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gradient ( Mills and Anderson 2003 ; Klein and Heinemann 2002 ; Heinemann and Klein 2002 ). Other case studies of downslope storms indicate the existence of mountain wave breaking ( Doyle et al. 2005 ) and the creation of mesocyclones ( Klein and Heinemann 2002 ). These results suggest the importance of a variety of forcings for individual downslope wind events, but to date there has been no generalized study of their characteristics, occurrence, and impacts. In contrast, other high-speed wind events
gradient ( Mills and Anderson 2003 ; Klein and Heinemann 2002 ; Heinemann and Klein 2002 ). Other case studies of downslope storms indicate the existence of mountain wave breaking ( Doyle et al. 2005 ) and the creation of mesocyclones ( Klein and Heinemann 2002 ). These results suggest the importance of a variety of forcings for individual downslope wind events, but to date there has been no generalized study of their characteristics, occurrence, and impacts. In contrast, other high-speed wind events
in areas south of Mt. Nagi. In late June 1998, for example, a Hirodo-kaze with V max of 25 m s −1 occurred in association with Typhoon Peter and caused damages of about $1.0 million (U.S. dollars). Previous studies considered that Hirodo-kaze winds are related to severe downslope winds on the southern slope of Mt. Nagi that are induced by strong lower-tropospheric northerlies accompanying an intense cyclone. Yoshino (1986) suggested that the orographic configuration of Mt. Nagi, a steep
in areas south of Mt. Nagi. In late June 1998, for example, a Hirodo-kaze with V max of 25 m s −1 occurred in association with Typhoon Peter and caused damages of about $1.0 million (U.S. dollars). Previous studies considered that Hirodo-kaze winds are related to severe downslope winds on the southern slope of Mt. Nagi that are induced by strong lower-tropospheric northerlies accompanying an intense cyclone. Yoshino (1986) suggested that the orographic configuration of Mt. Nagi, a steep
the United States. The valley is notorious for downslope windstorms, wave clouds, and rotors, which are typically associated with strong westerly winds impinging on the nearly north–south-oriented Sierra Nevada ridge. One of the first modern U.S. multiagency meteorological field programs, the Sierra Wave Project (SWP; Holmboe and Klieforth 1957 ; Grubišić and Lewis 2004 ) took place in the vicinity of Owens Valley in the early 1950s, during which a B-29 documented vertical velocities up to ±20 m
the United States. The valley is notorious for downslope windstorms, wave clouds, and rotors, which are typically associated with strong westerly winds impinging on the nearly north–south-oriented Sierra Nevada ridge. One of the first modern U.S. multiagency meteorological field programs, the Sierra Wave Project (SWP; Holmboe and Klieforth 1957 ; Grubišić and Lewis 2004 ) took place in the vicinity of Owens Valley in the early 1950s, during which a B-29 documented vertical velocities up to ±20 m
. 2005 ). Typically, over mountain slopes under quiescent synoptic conditions, winds blow upslope during the day and downslope at night in response to a horizontal temperature gradient between the air adjacent to the heated (daytime) or cooled (nighttime) slope surface and the ambient air at the same altitude ( Atkinson 1981 ; Whiteman 1990 ). Over the eastern slope of the Sierra Nevada, however, a downslope flow occurs regularly in the afternoon in opposition to local thermal forcing. This daytime
. 2005 ). Typically, over mountain slopes under quiescent synoptic conditions, winds blow upslope during the day and downslope at night in response to a horizontal temperature gradient between the air adjacent to the heated (daytime) or cooled (nighttime) slope surface and the ambient air at the same altitude ( Atkinson 1981 ; Whiteman 1990 ). Over the eastern slope of the Sierra Nevada, however, a downslope flow occurs regularly in the afternoon in opposition to local thermal forcing. This daytime
1. Introduction Coastal Santa Barbara County (SB), with a population exceeding 130 000 inhabitants, is among the most exposed communities to wildfire hazards in southern California ( Kolden and Abatzoglou 2018 ). The Santa Ynez Mountains (SYM) rise abruptly from coastal SB separating the Pacific Ocean on its south face from the Santa Ynez Valley (SYV) on its north face. Downslope, dry and gusty windstorms are frequently observed on the southern-facing slopes of the SYM. These winds typically
1. Introduction Coastal Santa Barbara County (SB), with a population exceeding 130 000 inhabitants, is among the most exposed communities to wildfire hazards in southern California ( Kolden and Abatzoglou 2018 ). The Santa Ynez Mountains (SYM) rise abruptly from coastal SB separating the Pacific Ocean on its south face from the Santa Ynez Valley (SYV) on its north face. Downslope, dry and gusty windstorms are frequently observed on the southern-facing slopes of the SYM. These winds typically
1. Introduction A variety of disturbances, including gravity (mountain) waves, downslope winds, and low-level blocking, may be produced when a stably stratified airstream encounters a topographic barrier. Mountain waves exert a decelerating force on the large-scale flow that is parameterized in large-scale weather and climate models ( Kim et al. 2003 ), although the precise impact of this forcing is not yet well understood. As mountain waves steepen and break, they generate clear-air turbulence
1. Introduction A variety of disturbances, including gravity (mountain) waves, downslope winds, and low-level blocking, may be produced when a stably stratified airstream encounters a topographic barrier. Mountain waves exert a decelerating force on the large-scale flow that is parameterized in large-scale weather and climate models ( Kim et al. 2003 ), although the precise impact of this forcing is not yet well understood. As mountain waves steepen and break, they generate clear-air turbulence
Wildfires are among the greatest natural hazards in the western United States and other parts of the world. Coastal Santa Barbara (SB), with nearly 160,000 inhabitants, is particularly exposed to wildfires, as communities live in a narrow zone between the east–west-oriented Santa Ynez Mountains (SYM) and the SB Channel ( Fig. 1 ). Gusty, downslope winds, known as Sundowner winds (or Sundowners) are frequently observed on the southern slopes of the SYM. These are episodes of northerly (cross
Wildfires are among the greatest natural hazards in the western United States and other parts of the world. Coastal Santa Barbara (SB), with nearly 160,000 inhabitants, is particularly exposed to wildfires, as communities live in a narrow zone between the east–west-oriented Santa Ynez Mountains (SYM) and the SB Channel ( Fig. 1 ). Gusty, downslope winds, known as Sundowner winds (or Sundowners) are frequently observed on the southern slopes of the SYM. These are episodes of northerly (cross
strongest wave events was found to include a prefrontal situation at Owens Valley. On some occasions, the generated waves may be large enough to control the winds occurring within the valley, with extensive strong downslope windstorms and possible formation of rotors. These may be referred to as dynamically forced downslope wind systems. A number of authors have discussed more-moderate downslope winds in Owens Valley that are forced by a thermal mechanism whereby the upstream air mass becomes cooler
strongest wave events was found to include a prefrontal situation at Owens Valley. On some occasions, the generated waves may be large enough to control the winds occurring within the valley, with extensive strong downslope windstorms and possible formation of rotors. These may be referred to as dynamically forced downslope wind systems. A number of authors have discussed more-moderate downslope winds in Owens Valley that are forced by a thermal mechanism whereby the upstream air mass becomes cooler
are due to downslope acceleration of flow being channeled through the gap that lies to the south of Monument Peak, which I will refer to as the “El Centro Gap” in Fig. 5b , and which is the lowest point (1170 m) in the north–south transect of the Peninsular Ranges. However, the winds are not associated with dust uplift, mainly because the surface to the east of the gap is very rocky with few emissive regions, and then quickly transitions to cropland (as evidenced by an in situ examination of the
are due to downslope acceleration of flow being channeled through the gap that lies to the south of Monument Peak, which I will refer to as the “El Centro Gap” in Fig. 5b , and which is the lowest point (1170 m) in the north–south transect of the Peninsular Ranges. However, the winds are not associated with dust uplift, mainly because the surface to the east of the gap is very rocky with few emissive regions, and then quickly transitions to cropland (as evidenced by an in situ examination of the
I DECEMBER 1985 RONALD B. SMITH 2597On Severe Downslope Winds RONALD B. SMITHYale University, New Haven, CT(Manuscript received 4 April 1985, in final form 24 June 1985)ABSTRACT Recent observations and numerical experiments indicate that during severe downslope windstorms, a largem~,,ion of slow turbulent air develops in the middle and upper troposphere while strong winds plunge underneath
I DECEMBER 1985 RONALD B. SMITH 2597On Severe Downslope Winds RONALD B. SMITHYale University, New Haven, CT(Manuscript received 4 April 1985, in final form 24 June 1985)ABSTRACT Recent observations and numerical experiments indicate that during severe downslope windstorms, a largem~,,ion of slow turbulent air develops in the middle and upper troposphere while strong winds plunge underneath
