Night time spotting of severe weather and tornadic storms is extremely difficult, and for the mobile spotter much more dangerous. These problems arise because there is no continuous source of light.

For effective night time operations, spotters must significantly increase their situational awareness since only background lightning and power line flashes will reveal the storms most active regions.  Copyright Milwaukee Area Skywarn Assoc.

Arcing and flashing powers lines (called Power flashes) are often seen as flashes of white or blue-to-green colored light originating at ground level or low angles to the horizon. These power flashes result from: (1) lightning and electrical surges hitting power lines or transformers, (2) wires that are being blown around and touching because of high winds, (3) damage debris and tornadoes intersecting power lines, (3) heavy rains and wet snows soaking wooden electric poles creating electrical fires.

In wide spread situations with extreme downbursts, straight-line winds or outflow gust fronts, often whole quadrants of the horizon, near ground level, and almost simultaneously, may show power flashes as a dangerous system approaches.

These same strong winds can also create a roaring sound or rushing noise that is similar to an approaching tornado. And severe storms with large hail can also create a similar roar or even a deep rumble.

Since there are documented cases of tornado producing storms with little or no lightning it is very important for the night spotter to have a good understanding of storm structure and wind fields. This is why it’s essential to attend storm spotter training programs. When severe winds are forecasted, night time spotters should pay attention to how rain drops bead-up and trail on windows and windshields, the movement of flags on flag poles, and if winds are blowing into or out of a storm. Any sudden or dramatic shift in direction or increase in hail size should heighten your awareness level.

Keep in mind that you will only have a few brief instants (over several lightning flashes) to correctly identify suspicious cloud features. Infrequent or occasional lightning is generally useless, moderate lightning amounts are hard on the eyes, and continuous lightning may create a strobe affect to further distort your depth perception. However, it can sometime provide a spectacular three dimensional view of cloud structures. As with daytime spotting you must be within a few miles of the active areas to accurate identify suspicious features.

If you observe a suspicious cloud feature, watch it for several minutes. Cloud features can change almost instantly depending on your point of view and the light source angle, whereas wall clouds, funnels, or tornadoes will be more constant.

Low to the ground wind blown cloud fragments, called Scud Clouds, when illuminated by lightning may be mistaken for a funnel or tornado. Also, a Shelf Cloud from a side view can be mistaken for a Wall cloud. Sometimes scud can be seen rotating around a wall cloud. Observed for several minutes, the scud will appear to be in different locations with succeeding flashes and can reveal cloud rotation. The spotter must be stationary to observe this effect.

Under darkness or poor light conditions; distant telephone poles, smoke stacks, smoke plumes, rain shafts, rain curtains or hail shafts silhouetted by certain light source or sun angles can also create a funnel or tornado look-alike. When in doubt watch the event for awhile. Take time to be sure of your observations.