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 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).

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 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.

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 Evolution of physicochemical species concentration in streams based on heavy rainfall event data obtained for high-frequency monitoring

RBRH ◽  
2016 ◽  
Vol 21 (4) ◽  
pp. 653-665
Author(s):  
Rubia Girardi ◽  
Adilson Pinheiro ◽  
Edson Torres ◽  
Vander Kaufmann ◽  
Luis Hamilton Pospissil Garbossa
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Atlantic Forest ◽  
High Frequency ◽  
Heavy Rainfall ◽  
Rainfall Event ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Frequency Monitoring ◽  
Heavy Rainfall Events

ABSTRACT Studies carried out over short time intervals assist in understanding the biogeochemical processes occurring relatively fast in natural waters. High frequency monitoring shows a greater variability in the water quality during and immediately after heavy rainfall events. This paper presents an assessment of the surface water quality parameters in the Atlantic Forest biome, caused by heavy rainfall events. The work was developed in two fluviometric sections of the Concordia River watershed, located in the state of Santa Catarina, southern Brazil. The spatial distribution of land use shows the predominance of Atlantic Forest in fluviometric section 1 (FS1) and pasture, forestry, agriculture, and Atlantic Forest in fluviometric section 2 (FS2). In each selected heavy rainfall event, the evolution rainfall height, the water level, and physicochemical parameters of water were analyzed. In all events, the water quality changed due to the heavy rainfall. After the events, an increase in water level and turbidity in both fluviometric sections were detected. In addition, the ammonium ion concentration increased in the river, and the pH value and nitrate concentration decreased. The electrical conductivity presented different behavior in each section. The dissolved oxygen concentration increased in 19 of 27 events. The principal component (PC1) correlated with the turbidity in FS1, and it correlated with level, turbidity, and pH in FS2.

On the Baiu frontal-scale rainfall characteristics and atmospheric conditions in the extremely heavy rainfall event around western Japan during 5-7 July 2018 with attention to the synoptic climatological viewpoint

2020 ◽  
Author(s):  
Kuranoshin Kato ◽  
Kengo Matsumoto ◽  
Takato Yamatogi ◽  
Chihiro Miyake
Keyword(s):  
Heavy Rainfall ◽  
Large Scale ◽  
Rainfall Amount ◽  
Heavy Rainfall Event ◽  
Atmospheric Conditions ◽  
Total Rainfall ◽  
Central Japan ◽  
Rainfall Characteristics ◽  
Western Japan ◽  
Eastern Japan

&lt;p&gt;&amp;#160;&amp;#160; In East Asia, a significant subtropical front called the Baiu/Meiyu front appears just before midsummer and brings the huge rainfall there, greatly influenced by the Asian summer monsoon. However, large-scale atmospheric features and rainfall characteristics (such as convective or stratiform rain) as well as the total rainfall amount around the front show rather great differences between the western and eastern portions. For example, in the western part of the Japan Islands (especially around Kyushu District, the most western part) and the Changjiang River Basin in Central China, the more frequent appearance of the heavy rainfall events due to the organized deep convective clouds than in the eastern Japan results in the larger climatological precipitation amount there. This is greatly related to the larger moisture transport toward the western part of the Baiu front than toward the eastern part. On the other hand, the rainfall characteristics around the front in the eastern Japan tend to be largely influenced by the cool Okhotsk air mass with rather stable stratification. Furthermore, their year-to-year, intraseasonal and short-period variations including the diversity of the &amp;#8220;heavy rainfall types&amp;#8221; are also very large.&lt;/p&gt;&lt;p&gt;The extreme events in association with the Baiu/Meiyu activity are greatly reflected by the above variability of the frontal activity. Inversely, it would be also important viewpoint that detailed examination of some extreme events could lead to the better understanding of the &amp;#8220;dynamic climatological features&amp;#8221; of the Baiu/Meiyu system itself.&lt;/p&gt;&lt;p&gt;In such concept, the present study will examine the frontal-scale rainfall features and the atmospheric conditions for the extremely heavy rainfall event around the Baiu front in western to central Japan during 5-7 July 2018. Although it is the common feature for the Baiu frontal rainfall heavy in western Japan that the frequent appearance of the meso-scale intense rain bands results in the huge total rainfall amount there, it is noted that the extremely large total rainfall area was distributed much more widely up to the central Japan with also considerable contribution of the long-persistent &amp;#8220;not-so-intense rain&amp;#8221; there, as often found in the heavy rainfall in the eastern Japan. Our analyses of the atmospheric fields suggest that this extreme event seems to be characterized by the strong mixture both of the large-scale factors for activating the &amp;#8220;western Japan Baiu&amp;#8221; and the &amp;#8220;eastern Japan Baiu&amp;#8221;.&lt;/p&gt;&lt;p&gt;As for the precipitation analyses, the 10-minute precipitation data at many meteorological stations in the Japan Islands area were used to discuss on the frontal-scale &amp;#8220;rainfall characteristics&amp;#8221; as well as the total rainfall amounts.&lt;/p&gt;

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.

Redistribution of landslide debris through episodic heavy rainfall events as revealed by multi-period Lidar DEMs

2020 ◽  
Author(s):  
Yu-Chang Chan ◽  
Yu-Chung Hsieh ◽  
Kou-Jen Chang
Keyword(s):  
Heavy Rainfall ◽  
Drainage Basin ◽  
Airborne Lidar ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Digital Elevation ◽  
Debris Removal ◽  
Elevation Changes ◽  
Heavy Rainfall Events ◽  
Landslide Debris

&lt;p&gt;Landslides are commonly triggered by heavy rainfall events, but how the loose landslide debris is redistributed through time and how fast the landslide scars are healed by vegetation are not well and precisely documented. Due to recent advances in airborne Lidar-derived digital elevation models, we are able to obtain precise DEMs at different time periods and analyze the redistribution of landslide debris that was once difficult to measure because of relatively minor elevation changes. Three periods of Lidar-derived DEMs were used to analyze a drainage basin that was affected by a heavy rainfall event and generated several landslide deposits and scars within the drainage basin in Taiwan. We selected a single drainage basin to better constrain the source of landslide debris for subsequent observations of landslide debris removal. How the landslide debris is transported and redistributed remains an important topic for understanding debris removal and evaluating post-landslide hazards in downstream areas. The multi-period high-resolution Lidar DEMs give the necessary accuracy to calculate small but significant volume changes that were not easily detectable from previous measuring techniques. Our results show that the landslide debris redistributed most effectively during later large rainfall events, and the landslide materials are minimally redistributed during small rainfall events. Areas without existing landslides were also insignificantly affected in terms of volume change even during large rainfall events. The standard deviation of elevations in the drainage basin is used to show how the topography was changed due to heavy rainfall events within the drainage basin. The concept of surface roughness may be useful to characterize the dissipation of landslide debris because the roughness values become lower during the debris redistribution process. The redistribution of landslide debris over the observed years suggests that the dissipation of landslide debris is mainly affected by by episodic heavy rainfall events and the landslide scars recover relatively quickly for smaller affected landslide regions.&lt;/p&gt;

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