2015-04-06 EVENT: KS/OK/TX

[Marcus Diaz]

So let's jinx this now. Monday has all the potential to be a big day...if it wasn't for the cap. Also, we have a case of "just-in-time" moisture. Although not deep moisture, it looks to be adequate for good supercell potential. But like I said, THE CAP, BRUH. The only good news is the NAM has been trending down on the cap along the dryline around the 21z time frame, as depicted in this graph of MLCAPE and MLCIN. Also this sounding from around El Reno shows a stout, but breakable cap.

The area south of I-40 has my eye the most since the deeper moisture will be down there. Some of the stronger mid level shear will be down that way as well. Although so far non of the models fire precip, that could always change come morning of. Aside from Wednesday, this day has the best looking dynamics for a classic dryline day in western OK. But if the cap holds, a lot of us will be getting sunburned more than likely. I might nose my way into Elk City to see if the cap breaks. If not, dinner at Carl's Jr before getting home at a reasonable hour.

 

[Derek S Baker]

Good explanation Marcus Ahhh...the benefits of living down there....not a terrible amount of driving to/from the target, so taking a chance on a bust is not out of the question. By the time the morning guidance comes out, it'll be too late for a lot of folks.

 

[Brandon Sullivan]

There are obviously some impressive soundings from Monday across OK, but models are dry. This likely stems from the moisture depth being too weak, quick veering winds shunting parcels off of the dryline quickly, and not a deep enough dryline circulation to get a parcel to the LFC.

The 21z SREF from today has a few members convecting, but that isn't enough to lead me to believe just yet.

Obviously, I would like to get a nice shortwave somewhere.. That would potentially solve the issues of the moist layer depth and winds, with some mid level backing as typical with shortwaves. I'm also interested in watching moisture return the next 24-36 hours to see if it's as prominent and rapid as models suggest.

NAM4 surface moisture convergence fields show some attempt at convergence, nothing significant.. 700mb UVV plot likely is just a reflection of the DL circulation.

Sounds like another wake up on Monday and get trolled by the HRRR until the 21z run where it stops showing the storm it had since the 10z runs

I wrote a blog here if anyone is interested

 

[Jeff Duda]

FWIW, the 00Z 4 km NAM has a DL bulge moving from NC OK to SC KS from 21Z to 00Z.

This kinda looks like a big teaser event, much like this past Thursday. I don't think I saw any 70 dewpoints make it north of the Red River on Thursday, though. Perhaps the slow green-up cost some moisture. I have certainly seen a lot of vegetation turn green around Norman over the past 10 days or so, so perhaps that will cease to be a big problem. Upper level soil moisture is tanking in Norman which is probably a good sign that vegetation is becoming healthy. For now, the soil is still pretty wet at all levels, but if we don't get some good rains here over the next week or two, the soil is going to quickly dry out and then we'll start seeing some problems with moisture really not making it.

Long story short, looks like high risk/high reward type setup with strong conditionality on CI. As Brandon said on the other thread (which is weird...we may need to merge), the SREF probabilities don't give a lot of hope for action, but the chance is also greater than 0%.

 

[Jeff Duda]

FWIW, the 00Z 4 km NAM has a DL bulge moving from NC OK to SC KS from 21Z to 00Z.

The models still generally don't have any precipitation for this day, but that DL bulge noted in the 00Z 4 km NAM is also present in the 12Z 4 km NAM and the 12 km NAM. So I'd say there's hope </wishcast>.

 

[Brett Roberts]

Also noteworthy is that the 05/09z SREF has non-negligible (30%) probabilities for convective QPF along much of the dryline both Monday and Tuesday. I certainly wouldn't write off the potential for a nice isolated, sculpted supercell somewhere in W OK or NW TX tomorrow. Thankfully, any surface-based convection either day would (likely) just be icing on the cake for this week.

 

[Ben Holcomb]

Definitely have had my eye on this for a few days as the NAM has been advertising 4000 CAPE and some decent hodographs. It seems the actual bulk shear is marginal for supercells, but maybe that is just me. Some of the soundings along the dryline are only showing 40 knots of 0-8km shear and a little less 0-6km.

There are a lot of negatives, but we should have a better idea tomorrow morning with the 12Z soundings. I won't be writing tomorrow off at any rate.

 

[StephenHenry]

Ugh I've been wishcasting the crap out of this day all weekend - really want to get out for that first chase. As others have mentioned, its a pretty great atmosphere that will possibly/probably go to waste due to capping.

@Brandon Sullivan's blog post is excellent and mentioned that there are a few SREF models with precip. Going with "the trend is your friend" mantra, I've compiled some dProg/dt SREF mean 3-hr precip plumes for stations between Wichita and OKC. The nice thing is that the latest (pink) run might hint at a little uptrend in precip the further south you go. But, the mean is pretty meager - certainly not a majority of SREF members with precip.

I've also tried to see if capping has a nice downward trend in the GFS or NAM. Here I picked 3 locations, Wichita, I-35 at the KS/OK border, and OKC. This is also a sort of dProg/dt graph, in that each line represents the cap strength at the same location at the same time tomorrow afternoon (either 21z or 00z) with older to newer model runs from left to right. This is probably the thing that will keep me home. GFS 00z SB Cap had a hint at a downward trend, but everything else, particularly the NAM, seems to be converging towards some unbreakable values up and down the dryline.

I'll certainly take one last look early tomorrow morning, but I probably won't head out. I'm def jealous of the people who can watch the obs till mid afternoon before they pull the trigger.

 

[Randy Jennings]

I'm not likening the chances for a cap break on Monday. I think in order for us to get storms along the dryline Monday we will need some good moisture at the mid levels around the dryline and some other type of lift to weaken the cap out east of the dryline. Mid level moisture looks too low in 05/18Z both the NAM and GFS. I'm also not seeing anything that might weaken the cap out ahead. As Brandon noted above, where is a good shortwave when you need one? I've already had to many cap busts here in north Texas this year. It's like we skipped March and April and went straight to May. Of course, one of these days a chaser who sits on the dryline is going to get lucky and I'll be eating crow.

 

[StephenHenry]

Fresh GFS 00z just now coming out. Cap trended higher along the ICT-OKC corridor.

 

[Jeff Duda]

I would agree that it looks to be a bit of a longshot, but there may be hope still. I see plenty of evidence that the models are trying to initiate convection (there are some deep UVVs along the dryline in the GFS especially). The SREF does indeed have a few members with precipitation even as early as 21Z, but the probs are still below 50%. What's startling to me is how different the surface moisture fields look between the NAM and GFS. The 00Z GFS is much more dry at the surface than the 00Z NAM (by a good 5 F). With widespread 65 Tds already encroaching the shore in SE TX (and with a patch of 70 Tds just offshore), I have a hard time believing 65+ won't make it at least into C OK by tomorrow 21Z. The NAM, SREF, and NSSL WRF (12Z) are all pretty confident of that.

Another thing - that DL bulge continues to show up in the 12 km NAM, the 4 km NAM, and the NSSL WRF. Same place as before. Either that is a highly predictable feature, or the accuracy with which the atmosphere is being sampled to provide IC/LBCs to the models has remained relatively constant over the last 36 hours.

I'm hopeful, but still kinda wishcasting. I'll have to wait until the last possible moment before I decide if the drive is worth it. Hopefully something will change by tomorrow midday to make it easier to decide (like HRRR forecasts showing something, for example).

 

[Nate Weikal]

The 00z NAM and GFS run does show an area of weakness in the cap around Wichita Falls/ Waurika, OK southwestward where the cape will be 3000+ j/kg. In my opinion, that would be the best area to hope for a supercell. Tornado threat seems low though. I'm not worried about tomorrow too much unless the latest data hints at something interesting. I'll be gearing up for Tues-Thurs.

 

[Ben Holcomb]

We're nearing noon today and the extensive cloud cover showing up on visible satellite is not good if we want to fire some storms later this evening. The dewpoints are here with low to mid 60s showing up across Oklahoma. The real question is if we can get some cooking going on soon or not.

 

[Jason Boggs]

Cant chase any day of the week except for today, so I'm going to pull the trigger. Looking at everything, I think I may play my odds at Seymour, TX. Good clearing in that area, along with Td's in the low 60's should yield some high CAPE. Also, the HRRR and the NAM 4km have signals in that area that something might form. It's going to be hard to get a storm to fire, but I at least have to try. Good luck to everyone going out today!

 

[JustinRudicel]

So HRRR you're saying there is a chance!? The lingering clouds east of the dryline I don't think hurt us too much as it will only sharpen up the dryline as it mixes east. Thinking positive here as that lone t'storm is less than an hour away. =) Cap & lack of convergence still has me pretty pessimistic with the overall storm threat today.