NASA's Opportunity rover has been on Mars for nearly 3,000 days out of its originally scheduled 90-day mission. It's currently on its fifth Martian winter, and its solar panels are getting so dusty that the reduced daylight and low sun angle are threatening to starve the rover for power. Since a helpful rain shower seems like a long shot, Oppy is hoping to instead get hit by a tornado.
Hoping for a passing tornado is not a completely crazy idea, since dust devils are a relatively common phenomena on Mars.
For example, here's a video of one whirling past Spirit a few years ago:
We've even spotted them from orbit, too, and JPL put together this cool 3D model of what a Martian tornado looks like:
The Mars rovers (or now, rover) have come to rely heavily on passing dust devils and other "cleaning events" to keep their solar panels generating power. Their original 90 day lifespan was based on reduction in power from dust accumulation, but thanks to the occasional gust of wind, the solar panels remained clean enough to keep the rovers functioning for a long, long time.
Opportunity will probably be fine in the short term: it's sitting on a slope, pointing its panels toward the sun, and not doing much besides trying to keep itself warm and alive. As spring springs on Mars, Oppy will (hopefully) start getting enough power to let it move around a bit and get back to doing some science.