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I saved this VWP just as the sh-t was hitting the fan. We had ridiculous SRH again with unimpeded buoyant inflow for proper updraft to utilize the streamwise shear.

On the latest PNS, it looks like they updated this tornado to include that debris: .Burlington, NJ to Bristol, PA Tornado... Rating: EF-1 Estimated Peak Wind: 90 mph Path Length /statute/: 2.8 miles Path Width /maximum/: 200 yards Fatalities: None Injuries: None Start Date: Sep 01 2021 Start Time: 6:59 PM EDT Start Location: 2 SW Burlington, Burlington Co, NJ Start Lat/Lon: 40.06/-74.89 End Date: Sep 01 2021 End Time: 7:04 PM EDT End Location: Bristol, Bucks Co,

I wanted to mention that in the first video from PA that you can make out that it hits something by the bridge and hurls debris northward, presumably into river. Try to watch it zoomed in to see debris. https://twitter.com/antmasiello/status/1434394952067387393?s=19

The Burlington Twp. tornado was a close one (passed 4 miles to my west)! I was curious about this portion of the investigation where they say it went over a power and steel plant without any damage and did not produce any damage thereafter either. In their track map, they have it going right over this structure just before the bridge crossing. Here is a google map's view of this structure looking east across the river: https://goo.gl/maps/nz1y4cGHF8Em2iks5 In this video, about 30 seconds in, you'll see the tornado interact with the plants: https://www.facebook.com/anth

Regardless of how you define the shear type, in general you'll see the climatological minimum in late July into August (and maximum in the winter). This is the time the westerlies are at their most poleward in the summer. You can get sounding climatology here: https://www.spc.noaa.gov/exper/soundingclimo/ I've attached the bulk shear 0-6km OKX July 30th plot for example purposes.

This is a nice summary by the NWS and the radar tab has excellent information. It makes you think about how much worse this could have been. https://www.weather.gov/phi/eventreview20210729

Check out Leigh Orf's work to learn more about the importance of the streamwise vorticity current (SVC) that originates from the front flank downdraft. Here's a good paper that talks about it, but visit the main page too. https://journals.ametsoc.org/view/journals/bams/98/1/bams-d-15-00073.1.xm https://orf.media/

Tom, you didn't do as bad as you think you did, but I admire your approach to verification. It doesn't do anyone any good to live in a reality where they think they always do well (some big accounts on Twitter act like they always get it right). In fact, you were one of the few being honest about the day's confusing set of conditions and not writing off anything totally. And here's the thing, perhaps if we repeated this setup with similar conditions another 10 times, it wouldn't work out quite to the extent that this one did. Your approach being objective and listing the pros/cons is a good on

It was referring to the moist profiles preventing dominating RFDs point.

Wise words indeed.

If we were able to somehow build a climo of types of setups here, this would definitely be 1 of the ways we would do it. The others would be tropical systems or systems with cold-season like dynamics/winds that produce powerful squall lines and embedded tornadoes (i.e. autumn of 1989 and 2003). It seems that the Ekster EML setups usually end up favoring interior areas into New England more than here, but we've seen those come down our way as well. In fact, NE NJ usually ends up participating in those. The Mid Atlantic threats with upper lows over the Central Appalachians usually end up to our

Thanks! The sun point is just to get us to think about the various factors and what it could have meant with things like the LCL height, e.g. In the DC area, they still had supercells with some producing tornadoes, after receiving more heating than our area. Of course, their low level winds veered out more being away from the warm front and their LCLs rocketed upward. So, perhaps we would have seen something more like VA/DC with more damaging wind, perhaps significant, with a tornado or two, but the outbreak scenario may have shifted north to wherever the gradient/front ended up. I'l

Jim, your thoughts look good to me. The RFD and FFD contributions to tornadogenesis remain a big research topic. Since tornadoes have been both observed and not observed in warm/cold RFDs, it appears that it doesn't solely determine tornado potential. In fact, occluding (sometimes more than once) is often associated with the mature stage of tornadoes (and then their death) and new tornadoes can quickly spin up next in cycle if the vorticity is channelized in the buoyant inflow properly. It's when the shear is not as streamwise where trouble starts with the mesocyclone and sub-tornadic vortices

One of the coolest questions left in meteorology with a frontier-like feel to it is, "why do tornadoes exist." Research in the last 20 years has applied field/case studies to figure out why some rather organized supercells under pristine conditions do not produce tornadoes and others do. In the last 5-10 years, there have been some really good papers on this topic, focusing on the lowest 500m of the near-structure/under-structure environment. The importance of 0-500m SRH & 0-3km MLCAPE cannot be stressed enough. Assuming all the usual environmental conditions are there and favorable for su

IIRC it was quite a potent signature on dual pol well beyond the Washington Crossing area. I suppose the heavily wooded park in epicenter of tornado lofted a ton of leaves/debris that lingered well beyond the tornado. The TDS signature continued to at least Ewing, if not further. It then completely diminished/became outflow dominant over Hamilton before tightening up again towards Robbinsville/Windsor for next tornado. A cyclic right turning supercell coming down into Mercer County is something else!

Thanks! 1. The modeling was weird/all over the place with convective evolution and its timing. But what they all agreed on is that this feature would rapidly increase low level winds, along with bringing a surface boundary through the area from W-E. The ramp-up was there in tornadic environment, even if the models failed to produce anything. The very high mixing ratios/low LFC+LCL environment were quite alarming. When I get a little time, I will post a bunch of images that I thought were alarming. I was impressed with the forecast scenarios on all guidance and felt the updrafts would have

A few things that have been on my mind about the 7/29 event that I would like to address here: I have mixed feelings on how the forecasting went with this one, particularly the short term/now-casting portion (midday 7/29 until real-time). On 1 hand, the tornadic conditions were present early/expected but more typical of the area, then quickly escalated 5-8 PM to atypical. Because of the rapid onset of the volatile conditions, I can appreciate the overall tone by various sources of playing it safe during the day. On the other hand, the conditions were getting worse with each passing hour (

A warmer planet means more convection, more westerly flows and rossby wave sources and potential new-comers to the wave-driven momentum process over the Tropics. The westerly QBO promotes an expanded Tropical Heating with more off-equator sources. I don't think it's a coincidence that its those shear stresses that have done that lately.

It might be one of those things where the Bermuda/Azores Ridge and, say, TUTT or PVS activity are both stronger than normal (and therefore correlated) but not necessarily causal. The Pacific and Americas will take turns pulsating monsoonal fluxes...we plot these pulses on time longitude maps and think they're MJO waves. But more often than not in the summertime, it's just pulsing monsoons with high frequency kelvin waves embedded within. These dictate which monsoonal ridge perks up and how the wave trains may behave. In the case of the Bermuda High, it's not necessarily its strength as much as

Hey, sorry for the late response. We had our first baby girl on 6/9 (what a ride it's been)! The TUTT is a stationary wave that forms every year and peaks with the Northern Hemisphere's summertime monsoon season. This is when land/sea temp contrasts peak and anticyclones are the most poleward/powerful. The mid-ocean cooling/troughs are a restoring force (driven by evaporational cooling and rotating Earth) of the diabatic warming centered over the Indian and American monsoons (see the climo 300mb temp plot for JJA attached). In addition to this general relationship from land/sea contrasts

I wanted to link this paper and forgot to when we were talking about temp trends: https://www.pnas.org/content/pnas/115/19/4863.full.pdf

Location of Warming & Its Effect on Summer Waveguide: Temperature gradients determine the location of jets through the thermal wind relationship and these jets determine wave behavior. The nature of how global warmth is distributed (currently accelerated at the poles through ice/snow albedo feedback) is having an effect on the way the temp gradients and jet streams manifest. This can give rise to a structure that favors a latitude-trapping waveguide in zonal wind. In the summertime, wavenumbers 5-8 tend to get trapped under this changing structure of warming, and this can promote QRA,

A few thoughts: 1. Kossin et al. is who released the controversial "TCs are slowing down" with global warming stuff. There is a sizable opposition to that finding and legit concerns with the dataset and conclusions. However, there are equally legit defenders of the findings and points made. 2. Satellite derived methods can overestimate intensity just as easily as it can underestimate. While the data is homogeneous in 1 sense, as authors describe, the actual atmosphere is not. I have yet to see a study on how the Dvorak technique, for example, can be influenced by changing upper tropo

There's still a debate on how AGW is altering the Tropics. There is some reason to believe there has been a net latitude gain in storm tracks over time with expanded Hadley Cell trend. It also appears like when conditions aloft are favorable, hurricanes have the ability to be stronger. But there are holes in other ideas like the idea that they're slowing down with time. The Atlantic is becoming increasingly filled with exhaust basically as the Pacific output, tropical forcing-wise, continues to expand. This added exhaust has made for some very dry/storm-less times as well. This has led to the

Outcomes probably from the same cause (AGW). The direct moisture flux from the ocean is keeping overnight lows warmer and warmer it seems.