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Severe WX Severe Weather Threat April 7-10, 2021

MattPetrulli said:
Looks a destructive cell merger just saved what looks like coulda been a significant tornado about to occur judging from the mesocyclone strength.
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Likely given that the Tornado Warning was only given a duration of 20 minutes. Let's hope the merging cells don't evolve into one MASSIVE supercell.
 
TH2002 said:
Likely given that the Tornado Warning was only given a duration of 20 minutes. Let's hope the merging cells don't evolve into one MASSIVE supercell.
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Looks like that's what is happening. 0246Z scan is ominous. It's a definite right-mover, too (ESE).
 

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CheeselandSkies said:
Looks like that's what is happening. 0246Z scan is ominous. It's a definite right-mover, too (ESE).
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Yeah, rotation is tightening for sure... this isn't looking too good.

Unrelated, but what program is that, the Windows 10 version of RadarScope?

Update: Well looks like I'm a bonehead. GRLevel3 is literally displayed at the top of the window.
 
Shakespeare 2016 said:
Why is there not a tornado watch for those areas? Sometimes you can get spin up significant or violent tornadoes.
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I believe they did mention potentially expanding the Tornado Watch to include portions of eastern LA, MS and even AL at one point. Guess they decided that the lingering severe threat isn't enough to warrant another watch.
 
Well folks, we have a pretty big model split like I've never seen. On the one hand, the Hi-res NAM is showing SigTor values over 4 for a good chunk of central Alabama at 21z today, but then the HRRR is showing not nearly as much. Now neither are showing much in the way of development if you look at simulated reflectivity or updraft helicity, but again, I'm not sure which one to trust.
 

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MattW said:
Well folks, we have a pretty big model split like I've never seen. On the one hand, the Hi-res NAM is showing SigTor values over 4 for a good chunk of central Alabama at 21z today, but then the HRRR is showing not nearly as much. Now neither are showing much in the way of development if you look at simulated reflectivity or updraft helicity, but again, I'm not sure which one to trust.
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Very strange contrast. SPC looks to err more on the HRRR side of things with only a marginal out for today.
 
That's a whale of an Enhanced risk (formed by the combined shapes of the 30% wind and hail contours)! Also, rather unusual for them to do such an in-depth discussion of the various models and why they are siding with the ones they are.

---model discussion---
The 08/00z and 07/18z NAM runs exhibit a too-cool bias with surface
temperatures east of the dryline across north-central TX (low to mid
70s near DFW metro), specifically near the I-35 corridor. Moreover,
it is likely strong heating will occur across central and north TX
during the day with temperatures at least 90 F west of the dryline
and into the middle 80s to the east in the warm sector. As a
result, ARW-based convection-allowing models (based on the parent
ARW model) are likely misrepresenting thunderstorm potential across
TX during the 21z-03z period. Conversely, the 08/00z and 07/18z GFS
runs are showing excessive boundary-layer mixing and a too-warm bias
across north-central TX with the dryline likely displaced too far
east compared to its likely position near I-35 by late afternoon.
The 07/12z ECMWF appears superior to the NAM/GFS in this regard with
adequate boundary-layer mixing implied by the warmer surface
temperatures (mid 80s F). This forecast across the southern Great
Plains coincides with model output similar to the ECWMF in recent
model runs.
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CheeselandSkies said:
That's a whale of an Enhanced risk (formed by the combined shapes of the 30% wind and hail contours)! Also, rather unusual for them to do such an in-depth discussion of the various models and why they are siding with the ones they are.
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Do these conditions warrant an upgrade to Moderate? A little less than 2 weeks back we had a fairly significant system but the SPC never upgraded from the Enhanced risk, though doing so was warranted by mid-late afternoon.
 
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