Lightning Jump – Week 1: 2 Apr 2012 – 9 Apr 2012

Moving an algorithm into real-time operations is full of pitfalls and challenges.  This first week of operations for the lightning jump algorithm was no exception.  No matter how much archive data you test on, there are certain aspects that change once you’re at the mercy of a real-time feed. Add to that, working with weather data where the outcomes are unknown and you get a great recipe for failure.

This first week we had three events to test data on, with the SHAVE project active on 2 of the days.  The below images (screenshots from the event) will give you a chance to see our visualization of the lightning jump for the SHAVE participants and what you can see real time during future events at:

Basically, the jump is currently being visualized by colored circles along the track of the centroid of the identified storm cluster. When a storm has a lightning flash rate > 10 flashes per min, but does not have an active ‘jump’ a gray circle is placed along the track.  When the storm meets the jump criteria, the circle changes to red.  The activity this first week was our first chance to see the visualization and get the data over to kml format (Kiel Ortega was instrumental in getting all of this up and going).

5 Apr 2012: Northern Alabama

(to be filled in w/ info on any jumps)

SHAVE closeout on Fri 06 Apr 2012 at 011011 GMT:  SHAVE made ~471 calls today. Today we had 98 hail reports with 11 being severe (1.0″+), 0 being significant (2″+).  We had 1 wind reports today.

SPC storm reports for this event:

7 Apr 2012:  Oklahoma

Google Earth image from 7 Apr 2012
Storm track in NW Oklahoma on 7 Apr 2012 at 0542 UTC showing no jumps, but flash rate above 10. Displayed in GoogleEarth.

SHAVE was not active on this day and there were no warnings or storm reports over any of the LMA regions.

9 Apr 2012:  Oklahoma

Activity on 9 Apr 2012 was primarily outside the central range of the OKLMA network, though there was a chance that storms would move into range. I’ve included it here mostly for illustration of storm cluster identification and storm tracking.

Screenshot at 2200 UTC from WDSSII/WG display. Left panel: storm clusters identified by Kmeans. Right panel: Reflectivity @-10C. NWS warnings/watches and NLDN lightning location and polarity are shown on both panels.

The kmeans storm identification works on 3 separate scales, simply thought of small, medium and large (or 1, 2 and 3).  Each of these is using Reflectivity at -10 C, with thresholds set such that all reflectivity less than 20 dBZ becomes 0 and all greater than 50 dBZ appears at 50 dBZ to the algorithm.  We are also using a percent filter such that pixels nearby that are partially filled or surrounded by pixels that are filled match the neighbors.  This acts to expand the cluster slightly, with the goal to pick up more of the lightning flashes.  Looking at the example in the screenshot above, all the CG flashes within the colored area would be counted as occurring with that storm, anything outside the area, even closely nearby will not be associated.  Sometimes (at scales 1 & 2 especially) this may combine storms that the human forecaster would deem to be separate entities.  This is typically a problem with smaller storms occurring in close proximity to each other as we had from this example on 9 Apr.

The corresponding visualization in Google Earth (or similarly on Google Maps) can be seen below.

Google Earth image from 9 Apr 2012 at 2230 UTC
Storms as seen via Google Earth around 2230 UTC. Gray tracks represent centroid of associated Kmeans storm cluster. Reflectivity at lowest level and NWS watches/warnings also shown. Green circle represents 125 km from LMA network center.

SHAVE closeout at Mon 09 Apr 2012 234803 GMT. SHAVE made ~109 calls today. We had 27 hail reports with 13 being severe (1.0″+), 10 being significant (2″+)