May 7th-10th Severe Outbreaks

[Smokey_mountain_vols]

Now that the southern segment has broken up into discrete cellular convection and the eastern segment has weakened some, I'm not too concerned that the current MCS will wreck tomorrow's setup -- although it will likely limit the northward extent of it more than the NAM/GFS/etc. have shown the past several days. What does seriously concern me is the potential for yet another morning MCS coming off the Caprock, which would probably be near-fatal to the hype/outbreak scenario that some are touting as a given tonight. There's no word for the HRRR but "ugly" regarding 12z-16z on the past couple runs, and the SPC 4 km WRF depicts a similar evolution. However, I will say the HRRR has been less impressive (and less consistent) in its forecasts for convective evolution the past few days than usual for the Plains. Still, gun to my head, I'd bet on a substantial amount of convection across W TX and the Panhandles before 18z tomorrow. If it weren't for that, this would of course be the most impressive setup for this region in at least 5 years, likely more.

Does this mean here in Tulsa we'll be getting the storms sloppy seconds?

[thewxmann]

A bit off topic, but this video of the Allison tornado is one of my all time favorite tornado videos from the pre-2000 era.

 

http://youtu.be/djk418z9cm4

 

Love the Allison tornado clip. Hoover's also pretty good.

 

And of course all the Pampa tornado clips. The benchmark for Panhandle events.

 

While we're still all dreaming about a 6/8/95 redux...

[brettjrob]

Yeah, 6/8/95 is one of those days that seems surreal and larger than life to anyone who started chasing much after it. It's pretty hard to even conceive of having the opportunity to be on that Pampa storm, especially after how the last 4-5 years have gone out there. All those years us chasers have spent talking about it, our mouths agape over videos such as the one above... and sometimes it all comes down to something as mundane as the possible MCS tomorrow morning.

[andyhb]

Yeah, 6/8/95 is one of those days that seems surreal and larger than life to anyone who started chasing much after it. It's pretty hard to even conceive of having the opportunity to be on that Pampa storm, especially after how the last 4-5 years have gone out there. All those years us chasers have spent talking about it, our mouths agape over videos such as the one above... and sometimes it all comes down to something as mundane as the possible MCS tomorrow morning.

 

Heh, new HRRR doesn't show an MCS and appears to be destabilizing rapidly in behind what morning convection it has. Oh the joys of last minute convective forecasting.

[Ian]

I'd be worried about moisture at least for a 1995 which I would take the under on officially, hah.  That event had super rich moisture -- 70+ dews bumping into the dry line the night prior around AMA -- which clearly CIPS don't give 2 ****s about.. the NAM is off a good bit already at least up into the panhandle. I've only chased around there like twice so I know nothing of the magic per se.. At the least for now feels like you'd have to favor more to the SE part of the panhandle or W/SW OK, maybe further into NW TX if you're feeling frisky (tho I wonder if this will end up the best chase target too).

[andyhb]

Shear through most of the column will likely be significantly stronger than what was in place for 6/8/95 though just as the counterpoint to lower moisture content this go around (as expected given seasonal/monthly climo differences).

[SmokeEater]

Day 1 moderate, and they were even thinking of downgrading.

[andyhb]

Yeah, early convection/etc. almost leading to a downgrade.

[Chicago Storm]

Still feel early initiation will be an issue on Saturday, and will probably keep it from being too sig of a day.

 

And now it looks like Friday will feature a similar issue as Thursday, an early MCS being the main show throughout the day.

[andyhb]

Still feel early initiation will be an issue on Saturday, and will probably keep it from being too sig of a day.

 

And now it looks like Friday will feature a similar issue as Thursday, an early MCS being the main show throughout the day.

 

I see no real MCS over western areas on the latest runs of the HRRR, especially compared to earlier. It starts off as more cellular convection and then congeals once it starts moving towards north-central TX.

 

Edit: Well nvm with the 05z run coming in.

[tornadotony]

HRRR and NSSL-WRF bring into real question the nature of what we're assuming is going to be an early-forming MCS.  Both models indicate quasi-discrete cellular-appearing features within the convective cluster with extremely high updraft helicity.  To me, this screams a cluster of quasi-discrete supercells riding the boundary more so than an MCS, particularly given the general lack of linear forcing at play.

[tornadotony]

e.g.

 

 

[andyhb]

HRRR and NSSL-WRF bring into real question the nature of what we're assuming is going to be an early-forming MCS.  Both models indicate quasi-discrete cellular-appearing features within the convective cluster with extremely high updraft helicity.  To me, this screams a cluster of quasi-discrete supercells riding the boundary more so than an MCS, particularly given the general lack of linear forcing at play.

 

If that's the case, some of these things are tracking rather close for comfort to the OKC metro by mid afternoon.

 

Case in point those images. Also Wichita Falls.

[tornadotony]

If that's the case, some of these things are tracking rather close for comfort to the OKC metro by mid afternoon.

 

Case in point those images.

FWIW, the HRRR has sig tor ranging from 3-7 ahead of that.  Again, I don't think we can rule out that it's going to be an MCS, but I certainly don't think we can bank on it.  If it's quasi-discrete, somewhere between OKC and ADM is probably going to be in trouble.

[thewxmann]

FWIW, the HRRR has sig tor ranging from 3-7 ahead of that.  Again, I don't think we can rule out that it's going to be an MCS, but I certainly don't think we can bank on it.  If it's quasi-discrete, somewhere between OKC and ADM is probably going to be in trouble.

 

There's of course the possibility that discrete supercells will form out ahead of the MCS ala Thursday... so yeah. Lots of options and scenarios still on the table.

[andyhb]

FWIW, the HRRR has sig tor ranging from 3-7 ahead of that.  Again, I don't think we can rule out that it's going to be an MCS, but I certainly don't think we can bank on it.  If it's quasi-discrete, somewhere between OKC and ADM is probably going to be in trouble.

 

Problem with this new idea is that it shifts the threat from the lesser populated TX Panhandle/W OK area to the heavily populated I-44 corridor, Lawton included as well. HRRR still seems to be destabilizing in behind that too FWIW.

[jhamps10]

So just woke up, and the ONLY thing on the radars is a tiny cell just north of Synder... unless it develops into an MCS I think AM MCS fears can be relaxed at least this morning anyway

[RCNYILWX]

So just woke up, and the ONLY thing on the radars is a tiny cell just north of Synder... unless it develops into an MCS I think AM MCS fears can be relaxed at least this morning anyway

10z HRRR breaks out a bunch of discrete cells 23z to 1z behind the afternoon MCS. Even has a right mover headed right toward the north part of the metroplex. This run focuses the afternoon MCS mainly north of I-44, which should keep the environment south of I-44 volatile. Showing STP values of 7-9 near the Red River just north of SPS by 21z.

[Quincy]

So just woke up, and the ONLY thing on the radars is a tiny cell just north of Synder... unless it develops into an MCS I think AM MCS fears can be relaxed at least this morning anyway

It's still a complex setup. Although radar looks good now, on water vapor, watch the area near the Texas/Mexico border. NAM/HRRR still want to develop a messy complex of storms by 17z with only a few stray supercells in the vicinity, or not even until nearly sunset further SW.

There's fog locked in across the Texas panhandle has much of western Oklahoma now too. The boundary should lift north a bit though. Don't want to speculate too much, given the degree of uncertainty, but maybe the risk area shifts back slightly to the SW? Even with the muddled HRRR setup, it still shows a fairly volatile environment, albeit over a relatively narrow corridor near Caprock.

[ZackH]

Posted this on stormtrack, but thought I'd post it again here. I still believe the moderate will verify and think they will hatch the tornado probability at the 8am update, personally:

 

Models all seem to be in agreement that there will be two rounds of storms. This initial elevated convection should really get going by 18-20z and quickly move north and east. As we get towards afternoon, some of this may become surface based into central and eastern OK, but the real threat will be the secondary convection that fires on the dryline. All of the models (with the exception of the bizarre RAP solution) paint a picture that the atmosphere will recover in plenty of time with an impressive parameter space by 21-00z in the eastern TX panhandle and into western OK. The NAM brings the initial piece of shortwave energy into the area around 18-20z which seems to coincide with the development of the initial convection. There will be a brief break in the mid-level flow before the next wave enters around 00-03z. I believe some small scale subsidence in between the two waves is what is helping to break up the clouds and letting the atmosphere recover by late afternoon and evening. Because of the modest cap and the nature of the forcing, I would not be surprised at all if we end up having a decent nocturnal tornado event, especially with that low level jet really kicking in by 03z. Let's just hope that initial surge of mid-level flow doesn't ruin the day.

If I were chasing today, and oh how I wish I were... I'd target Childress, TX and east. The biggest challenge for me would be whether to stay north or south of the river. However, the parameter space is a bit more impressive north or the river right now.

[Brick Tamland]

[tornadotony]

It's still a complex setup. Although radar looks good now, on water vapor, watch the area near the Texas/Mexico border. NAM/HRRR still want to develop a messy complex of storms by 17z with only a few stray supercells in the vicinity, or not even until nearly sunset further SW.

There's fog locked in across the Texas panhandle has much of western Oklahoma now too. The boundary should lift north a bit though. Don't want to speculate too much, given the degree of uncertainty, but maybe the risk area shifts back slightly to the SW? Even with the muddled HRRR setup, it still shows a fairly volatile environment, albeit over a relatively narrow corridor near Caprock.

The HRRR's not muddled.  It's got sig tor up to 15 in the inflow region of the cells it develops across southern OK and has propagating  NE.

[Quincy]

The HRRR's not muddled. It's got sig tor up to 15 in the inflow region of the cells it develops across southern OK and has propagating NE.

Strictly in terms of forecast reflectivities (which showed us on Wednesday are sometimes useless), the last couple runs have really come around. Seeing some intense updraft helicities with multiple discrete cells around 00z from the 11z run. The trends from the HRRR are encouraging and as mentioned, the environment feeding into the cells is quite impressive.

[LocoAko]

If I were chasing today, and oh how I wish I were... I'd target Childress, TX and east. The biggest challenge for me would be whether to stay north or south of the river. However, the parameter space is a bit more impressive north or the river right now.

 

Based on nothing else, I'd stay north of the Red River for the road options. Compared to the 1-mi grid over just about all of Oklahoma, the roads in north Texas along the Red River have caused me to rip my hair out more than  I'd like to admit. /rant

[tornadotony]

06z 4-km NAM doesn't have an MCS.  It has a band of discrete cells.  Assuming that an MCS is coming is not a good forecast strategy.  A better strategy would be to leave a window of possibility between MCS and supercells.

[jameswx]

Early convection for Saturday looks like an absolute mess.  It will be interesting to see how things evolve and how much destabilzation can occur Sat afternoon.

[Ian]

I think I'd lean to NW TX as of now today, tho feels like the wrong idea for some reason. SW of Wichita Falls generally.

[Ground Scouring]

Early convection for Saturday looks like an absolute mess.  It will be interesting to see how things evolve and how much destabilzation can occur Sat afternoon.

The negative tilt of the 700-mb low as it takes shape early Saturday (at least on the GFS) helps prevent the EML from advancing northeastward over most of OK, thus partly allowing the early convection. However, the 06Z 4km NAM (and previous 4km runs generally) shows much less widespread convection than does the GFS and the main NAM. To be honest, I do not think that we're going to get a good handle on the convection until early morning to midday Saturday. Other than convection, everything else looks quite favorable for a significant outbreak. If convection ends up less than forecast, then a threshold-High Risk event becomes quite possible, if not even likely. Back-veer-back looks to be an issue at first but then quickly improves after 21Z.

[WishingForWarmWeather]

Here in Central Texas (Temple/Ft.Hood area) it is so warm and wet outside.  75 degrees, 85% humidity.  It just smells/feels like severe weather ahead. 

[Roy]

Crapvection filling in quickly in central Texas but appears to be going more east now so maybe not as big a deal as I originally thought. Stuff in far western TX going north and will miss OK area.