A Couple of Examples of Total Lightning Benefits to Forecast Operations…

I wanted to point out a couple of operational advantages of total lightning data offered by current LMA networks scattered across parts of the CONUS, but also the advantages forthcoming with the GLM in the future GOES-R era.  While viewing the data today in conjunction with radar and NLDN data, two great examples were noticed.  First, let’s consider the situation where a cell becomes electrically active (intracloud lightning), but never produces a cloud-to-ground strike.  The first image below shows KHTX 0.5 reflectivity overlaid with LMA Flash Extent Density.

Image 1.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density valid 1735/1736 UTC 25 June 2014

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

 

Notice the small area of lightning detected by the North Alabama LMA in the central part of the image.  This cell never actually produced a ground strike.  So, using NLDN data alone, a forecaster would not have known that this cell was electrically active, and capable of producing lightning/thunder.  True, CG lightning was never observed by the NLDN network, but this is rather rare.

Next, let’s look at a situation where intra-cloud lightning preceded a CG strike as a cell was approaching an airport location.  Image 2 below, shows a cell that has just become electrically active as it was approaching the Tuscumbia/Muscle Shoals area around 1750 UTC.

Hi

Image 2.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1749/1750 UTC 25 June 2014

Notice in the image above that the first lightning detection by the LMA was during the 1749-1750 two-minute interval.  Now, we’ll take a look at an image just a little later, which shows the first incident of cloud to ground lightning as detected by the NLDN.

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

Image 3. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area), including CG strike (small cyan line) as indicated by NLDN  valid 1757/1758 UTC 25 June 2014

The image above (Image 3) shows the first CG strike, indicated by the small cyan line, which was about 7-8 minutes after the first intra-cloud flash.  Notice also that this cell was approaching the Muscle Shoals ASOS to the east, for which the HUN office has airport weather warning responsibilities.  These responsibilities include the issuance of warnings for CG lightning with 5 SM of the airport. So, not only do the total lightning data alert to the presence of lightning when a cell never even produces a CG strike, but intra-cloud flashes will often precede CG strikes.  In fact, research has shown this to be by about 5 to 10 minutes.  Forecasters here at the HUN WFO have been privileged to use these data in operations for over 10 years now.  These and future GLM data will be a boon to operations, allowing for earlier lead times in some warning and forecast situations.

 

Leave a Reply

Please log in using one of these methods to post your comment:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s