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7/29 Enhanced Risk Observations


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59 minutes ago, JimCaruso said:

Couple questions -

 

1. Where did the Bensalem storm initially form? I was in LBI, out with family and distracted, focusing mainly on the northern storm near home in Newtown going through Washington Crossing. There was also a gap around 6:30 until after 7 that I wasn’t looking at radar. I remember there had been just some light precip on radar around Philly, and everything was socked in with clouds, so wondering exactly where the Bensalem storm formed. Did it evolve from those light showers in Philly? Or from activity further west? Or did it somehow initiate just west of Bensalem despite the thick cloud cover? Did an outflow boundary from the northern storm have anything to do with it?

 

2. I found the warning language confusing. In all my years of Plains chasing, I have become fairly familiar with the various warning language. Usually the source is either radar indicated, OR confirmed visibly by a chaser, spotter, emergency management, law enforcement officer, or the public. But yesterday’s warnings featured language such “confirmed tornado” but then the source said “radar confirmed.” What is the criteria for “radar confirmed,” is it the strength of the couplet, or does there have to be a debris signature? Also surprised there never did seem to be any warning based on a confirmed sighting, unless I missed it. Another warning I thought was confusing was use of the language a tornado “is developing” for the same storm after having said “is occurring,” although that could have been just different phases of the storm. 

re:2, caught that last night too and thought it was odd. Just my 2 cents, but this is the first time I have seen a clear debris ball following a tornado around here. There were a couple of them, certainly the CNJ and Bucks Co ones both were pretty pronounced in the CC map. If I had a guess, that would be the indicator but couldnt tell you the tech language spec.

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Hey fellas, thought I'd check in. I live near welsh/boulevard. I saw the hook forming heading right towards Bensalem so I decided, since I'm crazy, to go drive and chase it. I drove right up the boule

Here I am, perhaps the only actual Plains storm chaser on the forum, coming to the party embarrassingly late... I am in LBI on a family vacation rental, and spent the entire evening pissed off at the

Strongest tornado on record for Bucks County. Not a pimple on the arse of the May 1985 PA outbreak, that was epic by Oklahoma standards let alone PA. Massive long track tornadoes including an F5

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5 minutes ago, JimCaruso said:

@colonel_kurtzThanks for your reply about the Bensalem storm. Do you know when the cell itself initiated? Did it pop up pretty close to Ft Washington and start rotating quickly, or was the cell previously part of a line or cluster that had been ongoing further west?

I believe door #2, part of the cluster that originated much further west / NW.

Initially it was severe thunderstorm warned for Lower Bucks before it went tornado warned.

Wife had channel 6 on & I thought Cecily did a great job covering both tornado's. She's very knowledgeable, more than I ever noticed but with that being said I rarely watch local news.

 

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17 hours ago, Parsley said:

Hmmm. Hopefully not too bad. 

His MIL said their house was ok, but there was a lot of trees down in the area.  She lives in Kempton which was under the warning as well.  

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Hi  @JimCaruso . I'm a Philly (Parkwood) native living in Towamencin, which is near Lansdale. This originated right near - right around the Skippack area. I started posting warnings to friends at about 6:20. I went outside and everything felt very weird and there was an eerie quality and sound (or lack)  I recognized from a tornado that hit my Philly neighborhood in 1998. Clouds were moving very rapidly - I posted two videos from outside my home. They are 1 or 2 pages back. There was a lot of scud rising up quickly. I attempted to chase, but had to give up just as I got into Maple Glen due to traffic. 😭 

 

I have some screenshots here. There is a gap in time due to me being on the road, but it remained on velocity the entire time from Skippack until it finally touched down in Bensalem. 

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2 hours ago, Heisenberg said:

Hey fellas, thought I'd check in. I live near welsh/boulevard. I saw the hook forming heading right towards Bensalem so I decided, since I'm crazy, to go drive and chase it. I drove right up the boulevard and made it to the Wawa near Neshaminy Motel, RIGHT AS THE TORNADO WAS FORMING. I was right up the road from where the tornado hit

I experienced one of the coolest things ever. It was pouring rain with low visibility, and then suddenly as the tornado passed to my North (I believe) the winds quickly changed directions, the sun became visible, and it got extremely gusty. Was a pretty cool experience.

My grandmother lives in the trailer park behind the car dealership that was destroyed. She had just got out of the hospital and my mother was with her. She is located in the back of the park. Luckily, it was the front of the park that took the most damage. She is without power but fine otherwise. 

I am glad your grandmother is safe. I hope her power is restores quickly. 

I am from Parkwood, just off Woodhaven. I live in Towamencin now, but my dad is still in Parkwood. He just got out of the hospital and requires 24 hour care, so my husband is staying with him. My husband said it was loud and windy. They already have an awning hanging by a thread from a storm a few weeks ago (I think the one that caused the Poquessing to flood near Andalusia) and have been waiting for insurance and PECO to ger in gear so it can be repaired. They dodged quite a bullet there. In just wish my husband went out and filmed. He knows better. 

 

Glad you are safe - both from the weather and that Wawa. 😉

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2 hours ago, Heisenberg said:

Hey fellas, thought I'd check in. I live near welsh/boulevard. I saw the hook forming heading right towards Bensalem so I decided, since I'm crazy, to go drive and chase it. I drove right up the boulevard and made it to the Wawa near Neshaminy Motel, RIGHT AS THE TORNADO WAS FORMING. I was right up the road from where the tornado hit

I experienced one of the coolest things ever. It was pouring rain with low visibility, and then suddenly as the tornado passed to my North (I believe) the winds quickly changed directions, the sun became visible, and it got extremely gusty. Was a pretty cool experience.

You probably experienced the RFD (rear flank downdraft) 

3EAE89DD-EC25-4457-BD6A-9E2AA3FF1980.jpeg

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47 minutes ago, bigtenfan said:

Thanks for the reply

 

I was watching this from Florida last night but we maintain an apartment in Paoli by the train station.

 

Also my daughter is about to close on a newly constructed house in Malvern.

 

Thanks again

Howdy, part-time neighbor!

If you ever need an update, just give me a yell here. More than happy to help. 😊

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1 hour ago, JimCaruso said:

Couple questions -

 

1. Where did the Bensalem storm initially form? I was in LBI, out with family and distracted, focusing mainly on the northern storm near home in Newtown going through Washington Crossing. There was also a gap around 6:30 until after 7 that I wasn’t looking at radar. I remember there had been just some light precip on radar around Philly, and everything was socked in with clouds, so wondering exactly where the Bensalem storm formed. Did it evolve from those light showers in Philly? Or from activity further west? Or did it somehow initiate just west of Bensalem despite the thick cloud cover? Did an outflow boundary from the northern storm have anything to do with it?

 

2. I found the warning language confusing. In all my years of Plains chasing, I have become fairly familiar with the various warning language. Usually the source is either radar indicated, OR confirmed visibly by a chaser, spotter, emergency management, law enforcement officer, or the public. But yesterday’s warnings featured language such “confirmed tornado” but then the source said “radar confirmed.” What is the criteria for “radar confirmed,” is it the strength of the couplet, or does there have to be a debris signature? Also surprised there never did seem to be any warning based on a confirmed sighting, unless I missed it. Another warning I thought was confusing was use of the language a tornado “is developing” for the same storm after having said “is occurring,” although that could have been just different phases of the storm. 

1. From Mt. Holly’s page: 59179166-C9FA-4FC6-810B-77550B94A55D.jpeg.fd928a5cfb751db17ab198359926d4f6.jpeg

Possibke tracks they’re investigating. Should give you a decent idea of the tracks. Surveys today will confirm. 
 

2. I believe if there’s a tight couplet, a hook echoe and the CC drop (correlation coefficient) that’s enough to issue the confirmed tornado. 
 

 

946CF700-6762-44BF-9F51-70DFA8CA73A8.png

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23 hours ago, frankdp23 said:

Got 1.05" of rain yesterday being on the northern end of some of the severe storms.  

Likewise. Got 1.44 inches. Spent an hour in our basement. Annoyed that I  got no WEA warnings on my iPhone. Fortunately my housemate did, and I heard first tornado warning on my weather radio. Talked to my carrier via twitter and hope problem is straightened out. But no way to test.

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4 hours ago, cbelke said:

Nice job calling the storms yesterday @tombo82685 on Twitter.  Pretty much spot on. 

Thanks Chris, I was wrong where I thought the best svr would be though. Thought it would be down south of philly where the best instability was, but down there dynamics and best shear were lacking and thus no storm development.

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7 minutes ago, tombo82685 said:

Thanks Chris, I was wrong where I thought the best svr would be though. Thought it would be down south of philly where the best instability was, but down there dynamics and best shear were lacking and thus no storm development.

It was a very fluid system, I don't think anyone called it perfectly. You did a great job on Twitter calling out the cells that were about to spin up a tornado. 

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This was when I was driving up the boulevard 

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I was so caught up with what was going on I didn’t save anymore radar pictures, but I swear my RadarScope blue circle indicator was right over the highest velocities once it got to my location. I JUST missed it./got the back of it as Irish said, or maybe got clipped. Was fun! On the last picture I was still driving NE. 

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Not sure if I'll ever forget watching the local live coverage of that Ewing / Trenton tornado yesterday. Still pretty stunned that this all happened without much sunshine or warmth (only a high of 78 at Trenton yesterday), so I can't imagine what it would have been like otherwise.

I remember back in 2016, I saw an article written by Jeff Frame (a professor at the University of Illinois) analyzing a surprise tornado outbreak around Indiana (linked it below). There ended up being around 35 tornado reports. The analysis went through the severe parameters leading up to the event and even during it, and I distinctly remember Jeff noting that armed with all of the knowledge of what was going on at that time, he still wasn't even sure if he would have put a 2% tornado risk over the affected area, let alone expected a full-blown outbreak.

All that just to say that tornadoes are still one of the most unpredictable things in nature, so it is both humbling and curious to see something like yesterday play out while there were still inhibiting factors.

https://www.ustornadoes.com/2016/08/26/surprise-indiana-ohio-tornado-outbreak-august-24-2016-happened/

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57 minutes ago, ACwx said:

Not sure if I'll ever forget watching the local live coverage of that Ewing / Trenton tornado yesterday. Still pretty stunned that this all happened without much sunshine or warmth (only a high of 78 at Trenton yesterday), so I can't imagine what it would have been like otherwise.

I remember back in 2016, I saw an article written by Jeff Frame (a professor at the University of Illinois) analyzing a surprise tornado outbreak around Indiana (linked it below). There ended up being around 35 tornado reports. The analysis went through the severe parameters leading up to the event and even during it, and I distinctly remember Jeff noting that armed with all of the knowledge of what was going on at that time, he still wasn't even sure if he would have put a 2% tornado risk over the affected area, let alone expected a full-blown outbreak.

All that just to say that tornadoes are still one of the most unpredictable things in nature, so it is both humbling and curious to see something like yesterday play out while there were still inhibiting factors.

https://www.ustornadoes.com/2016/08/26/surprise-indiana-ohio-tornado-outbreak-august-24-2016-happened/


Agreed it is surprising this happened without sunshine. I told a chaser buddy in Philly that nothing would happen down near him, seeing that the skies were thick with clouds between Lancaster and NJ. Soon thereafter, the Bensalem storm formed.

 

However, specifically with regard to temperature, the lower temperatures could have helped because it lowered the temp/dewpoint spread and LCL heights. When the temp/dewpoint spreads are too large, you get higher-based, outflow dominant storms that don’t produce tornados.

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@Gaia Thanks for that write-up. I feel like an idiot because I was down in LBI and only focused on the northern storm because it was so close to home. I told my Philly chaser buddy that the more southern area was screwed because of all the clouds. Then he sent me a text asking “thoughts on this storm”? I only looked at it quickly because I was out, and thought he was showing me the northern storm. At that point it was in central NJ and I said it was past its peak. I never even realized it was a totally new and different storm. There was a period of time I wasn’t looking at radar at all, and just wasn’t even aware of it. Even as it tracked across NJ, I was not paying attention. I saw it approach LBI and it didn’t look good at that moment but regained its tornado signature shortly thereafter. Some experienced Plains chaser I turned out to be, my young, new chaser buddy will probably never consult with me again LOL. My overall cynicism about this area’s potential to produce no doubt influenced me...

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This was posted on Stormtrack:


http://www.mikesmithenterprisesblog.com/2021/07/bensalem-tornado-another-dangerous.html

The Tweet he links to has a pretty cool video, but I don’t actually see the tornado. If anyone else does, let me know. I’m not sure he was correct that the warning was issued after the tornado, because I don’t see it, that could have just been the RFD, which tightened the couplet and prompted the warning. I thought there was algorithmic criteria that has to be tripped by the velocities, so not sure how the warning could have been late. And weren’t the initial warnings on the supercell earlier and further W/NW? Maybe the warning tone was just a later warning, there were multiple warnings...

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6 minutes ago, Parsley said:

Wonder where that ranks for the county and state. 

CC9C932D-0115-4B93-8252-ACEEC7035EF8.jpeg

Strongest tornado on record for Bucks County.

Not a pimple on the arse of the May 1985 PA outbreak, that was epic by Oklahoma standards let alone PA. Massive long track tornadoes including an F5 & seven F4's.

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35 minutes ago, Parsley said:

Wonder where that ranks for the county and state. 

CC9C932D-0115-4B93-8252-ACEEC7035EF8.jpeg

It was Montgomery County, but I believe the Limerick 1994 F3 tornado was the strongest on record in SE PA with winds between 158-206 mph.

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9 minutes ago, greg ralls said:

It was Montgomery County, but I believe the Limerick 1994 F3 tornado was the strongest on record in SE PA with winds between 158-206 mph.

For SE PA that was the strongest, deadliest & most costly tornado on record. That storm caused an estimated $50M in damage, significantly higher than the every other tornado in the 5 county area combined since 1950.

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21 minutes ago, greg ralls said:

It was Montgomery County, but I believe the Limerick 1994 F3 tornado was the strongest on record in SE PA with winds between 158-206 mph.

 

7 minutes ago, colonel_kurtz said:

For SE PA that was the strongest, deadliest & most costly tornado on record. That storm caused an estimated $50M in damage, significantly higher than the every other tornado in the 5 county area combined since 1950.

Drive by that spot routinely. Can’t imagine what that looked/sounded like in person. I’ve seen the footage on YouTube after it devastated that housing development. 

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On 7/30/2021 at 2:07 PM, JimCaruso said:

This was posted on Stormtrack:


http://www.mikesmithenterprisesblog.com/2021/07/bensalem-tornado-another-dangerous.html

The Tweet he links to has a pretty cool video, but I don’t actually see the tornado. If anyone else does, let me know. I’m not sure he was correct that the warning was issued after the tornado, because I don’t see it, that could have just been the RFD, which tightened the couplet and prompted the warning. I thought there was algorithmic criteria that has to be tripped by the velocities, so not sure how the warning could have been late. And weren’t the initial warnings on the supercell earlier and further W/NW? Maybe the warning tone was just a later warning, there were multiple warnings...

The eventual EF-3 that would hit Trevose/Bensalem began as a cluster of showers in Eastern Berks and Western Montgomery counties, and it eventually turned into a thunderstorm near Skippack just after 6:00 PM.  I have a radar map image in this thread showing the Washington Crossing circulation along with the broad circulation near Skippack from the view of TPHL at 6:11 PM.  I thought that the Severe Thunderstorm Warning was initially slow, as the cloud tops were already very high by the time it was issued at 6:45 PM, and it mentioned a tornado was possible.  Also in this thread, I have a radar velocity image of TPHL at 6:49 PM.  It was not far from the storm, and has 1-minute updates to better show how the storm shape and wind patterns are changing, giving clues to what might soon happen.  When I post radar images, I sometimes add my own polygons in the case of a storm that may not be getting much attention, is very serious in nature, or does not have an official warning in effect.

 

At 6:49 PM, I believe that the criteria was met for a tornado warning for NE Philly and Lower Bucks, not because of a clear TVS, but due to the way the wind patterns were shifting.  It is based on how some of these types of storms have produced tornadoes in the past, reviewing radar data and correlating it to storm surveys.  The images I posted show two circulations at that time, with one near Abington.  That one weakens a bit, however a bookend vortex begins to form on the back of the thunderstorm near Bryn Athyn and approaching Trevose.  This stronger circulation is shown in another TPHL image post at 7:03 PM.  At that point, there should have been a warning in effect, however it does not get issued until 7:07 PM, with the circulation on top of Trevose.  I understand the warning decisions for populated areas are not easily made, but the environment yesterday would have led me to be on the cautious side for that one.  Additionally, some damage was reported near NE Philly airport with the initial circulation as well, although it is unclear if this was due to a tornado.  At 7:12, with the Trevose tornado now confirmed, another image is posted from TPHL, showing the intense circulation approaching Hulmeville, and showing the weaker yet existing circulation near NE Philly airport.

 

To answer another question, the "Radar Confirmed" source in the warnings is when a TDS is observed on the Dual-Polarization data by the warning forecaster.  Every once in awhile there will be a false positive, but most of the time it is accurate, and is a good way to say that a tornado is in progress without having a visual.  Hopefully this will help with any deductions about the storms in that area.  If you wish to study the images you can look through yesterday's posts and find them mixed in.

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