A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical Context
Two heavy rainfall events occurring in early 2020 brought flooding, flash flooding, strong winds and tornadoes to the southern Appalachian Mountains. The atmospheric river-influenced events qualified as extreme (top 2.5%) rain events in the archives of two research-grade rain gauge networks located...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-06-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/13/13/2452 |
| _version_ | 1797529104886530048 |
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| author | Douglas Miller John Forsythe Sheldon Kusselson William Straka III Jifu Yin Xiwu Zhan Ralph Ferraro |
| author_facet | Douglas Miller John Forsythe Sheldon Kusselson William Straka III Jifu Yin Xiwu Zhan Ralph Ferraro |
| author_sort | Douglas Miller |
| collection | DOAJ |
| description | Two heavy rainfall events occurring in early 2020 brought flooding, flash flooding, strong winds and tornadoes to the southern Appalachian Mountains. The atmospheric river-influenced events qualified as extreme (top 2.5%) rain events in the archives of two research-grade rain gauge networks located in two different river basins. The earlier event of 5–7 February 2020 was an event of longer duration that caused significant flooding in close proximity to the mountains and had the higher total accumulation observed by the two gauge networks, compared to the later event of 12–13 April 2020. However, its associated downstream flooding response and number of landslides (two) were muted compared to the April event (21). The purpose of this study is to understand differences in the surface response of the two events, primarily by examining the large-scale weather pattern and available space-based observations. Both storms were preceded by anticyclonic Rossby wave breaking events that led to a highly amplified 500 hPa wave during the February storm (a broad continent-wide 500 hPa cyclone during the April storm) in which the accompanying low-level cyclone moved slowly (rapidly). Model analyses and space-based water vapor observations of the two events indicated a deep sub-tropical moisture source during the February storm (converging sub-tropical low-level moisture streams and a dry mid-tropospheric layer during the April storm). Systematic differences of environmental stability were reflected in differences of storm-averaged rain rate intensity, with large-scale atmospheric structures favoring higher intensities during the April storm. Space-based observations of post-storm surface conditions suggested antecedent soil moisture conditioned by rainfall of the February event made the widespread triggering of landslides possible during the higher intensity rains of the April event, a period exceeding the 30 day lag explored in Miller et al. (2019). |
| first_indexed | 2024-03-10T10:08:41Z |
| format | Article |
| id | doaj.art-9d5285ba911344848f4defb0ae5d00d5 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-10T10:08:41Z |
| publishDate | 2021-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-9d5285ba911344848f4defb0ae5d00d52023-11-22T01:22:20ZengMDPI AGRemote Sensing2072-42922021-06-011313245210.3390/rs13132452A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical ContextDouglas Miller0John Forsythe1Sheldon Kusselson2William Straka III3Jifu Yin4Xiwu Zhan5Ralph Ferraro6Atmospheric Sciences Department, University of North Carolina Asheville, Asheville, NC 28804, USACooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO 80523, USACooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO 80523, USASSEC Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin Madison, Madison, WI 53706, USAESSIC Cooperative Institute for Satellite Earth System Studies, University of Maryland, College Park, MD 20740, USANOAA-NESDIS Center for Satellite Applications and Research, College Park, MD 20740, USANOAA-NESDIS Center for Satellite Applications and Research, College Park, MD 20740, USATwo heavy rainfall events occurring in early 2020 brought flooding, flash flooding, strong winds and tornadoes to the southern Appalachian Mountains. The atmospheric river-influenced events qualified as extreme (top 2.5%) rain events in the archives of two research-grade rain gauge networks located in two different river basins. The earlier event of 5–7 February 2020 was an event of longer duration that caused significant flooding in close proximity to the mountains and had the higher total accumulation observed by the two gauge networks, compared to the later event of 12–13 April 2020. However, its associated downstream flooding response and number of landslides (two) were muted compared to the April event (21). The purpose of this study is to understand differences in the surface response of the two events, primarily by examining the large-scale weather pattern and available space-based observations. Both storms were preceded by anticyclonic Rossby wave breaking events that led to a highly amplified 500 hPa wave during the February storm (a broad continent-wide 500 hPa cyclone during the April storm) in which the accompanying low-level cyclone moved slowly (rapidly). Model analyses and space-based water vapor observations of the two events indicated a deep sub-tropical moisture source during the February storm (converging sub-tropical low-level moisture streams and a dry mid-tropospheric layer during the April storm). Systematic differences of environmental stability were reflected in differences of storm-averaged rain rate intensity, with large-scale atmospheric structures favoring higher intensities during the April storm. Space-based observations of post-storm surface conditions suggested antecedent soil moisture conditioned by rainfall of the February event made the widespread triggering of landslides possible during the higher intensity rains of the April event, a period exceeding the 30 day lag explored in Miller et al. (2019).https://www.mdpi.com/2072-4292/13/13/2452atmospheric riversextreme rainfalllandslidessouthern Appalachian Mountains |
| spellingShingle | Douglas Miller John Forsythe Sheldon Kusselson William Straka III Jifu Yin Xiwu Zhan Ralph Ferraro A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical Context Remote Sensing atmospheric rivers extreme rainfall landslides southern Appalachian Mountains |
| title | A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical Context |
| title_full | A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical Context |
| title_fullStr | A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical Context |
| title_full_unstemmed | A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical Context |
| title_short | A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains during Early 2020, Part I; Societal Impacts, Synoptic Overview, and Historical Context |
| title_sort | study of two impactful heavy rainfall events in the southern appalachian mountains during early 2020 part i societal impacts synoptic overview and historical context |
| topic | atmospheric rivers extreme rainfall landslides southern Appalachian Mountains |
| url | https://www.mdpi.com/2072-4292/13/13/2452 |
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