Interannual to decadal changes in extreme fire weather event frequencies across the southwestern United States

Abstract

Low-frequency changes (decades to years) in precipitation related to the El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO) are known to influence wildfire variability across the southwest United States. Little work has been done to identify whether daily fire weather variability, also important to wildfire activity, is influenced by these same climatic phenomena. This study identifies the synoptic climatological conditions associated with extreme fire weather events in the Southwest and constructs an extreme fire weather frequency data set for the period of 1958-2003 using a logistic regression technique. Interannual changes in extreme fire weather day frequencies are not linearly correlated with either ENSO or PDO, but do show significant deviations from expected values when grouped by PDO phase (positive or negative) and further subgrouped by ENSO state (La Niña, El Niño or neutral). A higher number of extreme fire weather days occur during the negative phase of the PDO, especially when accompanied by a La Niña event.

Atmospheric and Surface Climate Associated With 1986–2013 Wildfires in North America

“…Fire activity is also evident over the southern Rockies along the gradient between positive and negative height departures, over the southwest, and under the positive departures (subsidence) over much of Florida. The fires in western Canada and the PNW of the United States are associated with persistent blocking highs (Fauria & Johnson, ; Gedalof et al, ; Johnson & Wowchuk, ; Skinner et al, , ), whereas the fires in the southwest are associated with a suppressed south‐to‐north monsoonal circulation that resulted in displacing and confining precipitation to the east slope of the central and SRMs, conditions that favor large fires in the southwest (Crimmins, , ). Anomalous west‐to‐east wind flow in the middle and lower troposphere along the southern edge of the low in the southeast (Figures 3 and S3) suppressed precipitation over much of Florida where soil moisture anomalies were negative.…”

Intensified dust storm activity and Valley fever infection in the southwestern United States

“…Geophysical Research Letters 10.1002/2017GL073524 level. The teleconnection between SST anomalies and dust trend is likely to be realized through a similar mechanism to that for droughts and increased wildfires in the Southwest [Crimmins, 2010;Williams et al, 2014]. During the cold phase of PDO, the sea surface pressure gradient between the North Pacific high and North America low intensifies, driving northerly winds down toward the North American coast.…”

Causes and Implications of Extreme Atmospheric Moisture Demand during the Record-Breaking 2011 Wildfire Season in the Southwestern United States

“…During AMJ 1961-2014, the PDO correlated positively and the SOI correlated negatively with SW dewpoint (r 5 0.47 and 20.46, respectively; Table 1). Crimmins (2010) shows that La Niña and the PDO cold phase correspond positively to the frequency of days during which meteorological conditions are conducive to wildfire in the SW.…”