO THE SIZE OF

BASEBALLS AND 80 MPH WINDS. EVENTUALLY THE STORMS WILL CONGEAL INTO

A CLUSTER OF STORMS ACROSS NORTHEAST OKLAHOMA INTO NORTHWEST ARKANSAS

AND SHIFT TO THE SOUTHEAST WITH TIME TONIGHT INTO SATURDAY. THE

SEVERE WEATHER THREAT WILL CONTINUE THOUGH THE NIGHT WITH ALL MODES OF

SEVERE WEATHER POSSIBLE. HEAVY RAIN AND FLOODING BEGIN TO BECOME MORE

OF CONCERN BEGINNING TONIGHT AS THE STORMS REPEATEDLY MOVE ACROSS THE

SAME AREAS.

 

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Eh... probably, I'm just not sure it will be warranted. That type of UH signature existed over C OK yesterday, too. To me, the consensus of the current convection-allowing models suggests storm coverage may be more numerous than is ideal for a violent outbreak in OK. I certainly see the high ceiling today, though; just seems it's a lot more conditional than a 5/24/11 or 5/10/10.

 

 

It's convenient in that that I forgot to get the important stuff out of my bag when I got home last night, though.

 

Just as things yesterday went a bit off expectations of forecasters, today is seeing the opposite as warm h7 advection will keep area capped. Notable trough in mid levels and cooling over the TX/OK panhandles arrives later today. The increasingly backed flow later with the SLP / response to the wave actually produces something that resembles 5/20 in a sense later for the OKC area at the surface. An untapped CAPE field with strengthening LLJ is the exact opposite of yesterday.  

 

For all of those worried about waiting for the nocturnal jet to respond, this isn't actually that process, entirely. The low-mid level gradient actually intensifies with the upstream wave which begins increasing the flow. This isn't simply the inertial/diurnal cycle and the exceptionally high CAPE fields argue that as well.

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Just as things yesterday went a bit off expectations of forecasters, today is seeing the opposite as warm h7 advection will keep area capped. Notable trough in mid levels and cooling over the TX/OK panhandles arrives later today. The increasingly backed flow later with the SLP / response to the wave actually produces something that resembles 5/20 in a sense later for the OKC area at the surface. An untapped CAPE field with strengthening LLJ is the exact opposite of yesterday.  

 

For all of those worried about waiting for the nocturnal jet to respond, this isn't actually that process, entirely. The low-mid level gradient actually intensifies with the upstream wave which begins increasing the flow. This isn't simply the inertial/diurnal cycle and the exceptionally high CAPE fields argue that as well.

interesting.  Thanks for the clarification, HM.

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I disagree.  I can't access the archived soundings from the RAP on TwisterData (they've been having issues with the RAP output all week), but I can access the NAM and GFS, and the 12z guidance from yesterday didn't come close to depicting the messiness of the hodos that we saw verify.

 

It isn't something new in meteorology for two different mets to see two different things from the same product. I also understand that we see with our brains and all of that, so I'm trying to keep my thoughts balanced in that regard. Having said that, I'm not sure how you can say both the NAM and GFS at 12z didn't indicate those issues with the wind profile at OUN, 18z. Both indicated the VBV issue and lack of low-level winds during the early afternoon.

 

http://www.twisterdata.com/data/tmp/scratch/models/processing/GFS_3_2013053012_F06_35.0000N_97.5000W.png

 

http://www.twisterdata.com/data/tmp/scratch/models/processing/NAM_218_2013053012_F06_35.0000N_97.5000W.png

 

 

Sure, modeled soundings will smooth things over and never look as detailed as a real sounding. But the issues were certainly there.

 

Thunderstorms got started pretty much at the "wrong" time for a localized outbreak of tornadoes in OKC (a nice save). Being on the heels of something favorable as the trends suggest "things get even more unfavorable" is not the best thing. I wonder how yesterday would have worked out if thunderstorms didn't initiate as early. The s/w cooling response on the DL yesterday got things going pretty freakin' early.

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Rick Smith - WCM at Norman posted this on the Skywarn Facebook Page:

 

I'm not trying to freak anyone out (yet - that may come a little later today), but this is one of those days when the decisions you make could be life-or-death. We may not see a single tornado (I'm hoping!!) but if a tornado forms it could be very dangerous, including the OKC metro-Moore-Norman area. The danger peaks in the 5pm to 8pm timeframe. Have a plan, stay alert and above all do not wait too long to react when the warnings come. If you feel compelled to drive somewhere to be safe, you CANNOT wait until the warning is issued. You need to be in that place before the storms!

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interesting.  Thanks for the clarification, HM.

 

No problem. I also do agree with what you posted, in terms of waiting for the nocturnal jet to aid in low-level shear. On 5/20, we had something similar to today in a sense, where the mean LLJ was east of OKC (putting the area on the fringe). But, the western-edge ends up "expanding and increasing westwardly" in response to the next wave. IF this occurs and you see the formation of a DL bulge  / enhanced backed winds with lowering pressures, then we will likely see some strong tornadoes (and with later timing than 5/20).

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