See below.. app shows lightning, lightning is happening, but NS doesn't show it. All other values match. 

WeatherFlow doesn't report the actual lightning sensor data to the app.  What they report on the app is something they generate by looking at more than just your sensor.

The node server, when configured to read data from the local device, reports just what the local device reports.  For the rest of the data, this should be the same, it's just the lighting data that can differ.

The lightning data is also a bit different in that I think the app shows the last lightning strike data, the node server reports the last thing the sensor reports.  

From your app above, it shows the last strike was 7 minutes ago, the node server is displaying the current data reported by the sensor (not the data reported 7 minutes ago).

so if I want lightning data in the ISY, I should set up a second station as remote and it might pull it from the Tempest server?

Thanks.

I'm not sure what's returned in the data request.  It may be that the app is doing something with the data and you'd have to create programs on the ISY to mimic that behavior.