Being based in San Diego, I flew from December until April before I ever noticed a strike on my Stormscope – and that was in Texas, of course! Now, having taken 3 long trips from California to Chicago/Wisconsin/Minnesota, another to New England and my last one to Maine, I have accumulated a bunch of data about the utility and utilization of the Stormscope and its data display on the ARNAV and Sandel. Bottom line: don’t fly without it!
That first Texas experience was with strikes during the earliest stages of thunderstorm development. It was easy to match the Stormscope cells with isolated buildups, then deviate a few miles around the buildups and continue. However, one cell grew to be a monster that eventually got its own Convective SIGMET! (Texas is big enough that you can cross it while thunderstorms build, mature and dissipate!) I was surprised at how dark it appeared below the cells, so I was glad to be up around 8-10,000 feet picking my spots in the clear.
The second experience was with thunderstorms east of the St. Louis area, right where we planned to gas up and stay overnight. As we were flying just south of but parallel to the line of thunderstorms, and along the direction of their path, they were not going away so we diverted southeast into Kentucky. The Stormscope display on the ARNAV showed the shape of the storm area in more detail than the Conv SIGMET and then Flight Watch confirmed our deductions. (Sorry, we missed you Marty, but Paducah was only a quick stop!)
The most dramatic storm was in the Chicago area last Monday, July 22. Check out the Stormscope screenshot posted on the COPA photo gallery. This shows two lines of thunderstorms, one over Chicago and Lake Michigan, the other just north of Champaign and Springfield. My planned route took me between these two lines. As I watched the Stormscope in “cell” mode reveal the apparent motion of the thunderstorms, it seemed wise to divert south via Decator and abandon my “great circle” route to California in favor of a mid-continent crossing. 20 minutes later, this photo was taken – with 186 strikes per minute that rose up to a max of 214 – glad I wasn’t there! Stormscope gave me great situational awareness of developing problems along my route of flight, and even though the bases were above my 8,000 level of flight, it was prudent to avoid the worsening conditions.
Later that same flight, thunderstorms were developing in Missouri in an obvious line along a cold front, one that I remembered from the weather computer. The Stormscope showed how the line was moving farther south than I wanted, so we diverted again from Columbia to Jefferson City, which was clear. Just as we approached Jefferson City, a rain squall hit the far side of the airport but without any Stormscope strikes in the vicinity. So it seemed prudent to get down fast, land on the dry pavement and rollout into the rain, then taxi and wait for the squall to pass, which it did about 5 minutes later after the line guy got drenched!
My last experience, yesterday in Tuscon, confirmed the value of situational awareness of the Stormscope. Eastern Arizona had Convective SIGMETS for isolated thunderstorms all day. However, as we came within 200 miles, the Stormscope showed isolated strikes. Remember that the lightning detected by the Stormscope includes any electrical discharge, not just cloud to ground strikes. So these isolated strikes were not indicating the presence of any terrifying cells. And confirming with Flight Watch radar, I was able to safely continue the flight without any problems.
Generally, I configure the ARNAV at 200 miles with Stormscope data in CELL mode. The Sandel is also showing CELL mode data but at 10-20 mile range, depending on how close I am to my approach. CELL mode shows both isolated strikes as well as “clusters” of strikes, so you need to pay attention to the strike rate to figure out which is which. The former are often early indications of buildups with updrafts, the latter indicate trouble from more mature thunderstorms with potentially severe turbulence. The Sandel display is really tough to see the green color in daylight and the only night experience was when the lightning was so obvious in the sky that no display was needed. Perhaps in darker IMC you can see the green data okay, but the Sandel just never became my primary source of display.
Lessons learned so far?
Foremost, appreciate the advice stated several times on this forum: do not expect to navigate between thunderstorm cells with the Stormscope. Generally, I stayed well away.
Also, confirm your situation with Flight Watch. Having great situational awareness from the Stormscope helps, but talking it over with someone gave me the confidence in my deductions and plans.
Realize your limitations. For instance, despite all of these experiences, I’ve never had to deal with embedded thunderstorms. Somehow, I’ve always been above the clouds and could pick deviation routes around buildups. So, when I get into IMC with my Stormscope display all light up, I’m likely to choose a more cautious plan.
Have a great Cirrus day!