| Summary: | Wildfires are a major part of the Mackenzie River Basin climate system, and most wildfires within the basin are lightning-caused. Thus, a study has been conducted that identifies the atmospheric circulation patterns associated with extreme lightning events. In addition, events are stratified according to the number of resultant large wildfires to determine why some extreme lightning events induce a large quantity of wildfires within the basin, and why others do not. Extreme lightning events in the MRB are characterized by a strong, persistent upper-tropospheric ridge dominating the basin until event onset. The triggering mechanism of the majority of extreme lightning events is cyclogenesis in lee of the Rocky and Mackenzie Mountains. A Haines Index analysis has been used to show that lack of lower-tropospheric moisture and ample lower-tropospheric instability in advance of an extreme lightning event increase the probability of several resultant large wildfires. Furthermore, extreme lightning events with several induced large wildfires are characterized by a lack of moisture transport into the MRB from the northeast Pacific Ocean.
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