Lightning Jump – 13 April 2012: Technical Update & Norman Tornado

Posted in Lightning Jump Algorithm on by Kristin Calhoun.

Earlier entries (to be updated) have gone over a few of the technical issues we’ve found during these first couple of events.  Managed to find a new one on Friday.

Our flash sorting algorithm (i.e., w2lmaflash) seems to be having difficulty dealing with timestamps across multiple minutes from multiple domains coming in at the same time. For example, lets say the current time is 2012 UTC… the OK-LMA is sending 2009 UTC data (the more activity the slower the data transfer gets, up to about 4 min latency), but meanwhile there is no activity in the NA-LMA domain so the timestamp on the LDM feed the most recent data is 2012 UTC. This seems to be leading the w2lmaflash algorithm to be ‘prune’ (or drop) flashes that are more than a minute older (our current processing interval) than the most recent time from an LMA network…

At least that’s what I believe the problem is right now since it’s not reproducible in post-processing when it pulls from all the networks at the same time.

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I pulled all the data from Friday off the realtime feed and re-ran it over the weekend over the Oklahoma domain.  The Norman tornadic storm is labeled as Cell 1 in all the figures and tables below using scale 1 from the w2segmotionll (kmeans) storm tracking.

The total flash rate (TFR) rate for this storm peaked at 282 flashes per min at 2244 UTC, with jumps occurring at 1835, 1844, 1853, 1940, 1952, 2012, and 2027 UTC (Fig. 1).  Hail times from Local storm reports associated with this storm  were recorded at 2041 (1 in), 2055 (1 in), and 2142 (1.5 in).  The EF1 tornado moved through Norman, OK between 2102 and 2113 UTC (estimates from TDWR).

Time Series 20120413 Cell 1, Scale 1
Time series data (Total Flash Rate & MESH) for the Norman tornadic storm 1810-2200 UTC, Friday 13 Apr 2012. Yellow circles denote time of lightning jumps.

I’m discounting the lightning jump at 2012 UTC since there was no real-time radar merger between 2000 and 2008 UTC, hence nothing for the algorithm to track.  Oddly, during this same time period [2002-2008 UTC] four stations in the OKLMA were also not communicating, leading to too few stations to do any quality control for flash sorting.  So it is unknown whether the storm would have produced a lightning jump at this time had the merger/tracking been working correctly.

What is really interesting with this storm is how the character of the lightning changed prior to 2000 UTC and after 2010 UTC as the storm began it’s deviant motion right (towards Norman).  The animation below (5 min intervals) catches this character as lightning initiations grow not only in number but also across the storm. The flash rate continues to increase with initiations spreading into the anvil region by the time the core of the storm is over Norman.  This increase in flash rate and expanded coverage of lightning is reflective of change in the strength and size of  the main updraft core over the same time period (linked via storm electrification processes in around the updraft region).

20120413_animation (quicktime movie, looks a bit better than gif animation below. Either way, you’ll need to click on the link above or image below to see the animation)

gif animation for 13 Apr 2012
3 panel animation of storm between 1900 and 2125 UTC. Main panel: Kmeans storm clusters with cluster ID (yellow square) and past track (pink). Lightning initiation locations (green, gray, & yellow diamonds) overlaid. Top right: MESH (Maximum Expected Size of Hail). Bottom right: KTLX reflectivity at 0.5 deg.

There was also a tornado reported in Mustang at 12:45 am CDT, but I haven’t had time to evaluate that storm yet.

Feel free to leave any questions or comments below or send them directly to me at kristin.kuhlman -at- noaa.gov