scholarly journals 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

2021 ◽  
Vol 13 (13) ◽  
pp. 2452
Author(s):  
Douglas Miller ◽  
John Forsythe ◽  
Sheldon Kusselson ◽  
William Straka III ◽  
Jifu Yin ◽  
...  
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Appalachian Mountains ◽  
Environmental Stability ◽  
Antecedent Soil Moisture ◽  
Rainfall Events ◽  
Southern Appalachian Mountains ◽  
Low Level ◽  
Southern Appalachian ◽  
Heavy Rainfall Events

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).

scholarly journals A Study of Two Impactful Heavy Rainfall Events in the Southern Appalachian Mountains During Early 2020, Part II; Regional Overview, Rainfall Evolution, and Satellite QPE Utility

2021 ◽  
Vol 13 (13) ◽  
pp. 2500
Author(s):  
Douglas Miller ◽  
Malarvizhi Arulraj ◽  
Ralph Ferraro ◽  
Christopher Grassotti ◽  
Bob Kuligowski ◽  
...  
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Appalachian Mountains ◽  
Heavy Rainfall Event ◽  
Atmospheric Conditions ◽  
Rainfall Events ◽  
Southern Appalachian Mountains ◽  
Atmospheric River ◽  
Southern Appalachian ◽  
Heavy Rainfall Events

Two heavy rainfall events occurring in early 2020 brought flooding, flash flooding, strong winds, and tornadoes to the southern Appalachian Mountains. Part I of the study examined large-scale atmospheric contributions to the atmospheric river-influenced events and subsequent societal impacts. Contrary to expectations based on previous work in this region, the event having a lower event accumulation and shorter duration resulted in a greater number of triggered landslides and prolonged downstream flooding outside of the mountains. One purpose of this study (Part II) is to examine the local atmospheric conditions contributing to the rather unusual surface response to the shorter duration heavy rainfall event of 12–13 April 2020. A second purpose of this study is to investigate the utility of several spaced-based QPE and vertical atmospheric profile methods in illuminating some of the atmospheric conditions unique to the April event. The embedded mesoscale convective elements in the warm sector of the April event were larger and of longer duration than of the other event in February 2020, leading to sustained periods of convective rain rates. The environment of the April event was convectively unstable, and the resulting available potential energy was sustained by relatively dry airstreams at the 700 hPa level, continuously overriding the moist air stream at low levels attributed to an atmospheric river.

scholarly journals Investigation of Atmospheric Rivers Impacting the Pigeon River Basin of the Southern Appalachian Mountains

2018 ◽  
Vol 33 (1) ◽  
pp. 283-299 ◽  
Author(s):  
Douglas K. Miller ◽  
David Hotz ◽  
Jessica Winton ◽  
Lukas Stewart
Keyword(s):  
North Carolina ◽  
River Basin ◽  
Large Scale ◽  
Large Fraction ◽  
Appalachian Mountains ◽  
Warm Season ◽  
Atmospheric Rivers ◽  
Southern Appalachian Mountains ◽  
Low Level ◽  
Southern Appalachian

Abstract Rainfall observations in the Pigeon River basin of the southern Appalachian Mountains over a 5-yr period (2009–14) are examined to investigate the synoptic patterns responsible for downstream flooding events as observed near Knoxville, Tennessee, and Asheville, North Carolina. The study is designed to address the hypothesis that atmospheric rivers (ARs) are primarily responsible for the highest accumulation periods observed by the gauge network and that these periods correspond to events having a societal hazard (flooding). The upper 2.5% (extreme) and middle 33% (normal) rainfall events flagged using the gauge network observations showed that half of the heaviest rainfall cases were associated with an AR. Of those extreme events having an AR influence, over 73% had a societal hazard defined as minor-to-major flooding at the USGS river gauge located in Newport, Tennessee, or flooding observations for locations near the Tennessee and North Carolina border reported in the Storm Data publication. Composites of extreme AR-influenced events revealed a synoptic pattern consisting of a highly amplified slow-moving positively tilted trough, suggestive of the anticyclonic Rossby wave breaking scenario that sometimes precedes hydrological events of high impact. Composites of extreme non-AR events indicated a large-scale weather pattern typical of a warm season scenario in which an anomalous low-level cyclone, cut off far from the primary upper-tropospheric jet, was located in the southeastern United States. AR events without a societal hazard represented a large fraction (75%–88%) of all ARs detected during the study period. Synoptic-scale weather patterns of these events were fast moving and had weak low-level atmospheric dynamics.

scholarly journals Extreme Floods in the Eastern Part of Europe: Large-Scale Drivers and Associated Impacts

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1122
Author(s):  
Monica Ionita ◽  
Viorica Nagavciuc
Keyword(s):  
Water Vapor ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Flood Events ◽  
Rainfall Events ◽  
Catchment Areas ◽  
Large Scale Atmospheric Circulation ◽  
Heavy Rainfall Events

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the socio-economic impacts of the most extreme flood events (e.g., July 2008, June–July 2010, and June 2020) is given. Analysis of the largest flood events indicates that the flood peaks have been preceded up to 6 days in advance by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent cut-off lows over the analyzed region, and increased water vapor transport over the catchment areas of Siret and Prut Rivers. The vertically integrated water vapor transport prior to the flood peak exceeds 300 kg m−1 s−1, leading to heavy rainfall events. We also show that the implementation of the Flood Management Plan in Romania had positive results during the 2020 flood event compared with the other flood events, when the authorities took several precaution measurements that mitigated in a better way the socio-economic impact and risks of the flood event. The results presented in this study offer new insights regarding the importance of large-scale atmospheric circulation and water vapor transport as drivers of extreme flooding in the eastern part of Europe and could lead to a better flood forecast and flood risk management.

The role of monsoon low-level jet in modulating heavy rainfall events

2017 ◽  
Vol 38 ◽  
pp. e569-e576 ◽  
Author(s):  
Anu Xavier ◽  
Ajil Kottayil ◽  
K. Mohanakumar ◽  
Prince K. Xavier
Keyword(s):  
Heavy Rainfall ◽  
Rainfall Events ◽  
Low Level ◽  
Low Level Jet ◽  
Heavy Rainfall Events

scholarly journals Frequency of sprout-origin trees in pre-European settlement forests of the southern Appalachian Mountains

2016 ◽  
Vol 46 (8) ◽  
pp. 1019-1025 ◽  
Author(s):  
Carolyn A. Copenheaver ◽  
Tara L. Keyser
Keyword(s):  
Large Scale ◽  
Tree Mortality ◽  
Deciduous Forest ◽  
Appalachian Mountains ◽  
Acer Rubrum ◽  
Blue Ridge ◽  
Southern Appalachian Mountains ◽  
European Settlement ◽  
Southern Appalachian ◽  
Witness Trees

We hypothesized that tree form, recorded in historical public land surveys, would provide a valuable proxy record of regeneration patterns during early-European settlement of North America’s eastern deciduous forest. To test this hypothesis, we tallied stem form from witness trees used in land survey records in the southern Appalachian Mountains from 13 counties spanning four physiographic provinces: Piedmont, Blue Ridge, Ridge and Valley, and Cumberland Plateau. A total of 3% of witness trees used in the land surveys were of sprout origin. American basswood (Tilia americana L.) exhibited the highest proportion of sprout-origin trees at 12%. Other overstory species with a high proportion of sprout-origin trees were hickory (Carya sp.), red maple (Acer rubrum L.), and sycamore (Platanus occidentalis L.), all with 6% of stems being from sprout origin. Blue Ridge had significantly more sprout-origin trees compared with the other three physiographic provinces. Forests in the southern Appalachian Mountains during the pre-European settlement period had a suite of disturbances that controlled their growth and regeneration; however, most of these disturbances did not result in large-scale tree mortality, and therefore, sprouts were not an important source of regeneration.

scholarly journals Impact of low level jet on heavy rainfall events over Mumbai

MAUSAM ◽  
2021 ◽  
Vol 58 (2) ◽  
pp. 229-240
Author(s):  
VINOD KUMAR ◽  
D. K. U. R. BHAGAT ◽  
M. SATYA KUMAR ◽  
SHIV GANESH
Keyword(s):  
Heavy Rainfall ◽  
Rainfall Events ◽  
Low Level ◽  
Low Level Jet ◽  
Heavy Rainfall Events

Heavy Rainfall Events over Central Oahu under Weak Wind Conditions during Seasonal Transitions

2020 ◽  
Vol 148 (10) ◽  
pp. 4117-4141
Author(s):  
Feng Hsiao ◽  
Yi-Leng Chen ◽  
David Eugene Hitzl
Keyword(s):  
Mixed Layer ◽  
Land Surface ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Subsequent Development ◽  
Precipitable Water ◽  
Trade Wind ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Heavy Rainfall Events

AbstractShort-lived afternoon heavy rainfall events may form over central Oahu during seasonal transition periods (June and October) under favorable large-scale settings. These include a deep moist layer with relatively high precipitable water (>40 mm), blocking pattern in midlatitudes with a northeast–southwest moist tongue from low latitudes ahead of an upper-level trough, absence of a trade wind inversion, and weak (<3 m s−1) low-level winds. Our high-resolution (1.5 km) model results show that immediately before the storm initiation, daytime land surface heating deepens the mixed layer over central Oahu and the top of the mixed layer reaches the lifting condensation level. Meanwhile, the development of onshore/sea-breeze flows, driven by land–sea thermal contrast, brings in moist maritime air over the island interior. Finally, convergence of onshore flows over central Oahu provides the localized lifting required for the release of instability. Based on synoptic and observational analyses, nowcasting with a lead time of 2–3 h ahead of this type of event is possible. In the absence of orographic effects after removing model topography, processes that lead to heavy rainfall are largely unchanged, and subsequent development of heavy showers over central Oahu are still simulated. However, when surface heat and moisture fluxes are turned off, convective cells are not simulated in the area. These results indicate that daytime heating is crucial for the development of this type of heavy rainfall event under favorable large-scale settings.

scholarly journals An Expanded Investigation of Atmospheric Rivers in the Southern Appalachian Mountains and Their Connection to Landslides

Atmosphere ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 71 ◽  
Author(s):  
Douglas K. Miller ◽  
Chelcy Ford Miniat ◽  
Richard M. Wooten ◽  
Ana P. Barros
Keyword(s):  
North Carolina ◽  
River Basin ◽  
Appalachian Mountains ◽  
Extreme Rainfall ◽  
River Basins ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Southern Appalachian Mountains ◽  
Southern Appalachian ◽  
Western North Carolina

Previous examination of rain gauge observations over a five-year period at high elevations within a river basin of the southern Appalachian Mountains showed that half of the extreme (upper 2.5%) rainfall events were associated with an atmospheric river (AR). Of these extreme events having an AR association, over 73% were linked to a societal hazard at downstream locations in eastern Tennessee and western North Carolina. Our analysis in this study was expanded to investigate AR effects in the southern Appalachian Mountains on two river basins, located 60 km apart, and examine their influence on extreme rainfall, periods of elevated precipitation and landslide events over two time periods, the ‘recent’ and ‘distant’ past. Results showed that slightly more than half of the extreme rainfall events were directly attributable to an AR in both river basins. However, there was disagreement on individual ARs influencing extreme rainfall events in each basin, seemingly a reflection of its proximity to the Blue Ridge Escarpment and the localized terrain lining the river basin boundary. Days having at least one landslide occurring in western North Carolina were found to be correlated with long periods of elevated precipitation, which often also corresponded to the influence of ARs and extreme rainfall events.

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