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May 24 Plains/MW Severe Threat


Helicity

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You guys did a phenomenal job with the April outbreaks and to hear you say that makes me pretty concerned about the tornado situation for tomorrow. Hopefully most of the activity veers away from major cities, but that hasn't been the theme this year...

Unfortunately along I-35 from Salina to OKC there are 10,000+ people towns almost every 15 miles. So I am concerned that somewhere a populated place (8000+) will come under the line of fire tomorrow.

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Can comfort be taken in the fact that the SPC only has a moderate risk for tomorrow, or are high risks rarely given out beyond day 1?

Very strong wording. A High risk seems likely.

DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1216 PM CDT MON MAY 23 2011 VALID 241200Z - 251200Z ...THERE IS A MDT RISK OF SVR TSTMS FROM NWRN TX TO SRN NEB... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK OVER THE SRN/CNTRL PLAINS THROUGH THE OH/TN VALLEY TO SRN NY... ...TORNADIC OUTBREAK POSSIBLE ACROSS THE CENTRAL AND SOUTHERN PLAINS TUESDAY. AN UPGRADE TO HIGH RISK MAY BE WARRANTED AS SITUATION BECOMES MORE CERTAIN... A CLASSIC PLAINS TORNADIC OUTBREAK APPEARS TO BE EVOLVING ACROSS THE CNTRL/SRN PLAINS...ESPECIALLY FOR KANSAS AND OKLAHOMA.
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Very strong wording. A High risk seems likely.

I agree, when they are able to better define where the best threat is the High Risk will get hoisted. I have a feeling tomorrow could be a nasty day. My hope is that one of the ingredients isn't modeled correctly or is off and we don't see something quite as dramatic or bad as what we have this season. There is a lot of soggy ground over parts of the risk area so maybe that will have an effect of holding down the surface temps but that can also cause the LCL's to be lower too- which with good shear isn't a good thing. Time will tell come tomorrow. If you are in the risk area and you post on our boards please let someone know your information so we can make sure you are okay if something does occur.

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I agree, when they are able to better define where the best threat is the High Risk will get hoisted. I have a feeling tomorrow could be a nasty day. My hope is that one of the ingredients isn't modeled correctly or is off and we don't see something quite as dramatic or bad as what we have this season. There is a lot of soggy ground over parts of the risk area so maybe that will have an effect of holding down the surface temps but that can also cause the LCL's to be lower too- which with good shear isn't a good thing. Time will tell come tomorrow. If you are in the risk area and you post on our boards please let someone know your information so we can make sure you are okay if something does occur.

agree... I think SPC is just waiting for the best up to date data from the 0z runs to put that high risk... if I was to be the one pulling the trigger I would put it from say 20 miles west of I-35 along and north of I-40 (I-135 in KS) and head east to just west of the State line of Arkansas/Oklahoma and Kansas/Mo

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agree... I think SPC is just waiting for the best up to date data from the 0z runs to put that high risk... if I was to be the one pulling the trigger I would put it from say 20 miles west of I-35 along and north of I-40 (I-135 in KS) and head east to just west of the State line of Arkansas/Oklahoma and Kansas/Mo

A pretty good early call. If I were chasing I'd stage around or just E of Enid and from there you could head S further into Oklahoma or N into Kansas.

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A pretty good early call. If I were chasing I'd stage around or just E of Enid and from there you could head S further into Oklahoma or N into Kansas.

yeah. Plus Enid has good E-W road connections as well, this is one of those days that I for one hope busts, because if it verifies it won't be pretty at all...

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If you were writing a textbook on mesoscale meteorology and had to draw a schematic of a classic plains tornado outbreak setup, it would look exactly like tomorrow. It's petrifying.

If I had to take a stab at something that could go "wrong" with tomorrow, it's that the trough ejects out a few hours later, resulting in a delayed low-level jet intensification until a bit after sunset...and by that time storms would be somewhat less discrete. However, considering that the NAM has gradually trended towards a stronger LLJ over the past few runs, I think the chances of this happening are very low and dwindling.

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Here's my write up.

This is continuing to look like a dangerous situation. A forward propgating MCS looks to form in NW KS tonight and the move eastward tonight and into early tomorrow morning, there should be a cloud layer over SC KS but we should be able to clear it out. The shortwave is perfectly timed to come across an extremely unstable (3000-4500 J/kg CAPE) warm sector. The 0z NAM shows the area from US 50 near Hutch to US 412 near ENID to be what I consider to be the highest threat area. Hodo's in this area are borderline scary as the LLJ really starts to scream at 0z tomorrow. This will cause 0-1 KM Helicity to be nearr 300, and potentially even higher as it seems in recent weeks the models have been underestimating Helicity (joplin tornado had 400 SRH at the time of peak intensity, don't remember that being forecasted).

The dryline is in an unfavorable position when it comes to being near populated areas, so hopefully we don't have to deal with that tomorrow.

Some things I think worth noting, the Models have been consistently showing an area of weak 850 Dewpoints in the warm sector in KS, so this is something to keep an eye on as the morning turns to afternoon tomorrow. This is one of the main problems I have with areas north of Wichita tomorrow. I also don't like the weak Mean Flow from 500MB up in that area. The NAM is almost showing 240 degrees of turning because of a little veering with height above 500 MB in this area as well, might be a little too good, don't want those updrafts closed up.

So all in all fairly confident in the dryline/warm sector producing almost everywhere, however the maximized area should be between US 50 and US 421.

The 0z NAM has shifted things a little further east than the 18z NAM had with the dryline almost on top of I-35 tomorrow, however it shouldn't make too much of a difference wise other than shifting the target area towards more unfavorable terrain.

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If I had to take a stab at something that could go "wrong" with tomorrow, it's that the trough ejects out a few hours later, resulting in a delayed low-level jet intensification until a bit after sunset...and by that time storms would be somewhat less discrete. However, considering that the NAM has gradually trended towards a stronger LLJ over the past few runs, I think the chances of this happening are very low and dwindling.

patrick marsh over at stormtrack shares your concern about the low level wind fields not maximizing until after dark.

He also made a 4/26/91 reference as well...arrowheadsmiley.png

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In that case I will wait for the 0Z NAM to come out and see what's up.

0Z NAM is pretty incredible. Some of the forecast soundings I have seen at 0Z exhibit near dry-adiabatic lapse rates from sfc to H5, coupled with a 50kt LLJ and SSE winds at the head of a dryline bulge (not the nose, which will be further south in OK). Long looping hodographs are progged along with a deep moist layer. Near the OK/KS border is my "target" tomorrow. Given the drought in TX and the progressive nature of this system, would not be surprised to see the dryline mix all the way to I-35, but initiation should begin earlier further west around or shortly after 21Z.

The possible failure modes I have already explained. Shear profiles might take some time to become "epic", and with the strong forcing that is progged, storm modes may get messy before parameters get scary. Moisture may mix out south of I-40, and we could very well get vigorous initiation in that area which may cut off some of the inflow further north. Supporting this is the fact that the TX activity will be more thermodynamically driven as to dynamically driven, so it might actually initiate first, and it's in the presence of stronger anvil-level winds that could spread a stabilizing anvil around.

Ok, that was just for the sake of argument. At any rate, tomorrows setup looks impressive. I'll give this one a +1 relative to May 10 of last year, as we will have a wider instability sector to work with tomorrow.

EDIT: I swear I did not look at the EHI maps (below)... geez.

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Walked in Paul Sirvatka's office today....he goes "dude, I'm thinking about leaving tonight to go to KS for tomorrow". I rarely see him get this excited for a setup and be willing to drive that far to chase while he is not leading a COD trip. He was saying Ryan Jewell from SPC told him he couldn't find a negative with this setup.

Anyways, Paul isn't going to go, too tired after just getting home from a trip yesterday and going back out again friday.

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patrick marsh over at stormtrack shares your concern about the low level wind fields not maximizing until after dark.

He also made a 4/26/91 reference as well...arrowheadsmiley.png

I just pulled up http://www.tornadohistoryproject.com/ to research on the history of F4 and F5s in MO, and the random outbreak it gave me...... 4/26/91. Its an Omen. Harold Camping told me so.

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Another thing that could possibly go "wrong" with this setup is that the trough is so negatively-tilted that the winds back substantially in the 400-600 mb layer especially north of the KS/OK border. This creates a back-veer-back profile that isn't as favorable for sustained supercells. The GFS shows this appearing at 00z, while the NAM shows this occurring after 03z. This is one reason why I feel more confident about the tornado threat on the OK side.

I should note that this problem wasn't apparent in previous GFS runs, but the 00z run has the trough quite a bit deeper.

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Another thing that could possibly go "wrong" with this setup is that the trough is so negatively-tilted that the winds back substantially in the 400-600 mb layer especially north of the KS/OK border. This creates a back-veer-back profile that isn't as favorable for sustained supercells. The GFS shows this appearing at 00z, while the NAM shows this occurring after 03z. This is one reason why I feel more confident about the tornado threat on the OK side.

It's interesting to see the SREF hitting areas farther north, but I know it's only one tool. Will be interesting to see if that ramps up tomorrow.

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Another thing that could possibly go "wrong" with this setup is that the trough is so negatively-tilted that the winds back substantially in the 400-600 mb layer especially north of the KS/OK border. This creates a back-veer-back profile that isn't as favorable for sustained supercells. The GFS shows this appearing at 00z, while the NAM shows this occurring after 03z. This is one reason why I feel more confident about the tornado threat on the OK side.

This is a MAJOR concern of mine, would like to seee more of an open wave.

That ha happened so many times in KS this year, its ridiculous how many times it has.

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Just updated my SmartModel Output for tomorrow, current zoning in on an area from Tulsa, OK to Bartlesville, OK to Independence, KS to Miami, OK. Don't have specific indicies values as of yet. I think we could see the potential for the strongest Tornadoes in that zone for tomorrow. Thoughts?

usa.jpg

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