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andyhb

May 7th-9th Severe Weather Episodes

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Those mid level lapse rates are ridiculous and you can see it with an ML-LI of -13. This is what was missing from many of last year's events, because they had so many issues with column saturation/junk convection/etc.

 

This is what you need to get explosive updraft accelerations and they would without a doubt spin strongly with effective shear over 70 kts. That is easily a higher end sounding. The only thing it might be able to use a bit more of is stronger 0-1 km shear (which the Euro has).

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Those mid level lapse rates are ridiculous and you can see it with an ML-LI of -13. This is what was missing from many of last year's events, because they had so many issues with column saturation/junk convection/etc.

 

This is what you need to get explosive updraft accelerations and they would without a doubt spin strongly with effective shear over 70 kts. That is easily a higher end sounding. The only thing it might be able to use a bit more of is stronger 0-1 km shear (which the Euro has).

 

And the VBV on that sounding is ever so slight it's almost not even noticeable. I would have to think the boys at the Storm Prediction Center will go with an enhanced risk with the 0600z outlook tonight and OUN would ramp up their wording. I don't see what they are seeing in terms of a "low tornado threat." 

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And the VBV on that sounding is ever so slight it's almost not even noticeable. I would have to think the boys at the Storm Prediction Center will go with an enhanced risk with the 0600z outlook tonight and OUN would ramp up their wording. I don't see what they are seeing in terms of a "low tornado threat." 

I have to think that they want to wait and make sure that the storm mode will be supercellular after last week's bust.  Right movers are favored for most of the profile, but the area from about 7km-9km has me slightly worried.  Still shouldn't be a huge deal due to the great low level shear.  Also, you have to take into account any convection that happens tomorrow.  If things still look good, I envision an enhanced tomorrow at some point in the day. 

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OUN's talk about this event has been befuddling, and this AFD just furthers that. "weak short lived tornadoes" from line segments? What about that wind profile or anything says that line segments are going to the dominant storm mode? SPC was even odd with the D3. Given the model output from the GFS/NAM/Euro...

 

Looks like coverage could be a concern across the dryline in OK on sunday. GFS/NAM/4NAM all show pretty isolated convection across the dryline. Which does not make a ton of sense given that the main shortwave should eject into the warm sector sometime between 18-00z (depending which model you prefer)... If those solutions hold serve though, it could end up being a situation where we only get a few supercells... but they all have higher-end potential.

 

EDIT: FWIW 1999/05/04 at 00Z (so May 3rd at 7pm) is the #2 analog for sunday at 7pm.

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OUN's talk about this event has been befuddling, and this AFD just furthers that. "weak short lived tornadoes" from line segments? What about that wind profile or anything says that line segments are going to the dominant storm mode? SPC was even odd with the D3. Given the model output from the GFS/NAM/Euro...

 

Looks like coverage could be a concern across the dryline in OK on sunday. GFS/NAM/4NAM all show pretty isolated convection across the dryline. Which does not make a ton of sense given that the main shortwave should eject into the warm sector sometime between 18-00z (depending which model you prefer)... If those solutions hold serve though, it could end up being a situation where we only get a few supercells... but they all have higher-end potential.

 

EDIT: FWIW 1999/05/04 at 00Z (so May 3rd at 7pm) is the #2 analog for sunday at 7pm.

 

 

 

I could see an enhanced outlook for this event but do you think there could be a possible moderate when all is said and done?

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Looks like coverage could be a concern across the dryline in OK on sunday. GFS/NAM/4NAM all show pretty isolated convection across the dryline. Which does not make a ton of sense given that the main shortwave should eject into the warm sector sometime between 18-00z (depending which model you prefer)... If those solutions hold serve though, it could end up being a situation where we only get a few supercells... but they all have higher-end potential.

 

This is one of those cases where some quick synoptic analysis can really help recognize the potential for initiation. First, we have the backing winds east of the dryline due to pressure falls occurring with the lee cyclone. That is going to increase the convergence near the dryline. Secondly, there is a strong upper level left exit region ejecting right over top of the warm sector. Given the divergence aloft with that, you would expect synoptic scale ascent to increase during the afternoon. Thirdly, there are some fairly substantial 500 mb height falls going on in a relatively short timespan with Sunday's event. That also points to increased forcing for ascent over the warm sector.

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OUN's talk about this event has been befuddling, and this AFD just furthers that. "weak short lived tornadoes" from line segments? What about that wind profile or anything says that line segments are going to the dominant storm mode? SPC was even odd with the D3. Given the model output from the GFS/NAM/Euro

I think that they are basing some of their thoughts on what happened last tuesday. VBV causes messy storm mode. I think that are thinking it will get messy and not be supercellular due to bad splits.

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I could see an enhanced outlook for this event but do you think there could be a possible moderate when all is said and done?

Does it matter what the outlooks are? Why not focus on the actual meteorology and not outlooks by the SPC. I've seen so many posts trying to forecast a forecast and it's getting a bit stale now.

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I think that they are basing some of their thoughts on what happened last tuesday. VBV causes messy storm mode. I think that are thinking it will get messy and not be supercellular due to bad splits.

 

See the issue with that is that the VBV is nowhere near as cripping as it was last Tuesday (as it sits now) and the shear vectors are also much more orthogonal to the dryline, supporting propagation away from it.

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Wonder what kind of impact this event will have being that this Sunday is also Mothers day.  Roads/streets/business ect will be a little bit more busy than what it/they typically would be.  Might be good for the news stations ect start looking into this one a tad bit early.

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See the issue with that is that the VBV is nowhere near as cripping as it was last Tuesday (as it sits now) and the shear vectors are also much more orthogonal to the dryline, supporting propagation away from it.

Also liking the looks of the low PWAT and good anvil venting. Should help keep HP supercells to a minimum.

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Wonder what kind of impact this event will have being that this Sunday is also Mothers day.  Roads/streets/business ect will be a little bit more busy than what it/they typically would be.  Might be good for the news stations ect start looking into this one a tad bit early.

 

Mike Morgan should stay as far away from things as possible.

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Does it matter what the outlooks are? Why not focus on the actual meteorology and not outlooks by the SPC. I've seen so many posts trying to forecast a forecast and it's getting a bit stale now.

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Well, I'm not the only one (And not the first one) who has brought up the potential outlook from this thread.  I'm just curious to what these guys are thinking since they didn't agree with the SPC and the local NWS on the wording.  

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Well, I'm not the only one (And not the first one) who has brought up the potential outlook from this thread. I'm just curious to what these guys thing since they didn't agree with the SPC and the local NWS on the wording.

Wasn't trying to single you out, but it has been increasing quite a bit over the past few years.

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I think that they are basing some of their thoughts on what happened last tuesday. VBV causes messy storm mode. I think that are thinking it will get messy and not be supercellular due to bad splits.

 

The VBV is ever so slight in those soundings and is above 500mb.

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Wasn't trying to single you out, but it has been increasing quite a bit over the past few years.

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This is kind of a sign that collaboration/coordination between SPC/NWS offices/etc. may have taken a hit over the past few years. Lots of very uncertain setups certainly does no favours in that department.

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Wasn't trying to single you out, but it has been increasing quite a bit over the past few years.

Sent from my SM-G925V using Tapatalk

 

 

Understood.  It's all good

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Wonder what kind of impact this event will have being that this Sunday is also Mothers day.  Roads/streets/business ect will be a little bit more busy than what it/they typically would be.  Might be good for the news stations ect start looking into this one a tad bit early.

 

Also the OKC-Spurs game. Might be a little bit hectic if things get dicey and Mike Morgan gets involved.

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See the issue with that is that the VBV is nowhere near as cripping as it was last Tuesday (as it sits now) and the shear vectors are also much more orthogonal to the dryline, supporting propagation away from it.

Agreed 100%. I'm just trying to figure out what they may be thinking downstairs right now. Right now this looks fun to me. Tomorrow is going to be a massive study day so I can chase on Sunday.

As a tidbit, I use an SPC category as a rough guide for my thoughts. It makes communicating my opinion on the strength of the threat to those who aren't very technical in weather, but know what those mean. The outlook (and AFDs) is always the thing I look at after my forecast to see what the professionals are thinking.

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This is one of those cases where some quick synoptic analysis can really help recognize the potential for initiation. First, we have the backing winds east of the dryline due to pressure falls occurring with the lee cyclone. That is going to increase the convergence near the dryline. Secondly, there is a strong upper level left exit region ejecting right over top of the warm sector. Given the divergence aloft with that, you would expect synoptic scale ascent to increase during the afternoon. Thirdly, there are some fairly substantial 500 mb height falls going on in a relatively short timespan with Sunday's event. That also points to increased forcing for ascent over the warm sector.

 

Yeah, initiation should not be an issue. If anything, I'd be more concerned about morning crapvection laying down a cold pool, which some models seem to hint at.

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18Z GFS continues to look impressive across the dryline on sunday... This sounding is from Blaine co. Oklahoma.

18_GFS_054_35.94,-98.38_severe_ml.png

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People keep talking about last weeks bust, but was it actually a bust?  Last count on Fox23 last night the NWS had certified 17 tornado touchdowns in OK on Tuesday.  Hard to say it busted...

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People keep talking about last weeks bust, but was it actually a bust?  Last count on Fox23 last night the NWS had certified 17 tornado touchdowns in OK on Tuesday.  Hard to say it busted...

 

In terms of chasing and higher-end tornadoes - yes the PDS watch was a bust. In terms of the 10% TOR and remainder of the forecast? I'd say it went well. There were over 30 tornadoes confirmed from April 26/27 last I saw. 21 of those came from Tulsa. 

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People keep talking about last weeks bust, but was it actually a bust?  Last count on Fox23 last night the NWS had certified 17 tornado touchdowns in OK on Tuesday.  Hard to say it busted...

 

Well because people played it up to be some sort of dire outbreak i.e. 4/26/91 + 5/3/99 + *insert huge Plains tornado outbreak here* repeat.

 

Can't say the 06z D2 prior to it did much to temper that expectation, either.

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The actual location of those tornadoes was a "bust" though relative to where the higher tornado probabilities were. Same goes with many of the other severe wx reports... An event with 600+ severe reports, and 20+ tornadoes, certainly is an outbreak though... Just was not the classic tornado outbreak that it was hyped up to be... Something that seemed more than plausible a few days in advance.

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In terms of chasing and higher-end tornadoes - yes the PDS watch was a bust. In terms of the 10% TOR and remainder of the forecast? I'd say it went well. There were over 30 tornadoes confirmed from April 26/27 last I saw. 21 of those came from Tulsa. 

No doubt the PDS was a bust, but the SPC nailed down the percentages pretty well, perhaps a bit overdone on the hail.  

Bust for chasing?  Yes definitely, I didn't like that aspect more than anyone else who was out chasing.  But for SPC forecasters it really wasn't a bust at all.

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Last Tuesday was absolutely a bust. A PDS watch with zero strong tornadoes. Even the 10% hatched tor ... First of all, again, zero strong tornadoes. Second, no one made that 10% tor region thinking "Oh we better cover the QLCS tornado threat". No, that was entirely in anticipation of a supercell mode that never transpired. Hence also the error in location of tors, as pointed out above.

Finally, the outlook wording was always too strong. Constant mention of high risk, when the tor probs weren't even past the moderate risk threshold, and hail and wind probs were low end moderate. And the only way a high risk was happening without tors would be with an upgrade in wind probs, which was never a threat that was singled out for the day. I want to actually do a study on how many times "high risk" or "upgrade" has been mentioned in past moderate risks. It was absolutely completely unnecessary.

The SPC, along with almost everyone else, fell on their butts Tuesday.

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Well because people played it up to be some sort of dire outbreak i.e. 4/26/91 + 5/3/99 + *insert huge Plains tornado outbreak here* repeat.

 

Can't say the 06z D2 prior to it did much to temper that expectation, either.

People?  SPC didn't really play it up that much.  It was the TV folks that played it up.  SPC was maybe a tiny bit overhyped but the blame really lies with a few TV folks IMO.  

Anyway, lets not sidetrack this thread, sorry I brought it up :)

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