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Significant Severe Weather Threat Friday 10/4

tornadotony

By tornadotony,
in Central/Western States

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Ensō

Ensō

Posted
Posted

Good possible origin, although I would hope people could tell the difference between a predicted warning and an actual storm report.

 

You'd hope, but you'd be sorely disappointed. People apparently aren't very bright.

 

 

Which speaks to another problem with these new tiered tornado warnings.

 
I won't even get started on that.
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brettjrob

brettjrob

Posted
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Caught second half of Wayne tornado from a distance and bad terrain, then Woodbury Co. IA from genesis and relatively close range. Magnitude of the event seems close to Tony's and my expectations, just with really good luck in avoiding major population centers, plus the failure of C/E IA to destabilize.

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Minnesota Meso

Minnesota Meso

Posted
Posted

Obviously, today turned out just about as I expected.  But I have to admit, the number of extremely large tornadoes today kinda even caught me off guard just a bit.  No fatalities so far, and hopefully it stays that way.

 

First of all, I may have made a mistake last night with the marine layer, there was a 1030mb high located over southern Canada with winds blowing out of the NE over the lakes, at any rate that set up a huge temp contrast between Sioux Falls and points south.  I thought the best forcing was near the Omaha area and it looked extremely explosive to me, that's why I said the mod risk needed to located near Omaha.  Areas further east into central and northern IA were just to far away from the best forcing.  Just my honest opinion, I hope I didn't offend anyone last night.

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andyhb

andyhb

Posted
Posted

Caught second half of Wayne tornado from a distance and bad terrain, then Woodbury Co. IA from genesis and relatively close range. Magnitude of the event seems close to Tony's and my expectations, just with really good luck in avoiding major population centers, plus the failure of C/E IA to destabilize.

 

C/E IA did destabilize though (at one point I checked sfc obs and there were 70˚ dewpoints across like 3/4 of DMX's CWA, which is absurd for October along with 2500-3500 J/kg SB/MLCAPE), I'm wondering if the comparatively weaker 0-6 km shear (~35-45 kts as opposed to the 50 to near 70 kts around the tornadic supercells to the north) aided in the lack of storm organization in areas south of the main tornadic supercells (considering there were storms that did get going) as well as more subtle forcing for ascent (despite the cold front) as opposed to right near the triple point. 0-1 km shear was plentiful at 25-35 kts and would've definitely supported strong tornadoes had we'd seen the dominant supercells like further north.

 

Considering it looked for a bit there that everything was about to unzip and we'd have a full blown, high risk caliber tornado outbreak frankly given the parameters across OAX and DMX's CWA...

 

The supercells that did get going had some insane shear to work with, something like 500-800 m2/s2 0-3 km SRH right near the triple point there, and obviously produced the large, intense tornadoes to prove it.

 

Quite frankly it seems there is this theme this year, in that the events we do get aren't extremely prolific in terms of numbers of tornadoes (partly leading to the low totals this year)...but the ones that do occur are large, strong and noteworthy in their own rights (Kemper County (MS), Bennington, Rozel, Carney, Shawnee, Moore, El Reno and now today).

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thewxmann

thewxmann

Posted
Posted

Quite frankly it seems there is this theme this year, in that the events we do get aren't extremely prolific in terms of numbers of tornadoes (partly leading to the low totals this year)...but the ones that do occur are large, strong and noteworthy in their own rights (Kemper County (MS), Bennington, Rozel, Carney, Shawnee, Moore, El Reno and now today).

 

My thought exactly. This event played along with the theme of 2013 tornadoes to the tee.

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Jim Marusak

Jim Marusak

Posted
Posted

First of all, I may have made a mistake last night with the marine layer, there was a 1030mb high located over southern Canada with winds blowing out of the NE over the lakes, at any rate that set up a huge temp contrast between Sioux Falls and points south.  I thought the best forcing was near the Omaha area and it looked extremely explosive to me, that's why I said the mod risk needed to located near Omaha.  Areas further east into central and northern IA were just to far away from the best forcing.  Just my honest opinion, I hope I didn't offend anyone last night.

i don't think you offended ayone. but you might have had the wrong idea about the effect. yea I have seen the lake stabilize things in eastern WI and over in the arrowhead. But the 1030 high and the cooler air would be more like "Cold Air Damming" scenario than a "Lake-Effect" one.

 

As for the Moderate risk, I was talking about that as well, and I was seeing where the potential was there. Problem was, the dynamics to make that happen never really came in as well as the models said for central Iowa. The damming could be a part of that, but as well i think we were all doing the "model as god scenario". It's something I know I have to watch myself with, and a lot of us forecasters have to be vigilant of more often, even with the models being markedly better than the mid 90's when I came out of college. A lot of us are doing more "wish-casting" the last few years than we should be. The best thing you, me, and others should do, if anything, is just remember what actually happened, so that if we get something similar, we have a better chance of getting it right the next time.

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JoMo

JoMo

Posted
Posted

Quite possible considering it's still early October. November almost always seems to provide some surprises, sometimes significant ones. 

 

Like this in Iowa again. I had no idea that the young man that shot this footage died in 2010 from pancreatic cancer. I remember seeing this on Storm Stories. 

 

 

http://www.youtube.com/watch?v=iLRIBSp3REo

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thewxmann

thewxmann

Posted
Posted

i don't think you offended ayone. but you might have had the wrong idea about the effect. yea I have seen the lake stabilize things in eastern WI and over in the arrowhead. But the 1030 high and the cooler air would be more like "Cold Air Damming" scenario than a "Lake-Effect" one.

 

As for the Moderate risk, I was talking about that as well, and I was seeing where the potential was there. Problem was, the dynamics to make that happen never really came in as well as the models said for central Iowa. The damming could be a part of that, but as well i think we were all doing the "model as god scenario". It's something I know I have to watch myself with, and a lot of us forecasters have to be vigilant of more often, even with the models being markedly better than the mid 90's when I came out of college. A lot of us are doing more "wish-casting" the last few years than we should be. The best thing you, me, and others should do, if anything, is just remember what actually happened, so that if we get something similar, we have a better chance of getting it right the next time.

 

It's not cold air damming, which is topography induced. It's also not a marine layer, which is induced by temperature differences between sea and land. It's a plain old cP air mass advected in by high pressure associated with upper-level convergence to the north. 

 

SPC played it fantastically today, sticking with the 10% hatched despite the obvious ceiling this event had. The things that went "wrong", so to speak, were fairly well anticipated

 

-Elevated convection in central IA had a tough time leaving. This limited the breadth of the instability sector (cut off to the east and north). This happens a lot though, and usually isn't a big deal if the initiation zone is far enough back (which it was).

 

-Due to the geometry of the trough, large-scale ascent lagged slightly behind. Furthermore, it seemed like there was some weak shortwave ridging left behind the IA storms around midday. Hence, the area with the greatest frontal acceleration and strongest daytime heating -- KS -- blew up first. Either due to the diversion of moisture transport, or localized subsidence around convective updrafts, fledgling TCU immediately to the north in SE NE struggled as the KS storms intensified. The one updraft that managed to get going produced a funnel cloud in SW IA but dissipated shortly after. So this process cut off the southern extent of the "string of pearls" that ultimately formed. HRRR and SPC WRF did an exceptional job modeling this.

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andyhb

andyhb

Posted
Posted

I mean, to think of that we could've had 6 or 7 supercells producing tornadoes the size of the ones in NE Nebraska/NW IA is rather frightening, and potentially targeting areas like Des Moines and Omaha (kind of like 4/14/11 without the awry storm modes).

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nwburbschaser

nwburbschaser

Posted
Posted

After driving 1150 miles since Friday morning I don't feel like going into too much detail at the moment, but I will summarize the day. I ended up going after the first cell in Nebraska and caught up with it northeast of Stanton and was south of it as the tornado crossed Highway 15.  From my point of view it looked like a ground scraping meso.  After it crossed 15, it hit a house and snapped some power lines which blocked the road.  The house and property had some decent damage, trees stripped of all the leaves and the power pole was snapped like a tooth pick. The house was still standing but is probably a total loss as the damage was severe.  After the tornado passed there was a dog running through the yard and into the street, but it did not seem to be injured.  The power pole blocking the road essentially ended my chase. The forward speed of the storm was just too fast to overcome.  With the limited options to cross the Missouri I was concerned about going into Nebraska because I didn't want to lose the chance to be on any storms going into Iowa , but I guess that's just a lesson learned.  There was some really great lightning through most of Iowa on the way home. 

 

On a side note:

 

Did anyone else get stuck at the bridge construction just south of Stanton on 57?  That might have been the longest red light of my life. 

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Stebo

Stebo

Posted
Posted

I have to admit the models did pretty well in keying in on a significant potential early, the location was the only problem even right up to yesterday. Tony, you did a great job on calling this one though, you were all over it from the get go and nailed the magnitude of the event. Excellent work by everyone here in the pre-event discussion as well as during the event keeping focus on the most critical storms.

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ZackH

ZackH

Posted
Posted

Mad props to both Tony and Brett... When those guys get concerned, you know it's time to listen. What an unreal experience yesterday. Watched the Wayne wedge for about 20 minutes before stopping to help drag a family of 5 out of their destroyed house... Small house, not well built... But destroyed nonetheless. All were completely unharmed an had gotten into their completely underground basement. We pretty much called the chase there. This was a first type of damage/rescue experience for me chasing and I can't tell you how humble it made me. After reviewing the damage I saw in person, I am thinking high end EF-3 so far. The industrial area it hit looks impressive but I doubt it was very structurally sound and like I said... The house we saw was completely destroyed but I don't think it was an extremely solid structure.

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andyhb

andyhb

Posted
Posted

Joe, you might want to tell Adam Lucio that well...he's lucky (and he got way too close)...

 

 

Also, via Jeff Piotrowski, looks like surveyors found multiple farmsteads leveled near Moville and Pierson, IA. One of them had a Corvette (a classic one) thrown 1/4 mile from where it started. The cornfields where the tornado tracked are completely flattened. They also found a wooden post embedded 2 feet into an embankment.

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Chicago Storm

Chicago Storm

Posted
Posted

What a day...

 

Ended up chasing with Lucio yesterday. Started out the day with a "pre-chase" on the way out the the main target. We got on an elevated severe warned just south of I-80, east of DSM. The storm had some interesting structure, a lowering for a time and penny sized hail. We then continued west and made it to Council Bluffs by late morning. After making a few jumps north/west to keep just north of the CU field we made a play on the first main storm that developed near Stanton. It took a while but finall became mature...At the same time another cell quickly deveoped to it's south. Both storms showed rotation and we witnessed lowerings/a wall clouds with both as we approached them. We made a play on the southern cell first, it then weakened and the northern cell became dominant. We jumped north and followed it, eventually making it to the N/S Route 15, which goes into Wayne, NE. Driving northward the rain-wrapped tornado developed off to our west. As we continued north the tornado quickly grew in size, and quickly approached. We ended up throwing it in reverse as we were not going to make it north before it hit. While in the process of moving back south we ended up getting caught in the outter part of the circulation and had the back window blown out. The tornado then continued northeast. After making a stop to fix things up, we made a play on what was a new tor warned cell that developed behind the initial Wayne tor cell. We made it to this cell as it pushed towards the SD border, west of Sioux City. The storm had a lowering, but struggled. We then continued east to try and make a play on the far eastern tor warned cell and were able to get even with it, but ended up calling it a chase afther other development started to make things messy. Below is a pic for the tor as it moved through Wayne, NE. The video above that andyhb posted is Adam's video of the tornado approaching and brushing us. I have GroPro video that overlaps his video, and then continues as it pushes away...That will be posted tonight.

 

m8ax.jpg

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thewxmann

thewxmann

Posted
Posted

This is from Thursday (Bennet/Palmyra):

 

...DAMAGE SURVEY RESULTS FOR SOUTHEAST NEBRASKA TORNADOES ON
OCTOBER 3 2013...

THE NATIONAL WEATHER SERVICE IN OMAHA-VALLEY SURVEYED TORNADO
DAMAGE FROM THE STORMS THAT HIT SOUTH AND EAST OF LINCOLN DURING
THE EVENING OF THURSDAY OCTOBER 3 2013. THE FINDINGS ARE AS
FOLLOWS:

TORNADO TRACK NUMBER 1:
EF2 STRENGTH (MAX WIND SPEEDS 120 MPH)
PATH LENGTH:  16.5 MILES
PATH WIDTH: 300 YARDS

THE FIRST TORNADO TOUCHED DOWN APPROXIMATELY 2.5 MILES SOUTHWEST
OF HICKMAN NEAR THE STAGECOACH LAKE STATE RECREATION AREA. IT THEN
MOVED THROUGH THE WAGON TRAIN LAKE STATE RECREATION AREA WHERE IT
STRENGTHENED TO EF2 INTENSITY. IT CONTINUED TO TRACK TO THE
NORTHEAST...MOVING ABOUT 1 MILE SOUTH OF BENNET...THEN ENDED 1
MILE NORTHWEST OF PALMYRA. THE STRENGTH OF THIS TORNADO WAS RATED
EF2 BASED ON THE PROPERTY DAMAGE NEAR THE WAGON TRAIN LAKE STATE
RECREATION AREA...AND BASED ON THE PROPERTY DAMAGE JUST WEST OF
PALMYRA. THE INTENSITY WAS EF1 SOUTH OF BENNET...OTHERWISE THE
TORNADO STRENGTH WAS RATED EF0 ALONG THE REMAINDER OF THE TRACK.
THE TOTAL TRACK LENGTH WAS 16.5 MILES.


TORNADO TRACK NUMBER 2:
EF0 STRENGTH (MAX WIND SPEEDS 80 MPH)
PATH LENGTH:  4 MILES
PATH WIDTH:  100 YARDS

THE SECOND TORNADO TOUCHED DOWN 4.5 MILES SOUTH OF ELMWOOD WHERE
IT DID MINOR PROPERTY DAMAGE. IT THEN TRACKED NORTHEAST FOR 4
MILES AND ENDED 3.5 MILES SOUTHWEST OF ELMWOOD. IT MOSTLY MOVED
ACROSS OPEN COUNTRY AND CAUSED MINOR TREE DAMAGE.

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Buckeye05

Buckeye05

Posted
Posted

Or the embankment looked similar to that in the beginning, it'd be really hard to tell.

Maybe so, but It was "scoured" according to Piotrowski on twitter. You can see a pile of fresh dirt in the ditch that probably originated from that bluff, and it looks like you can see where the crumbly topsoil was removed, leaving the deeper, clay-laden soil exposed. Also, you can see where the root ball of that small tree near the top has been exposed.

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