2015-05-16 EVENT: TX, OK, KS, NE, SD, IA, MO,MN

[Brian McKibben]

00z runs are in... My thoughts regarding W/C and SW Oklahoma into the OKC Metro.

HRRR - Particularly worrisome (from a general public standpoint) with this one is that the precip doesn't look to work over the atmosphere too much tonight. Early morning precip begins to vaporize starting around 12z. And then mid morning (15z) it is already showing SBCAPE >2000. One can only imagine that number will climb as we get some sun and heating. Surface temps across SW Oklahoma are already in the mid to upper 70s by 15z.

RAP - SBCAPE >2500 by 18z and STP creaping up past 2. Not sure what to make of the morning convection with the RAP.

NAM - At 00z the NAM has a line of storms along Hwy-81 corridor at 00z, Tds ~ 70° F, SBCAPE 2500+, MLCAPE 1500-2500, STP approaching 4 in OKC Metro and 5 along DL. 250 hPa @ 110 kt over NM, 500 hPa speed max over SW Oklahoma @ 80 kt.

4km NAM - Brings convection over SW Oklahoma in the morning. Develops Storms along DL in East TX panhandle between 19-20z. Potentially a few warm sector storms along I-44 corridor possibly from morning outflow. Storms approach OKC metro by 01z (8pm). SBCAPE ~4000 at 22z. UH shows warm sector storm going over OKC at 00z and several other DL supercells approaching Hwy-81 corridor at 00z as well.

MPAS - I'll leave that up to our resident MPAS met Jeff Duda Thanks buddy!

If we wake up and see the radar looking better than last Saturday then we could be in for a long day.

Target: My upstairs window looking west and storm shelter in Moore. Good luck to all. If i could chase I would head west on I-40 and then decide whether to go North or South once the 12z runs come in.

 

[Eddie O'Neal]

00z runs are in... My thoughts regarding W/C and SW Oklahoma into the OKC Metro.

HRRR - Particularly worrisome (from a general public standpoint) with this one is that the precip doesn't look to work over the atmosphere too much tonight. Early morning precip begins to vaporize starting around 12z. And then mid morning (15z) it is already showing SBCAPE >2000. One can only imagine that number will climb as we get some sun and heating. Surface temps across SW Oklahoma are already in the mid to upper 70s by 15z.

RAP - SBCAPE >2500 by 18z and STP creaping up past 2. Not sure what to make of the morning convection with the RAP.

NAM - At 00z the NAM has a line of storms along Hwy-81 corridor at 00z, Tds ~ 70° F, SBCAPE 2500+, MLCAPE 1500-2500, STP approaching 4 in OKC Metro and 5 along DL. 250 hPa @ 110 kt over NM, 500 hPa speed max over SW Oklahoma @ 80 kt.

4km NAM - Brings convection over SW Oklahoma in the morning. Develops Storms along DL in East TX panhandle between 19-20z. Potentially a few warm sector storms along I-44 corridor possibly from morning outflow. Storms approach OKC metro by 01z (8pm). SBCAPE ~4000 at 22z. UH shows warm sector storm going over OKC at 00z and several other DL supercells approaching Hwy-81 corridor at 00z as well.

MPAS - I'll leave that up to our resident MPAS met Jeff Duda Thanks buddy!

If we wake up and see the radar looking better than last Saturday then we could be in for a long day.

Target: My upstairs window looking west and storm shelter in Moore. Good luck to all. If i could chase I would head west on I-40 and then decide whether to go North or South once the 12z runs come in.

Brian,

I agree. I am sitting here with my chase partner looking over the new models. I definitely have some concerns for the OKC metro area. If I look out my bedroom window mid-morning and see sunshine I feel like we are in for one heck of a day around here. I personally would like to chase a little further north tomorrow, but for now all we can do is wait and see. By the way this is my first post since becoming a member. I am very excited to learn and share with you all.


Edgar

 

[Brandon Clement]

It's going to take more than sunshine because early sunshine just means storms will fire fairly early. The higher 700mb temps to the south will need to push a bit farther north. But yes, big concern for the OKC metro, areas along the red river and even the DFW metro.

Not sure if this is the right place or not so I apoligize in advance if it is not.
Everyone chasing tomorrow please be very aware of flooding. Do not put yourself in a situation where you could get caught between a flooded road and a tornado. Sounds silly and simple but in the heat of the moment it's easy to forget.

 

[Andy Wade]

Out west, attempts at upscale growth into small line segments have floundered for the moment and disorganized, mostly sub-severe clusters dominate.

The trend in short-term guidance seems to be up. HRRR in particular does stand out as concerning. I don't want to punch my hype train ticket with so much unwanted convection still ongoing, but should widespread 3000+ J/kg SBCAPE at 18z verify, nobody here needs me to tell them that's a big day.

I see a couple possible complications, if a severe weather event does unfold...

- Open warm sector initiation. Little to no capping, synoptic forcing for ascent, and likely some remnant outflow boundaries would set the stage for convection to initiate away from the dryline/front. Multiple CAMs insist on it.

- Significant nocturnal tornadoes. There's not much room for quick PBL stabilization with deep rich moisture, relatively low T-Td spreads, and absence of the warm 850s that would accompany a stout EML. I've seen a whole lot of 03z forecast soundings that are basically moist adiabatic in the lowest levels with negligible CIN. One caveat--upscale growth could remove the supercell tornado risk by that time.

 

[Kelton Halbert]

The full 5 day run of the 3km CONUS MPAS (Model for Prediction Across Scales) isn't finished yet and won't be until morning (and therefore plots unavailable until after), but the first 24 hours are in so I went ahead and generated some of the output. This is 1km AGL reflectivity with hourly max UH tracks. I had made this for my friend Jamie, so I made sure to annotate the max UH tracks so he knows where to go .

Looks like Central OK is in for a rough day.

 

[Brian McKibben]

Well i just woke up to the sun shining through my window. I quick glimpse at Vis and Radar doesn't show much is the way of a big organized system to work over the Atmos this morning. The storms seem to be getting more diffuse as the work toward the I-35 corridor, similar to what the models were suggesting last night.

So, I would say get ready and see what the 12z gives us. Could be an active day. 2000+ SBCAPE in 12z OUN Sounding.

Just thought I would throw this out there... Here is a quick look at the HRRR showing a STP of 15 west of OKC at 01z.

 

[Bob Schafer]

Somebody please tell me that everything I ever learned about forecasting is wrong.

For one thing, the lid strength is gone by 18Z, per RAP and NAM, so. Then, the hodos stink. Where are the curves? It all looks pretty straight-line with the exception of right around extreme W & SW OK, and there's ongoing crapvection west of there as I type. Just look at forecast EHI's for confirmation of this.

I'm sure I'll be proven hideously wrong, like I often am, but I'm really scratching my head as to how we're going to get anything but a gigantic MCS from ND to TX.

 

[Tim Supinie]

The HRRR does seem to be handling the morning precip a little better today than it did last week. Still under-doing the amount of convection in the TX Panhandle, so I'm not entirely sold on it going bonkers later today. Last night's MPAS run also missed the convection in the TX Panhandle, so it's probably also unreliable.

 

[Andy Berrington]

Current observations show backing surface winds across N TX and much of OK. If we see this later on to any notable degree, tornado potential with any supercells is going to go up in a hurry.

 

[Warren Faidley]

Somebody please tell me that everything I ever learned about forecasting is wrong.

For one thing, the lid strength is gone by 18Z, per RAP and NAM, so. Then, the hodos stink. Where are the curves? It all looks pretty straight-line with the exception of right around extreme W & SW OK, and there's ongoing crapvection west of there as I type. Just look at forecast EHI's for confirmation of this.

I'm sure I'll be proven hideously wrong, like I often am, but I'm really scratching my head as to how we're going to get anything but a gigantic MCS from ND to TX.

I have to agree.

However, the ruc suggests the E/NE TX panhandle will offer a target in the 18-21z hours with no substantial DL push and favorable instability due to recovery. I also think numerous outflow boundaries will only enhance shear. I'm guessing the 16:30z outlook will move the mod. towards the west / nw.

This is also supported by the 13z HRRR that shows isolated cells in the same time frame.

Initial target will be Dumas, TX -- to be adjusted.

 

[Jeff House]

In infer from the SPC 13Z that they actually considered down to ENH but I am glad they kept MDT. Tornadoes will verify today, but perhaps not all up and down the DL. Hodos are not great. However where OFBs can enhance local low level shear, total hodos will indeed promote tornadoes - some maybe strong only along OFBs.

I infer SPC are concerned about uncertainty, thinking about ENH, but the synoptic pattern requires MDT. Any English majors in the house? I don't have a dog in the hunt. Reluctantly elected to sit out this one. My optimism along OFBs is not wish-casting, but based on my understanding of the meteorology. Good luck to everyone; and, with the messy mode and crowds, please chase extra safely today.

UNCERTAINTY IN THE SUBSEQUENT EVOLUTION OF THIS EARLY CONVECTION AND
DEGREE OF AIR MASS RECOVERY IN ITS WAKE DURING THE LATE
MORNING/AFTERNOON...AND HOW THIS EVOLVES WILL IMPACT LOCATIONS AND
LIKELIHOOD OF SEVERE STORMS THIS AFTERNOON AND EVENING. GIVEN THE
FAVORABLE SYNOPTIC PATTERN...HAVE OPTED TO MAKE LIMITED ADJUSTMENTS
TO THE OUTLOOK AREAS WITH THE EXPECTATION THAT THE MESOSCALE
SCENARIO WILL BECOME MORE EVIDENT AS THE DAY PROGRESSES.

 

[Jeff Duda]

Keep in mind that hodographs don't have to be nicely curved to get tornadoes. Check out the OUN soundings for May 6th. The 19Z sounding in particular looked pretty ugly in the 1-6 km layer, but nearly 30 kts of 0-1 km shear helped make it quite the tornado day for the area. Also keep in mind that LCLs and LFCs were pretty low that day, just like they are in the 12Z OUN sounding. The S-shaped hodographs tends to lead to messy or transient supercell structure, but that doesn't preclude storms producing tornadoes.

This might very well be a day filled with tornadoes lacking decent supercell structure aloft.

 

[Brian McKibben]

Edit: OUN launching 18z sounding

Per OUN emergency management briefing
New Moderate risk will likely look like this.

 

[Royce Sheibal]

I've been staring at models all morning and Nebraska is really up in the air. We've got morning blow-off covering SC Neb, but Omaha and Lincoln are almost at 80 already with almost 70 DP's. I really want to go chase the stuff that will form on this outflow from KS right now...but I know shear isn't here yet. 6pm to 10pm Tonight from Beatrice to Omaha high res models are still showing 3-4k Cape with 0-1KM SRH hitting almost 300. I'm expecting some sort of MCS to be pushing in from the west, but anything that forms on outflows or can get ahead of the line will be nasty. The Hallum, NE 2.5 Mile Wide Monster was a rogue cell out ahead of the main squall on a similar day. Cell produced for nearly 4 hours before picking up just south of Lincoln around 10pm. Where is Reed Timmer when I need him?

My Target today: Beatrice, NE around 5pm moving back to Omaha at Dark.

 

[Des Heyliger]

I-44 corridor is where it's at today. DPs in the 70s and clouds are clearing. In Joplin now. Taking I-44 southwest until storms start initiating. Then I'll head west to intercept.

 

[mkavulich]

Question, is this model an experimental mid-range derivative of the NAM combined with the hourly forecast projection of the HRRR?

@Russ Conlon, MPAS is a next-gen global model, it's not derivative of any existing model. It's a hexagonal grid, which allows it two major advantages over existing models:

1. It has no "pole problem" of messy singularities at the north or south pole that must be dealt with in ugly ways
2. It can have a continuously variable resolution across the globe unlike WRF-based models (NAM, HRRR), so that you don't get boundary-related issues as seen in those models

This presentation has a lot of details, including graphical examples of the variable mesh in action: http://www2.mmm.ucar.edu/people/skamarock/Presentations/AMWG_2013_skamarock.pdf

 

[Hannah.Taylor]

good line of storms beginning to fire east of Lubbock on into the pandle of TX, and moving NE towards SW OK. Positioning my crew (J.J. Tomash and John Reed) and I in Clinton,OK here shortly to stop for food and to re-assess the situation. A bit hesitant to move any further east just yet, but should still be in a good position to move E or SE to intercept if necessary, but we wont be out of position to backtrack to the west if we have to.

 

[Brian McKibben]

Storm south of Elmer, OK has a reported large tornado. Amazing hook and velocity values. Cor Coef. confirms tornado.

 

[BBauer]

David Drummond has large cone tornado on The Weather Channel via his dash cam, just a few minutes ago. On the Tipton storm

 

[Brian McKibben]

my goodness...

 

[JamesCaruso]

I was at a wedding Sat night (otherwise I would have flown out Fri night! ) so ended up first seeing the Tipton storm on my iPhone at about 6:20 CDT. Figured I would post that base velocity image in case anyone wants it. I am also attaching a later image - I don't recall previously seeing velocities in the brown shades at the highest end of the red spectrum!