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May 15th-16th Severe Events


andyhb

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It's time for everyone to R-E-L-A-X.  First off, showing multiple streaks of >100 UH in an environment of 10+ STP doesn't qualify as "not really showing too much" (especially SW/srn OK).  Secondly, look at the environment right now.  SE of the current convection, you have mid-60s dewpoints, SE winds, steepening lapse rates, and increasing low-level flow.  In the convective region, the radial velocity structure of that line segment W over Alva indicates to me that it's probably driven by a gravity wave, not by a cold pool.  You still have a cool, stable layer in place at the surface, but when you have convection like this, it tends to be associated with surface stable layers that are very shallow.  These stable layers, and the boundaries at their interfaces, are often among those most likely to be associated with enhancement of tornado risk.  Good examples are 4/27/11 across NE MS and N AL and 6/30/14 across N IL and N IN.  The HRRR has had an extremely persistent signal of a major discrete cell with high-end updraft helicity in the Gage/Woodward/Alva/Medicine Lodge/Hutchinson corridor.  I see no reason why a cell or cells in that area would not have the chance to be significantly, if not violently, tornadic.

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It's time for everyone to R-E-L-A-X. First off, showing multiple streaks of >100 UH in an environment of 10+ STP doesn't qualify as "not really showing too much" (especially SW/srn OK). Secondly, look at the environment right now. SE of the current convection, you have mid-60s dewpoints, SE winds, steepening lapse rates, and increasing low-level flow. In the convective region, the radial velocity structure of that line segment W over Alva indicates to me that it's probably driven by a gravity wave, not by a cold pool. You still have a cool, stable layer in place at the surface, but when you have convection like this, it tends to be associated with surface stable layers that are very shallow. These stable layers, and the boundaries at their interfaces, are often among those most likely to be associated with enhancement of tornado risk. Good examples are 4/27/11 across NE MS and N AL and 6/30/14 across N IL and N IN. The HRRR has had an extremely persistent signal of a major discrete cell with high-end updraft helicity in the Gage/Woodward/Alva/Medicine Lodge/Hutchinson corridor. I see no reason why a cell or cells in that area would not have the chance to be significantly, if not violently, tornadic.

Seems like people have forgotten that this stuff requires PATIENCE. Currently, the atmosphere is recharging and the parameters are coming into place. Latest soundings have looked good. I'd give this another 1-2hrs before jumping to conclusions...

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I was simply interpreting the run verbatim re early HRRR. Clearly the high moisture and low lcl environment given the rest is quite favorable. I've been on board with an outbreak for like a week.

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Seems like people have forgotten that this stuff requires PATIENCE. Currently, the atmosphere is recharging and the parameters are coming into place. Latest soundings have looked good. I'd give this another 1-2hrs before jumping to conclusions...

I wouldn't necessarily say so. OUN shows very weak directional shear at 18Z (much less than at 12Z) due to a more unidirectional wind profile at 700-500 mb. That will need to change, and I currently expect it to do so, but currently the profile over C OK is unfavorable for long-lived discrete supercells. For a widespread outbreak, outflow boundaries alone won't cut it, but backed low-level winds will also help.

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I wouldn't necessarily say so. OUN shows very weak directional shear at 18Z (much less than at 12Z) due to a more unidirectional wind profile at 700-500 mb. That will need to change, and I currently expect it to do so, but currently the profile over C OK is unfavorable for long-lived discrete supercells. For a widespread outbreak, outflow boundaries alone won't cut it, but backed low-level winds will also help.

 

Huh? Low level directional shear significantly increased vs the 12z sounding and also less VBV above 700 mb. How is the above in any way less favorable than this?

 

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Cell S of Claredon, TX heading towards Hedley, TX now tornado warned but couplet on radar has decreased in intensity from the previous 3 scans. Looks to be cycling as it begins to enter a more favorable environment for tornado development.

Couplet hasn't really weakened.  It was being contaminated by multiple-trip echoes.

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Looks like a TDS on CC scan or the beginnings of one.

b1f6374bfac8af7b737d4096685a255a.jpg

 

That's not a TDS...that's either some dust/dirt in the inflow region or perhaps (since it is under some reflectivity) some errant hail stones being tossed out of the E edge of the hail core. The lower CC values are not under the rotation.

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That's not a TDS...that's either some dust/dirt in the inflow region or perhaps (since it is under some reflectivity) some errant hail stones being tossed out of the E edge of the hail core. The lower CC values are not under the rotation.

Nope looks like it was a forming TDS per the following scan.. Also line up well with circulation.

085dc1a96ac0c9e30ca4b516d214c152.jpg

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Agree to disagree.. They are within a mile or so and the scans weren't taken at the exact same moment.

This isn't really a debatable subject.  That low rho-hv is from the sharp SNR gradient due to the very high reflectivity in the hail core/FFD, as well as inflow into the storm, not due to tornado debris.

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This isn't really a debatable subject. That low rho-hv is from the sharp SNR gradient due to the very high reflectivity in the hail core/FFD, as well as inflow into the storm, not due to tornado debris.

Interesting that spotters were reporting debris on the ground. Oh well doesn't really matter because it was short lived. Looks to have developed another possible TDS heading for Shamrock, TX but i'll wait for experts here to confirm..
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