2012-04-14 FCST: TX, OK, KS, NE, IA

[Sean Ramsey]

I've been debating exactly where I want to target today mainly due to not really getting a good feel for when initiation will occur. According to RUC, by mid to late afternoon CAPE and helicity values are maxed out from the west Kansas border all the way down to the west Texas border, with me sitting at home in between. I believe the way I will play this is stay home until early this afternoon and watch development, being able to move in any direction and still be reasonably in place, ultimately moving eastward with maturing storms into the late evening. Everyone be safe today.

 

[Mike Johnston]

12z NAM out, indicating the following changes:

- Surface low deepening to 986mb, and hanging back in northeast CO by 00z, with the effect of more backing of surface winds across a large swath of Kansas and Oklahoma.

- Instability really mazimizing across west central OK and south central KS, as dewpoints rise into the high 60s.

- The "coverage" question may not be as big of concern, as precip may be breaking out as early as 18z and by later in the evening a big swath of convective precip indicated from south central through east central KS.

Trends on the RUC seem to be supportive of the NAM forecast. I would think positioning on the southwest side of Wichita, with a view to forays west of Wichita during the daylight hours might be ideal for today.

 

[Mark Blue]

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[Trey Thee]

New RUC and NAM are painting a fairly large area of 4000j/kg + in central OK and plenty of shear to go with it. This area moves from just west of the OKC and Wichita metro areas and by 7pm or so is right over those two metro areas.

We've got convection going up way west as of now. I'm wondering what if any impact this will have on us later today/this evening? Generally it can water down the atmosphere but the upper air dynamics appear to be quite supportive of the supercell/tornado threat regardless of a little early convection. I think we'll see a PDS box for areas west of I35 by 1pm and first supercell initiation sometime between 2 and 4pm.


edit: ok, I missed the boat, PDS just went up for far NW OK and central KS.

 

[Warren Faidley]

Possible early initiation in west Texas and SW KS (see recent MSD) could be a game changer and might have a major impact on entire forecast for regions east... for obvious reasons. I am running out the door in Shamrock to head NW. Good luck to all and be safe.

W.

 

[David Wolfson]

My pattern recognition instincts suggest early initiation in the Shamrock-Childress-Sayre area. Firming dryline, best moisture, SRH and CAPE already in place, and thinning cloud cover. Last vis satellite (15:25 UTC) also seems to show a convergence line on the western edge of this triangle. FWIW.

 

[Tim Vasquez]

Thought I'd post this... it's about an hour old now but still might be of interest. Will try to post some more later if time permits. Click to enlarge.


http://www.weathergraphics.com/tim/2012-04-14-15_l.jpg

EDIT: Looked at this again around 2000 UTC and I don't think my position on the outflow boundary was right.. scroll down to post #57.

 

[Eric Birch]

SPC's RUC meso analysis is showing area between TX/OK border and 183 (basically around Elk City, OK) as juicy with multiple ingredients in place. Suspect as these storms hit border and more build south this will be the area in OK. It would also appear that this area is where dryline buldge will pass as well. TX panhandle mesonet is not as good as OK so will be able able to tell surface trends in coming 2 hours on a better pin point. I would still look for initiation around Shamrock, TX off slight oragraphics on the edge of the buldge, due to current CIN and CAPE, and move into the SW region of OK where evertything looks right. Due to having to come into work early this morning, I wasn't able to get out this morning. If anyone needs radar run, let me know.

 

[Tim Vasquez]

Just got done with a class... I've noticed a persistent area of convergence and slight rotation in the wind field in the far northeast Texas Panhandle, near Canadian... this is especially evident on the SPC kinematic fields. That should favor continued development of the Tcu cluster currently in that area, and would put the Gage-Woodward area under the gun for 1-2 hours from now. I'm less certain about the area near Childress, but I do see an east-west thermal boundary in southwest Oklahoma, probably lifting towards I-40 later in the afternoon, and that would provide a window of enhanced severe weather for any storms that manage to get going and cross that boundary. Lots of uncertainty whether initiation can get going any significant distance south of I-40 near the Red River / CDS / LTS... that may hinge on the slug of upper lift comes out of NM, maybe initiating after dark if not this afternoon.

 

[Tim Vasquez]

On second thought, I'm looking at the wall clock and it's 1:30 pm... that's still another 4 hours for heating and convergence to work its magic, I'd probably lay odds on the CDS-LTS area initiating this afternoon. I'm really hoping we don't have yet another horrible evening of weather in the OKC metro.

 

[Eric Birch]

Solar radiation on OK mesonet is finallly ramping up in Beckham county on that I-40 corridor up to Weatherford. Radar and satellite are now showing first initiation just north of I-40 by Sayre. We'll wait and see what this little guy will do and seems like a few more TCU trying to start SE of Shamrock on the border. Mesonet shows most winds from the south and over the border in OK veering to a SE component. It does appear on water vapor that there is a dry slot just north of Beckham county in OK so we will see how this affects the situation and storm formation/enhancement.

 

[Tim Vasquez]

For what it's worth, stepping away from my hand analysis above and looking at it again I can now see that the boundary across Oklahoma was not continuous as I had drawn, but rather extended from southwest Oklahoma this morning ESE to around Longview TX (non-convective in origin), and then the old outflow boundary in NE OK and N AR. The southern boundary appears to have lifted north and is now roughly from Clinton OK to McAlester OK. It's still pretty vague, largely obscured by clouds on visible imagery though I can make out the western portion south of Elk City.

Not sure how these boundaries will play into the forecast, if at all, and there's almost certainly a lot of small boundaries anyway in northern OK and KS anyway from last night's MCS for stormss to work with.

 

[Mike Johnston]

Initial convection around DDC evidently put down an outflow boundary, which is now clearly evident on radar from ~Cimarron, KS to Beaver, OK. A couple of storms have recently fired off this boundary. Dry line still hanging back west, with little eastward progress today. Still plenty of instability and low-level shear over the risk area, but now some indication of CIN setting in.

 

[Eric Birch]

Would appear the initiation area from Shamrock to Canadian TX was where the most of these OK supercells started out and moved into the same exact area all day with the high risk finally making itself known with the current long track tornado in OK. Most of the storms starting rotating around Arnett to Woodward and then continued into KS. I would say the play north of Elk City on 34 was the area to be once the bullseye of shear shifted during the day a little further north. Was a little suprised these storms didn't go slightly further south but in retrospect I obviously forgot to look at the mean flow of the winds that would drive these storms on the track they took but I also expected some right movers too. Either way, all the north nay sayers are probably wishing they had the patience to stay south (and deal with more chasers) and on the more discrete storms. I honestly thought I was going to have to hang my head in shame on the ole forecast but sometimes you gotta stick to your guns. Wish I could have gotten out today. Instead dealing with 60mph winds here in NM and dust storm.