scholarly journals Evaluation of Tools Used for Monitoring and Forecasting Flash Floods in the United States

2012 ◽  
Vol 27 (1) ◽  
pp. 158-173 ◽  
Author(s):  
Jonathan J. Gourley ◽  
Jessica M. Erlingis ◽  
Yang Hong ◽  
Ernest B. Wells
Keyword(s):  
United States ◽  
Flash Flood ◽  
The United States ◽  
Flash Floods ◽  
Urban Setting ◽  
Flash Flooding ◽  
Flood Prediction ◽  
Critical Success ◽  
Monitoring And Forecasting ◽  
First Time

Abstract This paper evaluates, for the first time, flash-flood guidance (FFG) values and recently developed gridded FFG (GFFG) used by the National Weather Service (NWS) to monitor and predict imminent flash flooding, which is the leading storm-related cause of death in the United States. It is envisioned that results from this study will be used 1) to establish benchmark performance of existing operational flash-flood prediction tools and 2) to provide information to NWS forecasters that reveals how the existing tools can be readily optimized. Sources used to evaluate the products include official reports of flash floods from the NWS Storm Data database, discharge measurements on small basins available from the U.S. Geological Survey, and witness reports of flash flooding collected during the Severe Hazards Analysis and Verification Experiment. Results indicated that the operational guidance values, with no calibration, were marginally skillful, with the highest critical success index of 0.20 occurring with 3-h GFFG. The false-alarm rates fell and the skill improved to 0.34 when the rainfall was first spatially averaged within basins and then reached 50% of FFG for 1-h accumulation and exceeded 3-h FFG. Although the skill of the GFFG values was generally lower than that of their FFG counterparts, GFFG was capable of detecting the spatial variability of reported flash flooding better than FFG was for a case study in an urban setting.

CONUS-Wide Evaluation of National Weather Service Flash Flood Guidance Products

2014 ◽  
Vol 29 (2) ◽  
pp. 377-392 ◽  
Author(s):  
Robert A. Clark ◽  
Jonathan J. Gourley ◽  
Zachary L. Flamig ◽  
Yang Hong ◽  
Edward Clark
Keyword(s):  
United States ◽  
Flash Flood ◽  
Weather Forecast ◽  
The United States ◽  
Future Research ◽  
Flash Flooding ◽  
Critical Success ◽  
Flooding Event ◽  
Flash Flood Guidance ◽  
Critical Success Index

Abstract This study quantifies the skill of the National Weather Service’s (NWS) flash flood guidance (FFG) product. Generated by River Forecast Centers (RFCs) across the United States, local NWS Weather Forecast Offices compare estimated and forecast rainfall to FFG to monitor and assess flash flooding potential. A national flash flood observation database consisting of reports in the NWS publication Storm Data and U.S. Geological Survey (USGS) stream gauge measurements are used to determine the skill of FFG over a 4-yr period. FFG skill is calculated at several different precipitation-to-FFG ratios for both observation datasets. Although a ratio of 1.0 nominally indicates a potential flash flooding event, this study finds that FFG can be more skillful when ratios other than 1.0 are considered. When the entire continental United States is considered, the highest observed critical success index (CSI) with 1-h FFG is 0.20 for the USGS dataset, which should be considered a benchmark for future research that seeks to improve, modify, or replace the current FFG system. Regional benchmarks of FFG skill are also determined on an RFC-by-RFC basis. When evaluated against Storm Data reports, the regional skill of FFG ranges from 0.00 to 0.19. When evaluated against USGS stream gauge measurements, the regional skill of FFG ranges from 0.00 to 0.44.

scholarly journals Diagnosing Moisture Sources for Flash Floods in the United States. Part II: Terrestrial and Oceanic Sources of Moisture

2019 ◽  
Vol 20 (8) ◽  
pp. 1511-1531 ◽  
Author(s):  
Jessica M. Erlingis ◽  
Jonathan J. Gourley ◽  
Jeffrey B. Basara
Keyword(s):  
United States ◽  
Boundary Layer ◽  
Land Surface ◽  
Flash Flood ◽  
The United States ◽  
Flash Floods ◽  
Heat Fluxes ◽  
Surface Model ◽  
Positive Anomaly ◽  
The Impact

Abstract Backward trajectories were derived from North American Regional Reanalysis data for 19 253 flash flood reports published by the National Weather Service to determine the along-path contribution of the land surface to the moisture budget for flash flood events in the conterminous United States. The impact of land surface interactions was evaluated seasonally and for six regions: the West Coast, Arizona, the Front Range, Flash Flood Alley, the Missouri Valley, and the Appalachians. Parcels were released from locations that were impacted by flash floods and traced backward in time for 120 h. The boundary layer height was used to determine whether moisture increases occurred within the boundary layer or above it. Moisture increases occurring within the boundary layer were attributed to evapotranspiration from the land surface, and surface properties were recorded from an offline run of the Noah land surface model. In general, moisture increases attributed to the land surface were associated with anomalously high surface latent heat fluxes and anomalously low sensible heat fluxes (resulting in a positive anomaly of evaporative fraction) as well as positive anomalies in top-layer soil moisture. Over the ocean, uptakes were associated with positive anomalies in sea surface temperatures, the magnitude of which varies both regionally and seasonally. Major oceanic surface-based source regions of moisture for flash floods in the United States include the Gulf of Mexico and the Gulf of California, while boundary layer moisture increases in the southern plains are attributable in part to interactions between the land surface and the atmosphere.

scholarly journals A Unified Flash Flood Database across the United States

2013 ◽  
Vol 94 (6) ◽  
pp. 799-805 ◽  
Author(s):  
Jonathan J. Gourley ◽  
Yang Hong ◽  
Zachary L. Flamig ◽  
Ami Arthur ◽  
Robert Clark ◽  
...  
Keyword(s):  
United States ◽  
Flash Flood ◽  
Relevant Information ◽  
The United States ◽  
Primary Sources ◽  
Flash Flooding ◽  
Regional Trends ◽  
Spatiotemporal Behavior ◽  
Flood Database ◽  
Flooding Events

Despite flash flooding being one of the most deadly and costly weather-related natural hazards worldwide, individual datasets to characterize them in the United States are hampered by limited documentation and can be difficult to access. This study is the first of its kind to assemble, reprocess, describe, and disseminate a georeferenced U.S. database providing a long-term, detailed characterization of flash flooding in terms of spatiotemporal behavior and specificity of impacts. The database is composed of three primary sources: 1) the entire archive of automated discharge observations from the U.S. Geological Survey that has been reprocessed to describe individual flooding events, 2) flash-flooding reports collected by the National Weather Service from 2006 to the present, and 3) witness reports obtained directly from the public in the Severe Hazards Analysis and Verification Experiment during the summers 2008–10. Each observational data source has limitations; a major asset of the unified flash flood database is its collation of relevant information from a variety of sources that is now readily available to the community in common formats. It is anticipated that this database will be used for many diverse purposes, such as evaluating tools to predict flash flooding, characterizing seasonal and regional trends, and improving understanding of dominant flood-producing processes. We envision the initiation of this community database effort will attract and encompass future datasets.

Real-Time Flash Flood Forecasting

2018 ◽  
Author(s):  
Jonathan J. Gourley ◽  
Robert A. Clark
Keyword(s):  
United States ◽  
Real Time ◽  
Flash Flood ◽  
Weather Prediction ◽  
The United States ◽  
Flood Forecasting ◽  
Flash Floods ◽  
Hydrologic Model ◽  
The World ◽  
Flash Flood Forecasting

Flash floods are one of the world’s deadliest and costliest weather-related natural hazards. In the United States alone, they account for an average of approximately 80 fatalities per year. Damages to crops and infrastructure are particularly costly. In 2015 alone, flash floods accounted for over $2 billion of losses; this was nearly half the total cost of damage caused by all weather hazards. Flash floods can be either pluvial or fluvial, but their occurrence is primarily driven by intense rainfall. Predicting the specific locations and times of flash floods requires a multidisciplinary approach because the severity of the impact depends on meteorological factors, surface hydrologic preconditions and controls, spatial patterns of sensitive infrastructure, and the dynamics describing how society is using or occupying the infrastructure. Real-time flash flood forecasting systems rely on the observations and/or forecasts of rainfall, preexisting soil moisture and river-stage states, and geomorphological characteristics of the land surface and subsurface. The design of the forecast systems varies across the world in terms of their forcing, methodology, forecast horizon, and temporal and spatial scales. Their diversity can be attributed at least partially to the availability of observing systems and numerical weather prediction models that provide information at relevant scales regarding the location, timing, and severity of impending flash floods. In the United States, the National Weather Service (NWS) has relied upon the flash flood guidance (FFG) approach for decades. This is an inverse method in which a hydrologic model is run under differing rainfall scenarios until flooding conditions are reached. Forecasters then monitor observations and forecasts of rainfall and issue warnings to the public and local emergency management communities when the rainfall amounts approach or exceed FFG thresholds. This technique has been expanded to other countries throughout the world. Another approach, used in Europe, relies on model forecasts of heavy rainfall, where anomalous conditions are identified through comparison of the forecast cumulative rainfall (in space and time) with a 20-year archive of prior forecasts. Finally, explicit forecasts of flash flooding are generated in real time across the United States based on estimates of rainfall from a national network of weather radar systems.

scholarly journals Diagnosing Moisture Sources for Flash Floods in the United States. Part I: Kinematic Trajectories

2019 ◽  
Vol 20 (8) ◽  
pp. 1495-1509 ◽  
Author(s):  
Jessica M. Erlingis ◽  
Jonathan J. Gourley ◽  
Jeffrey B. Basara
Keyword(s):  
United States ◽  
Flash Flood ◽  
The United States ◽  
Flash Floods ◽  
Reanalysis Data ◽  
Front Range ◽  
Flow Paths ◽  
South Central ◽  
Central Texas ◽  
Regional Reanalysis

Abstract This study uses backward trajectories derived from North American Regional Reanalysis data for 19 253 flash flood reports during the period 2007–13 published by the National Weather Service to assess the origins of air parcels for flash floods in the conterminous United States. The preferred flow paths for parcels were evaluated seasonally and for six regions of interest: the West Coast, Arizona, the Front Range of the Rocky Mountains, Flash Flood Alley in south-central Texas, the Missouri Valley, and the Appalachians. Parcels were released from vertical columns in the atmosphere at times and locations where there were reported flash floods; these were traced backward in time for 5 days. The temporal and seasonal cycles of flood events in these regions are also explored. The results show the importance of trajectories residing for long periods over oceanic regions such as the Gulf of Mexico and the Caribbean Sea. The flow is generally unidirectional with height in the lower layers of the atmosphere. The trajectory paths from oceanic genesis regions to inland hotspots and their orientation with height provide clues that can assist in the diagnosis of impending flash floods. Part II of this manuscript details the land–atmosphere interactions along the trajectory paths.

Changes in Future Flash Flood–Producing Storms in the United States

2020 ◽  
Vol 21 (10) ◽  
pp. 2221-2236 ◽  
Author(s):  
Erin Dougherty ◽  
Kristen L. Rasmussen
Keyword(s):  
United States ◽  
Climate Models ◽  
Flash Flood ◽  
Global Climate ◽  
The United States ◽  
Flash Floods ◽  
Global Climate Models ◽  
Future Climate ◽  
South Central ◽  
Rain Rates

AbstractFlash floods are high-impact events that can result in massive destruction, such as the May 2010 flash floods in the south-central United States that resulted in over $2 billion of damage. While floods in the current climate are already destructive, future flood risk is projected to increase based on work using global climate models. However, global climate models struggle to resolve precipitation structure, intensity, and duration, which motivated the use of convection-permitting climate models that more accurately depict these precipitation processes on a regional scale due to explicit representation of convection. These high-resolution convection-permitting simulations have been used to examine future changes to rainfall, but not explicitly floods. This study aims to fill this gap by examining future changes to rainfall characteristics and runoff in flash flood–producing storms over the United States using convection-permitting models under a pseudo–global warming framework. Flash flood accumulated rainfall increases on average by 21% over the United States in a future climate. Storm-generated runoff increases by 50% on average, suggesting increased runoff efficiency in future flash flood–producing storms. In addition to changes in nonmeteorological factors, which were not explored in this study, increased future runoff is possible due to the 7.5% K−1 increase in future hourly maximum rain rates. Though this median change in rain rates is consistent with Clausius–Clapeyron theory, some storms exhibit increased future rain rates well above this, likely associated with storm dynamics. Overall, results suggest that U.S. cities might need to prepare for more intense flash flood–producing storms in a future climate.

scholarly journals Mapping Flash Flood Severity in the United States

2017 ◽  
Vol 18 (2) ◽  
pp. 397-411 ◽  
Author(s):  
Manabendra Saharia ◽  
Pierre-Emmanuel Kirstetter ◽  
Humberto Vergara ◽  
Jonathan J. Gourley ◽  
Yang Hong ◽  
...  
Keyword(s):  
United States ◽  
High Resolution ◽  
Natural Hazard ◽  
Flash Flood ◽  
The United States ◽  
Flash Flooding ◽  
Fast Onset ◽  
Multidisciplinary Nature ◽  
Flooding Events ◽  
Gauged Basins

Abstract Flash floods, a subset of floods, are a particularly damaging natural hazard worldwide because of their multidisciplinary nature, difficulty in forecasting, and fast onset that limits emergency responses. In this study, a new variable called “flashiness” is introduced as a measure of flood severity. This work utilizes a representative and long archive of flooding events spanning 78 years to map flash flood severity, as quantified by the flashiness variable. Flood severity is then modeled as a function of a large number of geomorphological and climatological variables, which is then used to extend and regionalize the flashiness variable from gauged basins to a high-resolution grid covering the conterminous United States. Six flash flood “hotspots” are identified and additional analysis is presented on the seasonality of flash flooding. The findings from this study are then compared to other related datasets in the United States, including National Weather Service storm reports and a historical flood fatalities database.

scholarly journals The FLASH Project: Improving the Tools for Flash Flood Monitoring and Prediction across the United States

2017 ◽  
Vol 98 (2) ◽  
pp. 361-372 ◽  
Author(s):  
Jonathan J. Gourley ◽  
Zachary L. Flamig ◽  
Humberto Vergara ◽  
Pierre-Emmanuel Kirstetter ◽  
Robert A. Clark ◽  
...  
Keyword(s):  
United States ◽  
Real Time ◽  
Flash Flood ◽  
Rank Correlation ◽  
The United States ◽  
Hydrologic Model ◽  
Computationally Efficient ◽  
Modeling Framework ◽  
Flood Prediction ◽  
Peak Discharges

Abstract This study introduces the Flooded Locations and Simulated Hydrographs (FLASH) project. FLASH is the first system to generate a suite of hydrometeorological products at flash flood scale in real-time across the conterminous United States, including rainfall average recurrence intervals, ratios of rainfall to flash flood guidance, and distributed hydrologic model–based discharge forecasts. The key aspects of the system are 1) precipitation forcing from the National Severe Storms Laboratory (NSSL)’s Multi-Radar Multi-Sensor (MRMS) system, 2) a computationally efficient distributed hydrologic modeling framework with sufficient representation of physical processes for flood prediction, 3) capability to provide forecasts at all grid points covered by radars without the requirement of model calibration, and 4) an open-access development platform, product display, and verification system for testing new ideas in a real-time demonstration environment and for fostering collaborations. This study assesses the FLASH system’s ability to accurately simulate unit peak discharges over a 7-yr period in 1,643 unregulated gauged basins. The evaluation indicates that FLASH’s unit peak discharges had a linear and rank correlation of 0.64 and 0.79, respectively, and that the timing of the peak discharges has errors less than 2 h. The critical success index with FLASH was 0.38 for flood events that exceeded action stage. FLASH performance is demonstrated and evaluated for case studies, including the 2013 deadly flash flood case in Oklahoma City, Oklahoma, and the 2015 event in Houston, Texas—both of which occurred on Memorial Day weekends.

Variations in Flash Flood-Producing Storm Characteristics Associated with Changes in Vertical Velocity in a Future Climate in the Mississippi River Basin

2021 ◽  
Author(s):  
Erin Dougherty ◽  
Kristen L. Rasmussen
Keyword(s):  
United States ◽  
River Basin ◽  
Vertical Velocity ◽  
Mississippi River ◽  
Flash Flood ◽  
The United States ◽  
Flash Floods ◽  
Future Climate ◽  
Mississippi River Basin ◽  
Storm Characteristics

AbstractThe Mississippi River Basin (MRB) is a flash flood hotspot receiving the most frequent flash floods and highest average rainfall accumulation of any region in the United States. Given the destruction flash floods cause in the current climate in the MRB, it is critical to understand how they will change in a future, warmer climate in order to prepare for these impacts. Recent work utilizing convection-permitting climate simulations to analyze future precipitation changes in flash flood-producing storms in the United States shows that the MRB experiences the greatest future increase in flash flood rainfall. This result motivates the goal of the present study to better understand the changes to precipitation characteristics and vertical velocity in flash flood-producing storms in the MRB. Specifically, the variations in flash flood-producing storm characteristics related to changes in vertical velocity in the MRB are examined by identifying 484 historical flash flood-producing storms from 2002–2013 and studying how they change in a future climate using 4-km convection-permitting simulations under a pseudo-global warming framework. In a future climate, precipitation and runoff increase by 17% and 32%, respectively, in flash flood-producing storms in the MRB. While rainfall increases in all flash flood-producing storms due to similar increases in moisture, it increases the most in storms with the strongest vertical velocity, suggesting that storm dynamics might modulate future changes in rainfall. These results are necessary to predict and prepare for the multifaceted impacts of climate change on flash flood-producing storms in order to create more resilient communities.

The End of Empire and the Search for Justice

2018 ◽  
Author(s):  
John Linarelli ◽  
Margot E Salomon ◽  
Muthucumaraswamy Sornarajah
Keyword(s):  
United States ◽  
International Economic ◽  
International Law ◽  
International Economic Order ◽  
The United States ◽  
Economic Order ◽  
Global Context ◽  
Neoliberal Ideology ◽  
First Time

This chapter is a study of the themes of the New International Economic Order (NIEO). It begins with the notion of justice that had been constructed in imperial law to justify empire and colonialism. The NIEO was the first time a prescription was made for justice in a global context not based on domination of one people over another. In its consideration of the emergence of a new notion of justice in international law, the chapter discusses the reasons for the origins of the NIEO, and goes on to describe the principles of the NIEO and the extent to which they came into conflict with dominant international law as accepted by the United States and European states. Next the chapter deals with the rise of the neoliberal ideology that led to the displacement of the NIEO and examines the issue of whether the NIEO and its ideals have passed or whether they continue to be or should be influential in international law. Finally, the chapter turns to the ideas of the NIEO alongside new efforts at promoting a fuller account of justice by which to justify and evaluate international law.

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