NTS Lightning Climatology
The ARL/SORD lightning
detection network on and around the NTS is being used to identify the
warm-season lightning climatology over a high desert region of southern
Nevada. Eight years of warm-season (June through September) data, 1993
through 2000, have been summarized. For the eight warm seasons, a total
of 9,596 CG lightning flashes were detected on the NTS. For the
approximately 3,500 sq km NTS, this total yields an average, NTS
warm-season flash density, of 0.35 fl/km2. Project-specific flash
densities range from 0.20 fl/km2 at the Yucca Mountain Project, to 0.35
fl/km2 at BEEF, to 0.38 fl/km2 at the HSC, to 0.42 fl/km2 at Mercury.
Results of the analysis revealed that warm- season CG lightning occurred on 13.5% of the 976-day data base. There was also great inter-annual variability in total flash counts on the NTS, ranging from 409 CG flashes in 1995 to 2,532 flashes in 1999. Total flash counts on the NTS ranged from less than 1.0 fl/km2 (in Area 25) to 13 fl/km2 in Area 22 for all eight warm seasons. Of the total CG flashes, 2.6% deposited positive charge to the ground.
Climatologically, CG lightning activity begins to develop rapidly after 1100 PDT, reaching a peak between 1400 and 1459 PDT over the mesas and between 1500 and 1559 PDT over the southern half of the NTS. Although CG lightning has occurred during every hour of the day, minimum CG lightning occurs between 0600 and 1100 PDT, with 0800 to 0859 PDT being the hour of least CG activity.
Maximum daily warm season flash densities ranged from 3.0 to 7.0 fl/km2. The most active thunderstorms generated CG flash rates of 50 to 75 fl/hr. Average spacing between successive CG flashes was 3.4 mi, and 77% of these flashes were 5.0 mi apart. Maximum separation detected was 11.9 mi.
Results of the analysis revealed that warm- season CG lightning occurred on 13.5% of the 976-day data base. There was also great inter-annual variability in total flash counts on the NTS, ranging from 409 CG flashes in 1995 to 2,532 flashes in 1999. Total flash counts on the NTS ranged from less than 1.0 fl/km2 (in Area 25) to 13 fl/km2 in Area 22 for all eight warm seasons. Of the total CG flashes, 2.6% deposited positive charge to the ground.
Climatologically, CG lightning activity begins to develop rapidly after 1100 PDT, reaching a peak between 1400 and 1459 PDT over the mesas and between 1500 and 1559 PDT over the southern half of the NTS. Although CG lightning has occurred during every hour of the day, minimum CG lightning occurs between 0600 and 1100 PDT, with 0800 to 0859 PDT being the hour of least CG activity.
Maximum daily warm season flash densities ranged from 3.0 to 7.0 fl/km2. The most active thunderstorms generated CG flash rates of 50 to 75 fl/hr. Average spacing between successive CG flashes was 3.4 mi, and 77% of these flashes were 5.0 mi apart. Maximum separation detected was 11.9 mi.