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.

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