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5/6-5/9 Severe Threats


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23 minutes ago, nwohweather said:

Definitely deserving of a moderate risk today. Hot take, the NWS being in Norman, OK comes with biases

I really think they need an office for the northern plains, central plains, Midwest, and Dixie. All have those areas have their nuances with tornado forecasting

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17 minutes ago, mob1 said:

The cell approaching the northern burbs of Cincinnati could be trouble. 

Not going to rule anything out, but it looks like that storm moving into Cincinnati seems to be getting cut off by outflow. There may be some spin-up potential around Lebanon, OH as well.

There's also the storm moving towards the northern Columbus suburbs. Places like Plain City and Dublin will soon be in its path, and perhaps Westerville and New Albany down the line. On the other hand, SPC Mesoanalysis is showing a sudden drop-off in tornado ingredients around the Columbus metro, but I wouldn't count on the storm weakening before it impacts the Columbus metro, either. This storm is well-isolated from other storms, so there is definitely potential for concern.

EDIT: rotation tightening between Mechanicsburg and Plain City.

IMG_6897.jpeg

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Lewis Center/Orange Township/Powell, Ohio (North Columbus) here. 

We got some cool lightning and sirens but the tornado seems to have passed by a mile or two south of us. 

Pretty exciting night though. Had to wake the little guy up to get him in the basement. 

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4 minutes ago, Columbus said:

Lewis Center/Orange Township/Powell, Ohio (North Columbus) here. 

We got some cool lightning and sirens but the tornado seems to have passed by a mile or two south of us. 

Pretty exciting night though. Had to wake the little guy up to get him in the basement. 

I think this is when there was a confirmed tornado warning, but I wasn't quite paying attention at the time. Do you are think that this tornado went from Plain City to somewhere near Powell?

plain city 1.jpg

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5 minutes ago, Chinook said:

I think this is when there was a confirmed tornado warning, but I wasn't quite paying attention at the time. Do you are think that this tornado went from Plain City to somewhere near Powell?

plain city 1.jpg

It seems like it. We live at Powell Rd/315. There was a ton of lightning just south of us towards 270. My interpretation was that the tornado more or less followed the county line into Westerville before moving out to the boondocks. Does not seem like a touchdown, though, which is a lucky dodge.

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4 hours ago, largetornado said:

Rap sounding from  northwest Ohio. What prevented a mode significant tornado? 

IMG_6358.png

It just so happened that all of the ingredients, this time, came together further to the north and west.

This was a pretty significant outbreak for NW Indiana and SW Michigan.

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9 hours ago, largetornado said:

Rap sounding from  northwest Ohio. What prevented a mode significant tornado? 

IMG_6358.png

A late day lake breeze pretty much saved Toledo. Put one of those major tornadoes in metro Toledo, we would have had a very bad problem

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11 hours ago, largetornado said:

Rap sounding from  northwest Ohio. What prevented a mode significant tornado? 

IMG_6358.png

On that sounding the two main negatives that stand out to me are the poor low to mid-level lapse rates leading to a tall/skinny CAPE profile along with weak storm relative winds and a messy hodograph in the 2-4km layer. Here's essentially the same sounding from Pivotal with height in km placed on the hodograph,  helps visualize the lack of shear in the 2-3km layer (2 and 3km are almost on top of each other):

rap_2024050721_003_40.47--84_05.thumb.png.b5fe4481095be38ef0086f76d08e4357.png

I'm guessing that between the skinny low-mid level CAPE profile and relatively weak storm relative winds in the mid-levels there might have been more of a struggle to maintain strong/deep updrafts around NW OH than you'd otherwise expect with over 1500 J/KG of MLCAPE, 60+ knots of effective shear and 200-300 m2/s2 of effective SRH. You can sometimes get more severe wx out of a lesser amount of CAPE that's all focused below 400mb with a thicker CAPE profile than with a greater amount of CAPE but with a skinner CAPE profile through a deeper layer. 

CODNEXLAB-GOES-East-regional-northeast-08-02_11Z-20240508_map_data-21-6n-10-100.thumb.gif.10a4035dda1ec2d2a8c344d3cd559bc6.gif

The other thing that stood out to me in northwest / north central OH was just where storms initially developed. The storms that initially developed from east-central IL into central IN ended up being the main show in the northern OH Valley and fired on the nose of the deeper instability advecting in from the southwest. The mid-level flow was southwesterly, so these storms developed upstream of northwest OH. I am guessing that as these storms grew upscale that some subsidence and warming in the mid-levels occurred. I think that's why the cell that went tornado warned east of Fort Wayne into Northwest OH did OK for a bit but then started weakening as activity to the south/southwest continued to grow upscale. It's possible this led to warmer mid-levels and an even worse CAPE profile over NW OH in the evening than the RAP sounding suggested. The cells that developed over NE IL/far NW IN and tracked into MI were beneath the divergent left-exit quadrant of a jet streak rounding the base of a negatively tilted trough so had the benefit of stronger forcing and were more separated form the Ohio Valley storms. And as we all know those storms certainly produced. 

It's been a frustrating spring for convective forecasting in the northern 1/3 to 1/2 of OH. Every setup has had shear but most setups, outside of March 14th, have had relatively marginal thermodynamics. If you get sustained deep convection you'll get tornadoes in these set ups given the shear, but if you don't get that because there's just not quite enough instability everyone thinks we're nuts for predicting a risk of tornadoes. March 14th and April 17th produced (though March 14th had great thermos, the main uncertainty was how far northeast the instability would get behind earlier day rain). A few other of these high shear, marginal instability setups (April 2nd, April 11th, yesterday) did not produce locally. 

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2 hours ago, OHweather said:

On that sounding the two main negatives that stand out to me are the poor low to mid-level lapse rates leading to a tall/skinny CAPE profile along with weak storm relative winds and a messy hodograph in the 2-4km layer. Here's essentially the same sounding from Pivotal with height in km placed on the hodograph,  helps visualize the lack of shear in the 2-3km layer (2 and 3km are almost on top of each other):

rap_2024050721_003_40.47--84_05.thumb.png.b5fe4481095be38ef0086f76d08e4357.png

I'm guessing that between the skinny low-mid level CAPE profile and relatively weak storm relative winds in the mid-levels there might have been more of a struggle to maintain strong/deep updrafts around NW OH than you'd otherwise expect with over 1500 J/KG of MLCAPE, 60+ knots of effective shear and 200-300 m2/s2 of effective SRH. You can sometimes get more severe wx out of a lesser amount of CAPE that's all focused below 400mb with a thicker CAPE profile than with a greater amount of CAPE but with a skinner CAPE profile through a deeper layer. 

CODNEXLAB-GOES-East-regional-northeast-08-02_11Z-20240508_map_data-21-6n-10-100.thumb.gif.10a4035dda1ec2d2a8c344d3cd559bc6.gif

The other thing that stood out to me in northwest / north central OH was just where storms initially developed. The storms that initially developed from east-central IL into central IN ended up being the main show in the northern OH Valley and fired on the nose of the deeper instability advecting in from the southwest. The mid-level flow was southwesterly, so these storms developed upstream of northwest OH. I am guessing that as these storms grew upscale that some subsidence and warming in the mid-levels occurred. I think that's why the cell that went tornado warned east of Fort Wayne into Northwest OH did OK for a bit but then started weakening as activity to the south/southwest continued to grow upscale. It's possible this led to warmer mid-levels and an even worse CAPE profile over NW OH in the evening than the RAP sounding suggested. The cells that developed over NE IL/far NW IN and tracked into MI were beneath the divergent left-exit quadrant of a jet streak rounding the base of a negatively tilted trough so had the benefit of stronger forcing and were more separated form the Ohio Valley storms. And as we all know those storms certainly produced. 

It's been a frustrating spring for convective forecasting in the northern 1/3 to 1/2 of OH. Every setup has had shear but most setups, outside of March 14th, have had relatively marginal thermodynamics. If you get sustained deep convection you'll get tornadoes in these set ups given the shear, but if you don't get that because there's just not quite enough instability everyone thinks we're nuts for predicting a risk of tornadoes. March 14th and April 17th produced (though March 14th had great thermos, the main uncertainty was how far northeast the instability would get behind earlier day rain). A few other of these high shear, marginal instability setups (April 2nd, April 11th, yesterday) did not produce locally. 

Thanks for providing this synopsis. Seeing the thermals initially at the surface the environment seemed absolutely primed, but I was not thrilled at the mid levels. Interesting it was less lake influence and more warming in the mid levels.

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Intercepted a significant tornado 2 miles ENE of Nottowa, MI just after 5:45pm yesterday. Me and my friend Rune watched as it crossed M-66 in front of us. Multiple vortices were visible prior to the tornado crossing the highway. Afterwards it fully condensed and intensified before becoming shrouded from our vantage point by rain and trees. This tornado made the one I saw in Perry last year seem like a bird fart. We saw large debris from barns lofted, but thankfully no fatalities were reported. Fighting for a view through the trees was difficult (customary for chasing in MI), but we managed to get some decent shots. This tornado has been preliminarily rated EF2 with winds upwards of 130mph, with another damage survey taking place tomorrow. 
tornado4.thumb.JPG.8f6cbfbb726829d3dd27a9fcab5e6ceb.JPG
tornado5.thumb.JPG.c129c0151cebeb41af22157f5e5f861b.JPG
tornado2.thumb.JPG.1dd59ae2a7c151ee6d43641cf6c9880a.JPG
 

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8 hours ago, OHweather said:

On that sounding the two main negatives that stand out to me are the poor low to mid-level lapse rates leading to a tall/skinny CAPE profile along with weak storm relative winds and a messy hodograph in the 2-4km layer. Here's essentially the same sounding from Pivotal with height in km placed on the hodograph,  helps visualize the lack of shear in the 2-3km layer (2 and 3km are almost on top of each other):

rap_2024050721_003_40.47--84_05.thumb.png.b5fe4481095be38ef0086f76d08e4357.png

I'm guessing that between the skinny low-mid level CAPE profile and relatively weak storm relative winds in the mid-levels there might have been more of a struggle to maintain strong/deep updrafts around NW OH than you'd otherwise expect with over 1500 J/KG of MLCAPE, 60+ knots of effective shear and 200-300 m2/s2 of effective SRH. You can sometimes get more severe wx out of a lesser amount of CAPE that's all focused below 400mb with a thicker CAPE profile than with a greater amount of CAPE but with a skinner CAPE profile through a deeper layer. 

CODNEXLAB-GOES-East-regional-northeast-08-02_11Z-20240508_map_data-21-6n-10-100.thumb.gif.10a4035dda1ec2d2a8c344d3cd559bc6.gif

The other thing that stood out to me in northwest / north central OH was just where storms initially developed. The storms that initially developed from east-central IL into central IN ended up being the main show in the northern OH Valley and fired on the nose of the deeper instability advecting in from the southwest. The mid-level flow was southwesterly, so these storms developed upstream of northwest OH. I am guessing that as these storms grew upscale that some subsidence and warming in the mid-levels occurred. I think that's why the cell that went tornado warned east of Fort Wayne into Northwest OH did OK for a bit but then started weakening as activity to the south/southwest continued to grow upscale. It's possible this led to warmer mid-levels and an even worse CAPE profile over NW OH in the evening than the RAP sounding suggested. The cells that developed over NE IL/far NW IN and tracked into MI were beneath the divergent left-exit quadrant of a jet streak rounding the base of a negatively tilted trough so had the benefit of stronger forcing and were more separated form the Ohio Valley storms. And as we all know those storms certainly produced. 

It's been a frustrating spring for convective forecasting in the northern 1/3 to 1/2 of OH. Every setup has had shear but most setups, outside of March 14th, have had relatively marginal thermodynamics. If you get sustained deep convection you'll get tornadoes in these set ups given the shear, but if you don't get that because there's just not quite enough instability everyone thinks we're nuts for predicting a risk of tornadoes. March 14th and April 17th produced (though March 14th had great thermos, the main uncertainty was how far northeast the instability would get behind earlier day rain). A few other of these high shear, marginal instability setups (April 2nd, April 11th, yesterday) did not produce locally. 

I've observed that outside of the deep south and plains, tornadoes sometimes favor the margins of the highest CAPE.  There was a super sharp CAPE gradient over far SW Michigan.  The later batch of convection was associated with the leading edge of even higher CAPE with dewpoints near 70 pushing into the OV later in the evening.  This effect I've observed might just be a side effect of the wind being more backed in the lowest km near warm fronts or other types of horizontal temperature gradients.  The Michigan storms also seemed lower topped due to being closer to the upper low.  CAPE was possibly fatter despite being less overall.  The storms were also more strongly forced under an area of vorticity advection aloft as opposed to being driven by afternoon heating.

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I've observed that outside of the deep south and plains, tornadoes sometimes favor the margins of the highest CAPE.  There was a super sharp CAPE gradient over far SW Michigan.  The later batch of convection was associated with the leading edge of even higher CAPE with dewpoints near 70 pushing into the OV later in the evening.  This effect I've observed might just be a side effect of the wind being more backed in the lowest km near warm fronts or other types of horizontal temperature gradients.  The Michigan storms also seemed lower topped due to being closer to the upper low.  CAPE was possibly fatter despite being less overall.  The storms were also more strongly forced under an area of vorticity advection aloft as opposed to being driven by afternoon heating.

One other thing to look back at is the amount of low level (0-3km) CAPE. Not sure how high it was on Tuesday but the general rule of thumb here in Minnesota and northern plains is if the 0-3km CAPE is 150 or above the storms usually do well. Overlapping this low level CAPE with a lot of vorticity is how we get a lot of our “surprise” tornado days. It makes sense. Even if the mixed layer is on the marginal side for CAPE, if a lot of it is loaded in the lowest levels, it can still produce some significant storms. The Ashby, MN tornado was a perfect example, although we had the extra benefit of extreme MLCAPE.


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19 hours ago, nwohweather said:

Thanks for providing this synopsis. Seeing the thermals initially at the surface the environment seemed absolutely primed, but I was not thrilled at the mid levels. Interesting it was less lake influence and more warming in the mid levels.

I do think that if a tornadic supercell played out over NW OH that the lake influence may have still had in effect on it as it approached the lake, though in this case I think other factors just prevented a tornadic supercell altogether. 

13 hours ago, frostfern said:

I've observed that outside of the deep south and plains, tornadoes sometimes favor the margins of the highest CAPE.  There was a super sharp CAPE gradient over far SW Michigan.  The later batch of convection was associated with the leading edge of even higher CAPE with dewpoints near 70 pushing into the OV later in the evening.  This effect I've observed might just be a side effect of the wind being more backed in the lowest km near warm fronts or other types of horizontal temperature gradients.  The Michigan storms also seemed lower topped due to being closer to the upper low.  CAPE was possibly fatter despite being less overall.  The storms were also more strongly forced under an area of vorticity advection aloft as opposed to being driven by afternoon heating.

Fully agree with this. I do think that as you suggested, the CAPE gradient suggests some sort of boundary (often a front or outflow, sometimes differential heating) with winds often more backed along and on the cool side of boundaries...with boundaries also providing for low-level convergence/lift which can aid in getting stronger updrafts. Whatever the reason(s), I've heard the words "it's always on the gradient" uttered more than a few times in operational meteorological settings. Also agree that the storms in Michigan on Tuesday benefited from stronger forcing, and per this RAP sounding (likely not perfect but hopefully close) low-mid level lapse rates were steeper than the NW OH sounding. Can also note some very large hail analogs on the bottom right, with a higher % of the loose matches being significant than in the NW OH sounding. Surface winds along and on the cool side of the warm front were SE, which would increase SRH from what this sounding shows:

rap_2024050721_002_area_41.55-41_82.-85.89--85_53.thumb.png.096ed231c656320342e510c510e199f2.png

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