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Severe WX April 11th-13th, 2020 Severe Weather Threat

Yeah if SPC pulled the trigger based on just two HRRR runs and a sudden shift in upstream activity after an afternoon with numerous questions we'd have way more high risk busts than we do
 
What was the risk in Nashville last month? I don't remember hearing anything about the potential for strong tornadoes that day & night. But they got twisters, including an EF-3 & 4.
 
Here was the 0100z outlook; Nashville was just in a 2% area (below the threshold for even a Slight risk) and Cookeville, where the EF4 hit, was outside of the tornado probabilities altogether. It was also outside the initial tornado watch until NWS Nashville extended it. A humbling example that this science is far from perfect
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Equus said:
Here was the 0100z outlook; Nashville was just in a 2% area (below the threshold for even a Slight risk) and Cookeville, where the EF4 hit, was outside of the tornado probabilities altogether. It was also outside the initial tornado watch until NWS Nashville extended it. A humbling example that this science is far from perfect
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I thought that the SPC had dropped the ball there. While I still argue that its easier to miss or minimize a winter weather event than a significant severe weather outbreak, obviously the latter can & does happen.

However, I will say that since the SPC didn't include upgrade wording with this update, the chance for them later raising it to an Extreme/45% Risk now looks a lot less likely.
 
Equus said:
Here was the 0100z outlook; Nashville was just in a 2% area (below the threshold for even a Slight risk) and Cookeville, where the EF4 hit, was outside of the tornado probabilities altogether. It was also outside the initial tornado watch until NWS Nashville extended it. A humbling example that this science is far from perfect
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One more question before sleep time. Back in March 2019 when the EF-4 tornado tore thru Auburn, I think that the SPC had issued a High Risk & PDS Tornado Watch for parts of Alabama. But was Auburn actually south of that 30% contour?
 
3/3/19 was surprisingly just an Enhanced risk day (10% tor) though it would have easily verified MDT or high in retrospect. I think the tornado watch may have been a PDS (I can't remember) - the tornado was basically along the warm front north of all the other tornadoes of the day so I think it was on the edge of the risk area and further up than I was actually watching that day until the debris ball showed up lol
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Meanwhile, the 06z HRRR continues the trend of pushing the MCS ever so slightly north each run. Fires supercells slightly later and slightly more isolated but still indicative of a scary environment. If it's catching onto upstream changes in the MCS track and intensity I'd be more inclined to think it's getting a handle on the supercell development here so clearly the trend is still looking pretty nasty. RAP isn't that far off either on first glance but I'm gonna sleep while I still can and catch back up in the morning...
 
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Evan said:
It's really a question of confidence at this point. The parameters will be there whether moderate or high. Mesoscale features will determine the ceiling. SPC will want to see the trends tomorrow before upgrading, but really it is just semantics at this point. There have been plenty of moderate risk days that produced like a high risk, so I wouldn't focus too much on the nomenclature.
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xJownage said:
Taking the current DPs/Temps and saying "the models are wrong about what's going to happen because of what's happening now" still a full day out just seems irresponsible. We won't know much from surface obs until at least tomorrow morning as it'll give us a better idea of which models are handling this event better.
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There getting pretty stingy with these high risk these days ... no mentioned of upgrade just yet either on this update thought the moderate risk would get expand north some wth high risk from north central ms to western edge central Alabama
 
Equus said:
4/15/11 and 11/24/01 certainly show that moderate risk days can produce some of the most prolific outbreaks in state history; I'm sure we get too hung up on waiting for a 30% SIG contour to start sounding the alarms but really the 10/15 hatch days can be brutal (or hey even 2% in Cookeville's case) as can the 5-15% risk areas on a high risk day. Beauregard happened in an enhanced; Moore, Joplin, and El Reno in moderates. I'm too worried about potential impact really close to home to get hung up on probabilities at the moment hoenstly
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3/13/90 was also prolific as well. Though that day definitely warranted a high risk I believe it was officially a moderate risk. It produced 2 F4s and 2 F5s.
 
The southern tornado warned storm looks interesting to my untrained eye on super velocity via radar scope
 
Scott81 said:
Are things still on track for today in AL? Was wondering what the models were saying this morning..
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Some slight variations, but pretty much unchanged from 12-18 hours ago.The HRRR was showing a good bit of junk convection for a few runs possibly lowering the TOR risk, but seems to have trended back to a more supercell alignment in the warm sector which is no bueno.
 
Scott81 said:
Are things still on track for today in AL? Was wondering what the models were saying this morning..
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the hrrr is just disastrous with a large uncontaminated warm sector from Miss into Al., started showing this around 10pm last night and continues....BMX disco mentions that there could be very little with the warm front and a stout cap will develop of the early and mid afternoon....everything seems to be coming together
 
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