This imagery from GOES-16's Geostationary Lightning Mapper features flashes of lightning, but not necessarily where you might expect to see them. Here's why.
Notice anything interesting about this imagery from GOES-16's Geostationary Lightning Mapper?
In addition to showing Hurricane Eugene swirling in the east Pacific Ocean for more than a 48-hour period beginning July 8, 2017, and ending July 10, it also offers a good demonstration of how lightning is more apt to occur over land than ocean, and how hurricanes generally don't produce much lightning.
As indicated by the flashes of lightning along the west coast of Mexico in this animation, lightning occurs more frequently over land because the bright sun in the region heats up the land far quicker than the water, so convection -- the vertical transport of heat and moisture in the atmosphere -- typically begins there first. The terms "convection" and "thunderstorms" often are used interchangeably, although thunderstorms are only one form of convection. The formation of cumulus clouds over land on a sunny day is another example.
As for the lack of lightning in hurricanes, this happens because these storms don't often have the strong vertical updrafts more typical of continental or land based storms, which loft rain drops to high altitudes where they can freeze and make the storm electrification recess more efficient, leading to lightning. A hurricane's winds are mostly horizontal, so the vertical churning that leads to lightning doesn't normally happen. However, lightning in a hurricane's rainbands is more common as the storm moves over land than in the eyewall over the open ocean. When lightning is seen in the eyewall, it's an indication of possible changes in storm intensity.
The first instrument of its kind in geostationary orbit, GLM observes total lightning (both in-cloud and cloud-to-ground) and provides a constant vigil for lightning flashes day and night across the Western Hemisphere. Rapid increases of lightning are a signal that a storm is strengthening and could become more dangerous. GLM, in concert with other forecaster tools, will help provide more accurate and earlier warnings of developing severe storms and give communities more time to prepare for impending severe weather.
To learn more about GLM and how it will improve the forecasting of dangerous weather, visit the GOES-R website.
Please note: GOES-16 data are currently experimental and under-going testing and hence should not be used operationally.
Imagery Credit: Lockheed Martin.