• Member Statistics

    16,018
    Total Members
    7,904
    Most Online
    anathema
    Newest Member
    anathema
    Joined
Sign in to follow this  
andyhb

April 13th-14th Severe Threat

Recommended Posts


 Some lingering questions about the tornado risk remain due in part
   to some conditional factors yet to occur.  However, it appears the
   tornado risk may maximize in 2 corridors.  First, a diurnally
   focused tornado risk (primarily supercellular) across northern LA
   into far southern AR vicinity between 3-9pm.  A second area of
   potential concern may focus from northeast LA near the MS River
   east-northeast across central and into parts of northeast/east MS
   during the evening into the overnight.  A mix mode of supercell/QLCS
   or hybridization of the two within a convective line are possible. 
   Along with damaging gusts, strong tornadoes may also occur with a
   few of the most intense storms.  While the pre-frontal, cellular
   convection should diminish overnight, a semi-organized band of
   storms -- with embedded rotating updrafts and continued
   severe/tornado potential -- will move across the central Gulf Coast
   states through the end of the period.

 

swody2_severeprob.png?v=833

Share this post


Link to post
Share on other sites

I grew up here (NE Texas) but moved away in 2006. The public hype for tomorrow is nothing I’ve seen here. I’m here for a wedding that’s at 4 p.m. Saturday. It’s outdoors. lol

  • Haha 1

Share this post


Link to post
Share on other sites
18 minutes ago, canderson said:

I grew up here (NE Texas) but moved away in 2006. The public hype for tomorrow is nothing I’ve seen here. I’m here for a wedding that’s at 4 p.m. Saturday. It’s outdoors. lol

What part of NE Texas?

Share this post


Link to post
Share on other sites
Outside Longview. Little place called White Oak. 
I'm vaguely familiar with the area. Haven't been up in that part of the state in a long time. Palestine is usually the furthest.

Sent from my Pixel 3 XL using Tapatalk

Share this post


Link to post
Share on other sites

18z HRRR still showing numerous discrete cells in Lousiana with very impressive parameters. However, cells may be a little too closely spaced for my liking, so that may be more of a concern than I originally though (I.E. 4/2/17). Still am expecting multiple siggys, but this shouldn't be ignored. HRRR's resolution also may be inflating storm size a little bit too.

27

29

  • Like 2

Share this post


Link to post
Share on other sites

Yea I'm getting flashbacks of 4-2-17 with this. Very impressive parameters but not enough cap to prevent widespread storms from going up. Imo this looks to be very messy and in terrible terrain. I do think there could still be significant tornadoes but they're going to be tough to see

  • Like 2

Share this post


Link to post
Share on other sites

 Cell interference is what I was first and foremost seeing as the biggest negative with this. Even if storms congeal early on, there should be a very high damaging wind threat. Possibly derecho from LA into MS? 

  • Like 1

Share this post


Link to post
Share on other sites

I'm not convinced that cell interference will be a problem.  Firstly, 4-2-17 had slightly weaker deep-layer and low-level shear.  The shear magnitudes in these profiles are more akin to 4-27-11.  Remember that day didn't have much of a CAPE either, but cells stayed discrete.  Stronger deep-layer shear and substantial boundary-perpendicular deep-layer shear should keep things discrete, IMO.

  • Like 1

Share this post


Link to post
Share on other sites

I do agree that overall storm mode is still somewhat questionable for tomorrow, but the magnitude of effective shear we have available is pretty astounding. Even if things congeal a little too quickly during the course of the afternoon, we'll definitely have to watch for embedded strong mesocyclones. Just the thought of rain-wrapped tors with already poor visibility is pretty unnerving. 

(The overlay feature on weathernerds is pretty awesome by the way) dfaa51035bd5316411f76ca9c87a8ce1.png

  • Like 2

Share this post


Link to post
Share on other sites
1 hour ago, Superstorm93 said:

I do agree that overall storm mode is still somewhat questionable for tomorrow, but the magnitude of effective shear we have available is pretty astounding. Even if things congeal a little too quickly during the course of the afternoon, we'll definitely have to watch for embedded strong mesocyclones. Just the thought of rain-wrapped tors with already poor visibility is pretty unnerving. 

(The overlay feature on weathernerds is pretty awesome by the way) dfaa51035bd5316411f76ca9c87a8ce1.png

 

Also good to remember that while 3 km models are commonly referred to as "convection resolving" or "convection allowing," they do not have sufficient resolution to properly portray many attributes of convection.  For instance, typical supercell updrafts are on the order of 8-12 km wide.  A 3 km model will only have a few grid points across the extent of an updraft.  The result of this insufficient resolution is that 3-4 km models tend to produce updrafts and storms that are unrealistically large, and may "unfairly" show more connection/congealment between cells during events like this.  

Given the magnitude of the deep-layer shear and what we know about supercell dynamics, what has happened in past similar events, and the fact that there isn't strong synoptic scale forcing overriding the warm sector, I would bet money that we see something more like widespread scattered supercells rather than a QLCS with embedded circulations.

 

  • Like 4

Share this post


Link to post
Share on other sites

Agree. It'll stay discrete longer than progged. Also could be more spacing. Finally, even if morning stuff conceals, it could actually break up again in the afternoon. Happened before plenty of times these shear profiles.

  • Like 1

Share this post


Link to post
Share on other sites

Last couple of HRRR runs want to push an isolated cell through Central LA overnight with the warm front retreating north. Cant think this would really cause too many problems with the overall environment... But wonder if it could leave some remnant mesoscale boundaries that could persist until initiation time tomorrow.

refcmp_uh001h.us_sc[1].png

Share this post


Link to post
Share on other sites

Worth nothing that WFO Birmingham has their entire CWA under an enhanced risk, contrary to what SPC has. 16a86f6c2d35e29e1827ec951fa9c6d5.jpg

Sent from my Pixel 3 XL using Tapatalk

Share this post


Link to post
Share on other sites
Just now, wotan said:

Worth nothing that WFO Birmingham has their entire CWA under an enhanced risk, contrary to what SPC has. 16a86f6c2d35e29e1827ec951fa9c6d5.jpg

Sent from my Pixel 3 XL using Tapatalk
 

00z NAM Sharpy triggered PDS TOR over Birmingham this run

Share this post


Link to post
Share on other sites
00z NAM Sharpy triggered PDS TOR over Birmingham this run
It's Palm Sunday.

Sent from my Pixel 3 XL using Tapatalk

Share this post


Link to post
Share on other sites

Not to be overdramatic, but that 00z HRRR run is quite possibly the most dangerous looking solution I've seen from that model since maybe 4/27-28/2014, and possibly even back to 2011. The number of supercells it has interacting with an extremely favorable low level environment is pretty unreal. It's not alone in upticking the apparent threat at 00z, either. Taken face value, we're easily looking at a high risk setup, but I can definitely understand if SPC wants to delay an upgrade until the situation is more certain tomorrow morning in case any convection decides to blow up on the warm front potentially limiting its movement north (but, at the same time, I could very easily see one at 06z).

  • Like 8

Share this post


Link to post
Share on other sites
Not to be overdramatic, but that 00z HRRR run is quite possibly the most dangerous looking solution I've seen from that model since maybe 4/27-28/2014, and possibly even back to 2011. The number of supercells it has interacting with an extremely favorable low level environment is pretty unreal. It's not alone in upticking the apparent threat at 00z, either. Taken face value, we're easily looking at a high risk setup, but I can definitely understand if SPC wants to delay an upgrade until the situation is more certain tomorrow morning in case any convection decides to blow up on the warm front potentially limiting its movement north (but, at the same time, I could very easily see one at 06z).
You certainly aren't alone in thinking it's been awhile since we've seen something like this. 0a79a95809b32fdf5808912839144bc3.jpg

Sent from my Pixel 3 XL using Tapatalk

Share this post


Link to post
Share on other sites

Anything that goes up early along I-45 is going to have just about the same type of volatile parameter space seen in Louisiana in the afternoon. The 00Z HRRR actually takes a UH streak over my apartment between 14-15Z.

Share this post


Link to post
Share on other sites
Anything that goes up early along I-45 is going to have just about the same type of volatile parameter space seen in Louisiana in the afternoon. The 00Z HRRR actually takes a UH streak over my apartment between 14-15Z.
I'm near the boundary between the marginal and slight risk areas (Fort Bend county). TWC showed some graphics earlier that had stuff at least somewhat close in the morning. I'm still trying to decide if I'm going to the Hill Country for the day. I'd be getting on the road during roughly the highest risk for us.

Sent from my Pixel 3 XL using Tapatalk

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.