2015-03-25: Moore, OK tornado and damage survey

Wednesday’s non-chase consisted of me looking up from my son’s bowl of mac and cheese, and seeing a tornado out the window. Okay, there was a little more to it than that. But lately, the storms have considerately come to me when I can’t chase. It’s one of the reasons I live in Norman!

I was aware of the SPC’s moderate risk for severe weather, but I had all but dismissed the tornado risk based on the crashing cold front setup. That setup had burned me too many times in the past. I’ve driven hundreds of miles just to watch nascent storms wither as a relentless southward surge of cold air sliced the legs out from beneath them, leaving me low and gas and without much to show for it. Instead, Wednesday’s storms latched onto the front and rode it south and east. We followed coverage on a couple of the local news networks, watching with rapt fascination as a storm that appeared postfrontal and undercut produced a 30-second funnel cloud near El Reno, OK.

Moore, Oklahoma tornado on 2015-03-25

As seen from near my home in southeast Norman.

Fast forward about an hour: the same storm marched onward to Moore, and in helicopter video, power flashes erupted all over the I-35 corridor. My husband, who had been admiring the mammatus under the anvil in our driveway, suddenly charged into the house, shouting, “I can see it!” I grabbed my son and we dashed across the street. To the north, between two houses, a tapered funnel cloud was clearly visible. I didn’t have time to grab my “good” camera, only got a few grainy pictures with my iPhone. This counts as my son’s first (ex-utero) tornado.

As the damage reports filtered in, and the complexity of the situation became clear, I felt inspired to email some people in the know about participating in the damage survey the next day. It may come as a surprise to some that I’ve never actually participated in a tornado damage survey before. I resolved this year that I would assist in at least one in order to learn firsthand, from the experts, how it was done. By the next morning, I had an invitation. Doug Speheger of the Norman NWS-WFO was gracious enough to let me join his team as they surveyed part of the preliminary track. Rick Smith, the WCM for Norman, tasked us with characterizing the event and focusing in directionality of wind damage indicators (DIs). Signals of a mixed-mode (tornado / straight-line wind) event were already evident in video and reports from the day before.

The Moore EOC whiteboard

The Moore EOC whiteboard listing preliminary damage reports as they came in the evening before.

We started the morning at the Moore EOC, where we conferred with EOC staff. Doug divided up the preliminary track among three teams. Instead of dividing the track into equal thirds, our team took a relatively short but more densely-populated segment near the middle, where local officials had tagged a couple of possible EF2/3 candidate structures. The other two teams took the remaining two, more rural sections of the track, with the added task of determining its start and end points.

I was worried that I might not have the training necessary to contribute to the survey, but instead of clipboards and cameras, we went into the field armed with a pair of iPads. The NWS uses a newbie-friendly, menu-driven app called the Damage Assessment Toolkit (DAT). We snapped pictures of damage, characterized the structures, typed in our comments, and uploaded the data points over the network to the NWS. Rick Smith said it was fun tracking our progress, watching as our data points gradually mapped out the track on screens back in the Norman office.

As we initially drove through the neighborhood northwest of I-35 and 4th St. around 9 a.m., I was surprised by how much cleanup had already been done. The streets were already clear and passable. Piles of branches and shingles had already been hauled to curbs, and some of those piles disappeared over the course of the survey. A handful of heavily damaged houses were marked with a bright orange “X,” indicating that the search-and-rescue teams had paid a visit. Workers were actively moving large, heavy debris out of yards and driveways even as we went door to door. We were actually in a race against time to document the “raw” damage before it was cleaned up.

Crumpled KOMA radio tower in Moore, OK

Of the three ex-KOMA (now KOKC) radio towers, this was the only one left standing, and bent over at that.

We entered some data points in “drive-by” mode; for others, we got out and walked gingerly among roof shingles, shards of glass, and boards with protruding nails. An active hum emanated from the entire damage zone. Chainsaws growled, generators purred, and helicopters circled overhead. News crews, police, and city workers were everywhere. Vans filled with ServeMoore volunteers (many of them teenagers, released from class by Moore Public Schools) went from house to house, offering cleanup help. A cherry-red Coca-Cola delivery truck cruised up and down the streets, the driver handing out bottled water. We overheard the neighborhood mail carrier telling the resident of an “orange X” house that she could apply for a free PO box to use until her house was repaired. She later told a reporter that she had “had it” with Moore after suffering tornado damage three times; she would be moving away soon for good.

We documented a shed blown onto its side, a section of roofing lofted two or three blocks (recognizable from the shingle color), damage to the three ex-KOMA radio towers (two fell down, the one left standing folded 1/3 of the way down at its guy point). Even as we went about our duties, we were aware that the residents were grappling with an unexpected and upsetting interruption in their lives. As a home owner, I empathized with the loss of houses and the scattering of neighbors. After almost two decades with the NWS, Doug is well-practiced in performing damage surveys, and he asked his questions with sensitivity. “Were you here when this happened? Did you have enough warning? Was anyone hurt? We’re glad you’re okay.”

Checking the damage

Tiffany Meyer (left) and Doug Speheger examine the bottom of a collapsed wall in a home near NW 2nd & Arnold Sts in Moore.

We found two particularly intense damage examples that might have qualified as EF2 or greater damage but for some mitigating factor. In one case, a home’s roof had been lifted off, but the failure point was evident. A carport, bolted to the roofline, had been lifted from the driveway by the storm’s winds and peeled off the roof as it blew away. In another, the exterior walls of a home had all collapsed, leaving the interior walls standing like an oversized wine bottle divider. That type of damage might have merited an EF3 rating, but closer examination revealed that the anchor bolts were spaced 8-10 feet apart and only driven about 2 in into the concrete walls. In both cases, the rating stayed at EF1.

It was difficult to differentiate the wind and tornado damage in some areas. For the most part, the winds had moved debris from west to east. We found a few small zones (about half a block in size) where the damage was relatively intense, and clearly convergent. My impression was that we were dealing with a wide swath of mostly straight-line wind damage, with a few small tornadic spinups lasting only a few seconds. A few structures would need to be examined in greater detail.

Compiling the damage survey info in the NWS-Norman WFO

Reconvening with Rick Smith (left) in the WFO, it was decided to announce the finding of EF1 damage and continued investigation.

We returned to Norman around 3 p.m. along with one of the two other survey teams, and related our impressions to Rick Smith and the rest of the office. Based on our report, Rick sent out the following tweets “in time for the four-o’clock news”:

Thanks again to the NWS office in Norman for letting me help make the news!

Edit: Thanks to Doug Speheger for correcting the my interpretation of the “orange X” markings.

Update, 3/30/2015: After some spot-checking of a few structures and a follow-up meeting on 30 March 2015, it was decided to upgrade the house at 2nd & Arnold, as well as a few others, to EF2. NWS-Norman released this damage contour map that afternoon:

Note that this map is still preliminary and could change further!

Update, 4/3/2015: Jim LaDue, another damage survey participant with much more experience than I, conveys his detailed thoughts on this event here.

Purple for Pam

Dr. Pam Heinselman needs no endorsements from me, because the quality of her work speaks for itself. Throughout my graduate school career, she was invariably lauded as someone I should emulate. Chuck Doswell called her “a class act.” In addition to being the leader of the Phased Array Meteorological Studies (PAMS) Team and a Presidential Early Career Award winner, she is the public face of the Phased Array Radar program here at NSSL, actively producing educational materials for public consumption and starring in NSSL podcasts and video shorts like this one.

Pam took me under her wing after I got my meteorology shingle from OU in 2011, first as a postdoctoral research scientist (until this September) and now, as a full research scientist. Pam has the pulse of NSSL, and keeps those of us on the PAMS Team up to speed. She also stays abreast of what we are working on, and comes to every meeting prepared to pick up right where we left off. When I send her draft writing, she gently suggests changes in a way that made me feel empowered, not stupid. She’s also given me her full and unwavering support during my transition to motherhood. I’m honored to call her my friend as well as my supervisor.

Purple for Pam

Purple for Pam at SLS

Pam went public a couple of weeks ago with the news that she is suffering from non-Hodgkin’s lymphoma. She posted on Facebook that her first chemo port was purple, which prompted a number of us to wear purple clothes, scarves, and other royal attire to show our moral support. Pam has had a great attitude about her illness and her chances for beating it. Here’s my #purpleforpam pic, taken while I was at the 27th Severe Local Storms conference in Madison, WI last week. Yes, I know I often break out the purple suit for conferences, but this time it has a special significance. I would not be where I am were it not for Pam Heinselman. My warmest hopes are with her as she pursues remission.

I’m not dead

Yes, I’m still here. As I alluded to in my last post, I became a mom partway through 2013, and that effectively devoured all of what I once considered “my free time,” including that which I used to devote to blogging. I’ve enjoyed watching my son grow from a tiny bundle of reflexes in the crook of my arm, into an chatty, inquisitive toddler who stuffs fistfuls of spaghetti into his mouth, forcefully demands more graham crackers, and rearranges objects around the house without consulting us. (Case in point, my husband’s glasses. We haven’t seen them in a month! They probably went out in the garbage.) It’s been grueling, and sometimes maddening, but motherhood nourishes my spirit like nothing I’ve ever known.

I’ve been reasonably successful at integrating motherhood and my science career. Perhaps I will write more about that topic in the future, when I have a longer view.

Why so quiet? The Oklahoman atmospheric offerings of 2014 were slim to none, and I was on a short tether because, well, baby. My husband went on a couple of panhandle chases, and may have glimpsed a tornado near Larned, Kansas, back in June. I operated KOUN all of once this year with my son babbling happily in his portable playpen beside me. But 2014 has been the first year since 2001 that I actually did not chase at all. Quite frankly, if I had to take a year off, this year would be a good choice.

An update on me: I’m wrapping up a two-year postdoc stint at NSSL, looking at storm mergers and tornadogenesis. I’m about to submit a paper about the 24 May 2011 El Reno tornadic storm, and hope to be able to share more from it soon. (I’ve been dropping some hints on my Twitter feed.) I’ll be starting as a research scientist at CIMMS at the end of September, collaborating intensely with NSSL. I’m pumped! Working with NSSL has always been one of my primary career goals.

For now, I’ll leave you with this photo Tim Marshall shared of us at the TWISTEX memorial back on 31 May 2014. It was a nice remembrance event. Some kind individuals even provided water and pizza to those who came.

Us and Tim

Checking in with Tim Marshall at the TWISTEX anniversary remembrance.

I met Deputy Doug Gerten, the first responder to the tragedy, who’s spearheading an effort to have a permanent roadside memorial erected.
Deputy Doug Gerten (Center)

Canadian County Sheriff Deputy Doug Gerten (center), who found the white Chevy Cobalt.

I think we were the only ones at the gathering with an infant in arms. I called him “the littlest witness to the El Reno tornado.” At the end, we watched the release of three orange balloons representing the departing spirits of our friends.
Preparing for the balloon release.

Preparing for the balloon release.

2014-05-31 TWISTEX Memorial 022

If it looks like a tornado…

I have a new paper in the November issue of Monthly Weather Review entitled, “Near-Surface Vortex Structure in a Tornado and in a Sub-Tornado-Strength Convective-Storm Vortex Observed by a Mobile, W-Band Radar during VORTEX2,” written the help of six patient co-authors and three reviewers. This paper addresses the question, “If it looks like a tornado, lasts as long as a tornado, and behaves like a tornado, but only on radar, is it still a tornado?”

We examined two cases from VORTEX2. In the first (25 May 2010 near Tribune, Kansas), both humans and radars observed a tornado under the hook echo of a supercell. Here is a photo of the Tribune tornado, along with some the W-band data Krzysztof Orzel (UMass) and I collected:

Top: W-band radar truck with Tribune tornado, and data collected.

(top) The UMass W-band radar collects data in the 25 May 2010 Tribune tornado. Krzysztof Orzel (UMass engineer) can be seen next to the truck. (bottom) W-band reflectivity (left) and Doppler velocity (right) in the intensifying Tribune tornado.

In the second (26 May 2010 near Prospect Valley, Colorado), the radars observed a feature beneath the hook echo of another supercell that looked similar to the tornado seen the previous day, none of the hundreds of storm chasers in the area, including about 100 VORTEX2 participants (some of whom can be counted among the most experienced storm chasers in the world!), reported a tornado or even a funnel cloud. (The Prospect Valley storm produced tornadoes earlier in the afternoon near DIA, but none during VORTEX2 operations.) Indeed, I didn’t even know the vortex was there until the data were post-processed, because it was too small to see on our in-cab display. Closer examination revealed seven of these tiny vortices spinning up in tornado-family-like fashion on the tip of the hook. The one pictured below (#5) was the strongest and longest-lived.
Top: W-band radar truck under Colorado supercell. Bottom: W-band radar data collected in a vortex near the tip of the hook.

(top) The UMass W-band radar collects data beneath the hook echo of the Prospect Valley storm. The black arrow indicates a small cloud base lowering that persisted for more than 30 minutes. (bottom) Radar data collected in the hook echo, showing a vortex with a weak-echo hole that lasted 8 min.

Here’s a screenshot from our in-cab Situation Awareness for Severe Storm Intercept (SASSI) display around the time the above data were collected, showing participants reporting a “small circulation” and “rising motion”. But, no one says the T-word.

SASSI screen grab from Prospect Valley

SASSI screen grab from 2240 UTC on 26 May 2010, showing VORTEX2 vehicles deployed under the Prospect Valley storm. Orange circles are dual-Doppler lobes drawn by the radar coordinator, and the purple cone denotes where the field coordinators believed the circulation would go. “UMW” is the W-band radar.

The radar presentations look similar, no? Those of us who use mobile radar data need “tornado threshold” criteria in order to determine objectively such parameters as tornado start and end times. While there is no universally accepted Doppler velocity threshold for tornadoes, the Alexander and Wurman (2008) criterion (40 m/s across <= 2 km diameter, and persisting for at least two consecutive scans) is used in a number of studies. Both the 25 May and 26 May vortices met this criterion and lasted about 8 minutes, but had it not been for radar observations, we might not have known a vortex was present on 26 May.* We appear to have caught a vortex that just barely tickled the lower end of the tornado spectrum. The surface dew point depressions were much higher - about 12 oC – than on the previous day (8 oC). We speculate that just a little additional moisture would have made this vortex visible and changed the designation of the 26 May case from non-tornadic to tornadic in the VORTEX2 logs.

One might ask, “Who cares? The Prospect Valley vortex damaged nothing and injured no one.” As a scientist, I care. Documenting these types of events with high-quality observations demonstrates that the boundary between tornadic and non-tornadic vortices is fuzzy, and that human and radar detection of tornado occurrence may not always be consistent. Since this article appeared online last week, I’ve gotten a number of e-mails from other scientists who have made similar observations of weak vortices under supercells, but who weren’t sure how to categorize them. We didn’t want to make a new category of vortex for this type of event – there are already enough animals in the zoo*,** – but in this paper we use the clunky term “sub-tornado-strength, convective-storm vortex (SCV)” to describe the Prospect Valley not-quite-tornado.

* Dr. Chuck Doswell documents a similar case using a photograph from Dr. Bill Gallus in his essay, “What is a tornado?” Incidentally, that tornado also occurred in Colorado. The Prospect Valley vortex would not meet Chuck’s tornado definition because it caused no damage.
** CSWR documents a number of these in a recent paper in Weather and Forecasting, including what they call “marginal tornadoes.”

On the passing of Tim Samaras, Paul Samaras, and Carl Young

Very early this morning, I was jarred awake by a rumor that Tim Samaras, his son Paul, and fellow storm chaser Carl Young passed away in the El Reno, OK tornado on Friday. I was unable to independently confirm the rumor, but it originated from a reliable source. The more I thought about it, the more the puzzle pieces fit together: Seven in-vehicle fatalities were confirmed in Friday’s El Reno tornado (which my husband and I witnessed from the vicinity of Union City, OK), of which four had been either publicly identified or described, leaving three people undescribed and unidentified. Tim Samaras’ Facebook and Twitter feeds had both been ominously silent since mid-Friday afternoon. This morning, our worst fears were confirmed by Tim’s brother Jim.

I will admit that I did not know Paul Samaras and Carl Young very well, but likely rubbed elbows with them at chaser conventions, picnics, and meetings. Tim Samaras can introduce himself to you in this “About Me” video on his web site.

I first met Tim in the field in 2004, on a storm chase near the Kansas-Nebraska border. I don’t recall the exact date, but it was one of the first times I had gone chasing in the UMass W-band radar as its primary operator. We found Tim and his TWISTEX crew waiting for CI just north of (I think) Beloit, Kansas. Howie Bluestein (my graduate adviser) introduced me to Tim, and Tim asked if I would be willing to collect W-band radar data over his probes if he had a successful deployment that day. He talked directly to me, not to Howie. Here I was, still relatively new in the field and wet behind the ears, and Tim was inviting me to collaborate! If memory serves, that day was a bust – the cumuli bubbled, but tornadic storms were not to be had.

Tim’s primary instruments in the early 2000s were a set of probes called Hardened In Situ Temperature and Pressure Recorders (HITPRs). A HITPR was about the same size and shape as an Asian conical straw hat, and painted bright orange to make it easy to find if it was moved or covered in debris. The HITPR was basically a miniaturized version of the TOTO probe that was used in early 1980s tornado intercepts, with the distinct advantage of having multiple copies. This 4-minute video from National Geographic shows how Tim used the HITPRs to collect measurements in the 2003 Manchester, South Dakota tornado. These and other measurements confirmed some of our conceptual models about pressure fields in tornadoes.

Tim also built a larger probe, containing seven video cameras, to record a tornado’s passage at close range for photogrammetric analysis. All seven cameras had to begin recording with the flip of a single switch – no easy engineering feat. His probe designs were frequently imitated, but never replicated. The video he took in the 2004 Storm Lake, Iowa tornado is on his jaw-dropping Driven by Passion DVD, which occupies a high spot on my chase DVD shelf and which I still use instructionally to demonstrate the perils associated with flying debris. (A sample can be seen at about 2:40, here.)

Tim’s deployment strategy involved getting very close to tornadoes, but he was NOT one of the debris-kissing yahoos. He had genuine intellectual curiosity and the skills to build instruments needed to address crucial scientific questions. He presented his results eloquently at scientific conferences and submitted them for peer-reviewed publication. He was also a multimedia wizard, perfectly synchronizing side-by-side video and measurement traces. And finally, he was a solid media personality, appearing for several years in National Geographic specials and a season or two on the Discovery Channel’s Storm Chasers with his TWISTEX program. Whenever Tim was on the screen, you knew there would be minimum drama and maximum science.

Tim Samaras’ loss leaves a raw and painful void in tornado research. There is literally no one else in my field who possesses the multifaceted portfolio of expertise in engineering, science, writing, videography, and entertainment that he did. I am still gobsmacked at the news of his passing, and stunned to hear that it occurred so close to us. But the grief of the severe weather research and storm chaser communities can only pale in comparison to the grief endured by their families and friends. My deepest sympathies go out to the Samaras and Young families. They can take comfort in knowing that Tim Samaras and his crew were a class act, universally well-respected, and represented the best of our community.

Update, 7:51 p.m. CDT: My former graduate adviser Howie Bluestein (whom I mentioned above) gave me permission to re-post his tribute to Tim, which was sent out in his daily status message to his colleagues:

Hi all: I am sad and shocked to tell those of you who have not already heard that Tim Samaras, his son Paul, and Carl Young died while chasing the El Reno tornado on Friday. While I have been receiving unconfirmed reports of this since early this morning, the most recent, from Channel 7 in Denver (via Lou Wicker), seems to confirm this tragic news. I have known Tim for many years as someone who shared our enthusiasm for severe weather. He designed some of the early miniature instruments deployed in the paths of tornadoes, particularly those with video cameras and temperature and pressure sensors. His work has been showcased and supported in part by the National Geographic Society, and displayed at the Denver Science Museum. More recently he has been working with high-speed lightning cameras. We have in the past, for a number of years, shared our groups’ status-update messages. He and Roger Hill ran the very successful National Tornado Chasers’ Convention in Denver each February. He was always a gentleman and shared his enthusiasm with the community. While not an academic or a member of a meteorological research laboratory, he has had a profound influence on all of us, and in particular through publications of the analyses of his data from TWISTEX.

The situation gets serious

I am still getting my bearings back after three straight days of tornadoes. Yesterday, I watched the Moore tornado form from the controls of the KOUN radar on the north side of Norman.

It was my first time to see a tornado while not actively chasing. As I watched it track past me to the northwest and disappear into the murk, I crossed my fingers that it would spare Moore. It didn’t. It crossed I-35 between 4th and 19th street, scattering cars, houses, and people like a mammoth lawn mower. The Warren Theater, where I watched a sneak preview of the new Star Trek movie last week, was damaged and pressed into use as a triage area.

I was ready to write two relatively light-hearted posts about my chases last weekend. I just don’t feel that lighthearted anymore. A co-worker of mine lost her home, but fortunately is not injured. My husband and I are going to go through our garage tonight and gather items to donate to people a few miles away who literally lost everything they own. Honestly, how many times can a nightmare repeat itself?

VORTEX2 science workshop recap

It’s been nearly three years since the field phase of VORTEX2 ended. Two weeks ago, a group of about 30 PIs and scientists reunited at a retreat near Austin, Texas. I was asked to send a few tweets from the workshop since the V2 media liason wasn’t in attendance.

VORTEX2 science workshop group photo

VORTEX2 science workshop group photo

At the end of the field phase, the PIs divided up case studies and initiated collaborations. Over the three-and-a-half days of the workshop, participants updated the group on their most recent findings, including low-reflectivity ribbons (a feature whose significance is still not completely clear), an apparent case of bottom-up tornadogenesis, an uber-composite supercell environment generated from over 700 rawinsonde launches, and UAV transects across multiple gust fronts. There were also discussions about lessons learned (particularly from the UAV group), new tools (EnKF analyses have proven to be a popular tool for filling in the spatiotemporal gaps between observations), and directions for the future.

In the past three years, life has changed for many of the participants. Some have changed jobs or institutions, graduated (waves), or had families. In spite of all this mobility, electronic collaborations and conferences have enabled quick dissemination of results. (It took 10 years for some results from the original VORTEX to see print.) Josh Wurman aggregated a list of all the peer-reviewed VORTEX2-related manuscripts published so far: the paper count currently stands at 14, with 9 more either accepted or in press. It was decided that the group will shift focus in the next few years towards synthesis studies rather than individual case studies.

It wasn’t all work, of course. There was time for some fun, including a zip line ride across Lake Ted!

New pub

This month’s issue of Monthly Weather Review contains my newest paper, EnKF assimilation of high-resolution, mobile Doppler radar data of the 4 May 2007 Greensburg, Kansas supercell into a numerical cloud model, describing the second half of my dissertation research. (Yes, I know I graduated over a year ago… Publication takes a long time, as well it should!) The take-home message of the paper is that low-level (< 1 km AGL) wind observations make more realistic analyses of supercells (and other rapily-changing atmospheric phenomena). Supercells have a lot going on under the hood – updraft and downdraft pulses, mesocyclone cycling, cold pool generation, etc. – not all of which are apparent to the naked eye or even to an advanced, 4D observing system like a radar. Computers can help fill in some of the gaps via process called data assimilation (DA).

For those not familiar with DA, it means combining atmospheric observations (such as those from a radar) with a computer-generated weather forecast in order to produce a mathematically optimal, 3D analysis of the atmospheric state. You then use the analysis to launch a new forecast. Rinse and repeat every few minutes. The end result is a series of 3D snapshots of the storm, which you can use to diagnose the storm’s inner processes. (There is a gargantuan body of theory required to combine these two very different types of input and assess the quality of the analyses. I shan’t bore you with the two semesters’ worth of details that I slogged through in grad school.)

For this study, I used an advanced DA technique called the ensemble Kalman filter (EnKF) to assimilate NEXRAD (from Dodge City, Kansas) and UMass X-Pol data collected in the Greensburg storm. In one set of experiments, I withheld the UMass X-Pol data (which were collected more frequently and closer to the surface). The mesocyclone of the simulated Greensburg storm was much stronger and more persistent in the experiments where I used the UMass X-Pol data, and the updrafts and downdrafts stronger and more compact. While we lacked independent data to use for verification, making our assessment necessarily qualitative in some regards, our results are consistent with previous DA studies using artificial, “perfect” radar observations.

Simulated Greensburg storm (reflectivity)

Here’s the simulated reflectivity in the Greensburg storm, after assimilating (left) WSR-88D data only and (right) also UMass X-Pol data. Both storms are in the same place and look similar overall…

Simulated Greensburg storm (vertical velocity, vorticity)

BUT… the velocity fields are very different! Updrafts (red) and downdrafts (blue) are more intense. Also, the vorticity bullseye corresponding to the Greensburg tornado (black contours) is much stronger.

I described in a previous post our serendipitous UMass X-Pol data collection in the Greensburg, Kansas storm of 2007, and how that evolved into a detailed case study published last year. My husband lead-authored a companion study earlier last year where he assessed whether modifications to the initial model environment changed the forecasts. (Answer: Yes. Quite a bit, in fact.) This pub completes the trifecta. As we were about to submit this paper for peer review, we made a last-minute decision to switch the DA software to a system that was more extensively tested for severe storms. Even though that added a month to the prep time, I am glad that we did, because the resulting analyses, generated from the same observations, looked markedly better.

I wrote this paper during my CAPS postdoc with the able assistance of my co-authors, representing a fruitful collaboration between SoM, NSSL, and CAPS. I manually edited and dealiased all the radar data (a task that took nearly two months). I had the benefit of two astute reviewers (including my brother-in-EnKF, Dr. James Marquis) who asked some mighty tough questions. And I got to share this MWR issue with some other super scientists – Tom Galarneau, Jeff Beck, and Chris Weiss.

Heads up, Madison!

I’ll be back in my undergrad stomping grounds to give a talk entitled “Unraveling tornadoes with mobile Doppler radar: Scientific storm chasing on the Great Plains” to the Madison, Wisconsin IEEE section on Friday, 16 November 2012. (The section is generously sponsoring my travel. Thanks, guys!) Here’s their announcement for the talk.

In other news: I’ve got a new job! As of today, I have transitioned to an NRC postdoctoral fellowship at the National Severe Storms Laboratory. I will be working with Dr. Pam Heinselman analyzing phased-array radar data. I’m excited to join her and the Radar Research and Development Division (R2D2)!

Last but not least, please enjoy this sunrise time-lapse I shot from the south rim of the Grand Canyon a few weeks ago on my vacation.

Originally, I uploaded sans audio, but YouTube suggested Carly Comando’s pleasant piano piece “Everyday,” and I decided it was a good fit.

New pub

I’ve got a paper in this month’s Monthly Weather Review entitled Mobile, X-band, Polarimetric Doppler Radar Observations of the 4 May 2007 Greensburg, Kansas, Tornadic Supercell. This is the first of two planned papers based on my Ph.D. research, an observational study based on UMass X-Pol data that we collected in the Greensburg storm.

UMass X-Pol on 4 May 2007

UMass X-Pol on 4 May 2007. Had it not been for the blown tire, we might not have collected data in the Greensburg storm.

Operations on 4 May 2007 started off on a low note. Howie, Kery H., and I were driving the UMass X-Pol to Dodge City, Kansas on our first chase of the season, when we blew a tire. With the aid of a good samaritan who just happened to have a spare that was the right size, we limped into Protection, Kansas. Tornado reports near Arnett, OK tempted the rest of our group back south, and we figured we had a bust chase on our hands. As soon as the new tire was on, a storm erupted southwest of Protection, and we decided to collect some “consolation data” in it and shake down the system.

A local sheriff showed us to his favorite storm spotting place on a hill looking over Protection. That road was too muddy for us to use, so we moved about two miles east and deployed on a packed gravel road. As we lost daylight fast, the storm dropped a rotating wall cloud, followed by a brief tornado and an additional funnel cloud to our west. We got volumetric, polarimetric X-band data of all these features. At one point I had to back the truck up to avoid beam blockage from telephone poles along US Hwy. 160, resulting in a small gap in the data.

The Greensburg tornado (#5) illuminated by lightning. These are frame grabs from my handheld video.

The Greensburg tornado (#5) illuminated by lightning. These are frame grabs from my handheld video.

As night fell, we lost visual on the wall cloud, but the radar presentation showed a giant spiraling hook echo. We were certain there must be a tornado occurring, so we kept collecting data. We had barely any reception of weather radio, but between the lightning crackles we could make out a series of urgent tornado warnings on our target storm issuing from the NWS office in Dodge City, including indications of a large tornado. Occasionally, flashes of lightning outlined a large lowering in the cloud base to our north (see images at right). After collecting more than an hour of data, we finally shut the system off around 9:30 p.m., when the deep-cycle marine batteries on board the UMass X-Pol, used to power the antenna pedestal and computer, completely drained.

En route back to Norman around midnight, congratulating ourselves on a great first deployment of the season, my cell phone rang. Chip L. had been chasing with us earlier in the afternoon, but split off after our tire mishap. “Greensburg has been completely destroyed,” he said solemnly. As an EMT, he had gone there to assist, and witnessed near-complete devastation of a town of ~1500. We stopped at a fast food restaurant in Ada, where a TV screen in the corner of the room flickered images that looked like they’d come from a war zone. The remainder of the drive back was much quieter and more somber.

Reflectivity, Doppler velocity, and storm-relative Doppler velocity data in the Greensburg tornado

Reflectivity, Doppler velocity, and storm-relative Doppler velocity data in the Greensburg tornado

Over the next few days, back in Norman, I pored over the data, and it quickly became clear that this would be my dissertation case. We had captured not only the genesis of an EF-5 tornado, but several weaker, antecedent tornadoes. In trying to figure out why the Greensburg storm changed tornado production “modes”, a wealth of information offered itself up, and that information forms the basis for this paper. Other scientists, most notably Jana H., Howie, Mike U., Jeff H., contributed data, discussion, and analysis to the study. Two anonymous reviewers also helped me to sculpt the messy initial version into something clearer and more concise. (Word to the wise: Don’t just copy-and-paste half of your dissertation into a journal template and submit it. I was lucky the first version didn’t get rejected outright!)

In the years since that night, I’ve driven through Greensburg several times, and have been continually amazed by the community’s resilience and resurgence. When the time came, I dedicated my dissertation research to all the victims of the Greensburg tornado. Although improved scientific understanding can never undo the pain to the Greensburg community, I’d like to think that this study was one small, positive thing that came of an otherwise wholly devastating event.