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2019 Rain Thread

Biff Tannen

By Biff Tannen
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phdhorn
phdhorn

Figured I'd post this here, it's where you'd look for me. First, thanks very much for the concern (I had no idea), it's appreciated.  I mean, really?  Wow, that's been surprising. Second, I'm fi

DonnyKerabatsos
DonnyKerabatsos

is the excessive rain this year being triggered from the ash rising to the atmosphere from the concentration camps on our border?  Like volcanoes creating storms when the erupt? 

Patricio Swayze
Patricio Swayze

So after my company started sending people home, a coworker of mine who takes the metro in from cypress left to catch the bus. He got to the NW transit center at 610 and old Katy road and they decided

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Hate

Hate 20108

Posted
Posted (edited)
8 hours ago, phdhorn said:

Oh man, these aren't quickie answer questions... but...
... I'll make 'em quick (for now).

- Some of these features have been around for years, some now just cropping up on "radar packages"... most are good descriptors of what's going on but should not be used to make decisions per se.  It's more during/after the fact.  Plus, you can easily have a tornado (especially a weak one) without some of these factors.

- One more quick context:  for several decades, but especially the last 15 or so, one "breakthrough" that seems to have occurred with understanding tornadoes is that sorta somehow, a wind "gets going" on the surface, a circular type of thing, kind of like a "sideways tornado" only the wind isn't (yet) nearly as fast.  That "sideways wind" gets picked up in a supercell as updrafts increase (i.e. air going up into the cell and becoming vertical).  Then that air cools as it rises, gets faster, and begets all kinds of hell (hail, electricity... and spinning vertically).  So the idea is that a tornado usually (well, educated guess) develops when 2 factors are present, and usually both must be present - only one doesn't cut it.  The factors are:  1) velocity of the column of air begins to show a great contrast (usually the upper part in mid-level atmosphere spins a lot faster than the lower part).  And: 2) there needs to be sort of a continual 90° "bend" of horizontal inflow air, which gets pulled up, gets vertical, and spins faster.  Again, this seems to be a reliable factor, but it's the tip of an otherwise non-really-well-understood deal.  So what some of these values are, are measures of the strength of the differences in velocities through the air at lower levels (LLRV in the graphic above), maximum difference between velocities measured at various levels (MRV), and the greatest difference in the lowest clear level of rotation (LLDV).  What all this boils down to is that tornadoes like 1) "bent" wind coils, and 2) different velocities (shear) up the column.  

Basically this is akin to sabermetrics in baseball... a lot of newfangled measurements that might mean something significant... but might not.  Fun stuff to play with, but not supposed to be at this point anyway the Ten Commandments of Tornado Formation.

So I'm gonna skip over the very long links between this idea and the metrics for the most part (lots of calculus there), so I'll just answer the others you named:

- Storm relative depth - this is a general number derived by calculating the distance between the storm's inflow (usually at or near ground level) and the height of the storm's most pronounced shear point (greatest difference in velocities in the column) within the lower levels of the storm (something called effective bulk shear, or EBS).  These are complex calculations, with readouts that would stymie Einstein, but it's sort of boiled down here to the percentage of the column where these extremes take place; i.e. the distance is about 62% of this column in the lower part of the storm.  It is not a simple measurement of the storm's height or whatever.  The idea here is that the larger the % in this figure, the more likely a storm is to have tornadic potential - but again, it doesn't mean it'll happen.

- Strength index is again a fancy calculation of measured points in the lower level of the storm.  The idea here is that it seems that storms that might go tornadic often have strong rotation, often the strongest in their lower levels (makes sense, a storm with higher speed rotation in the upper levels might not touch down and so there's no tornado).  Storms with higher lower-level rotation get the higher number... so a storm with say 2,304 is going to be "less likely" to go tornadic as one with say 6,403.  In this case, 4392 is about lower-mid severity on the scale.  Storms with 6500 or above are most often associated with tornadoes.

- TVS signature - this is a 1/0 terminology determined by a bunch of calcs (duration, depth of shear/column, speed, etc. a figure that covers the speed of rain moving to/from the sample point, etc.) that all gets boiled down to a "true" or "false".  However, again, 1) storms that show "true" might be rotating higher up, so it's not a given that it's going to be a touchdown, and 2) there have been tornadoes, especially weaker ones (EF0-2) that might not even have this signature because the vertical column of shear might be very shallow or so discombobulated that the signature hasn't shown up.  You often see these signatures in the well-known "red/green -yin/yang" Doppler signatures air/rain moving toward the sample point shows up green, moving away red).  Usually when you see that popping up, you tend to ignore the "true" or "false" determinations (it's right there before your eyes, though 99% of the time it'll be "true).  This is more for less-developed shear storms.  In this case it says that it's not  (yet?) picking up the traditional to/from diversity in a rotating storm.

The calculations themselves are way out of my league, but I sort of understand what they mean.  Good enough for now, I guess.

This is great stuff!

 

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Jhawk

Jhawk 1075

Posted
Posted (edited)

Reporting live from downtown Tulsa. Sirens were going off about 645am. Apparently it got pretty bad but I slept through it. No real damage other than 2 houses north of downtown. 4K+ without power. 

Wouldn't you know it, I’ve had some really bad diarrhea this morning. Going to die on the shitter. 

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Hate 20108

Posted
Posted
1 hour ago, Jhawk said:

Reporting live from downtown Tulsa. Sirens were going off about 645am. Apparently it got pretty bad but I slept through it. No real damage other than 2 houses north of downtown. 4K+ without power. 

Wouldn't you know it, I’ve had some really bad diarrhea this morning. Going to die on the shitter. 

At least you'll die doing what you love.

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phdhorn

phdhorn 6224

Posted
Posted

These better require long answers, but for now I'll knock 'em out as briefly as I can:

9 hours ago, Assman said:

I can't rep this enough.  Thanks for the explanation...which of course leads to some follow up questions in which you can politely tell me to STFU if you wish.1.  With the LLDV, since this is a delta, with a number like 108kts in the example above, does this mean that the max winds within the column of air are way above 108kts?  Or is it possible that the max could be 109kts and the min 1kt, hence the 108kt delta? 

The second point here, bolded.

Quote

Also, since you're saying the more shear, the more likely a tornado, in general, can you say the higher LLRV, LLDV, and MRV are, the more likely a tornado, and/or the greater chance for a strong tornado?  Is there one value that is more indicative of a tornado than others?  I think I'm tracking that MRV + LLRV = LLDV?

LLRV and LLDV in general, yes, I'd say so.  MRV not necessarily.  MRV can be calculated all throughout a storm's height.  If MRV is calculated within a traditional lower part of the storm, yes.  Why calculate MRV's at different shear heights?  Because you're not always looking for a tornado; MRV's can be good predictors of hail, which can of course happen in non-rotating storms.  Also, be cautious not to automatically make the link; you can have tornadoes, especially weak ones, where these values are low; conversely you can have high values without a tornado; keep in mind that these measure the strength of the shear, which is one, but not the only, component which makes up a tornado.  But as I said, you're likely to have conditions for tornadic formation if the LLRV and LLDV are relatively higher.

Quote

2.  With the storm relative depth, you say the % is the total distance from the inflow to the max shear point, and that a higher % means a greater potential for a tornado.  However, wouldn't a low % mean a lower-level shear point (altitude wise) which might indicate more instability on the surface?

No.  Again you're looking at shear within the all-important (for tornadoes) lower part of the storm.  Consequently, a higher storm relative depth = a larger column of "messed up shear air" within that portion, which probably means more violence and likelihood to have riper tornado conditions.  If this were a simple measure of total storm shear height or voricity, then your thought makes more sense.  

These things are crazy nerdy calculated, and again, the lower part of the storm matters more when looking for tornadoes, but of course upper level shear matters and is worth measuring because storms can be damaging (hail, wind, etc.) without dropping a twister.

 

Quote

3.  On my first post on the previous page, I included a TVS readout.  One of the parameters is max shear (measured in m/s/km) and height of max shear.  Is there a scale for max shear?  What's considered a lot? 

Hmmm... well sort of, but it's usually in single digit units (after a shitload of fluid dynamics calculus equations), as this is a straight outta Fluid Dynamics value.  After all the number crunching is done, I'm used to seeing the units as a single digit scale:

0 to 3 weak, 4 to 5 moderate, 6 to 7 large, 8+ extreme

I.e. gradient values (uh, max shear = max gradient value) of tornadoes usually are seen in the 5-8+ extreme.  I honestly don't know why this number is double digit... I guess I have to look at it (or think more).

I can also tell you that the m/s value in the other readout formats I've seen are pretty much 1/2 of the wind variation in kts.  That is, 40 m/s = roughly 80 kts.  It could be in this case that 80 m/s/km = the divergence in the wind is 160 mph (i.e. the wind moving "away" at 80 kts + the wind moving "toward" at 80 kts = 160 kts.   But this is one I don't know... yet.  Seems app-specific.  Maybe it's just their way of saying that the winds at the max shear point are 80 kts.  But I don't know.

Based on this, I would simply say that doing this simple math, any value you get on this app number would seem to need to be over about 50 m/s/km or so to be of tornadic concern.  Maybe some engineer can help interpret this, I'm used to seeing the single digits, i.e. 4.2 m/s/kt.

Quote

Also, if you look at that read out, the Height of Max Delta Velocity, storm base, and Height of Max Shear are all at 1.9K feet.  Does this mean the maximum shear is right at the cloud base?  This kind of ties into my second question about the "ideal" altitude for shear.  What's worse:  high altitude or low altitude shear?

I believe this is more of a measure of conditions at the radar measuring point within a given period of time.  I.e. at 1.9k feet where the measurements are being done, they picked up a max Delta Velocity of nnn.

On the second question, I guess you certainly don't want a lot of high value low altitude shear when considering tornadoes.  But since we don't know a lot about the physical dynamics of tornado clouds (still), you probably don't want a lot of high shear either.  I.e. a storm with low-level shear but no higher level might fall out to a strong line of winds that could be tornado-like but not a true rotation (I've had that happen here and had wind damage from it).  A storm with both might have the fuel to sustain a long, more damaging tornadic run (remember shit goes up and down through storms, not just sideways).  A storm with significant variance in mid/high level shear might provide the fuel on its downdraft (and tornadoes are pretty much really bad, rotating downdrafts) to keep one going.  Also keep in mind that a storm with weak low-level shear could be ramped up by high-level shear moving down through the storm and organizing.   I think strong shear of any height isn't too welcome.

I think in one of weather's greatest ironies, you don't want strong shear in a tornado or mesocyclone, whereas in hurricane (non) development you do want shear because that busts up the otherwise large-scale column of air rotating in a hurricane and rips it apart.  So one one hand, shear is the worst case, while on the other, it's the best.

Holy shit explain that, Einstein.  Weather is hard.

Hope this helps, even if I'm not 100% sure on some of it.

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Jhawk

Jhawk 1075

Posted
Posted
25 minutes ago, Okie State said:

Got some pork rinds in my truck. Probably eat those and take a nap.

Awesome.

This guy is basically my experience living in and visiting oklahoma since 2015.  My Ex's brother in law didn't have a job for a real long time and his wife was a teacher making like $28k a year.  He woke up and went fishing every morning to literally put food on the table.  I appreciate that he did that but he could have gotten a job instead of napping in a lawn chair the rest of the day.

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Okie State

Okie State 3819

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Posted
This guy is basically my experience living in and visiting oklahoma since 2015.  My Ex's brother in law didn't have a job for a real long time and his wife was a teacher making like $28k a year.  He woke up and went fishing every morning to literally put food on the table.  I appreciate that he did that but he could have gotten a job instead of napping in a lawn chair the rest of the day.
Holding out for a management position.
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atomheartbevo

atomheartbevo 89660

Posted
Posted
3 hours ago, Jhawk said:

This guy is basically my experience living in and visiting oklahoma since 2015.  My Ex's brother in law didn't have a job for a real long time and his wife was a teacher making like $28k a year.  He woke up and went fishing every morning to literally put food on the table.  I appreciate that he did that but he could have gotten a job instead of napping in a lawn chair the rest of the day.

Many people spend decades working up to the point where they can spend their days fishing.  He did it much sooner.  

#respectthedream

 

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atomheartbevo

atomheartbevo 89660

Posted
Posted
4 hours ago, Okie State said:

Got some pork rinds in my truck. Probably eat those and take a nap.

Awesome.

I like the guy.   With all of the shit going down in his life, and you know it’s a lot more than being stuck in traffic, he has a fleeting minute of fame handed to him, and instead of a shout-out to his family,  he makes damn sure that everybody knows who he hates.  

Plus, he knows what’s going down October 12th. 

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Assman

Assman 1830

Posted
Posted
12 hours ago, phdhorn said:

These better require long answers, but for now I'll knock 'em out as briefly as I can:

The second point here, bolded.

LLRV and LLDV in general, yes, I'd say so.  MRV not necessarily.  MRV can be calculated all throughout a storm's height.  If MRV is calculated within a traditional lower part of the storm, yes.  Why calculate MRV's at different shear heights?  Because you're not always looking for a tornado; MRV's can be good predictors of hail, which can of course happen in non-rotating storms.  Also, be cautious not to automatically make the link; you can have tornadoes, especially weak ones, where these values are low; conversely you can have high values without a tornado; keep in mind that these measure the strength of the shear, which is one, but not the only, component which makes up a tornado.  But as I said, you're likely to have conditions for tornadic formation if the LLRV and LLDV are relatively higher.

No.  Again you're looking at shear within the all-important (for tornadoes) lower part of the storm.  Consequently, a higher storm relative depth = a larger column of "messed up shear air" within that portion, which probably means more violence and likelihood to have riper tornado conditions.  If this were a simple measure of total storm shear height or voricity, then your thought makes more sense.  

These things are crazy nerdy calculated, and again, the lower part of the storm matters more when looking for tornadoes, but of course upper level shear matters and is worth measuring because storms can be damaging (hail, wind, etc.) without dropping a twister.

 

Hmmm... well sort of, but it's usually in single digit units (after a shitload of fluid dynamics calculus equations), as this is a straight outta Fluid Dynamics value.  After all the number crunching is done, I'm used to seeing the units as a single digit scale:

0 to 3 weak, 4 to 5 moderate, 6 to 7 large, 8+ extreme

I.e. gradient values (uh, max shear = max gradient value) of tornadoes usually are seen in the 5-8+ extreme.  I honestly don't know why this number is double digit... I guess I have to look at it (or think more).

I can also tell you that the m/s value in the other readout formats I've seen are pretty much 1/2 of the wind variation in kts.  That is, 40 m/s = roughly 80 kts.  It could be in this case that 80 m/s/km = the divergence in the wind is 160 mph (i.e. the wind moving "away" at 80 kts + the wind moving "toward" at 80 kts = 160 kts.   But this is one I don't know... yet.  Seems app-specific.  Maybe it's just their way of saying that the winds at the max shear point are 80 kts.  But I don't know.

Based on this, I would simply say that doing this simple math, any value you get on this app number would seem to need to be over about 50 m/s/km or so to be of tornadic concern.  Maybe some engineer can help interpret this, I'm used to seeing the single digits, i.e. 4.2 m/s/kt.

I believe this is more of a measure of conditions at the radar measuring point within a given period of time.  I.e. at 1.9k feet where the measurements are being done, they picked up a max Delta Velocity of nnn.

On the second question, I guess you certainly don't want a lot of high value low altitude shear when considering tornadoes.  But since we don't know a lot about the physical dynamics of tornado clouds (still), you probably don't want a lot of high shear either.  I.e. a storm with low-level shear but no higher level might fall out to a strong line of winds that could be tornado-like but not a true rotation (I've had that happen here and had wind damage from it).  A storm with both might have the fuel to sustain a long, more damaging tornadic run (remember shit goes up and down through storms, not just sideways).  A storm with significant variance in mid/high level shear might provide the fuel on its downdraft (and tornadoes are pretty much really bad, rotating downdrafts) to keep one going.  Also keep in mind that a storm with weak low-level shear could be ramped up by high-level shear moving down through the storm and organizing.   I think strong shear of any height isn't too welcome.

I think in one of weather's greatest ironies, you don't want strong shear in a tornado or mesocyclone, whereas in hurricane (non) development you do want shear because that busts up the otherwise large-scale column of air rotating in a hurricane and rips it apart.  So one one hand, shear is the worst case, while on the other, it's the best.

Holy shit explain that, Einstein.  Weather is hard.

Hope this helps, even if I'm not 100% sure on some of it.

Thanks again for the explanation.

At the end of the day, what I'm looking for a way differentiate the strength of a mesocyclone or TVS versus another.  Given all the parameters that I can see on this app, which one is the best indicator of a tornado?  Based on what you've said, it seems like the higher the LLRV/LLDV, the higher the shear value, and the higher the strength index, the stronger the rotation and the greater chance for a tornado.  If true, this seems pretty straight forward.  Going back to Storm Relative Depth for a minute, does a storm with a 100% SRD vs. one with a 50% have a higher chance for a tornado?  Or is SRD just more of a geez whiz type info that really isn't a great tornado indicator?

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'stache

'stache 21815

Posted
Posted (edited)

Epic rains have resulted in record releases from Keystone Dam upriver from Tulsa. The fucking casino is closing. That’s when you know shit is serious. There is about 15 feet of bike trail and shorline underwater in this pic. It looks like it's taking over the pool area too.

4d385899763851b4a7ef489c27c76c79.jpg

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'stache

'stache 21815

Posted
Posted
Reporting live from downtown Tulsa. Sirens were going off about 645am. Apparently it got pretty bad but I slept through it. No real damage other than 2 houses north of downtown. 4K+ without power. 
Wouldn't you know it, I’ve had some really bad diarrhea this morning. Going to die on the shitter. 

This pic is from yesterday morning at the end of my street looking towards downtown. Luckily it moved a few miles north towards the airport before it touched down.

9c0e1ad45c4ddfa67fe5e04824aa416e.jpg
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clapclapclap

clapclapclap 9000

Posted
Posted (edited)

And a Moderate Risk for tornadoes (2nd highest category) over SE MO on the anniversary of the Joplin killer tornado.

I remember the continued shocked demeanor of TWC's Mike Bettis covering the aftermath live from Joplin, perhaps the first time for him to see up close a disaster of that scale.

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jimmyjazz

jimmyjazz 45926

Posted
Posted
9 minutes ago, clapclapclap said:

And a Moderate Risk for tornadoes (2nd highest category) over SE MO on the anniversary of the Joplin killer tornado.

I remember the continued shocked demeanor of TWC's Mike Bettis covering the aftermath live from Joplin, perhaps the first time for him to see up close a disaster of that scale.

First girlfriend . . . first <ahem> . . . the lovely Rhonda C from Webb City, a "suburb" of Joplin.  

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phdhorn

phdhorn 6224

Posted
Posted
1 hour ago, clapclapclap said:

And a Moderate Risk for tornadoes (2nd highest category) over SE MO on the anniversary of the Joplin killer tornado.

I remember the continued shocked demeanor of TWC's Mike Bettis covering the aftermath live from Joplin, perhaps the first time for him to see up close a disaster of that scale.

Yeah then he almost got kilt when one in El Reno took his SUV and flipped it like a ref tossing a coin in the air.  5 years ago next week.
That pretty much caused him to stop chasing 'em.

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atomheartbevo

atomheartbevo 89660

Posted
Posted

Family up there is flipping out over the hail and additional rain.

And Grand Lake, a lake I spent many a youthful summer around is apparently pumping out 70,000+ gallons a minute, while taking in over 105,000 gallons a minute.  It's taking the length, but for how long, who knows - this http://grandlake.uslakes.info/Level.asp says it's 15 feet above full pool.

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Okie State

Okie State 3819

Posted
Posted
Family up there is flipping out over the hail and additional rain.
And Grand Lake, a lake I spent many a youthful summer around is apparently pumping out 70,000+ gallons a minute, while taking in over 105,000 gallons a minute.  It's taking the length, but for how long, who knows - this http://grandlake.uslakes.info/Level.asp says it's 15 feet above full pool.
Wow. My family has a place over there. Water has never reached it that I'm aware of, but it has been close to the lower level before.
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atomheartbevo

atomheartbevo 89660

Posted
Posted
23 minutes ago, Okie State said:
34 minutes ago, atomheartbevo said:
Family up there is flipping out over the hail and additional rain.
And Grand Lake, a lake I spent many a youthful summer around is apparently pumping out 70,000+ gallons a minute, while taking in over 105,000 gallons a minute.  It's taking the length, but for how long, who knows - this http://grandlake.uslakes.info/Level.asp says it's 15 feet above full pool.

Wow. My family has a place over there. Water has never reached it that I'm aware of, but it has been close to the lower level before.

Apparently tornadoes on the ground tonight.

And just talked to my great-aunt, and Grand Lake is having to hold back as much as possible, because Hudson, Gibson, and Eufala are all full or above-full and flooding like crazy.  I think the main dam there at Grand Lake was built in the 40s.  I'd be be getting the hell out of Dodge if I was anywhere downstream.  I always hated driving over dams in that area.

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Okie State

Okie State 3819

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Posted
Apparently tornadoes on the ground tonight.

And just talked to my great-aunt, and Grand Lake is having to hold back as much as possible, because Hudson, Gibson, and Eufala are all full or above-full and flooding like crazy.  I think the main dam there at Grand Lake was built in the 40s.  I'd be be getting the hell out of Dodge if I was anywhere downstream.  I always hated driving over dams in that area.

We always joked about what you'd do if the dam broke while you were driving over. My Uncle liked to say 'Just go with the flow I guess.'

 

It's crazy if you go down below them while they are letting water out. One wrong step and you're history.

 

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