Weekend Severe Weather Threat

[Bob Hartig]

The 12Z NAM is in, and I had a feeling things were moving in this direction. I wouldn't write off this system's tornadic potential entirely; I just wouldn't plan on it materializing even a little bit in Texas. Way east in Louisiana is where there appears to be some possibility for Sunday. If storms can fire in the warm sector, then there may be ample shear to support supercells and enough low-level helicity for a tornado or two. NAM wants to break out precipitation. But model soundings look quite saturated. This stuff still has four days to incubate, but what I see right now suggests a rainy afternoon in the swamps wrasslin' alligators.

 

[DNewman]

The spc has issued a low end slight risk for parts of central and western texas into parts of north central Texas for Saturday. However there still appears to be some uncertainties about exactly how everything will play out.Guess well have to wait until Friday to really see the setup of how everything will play out, because it looks that the dry-line wont set up any storms as the main point of storm initiation until early Sunday at this time anyway.

Skip thanks for clarifying the Z time frame, I actually understand it now.

 

[DNewman]

Yea Bob Im really not impressed with the tornadic potential for Texas either, for now it looks like everything really ramps up by Sunday, and by that time it will be east Texas and Louisiana.

 

[Shawn Schuman]

DNewman, if you still have any trouble with Z time, Jeff Haby's site has a handy graphic that helps you convert it really quickly. It was sure useful to me when I first started out. You can find it toward the bottom of this page, along with a good summary of the scale.

http://www.theweatherprediction.com/basic/ztime/

 

[Dan Robinson]

I found it helpful to start by just memorizing whatever local time 12z and 00z is, then add/subtract as needed. For example, on CST those are 6AM and 6PM (7AM/7PM CDT during most of the spring). Eventually you'll start remembering the other times out of habit.

 

[Bob Hartig]

Maybe a forecast discussion for the Gulf Coast is in order for Sunday, but I'm electing to keep this post here for now rather than initiate a new thread because (1) there have actually been a couple issues blending together here and it's probably profitable to keep things that way; and (2) this isn't a clear-cut spring chase scenario.

That said, I've become more intrigued with LA and decided to run a few forecast soundings. I have to say, in the words of an old, now deceased buddy of mine, that I wouldn't kick the skew-T below out of bed for eating crackers. It's today's OOZ NAM for 22Z Sunday evening at KLFT, Lafayette, LA. There's certainly ample CAPE for this time of year, and the hodograph is nothing to apologize for. Look at the SRH--that'll get the job done. It's a pretty moist profile, but I guess that's what you get in Dixie Alley. Really, everything is there but sunshine, and maybe that won't matter. It'll be interesting to watch what happens down there this Sunday.

 

[DNewman]

As a matter of fact that's just the website I went to to learn about it too! We must think alike. I go to that website quite often to learn about the questions I have about weather, and its a great tool for studying!

 

[Marcus Diaz]

Tonight is the first I've seen of this weekend. Got my eyebrow raised at some potential for Saturday here locally down I-27. Looks like a classic high shear/low CAPE day. Not expecting tornadoes per-say, but definitely looks like potential for some low topped supercells. The NAM is looking great for said situation, but the high res models are really struggling with moisture return. TTU 12km/3km WRF barely pulls up low 40F dews before that backside cold front dries everything out. But seeing the GFS and NAM agree on all the features has my hopes up. This setup reminds me all too much of Feb 2, 2012 that ended up not materializing. All the shear parameters were in place, but the moisture couldn't make it in time. Then again the surface low that day was wayyy south and not as deep as the models are predicting. I think if we can get low 50 TDs to the Red River and enough clearing to get 750+ J/Kg, then I think there's a good shot at some storms.

 

[Bob Hartig]

My concern with Saturday was formidable capping per NAM and GFS. But I honestly haven't dug into Saturday very deeply, Marcus--that was just my thinking at a glance based on last night's models. I looked at the CINH maps for Texas, saw the big 850-700 mb "nose" on some model soundings, and thought, oh well. But maybe things have started to change this morning. I haven't had time to look, but I'd be very pleased for you Texans if things turned out otherwise.

 

[DNewman]

Yea you really never know what will really happen in Texas, so well see when tomorrow comes. Ive known crazy severe weather episodes to happen in the most non significant severe weather setups. Just take june 13,2012 for example even though there was a somewhat risk of an isolated severe storm, most meteorologists gave up on seeing severe weather with mainly clear skies and strong cap. But sure enough a cluster of supercells popped and boom!Major hailstorms and one tornado and scary wall cloud ( which was literally on top of my neighborhood!)with a couple of storms. Took many people by surprise and me as well!

 

[Marcus Diaz]

The thing I like about Saturday is that indeed the NAM breaks precip out in the panhandles. The capping is weak further north where shear parameters are very nice. It's really coming down to the moisture return. I think I'm going to take a drive down 287 and see what happens. Although everything seems to be in place, I'm still thinking something won't be there. It's going to take a perfect day tomorrow for us to see any tornadoes.

 

[DNewman]

This is the latest NWS update concerning the severe potential for Saturday. It appears that the models are looking much better as far as moisture is concerned especially instability. The threat may begin in the panhandle of Texas and south west Oklahoma!and do I see an opportunity for tornadoes... I think so, but I won't get my hopes up until I see the first warnings tommorow.


.SWRN KS INTO THE OK/TX PANHANDLES LATE AFTERNOON/EARLY EVENING...

STRONG HEATING WILL OCCUR BEHIND THE DRYLINE AND AHEAD OF THE
DEVELOPING COLD FRONT ACROSS THE SRN HIGH PLAINS WITH LIMITED
MOISTURE INITIALLY. HOWEVER...AS FORCING CONTINUES TO SPREAD EWD
STORMS SHOULD FORM JUST AFTER 00Z. MOISTURE WILL BE INCREASING
RAPIDLY NWWD...AND THERE MAY BE A NARROW WINDOW OF OPPORTUNITY FOR
SUPERCELLS BEFORE THE COLD FRONT OVERTAKES THE DRYLINE...RESULTING
IN A LINEAR STORM MODE. WITH STRONGLY VEERING WIND PROFILES AND
STEEP MIDLEVEL LAPSE RATES...DEWPOINTS INTO THE 50S COULD SUPPORT A
FEW TORNADOES AND LARGE HAIL IF SUPERCELLS CAN FORM.


So what are y'all thinking now?

 

[DNewman]

Here are some maps just to give an idea on the latest severe potential tommorow.