Topography and Tornadoes: a Recent Case Study

In the ten years since I became interested in this question, there have been several significant advances in understanding the influence of topography on tornado development. The Midwest, a region known for flat and boring terrain, serves as an ideal testbed to observe these influences, offering the ability to isolate topographical variables against a flat control domain. This post seeks to identify topographical drivers and assess the physical mechanisms within a recent tornado outbreak that spawned over a dozen tornadoes across Ohio, Indiana, and Illinois on March 14th.

Zooming out to assess all possible terrain variables, Kellner (2012) first employs GIS methodologies to establish statistical correlations between tornado touchdown points and several spatial features: elevation, land use, surface roughness, antecedent rainfall, and more. Using a high-resolution buffer analysis, the study highlighted that 64% of all tornado touchdowns occurred near urban land use and 42% near forests, a moderate-to-strong correlation given the overwhelming presence of flat farmland and range. The consensus explanation for this correlation is that increased surface roughness causes more horizontal vorticity that can contribute rotational energy when advected into a tornadic storm via the streamwise vorticity current, though I would also posit that urban heat island effects can add significant energy (localized SBCAPE) as well. A strong example of this formation mechanism occurred when a tornado coalesced downwind of Muncie, IN as an EF2, briefly lifted off the ground over Farmland (that’s a town name, though the terrain type is implied), then churned at up to EF3 strength for another 40 miles into Ohio.

Selma, IN (EF2) and Winchester, IN (EF3) tornado damage paths from the evening of 3/14/24 (NWS)

To dive deeper into the physics of tornado-ground interactions, Satrio (2020) experiments with a well-established LES model to simulate how a tornado-like vortex moves over various hill configurations. Near-ground flows have been a popular research topic for their damage potential and effects on vortex stability, inspiring numerous observational studies using radar, photogrammetry, and debris impact analysis. Satrio’s simulation results paint a particularly cogent picture of tornado dynamics, how uphill slopes can cause a low-level vortex disruption, how downhill slopes cause an intensification of swirl, and how vortices can bend to remain perpendicular to sloped terrain. All three of these effects can be clearly observed in the tornado that touched down near Hanover, IN: after crossing the Ohio River, the tornado weakened to an EF0 at the top of the first ridge, intensified to an EF2 as the track turned to follow the southern edge of the valley, weakened back to an EF0 over the second ridge, and reintensified to an EF2 upon crossing the valley again. Variations of this tornado evolution behavior have been corroborated numerous times in recent literature, most clearly by Lyza and Knupp (2018) on the periodic ridges of northeast Alabama, Bosart (2006) in the Hudson Valley, and Wagner (2018) near the Kansas River.

Hanover, IN tornado (3/14/24) damage path strongly influenced by Ohio River valley terrain (NWS)

However, tornado damage paths do not always show such visible signatures of terrain influence. Sometimes, as in the brief EF2 tornado near Plymouth, OH, there are absolutely no interesting topographical features in sight (though I would argue that the absence of terrain heterogeneities likely prevented further intensification within this supercell). In other instances, inferences about the nature of storm inflow would be needed to consider any terrain interactions. For example, the long-track tornado that struck Lakeville, OH as an EF3 does not have any significant hills, cities, forests, or geographic boundaries along its path. But, when the initial EF0-EF1 tornado crossed Grand Lake, the vortex was turned northward to favor the inflow side. Several miles later, likely due to the increased humid inflow, the tornado reformed as an EF3 near Wapakoneta and rumbled for almost an hour toward the northern suburbs of Columbus. The presence of the urban/suburban roughness on the inflow side, along with the Scioto and Olentangy River valleys, likely gave this tornado the extra push to reform as a long-track EF1 near Delaware, OH. These terrain influences are more subtle and speculative, of course, but the potential for these types of observations sparked my interest in tornado simulation and prediction in the first place. I firmly believe that localized surface conditions play a major role in the formation of not just tornadoes but many weather phenomena, and it’s always gratifying to find physical evidence in support.

Grand Lake, OH EF1 tornado that preceded the Lakeville, OH EF3 on the evening of 3/14/24 (NWS)

Delaware, OH long-track EF1 tornado formed from the remains of Lakeville, OH tornado (NWS)

Bunch of nothing around Plymouth, OH EF2 tornado path, 3/14/24 (NWS)

Tornado path maps from the NWS Damage Assessment Toolkit, preliminary data

My Long Journey Back

Today marks two years since I underwent lower back surgery for a herniated L5-S1 disk.  A common injury for manual laborers and desk-bound professionals (at the time, I was both), the odds for a successful operation hovered around 70%, according to my surgeon.  Fortunately, my surgery was a success in that it immediately eliminated the intense sciatic pain that had become unbearable over the previous 4 months.  However, I faced all kinds of challenges during my recovery – physical, mental, professional, social – this post seeks to chronicle the lengthy process of regaining my mojo, and exactly what it will take to continue on an upward trajectory into the future.

My microdiscectomy was a comparatively easy procedure: I was under anesthesia for about 2 hours and able to leave the hospital the same day with an incision the size of a thumbprint. I rested for a week or two, walking around every hour per the surgeon’s instructions and limiting my workload when I couldn’t stay home entirely. My spine felt uncomfortably compressed for several weeks, a persistent dull ache that my surgeon assured me was perfectly normal as the location of the excised hernia was healing with healthy tissue. I began physical therapy in April, first regaining basic movements in my lower trunk and right leg then slowly adding balance and strength. It took nearly 3 months of daily ‘nerve glide’ exercises to straighten my sciatic nerve from where the disk once impinged, a continuous cycle of patience to progress to pain again. I was cleared for gentle activity like hiking and kayaking by summer, though every so often I would feel the compression in my spine while doing simple movements like washing dishes or picking my shoes up off the floor. Once again I would end up on my back for a day, avoiding painkillers but returning to square one in my physical therapy regimen.

At times, I felt frustrated. My surgeon had nonchalantly spoken about a healing period of 6-8 weeks, but that’s just the time it took for the wound to close.  I could feel that my lower spine was usually misaligned, that there were little knots that would flare up in localized pain, that my tight hamstrings were preventing my sciatic nerve from permanently returning to its proper position. After my physical therapy ended in July, I began regular Pilates exercises; gradually, these workouts built up essential deep core strength that helped stabilize my spine.  I now swear by Move with Nicole on YouTube, following her core-focused Pilates workouts at least 5 times per week.  To improve my hamstring flexibility and alignment, I gradually peppered in some trail-running, which seemed to be helping greatly until I developed some Achilles tendinitis last summer. Only recently do I feel like I’ve regained my full range of motion, that both legs are balanced and that my spine can withstand normal activities.  I have learned to diligently prepare for any strenuous physical activities with stretching and core stabilization exercises; as I result, I can still lift at least 50 pounds and do high-adventure sports like skiing, surfing, mountain climbing, ziplining, and whitewater rafting.  Gone are the days when I could take my good physical fitness for granted, but I can feel the benefits of mindfully maintaining this fitness program and intend to continue for many years to come.

Perhaps more challenging than the physical recovery, it has taken a long time for my mentality to bounce back.  To make light of my physical limitations, I would introduce myself as the “guy who needed back surgery upon turning 30”… fun, right?  However, this was problematic for a number of reasons, foremost that a victim mentality, even when justified, can adversely affect a wide range of social interactions and relationships.  In a time when we were collectively sweeping the pandemic under the rug, I was breaking under the cumulative weight of everything that had happened since 2020.  I sought therapy for the first time in my life, which helped me unpack then compartmentalize the painful experiences of working for negligent criminals in west Texas, losing my car in a jarring accident, entrapping myself within a different backward company, tabling my passion project indefinitely, and straining several close relationships in the process.  Time helped to heal these wounds, as did spending a year close to my grandmother and taking a few truly awesome trips.  Now I am motivated to wake up every morning, take a walk, and get to work, a major step forward from where I was even a year ago.

The last piece of my recovery, taking even longer than the physical and mental components, is putting my career back together.  Complicating matters was a fractured relationship with my last employer: after my initial injury occurred when a 300-pound impeller assembly fell on my back as I was inspecting a blend tank, my supervisors refused to acknowledge my incident report and exacerbated my hernia by giving me physical labor assignments on the packaging line.  When I needed to seek treatment for sciatic pain and wanted to report this as a workplace injury, they threatened to fire me and fought my time-off requests.  After my final physical therapy session, I resigned and immediately consulted a personal injury attorney, who helped alleviate the burden of belated bills.  But despite pouring my soul into that job for 2 years, I have no professional reference from that period – how would I explain this situation to a future employer?  After 120 applications and 30 interviews, I was surprised to find myself still without full-time work to begin 2024.  Not to say I stagnated in 2023, because I learned from several code consulting assignments, earned my FE Certification, and practiced my Spanish intensively, striving to improve my skills but also understanding that my self-worth is not contingent upon career success.  At long last, I have a job offer in hand – to be a patent examiner and subject-matter expert in chemical engineering for USPTO.  With no more reasons to scrutinize the past, I am looking forward to the next steps of this journey!