2015-03-19 EVENT: NW TX / SW OK

[James Langford]

I'm surprised to not see any discussion for Thursday here given all that I have seen on social media.

A marginal event for sure, but being in my back yard one I may get out for.

Primary Target : Wichita Falls at 6 PM
Secondary Target: Graham at 6 PM for isolated storms farther from the cold front

Positives

• Decent 500 mb winds for upper level support
• Surface temps look to get into the 80s with 60 DPs
• Possibility for backed surface winds due to nearby surface low. Seems like only the TTU WRF is backing the winds

Negatives

• Quickly moving cold front undercutting storms closer to the better forcing
• Uncertainty on location of surface low
• Limited instability
• Weak surface and 850 winds
• Questions on cloud cover keeping down temps

Thoughts?

 

[Jason Boggs]

We were on the same thinking, but you beat me by 14 minutes!

My thoughts are pretty much the same as yours. Decent shear and Td, but lack of sufficient instability and undercutting of storms is definitely a fly in the ointment. I'll likely get out to just test equipment and relieve a little of my SDS built up over the winter. Of course I said the same thing with the Hammon, OK event on 3-8-10, so you never know what to expect on any given chase day.

TARGET AS OF RIGHT NOW: ELECTRA, TX

 

[James Gustina]

The cold front's motion is really the biggest concern, because the models can't seem to nail it down and as a result can hit on the SFC cyclone or how deep it'll be. Other than instability also looking meh (750-1000 ML) I'm not taking issue with anything else. 6.5C/km lapse rates are more than ample in my opinion and if SFC temps hit the mid-70s instability may be a smidge better. I'm still very much on the fence as much as I'd like to get out.

Preliminary Target: Grandfield, OK. River crossings are a bit meh down that way but its a good staging point with a good restaurant.

 

[Jeff Duda]

Quite marginal. Shear and lift look to be sufficient, but instability is really meager and it won't hang around for long. Looks like a pretty narrow window of opportunity during the late afternoon. The NAM seems to have a hard-on for this setup and really wants to fire storms along the cold front. If a storm can fire on the front and not get undercut by it, then something could happen. Forecast storm motions suggest it's possible a storm could ride along the front instead of being immediately undercut, so it's possible. Could be worth a short drive out there.

ADD: 15Z SREF and 12Z GFS show poor lapse rates and poor CAPE compared to the NAM. What little CAPE there is is pretty skinny. Perhaps if the profile was shortened such that NCAPE was higher I'd be more excited than I am about this. It really looks like a pretty meager setup.

 

[Jeremy Perez]

I’ve been watching the GFS signals for Thursday flicker on & off for the past week. It’s nice to see a thin glimmer of hope for tomorrow. I can’t add much better than what’s already been discussed. 18Z NAM shows 0-3 km Helicity maximized up to 250-350 m2/s2 narrowly along the cold front near the triple point at 00Z in the vicinity of Crowell, TX. 0-1km SRH is localized and probably barely worth noting near the triple point in the 50-100 m2/s2 range. 18Z GFS is much more conservative and also points further east—south of Wichita Falls. Obviously wouldn’t mind NAM’s optimism working out moreso than GFS at this point and I’m planning to give it a shot just in case. I’m planning to head out of Elk City with an initial target of Vernon, TX by early afternoon.

 

[Todd Rector]

Although I am totally amped for the 2015 season to begin and have 3 weeks of vacation time saved up for it, I am going to sit this one out (too far to drive from Iowa for a marginal setup). Like much of 2014, since I won't be there you are nearly guaranteed a large, photogenic tornado. (You're welcome)

 

[Marcus Diaz]

I HHHHAAAATTTEEE forecasting days like tomorrow. Crappy enough to blow it off, but meager and close enough to deeply consider driving out. The NAM is pulling it's own antics showing a decent setup at the tail end of the forecast period back west, then slowly moving it east and tossing more dead flies in my Vaseline. I've seen setups like this many times in the past, and have only seen it work out a couple times. Everyone pretty much nailed the different aspects of this setup, and I probably won't decide if I hear out until noonish.

 

[Jason_Dasho]

I will be most likely heading out late tomorrow afternoon. This will be a low investment gamble since I will be leaving from Ardmore. Not expecting anything significant. I think this will be a good opportunity to clean out a few cob webs and to practice with my new DSLR getting ready for the upcoming season. If things do get going in a minimal way, I hope they stay off the Red River so I don’t have to deal with limited river crossings, and localized poor viewing terrain. Either way it’s just nice to get out.

 

[Mike Marz]

If I lived down in that region and I was within a couple hours drive, I would probably make the trip to see what happens tomorrow. Even if the storms that do develop get completely undercut by the front, I would still like to get out and see some storms. I also miss what 60's dew points feel and smell like, which is a positive for this event, it appears dew points will not be an issue. If there is enough clearing and a bit more CAPE can develop, there is enough shear to make things somewhat interesting. Who knows, maybe things workout where a few isolated cells can fire a little ahead of the front. I would target Wichita Falls or just a bit west of there if I were to chase this event.

 

[Marcus Diaz]

What bothers me the most about tomorrow...

Smack dab in the exceptional drought. I would be really surprised to see dewpoints get as high as they're forecasted. Maybe some 60-61° dews at some stations. We'll see how it looks in the morning. That cold front placement is also a main concern tomorrow, which will need to be monitored.

 

[Jason Boggs]

I'm much more worried about the lack of instability than I am drought conditions. I hope reality gives us a bit more to work with tomorrow in the way of CAPE values and cold front location/speed. Td's should at least get into the upper 50's to near 60 in the warm sector tomorrow which will be plenty. I think there might be too much shear with insufficient CAPE values which may spell disaster for updraft survival.

 

[Todd Rector]

^^ That's what I have been thinking ^^ Models overestimating dewpoints. I don't necessarily think it will make for a failed day tomorrow, but it's definitely something to factor in.

 

[Randy Jennings]

I do like the shear the 3/18 18Z GFS and NAM are showing in the Wichita Falls area at 3/20 00Z. Their is actually a little curve to the model hodographs. But after that I think the models are a mixed bag - one things perks my interest and another thing makes me write it off. So I went and took a look at the observed soundings from tonight (0Z 3/19). Looking at the gulf cost area, BRO and LIX have decent surface dewpoints and CAPE, while the 2 soundings between them (CRP and LCH) have ok dewpoints, but less impressive CAPE. So do we have enough mT air that might make it up to north TX and southern OK? Maybe. Looking out west, the lapse rates in EPZ and ABQ look decent, so I suspect we will be seeing similar lapse rates around Wichita Falls and across the red river into OK on Thursday around the same time. My gut on this is frontal position and timing is everything on this event.

So I'll go for Wichita Falls at 00Z. That is a 2 hr drive for me from Dallas, and the setup looks marginal at best, so I'll be staying work/home unless something changes. I think if something does happen, it will be in TX, as I like the lapse rates further south and it's early in the season, so that causes a natural southern bias for me. I will say that one of the best super cells I saw last year was on a marginal day in March. Sometimes these days we write off turn out to be good ones.

On a side note, the OK and West TX mesonets show this area we are all talking about as having gotten around 1 inch of rain this month. I'm on the fence when it comes to how much of an impact local ground moisture has on weather systems.

 

[James Gustina]

Latest RAP has moistened significantly from earlier this morning with much more impressive veering with height/magnitude. Down on the Red River on the Texas side looks like it has the best shot of spitting out something pretty in the 21-23Z timeframe.

 

[Michael Gavan]

I'm virtual chasing today. For fun, I'm going to base as much of my forecast on surface obs and real soundings as possible. So please excuse the Mr. obviousness of some of this. Totally meant as a "Reality check" against what the models produce. and besides, Rich says we should. 12Z soundings up stream near the Rio Grande are beginning to show 100+ kt 300 mb winds. These are huge numbers that could affect storm anvil and precipitation. 500 mb winds are weakest in West Texas, but a bit stronger up stream, 40 kt+. EMLs in that area, although I'm not well versed in this area...look terrible to me. Lapse rate are lousy everywhere I look, but capping appears to be a non issue, afternoon temps in at least the mid 70's will easily overcome this. Surface dews in south and east Texas range from 65-72. Surface winds appear to be moving this moisture toward Childress, Guthrie, Seymour area. Most of these winds are backed currently. Dryline is very diffuse currently and doesn't look likely to tighten up too much. Satellite images show low clouds all over Texas, some of this should burn off later today. Area west of Upper level jet is visible in the satellite as well. Together they give a nice top down view of the 850 vs 5-300 mb sheer present over the entire state. Surface front / wind shift appears to be parallel and just south of the red river valley and extending into northern New Mexico where a weak surface low reamins nearly stationary or drifting ESE slightly as the front drifts north. The most likely area of interest for storm initiation appears to be around Guthrie Texas based on these morning surface obs, orographic/upslope might come into play here. Current dews in the area are approaching the upper 50's and should trend higher. As it turns out, this area is under full sunshine currently, and is the only area in the state as such. If moisture arrives in this area sooner rather than later, CAPE values should climb into acceptable levels. Weak LP supercells appear to be the best possible convective mode. Because of the weak lapse rates, poor EML, and tight-small surface hodographs that appear likely later today, A Tornado can't be ruled about but the odds are very low.

I am Virtually driving to Guthrie, waiting for sunshine to arrive.