It is true that we observe no concentration (extremum) of lightning in
the Rocky Mountains. While many storms form on the front range of the
Rockies, they tend to organize, multiply and intensify as they move
downslope and into the Great Plains. The steadily increasing availability
of moisture as one moves eastward also increases the
frequency of occurrence of thunderstorms.
(1) The map for the public story was generated using a 2.5 degree (~ 250 km)
moving average operator, so the results are somewhat "blurred" and small
scale features are not represented. With the current Low Earth Orbit
satellite coverage, we must make a trade-off between spatial resolution and
confidence in the estimate. The numbers on the map
represent the average behavior of the overall region, and may not be
directly applicable to a point location.
(2) Note that the "color bar" increments on the map are very nonlinear,
there can be big jumps from one color to the next. This is needed as total
lightning production, globally, has a very wide "dynamic range", but can
result in visually deemphasizing local differences which turn up "in the
(3) Measurements of ground strike-only concentrations, by Global
Atmospherics, Inc. (www.glatmos.com), using a ground-based detection
network, have found very small scale enhancements in cloud-to-ground
lightning activity near mountain peaks; I believe this has been demonstrated
near Tucson, Arizona, at least. This sort of fine-scale feature
resolution is beyond the capability of the satellite sensors.
(4) One anomaly that we _do_ observe in mountain regions with the satellites
and ground networks is that the ratio of in-cloud flashes to ground flashes
is much lower there. The US average is ~ 3-4 intracloud flashes for every
ground flash; over mountains, it is closer to 1:1. This was reported in
Monthly Weather Review, Jan, 2001.
Hope this is helpful...
Dr. Dennis Boccippio, NASA/MSFC