Ensemble-Based Analysis of Factors Leading to the Development of a Multiday Warm-Season Heavy Rain Event

2011 ◽  
Vol 139 (9) ◽  
pp. 3016-3035 ◽  
Author(s):  
Russ S. Schumacher
Keyword(s):  
United States ◽  
Numerical Models ◽  
Spatial Scales ◽  
Deep Convection ◽  
Warm Season ◽  
Heavy Rain ◽  
The United States ◽  
Rain Event ◽  
Slow Movement ◽  
Southern Plains

This study makes use of operational global ensemble forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) to examine the factors contributing to, or inhibiting, the development of a long-lived continental vortex and its associated rainfall. From 25 to 30 June 2007, a vortex developed and grew upscale over the southern plains of the United States. It was associated with persistent heavy rainfall, with over 100 mm of rain falling in much of Texas, Oklahoma, Kansas, and Missouri, and amounts exceeding 300 mm in southeastern Kansas. Previous research has shown that, in comparison with other rainfall events of similar temporal and spatial scales, this event was particularly difficult for numerical models to predict. Considering the ensemble members as different possible realizations of the evolution of the event, several methods are used to examine the processes that led to the development and maintenance of the long-lived vortex and its associated rainfall, and to its apparently limited predictability. Linear statistics are calculated to identify synoptic-scale flow features that were correlated to area-averaged precipitation, and differences between composites of “dry” and “wet” ensemble members are used to pinpoint the processes that were favorable or detrimental to the system’s development. The maintenance of the vortex, and its slow movement in the southern plains, are found to be closely related to the strength of a closed midlevel anticyclone in the southwestern United States and the strength of a midlevel ridge in the northern plains. In particular, with a weaker upstream anticyclone, the shear and flow over the incipient vortex are relatively weak, which allows for slow movement and persistent heavy rains. On the other hand, when the upstream anticyclone is stronger, there is stronger northerly shear and flow, which causes the incipient vortex to move southwestward into the high terrain of Mexico and dissipate. These relatively small differences in the wind and mass fields early in the ensemble forecast, in conjunction with modifications of the synoptic and mesoscale flow by deep convection, lead to very large spread in the resulting precipitation forecasts.

scholarly journals Composites of Heavy Rain Producing Elevated Thunderstorms in the Central United States

2017 ◽  
Vol 2017 ◽  
pp. 1-19 ◽  
Author(s):  
Laurel P. McCoy ◽  
Patrick S. Market ◽  
Chad M. Gravelle ◽  
Charles E. Graves ◽  
Neil I. Fox ◽  
...  
Keyword(s):  
United States ◽  
Heavy Rainfall ◽  
Warm Season ◽  
Heavy Rain ◽  
The United States ◽  
Large Variability ◽  
Null Case ◽  
Central United States ◽  
Mean Fields ◽  
Event Occurrence

Composite analyses of the atmosphere over the central United States during elevated thunderstorms producing heavy rainfall are presented. Composites were created for five National Weather Service County Warning Areas (CWAs) in the region. Events studied occurred during the warm season (April–September) during 1979–2012. These CWAs encompass the region determined previously to experience the greatest frequency of elevated thunderstorms in the United States. Composited events produced rainfall of >50 mm 24 hr−1 within the selected CWA. Composites were generated for the 0–3 hr period prior to the heaviest rainfall, 6–9 hours prior to it, and 12–15 hours prior to it. This paper focuses on the Pleasant Hill, Missouri (EAX) composites, as all CWA results were similar; also these analyses focus on the period 0–3 hours prior to event occurrence. These findings corroborate the findings of previous authors. What is offered here that is unique is (1) a measure of the interquartile range within the composite mean fields, allowing for discrimination between variable fields that provided a strong reliable signal, from those that may appear strong but possess large variability, and (2) composite soundings of two subclasses of elevated thunderstorms. Also, a null case (one that fits the composite but failed to produce significant rainfall) is also examined for comparison.

Heavy Rainfall and Flash Flooding

2017 ◽  
Author(s):  
Russ S. Schumacher
Keyword(s):  
Land Surface ◽  
Heavy Rainfall ◽  
Numerical Models ◽  
Spatial Scales ◽  
Deep Convection ◽  
Heavy Precipitation ◽  
The United States ◽  
Coupled Processes ◽  
Flash Flooding ◽  
The World

Heavy precipitation, which in many contexts is welcomed because it provides the water necessary for agriculture and human use, in other situations is responsible for deadly and destructive flash flooding. Over the 30-year period from 1986 to 2015, floods were responsible for more fatalities in the United States than any other convective weather hazard (www.nws.noaa.gov/om/hazstats.shtml), and similar findings are true in other regions of the world. Although scientific understanding of the processes responsible for heavy rainfall continues to advance, there are still many challenges associated with predicting where, when, and how much precipitation will occur. Common ingredients are required for heavy rainfall to occur, but there are vastly different ways in which the atmosphere brings the ingredients together in different parts of the world. Heavy precipitation often occurs on very small spatial scales in association with deep convection (thunderstorms), factors that limit the ability of numerical models to represent or predict the location and intensity of rainfall. Furthermore, because flash floods are dependent not only on precipitation but also on the characteristics of the underlying land surface, there are fundamental difficulties in accurately representing these coupled processes. Areas of active current research on heavy rainfall and flash flooding include investigating the storm-scale atmospheric processes that promote extreme precipitation, analyzing the reasons that some rainfall predictions are very accurate while others fail, improving the understanding and prediction of the flooding response to heavy precipitation, and determining how heavy rainfall and floods have changed and may continue to change in a changing climate.

scholarly journals Fungicide Rotation Programs for Managing Phytophthora Fruit Rot of Watermelon in Southeastern United States

2017 ◽  
Vol 18 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Chandrasekar (Shaker) S. Kousik ◽  
Pingsheng Ji ◽  
Daniel S. Egel ◽  
Lina M. Quesada-Ocampo
Keyword(s):  
United States ◽  
South Carolina ◽  
Phytophthora Capsici ◽  
Southeastern United States ◽  
Heavy Rain ◽  
Integrated Approach ◽  
The United States ◽  
Fruit Rot ◽  
Management Options ◽  
Before And After

About 50% of the watermelons in the United States are produced in the southeastern states, where optimal conditions for development of Phytophthora fruit rot prevail. Phytophthora fruit rot significantly limits watermelon production by causing serious yield losses before and after fruit harvest. Efficacy of fungicide rotation programs and Melcast-scheduled sprays for managing Phytophthora fruit rot was determined by conducting experiments in Phytophthora capsici-infested fields at three locations in southeastern United States (North Carolina, South Carolina, and Georgia). The mini seedless cultivar Wonder and seeded cultivar Mickey Lee (pollenizer) were used. Five weekly applications of fungicides were made at all locations. Significant fruit rot (53 to 91%, mean 68%) was observed in the nontreated control plots in all three years (2013 to 2015) and across locations. All fungicide rotation programs significantly reduced Phytophthora fruit rot compared with nontreated controls. Overall, the rotation of Zampro alternated with Orondis was highly effective across three locations and two years. Rotations of Actigard followed by Ranman+Ridomil Gold, Presidio, V-10208, and Orondis, or rotation of Revus alternated with Presidio were similarly effective. Use of Melcast, a melon disease-forecasting tool, may occasionally enable savings of one spray application without significantly impacting control. Although many fungicides are available for use in rotations, under very heavy rain and pathogen pressure, the fungicides alone may not offer adequate protection; therefore, an integrated approach should be used with other management options including well-drained fields.

scholarly journals Fine-Scale Population Genetic Structure and Within-Tree Distribution of Mating Types of Venturia effusa, Cause of Pecan Scab in the United States

2018 ◽  
Vol 108 (11) ◽  
pp. 1326-1336 ◽  
Author(s):  
Clive H. Bock ◽  
Carolyn A. Young ◽  
Katherine L. Stevenson ◽  
Nikki D. Charlton
Keyword(s):  
United States ◽  
Genetic Diversity ◽  
Asexual Reproduction ◽  
Population Genetic ◽  
Spatial Scales ◽  
The United States ◽  
Source Population ◽  
Mating Types ◽  
Fine Scale ◽  
Scale Population

Scab (caused by Venturia effusa) is the major disease of pecan in the southeastern United States. There is no information available on the fine-scale population genetic diversity or the occurrence of clonal types at small spatial scales that provides insight into inoculum sources and dispersal mechanisms, and potential opportunity for sexual reproduction. To investigate fine-scale genetic diversity, four trees of cultivar Wichita (populations) were sampled hierarchically: within each tree canopy, four approximately evenly spaced terminals (subpopulations) were selected and up to six leaflets (sub-subpopulations) were sampled from different compound leaves on each terminal. All lesions (n = 1 to 8) on each leaflet were sampled. The isolates were screened against a panel of 29 informative microsatellite markers and the resulting multilocus genotypes (MLG) subject to analysis. Mating type was also determined for each isolate. Of 335 isolates, there were 165 MLG (clonal fraction 49.3%). Nei’s unbiased measure of genetic diversity for the clone-corrected data were moderate to high (0.507). An analysis of molecular variance demonstrated differentiation (P = 0.001) between populations on leaflets within individual terminals and between terminals within trees in the tree canopies, with 93.8% of variance explained among isolates within leaflet populations. Other analyses (minimum-spanning network, Bayesian, and discriminant analysis of principal components) all indicated little affinity of isolate for source population. Of the 335 isolates, most unique MLG were found at the stratum of the individual leaflets (n = 242), with similar total numbers of unique MLG observed at the strata of the terminal (n = 170), tree (n = 166), and orchard (n = 165). Thus, the vast majority of shared clones existed on individual leaflets on a terminal at the scale of 10s of centimeters or less, indicating a notable component of short-distance dispersal. There was significant linkage disequilibrium (P < 0.001), and an analysis of Psex showed that where there were multiple encounters of an MLG, they were most probably the result of asexual reproduction (P < 0.05) but there was no evidence that asexual reproduction was involved in single or first encounters of an MLG (P > 0.05). Overall, the MAT1-1-1 and MAT1-2-1 idiomorphs were at equilibrium (73:92) and in most populations, subpopulations, and sub-subpopulations. Both mating types were frequently observed on the same leaflet. The results provide novel information on the characteristics of populations of V. effusa at fine spatial scales, and provide insights into the dispersal of the organism within and between trees. The proximity of both mating idiomorphs on single leaflets is further evidence of opportunity for development of the sexual stage in the field.

DNA-based quantification of Fusarium oxysporum f. sp. vasinfectum in environmental soils to describe spatial variation in inoculum density

Plant Disease ◽  
2022 ◽  
Author(s):  
Roy Davis ◽  
Thomas Isakeit ◽  
Thomas Chappell
Keyword(s):  
United States ◽  
Fusarium Oxysporum ◽  
Spatial Scales ◽  
The United States ◽  
Inoculum Density ◽  
Root Knot Nematode ◽  
West Texas ◽  
Sudden Appearance ◽  
Digital Polymerase Chain Reaction ◽  
Race 4

Fusarium wilt of cotton, caused by the soilborne fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV), occurs in regions of the United States where cotton (Gossypium spp.) is grown. Race 4 of this pathogen (FOV4) is especially aggressive and does not require the co-occurrence of the root knot nematode (Meloidogyne incognita) to infect cotton. Its sudden appearance in far-west Texas in 2016 after many years of being restricted to California is of great concern, as is the threat of its continued spread through the cotton-producing regions of the United States. The aim of this research was to analyze the spatial variability of FOV4 inoculum density in the location where FOV4 is locally emerging, using quantitative and droplet digital polymerase chain reaction (qPCR and ddPCR) methods. Soil samples collected from a field with known FOV4 incidence in Fabens, Texas were analyzed. Appreciable variation in inoculum density was found to occur at spatial scales smaller than the size of plots involved in cultivar trial research, and was spatially autocorrelated (Moran’s I, Z = 17.73, p < 0.0001). These findings indicate that for cultivar trials, accounting for the spatial distribution of inoculum either by directly quantifying it or through the use of densely-distributed “calibration checks” is important to the interpretation of results.

Thinking through Scale: The Role of State Governance in Globalizing North Pacific Fisheries

10.1068/a3469 ◽  
2001 ◽  
Vol 33 (10) ◽  
pp. 1807-1827 ◽  
Author(s):  
Becky Mansfield
Keyword(s):  
United States ◽  
North Pacific ◽  
Global Economy ◽  
Urban Governance ◽  
Spatial Scales ◽  
Full Range ◽  
The United States ◽  
International Partnerships ◽  
The North ◽  
Static View

Debates about the relationship between globalization and state power have often relied on a static view of spatial scales as discrete stages for social interaction. Focusing instead on the ‘production of scale’, several researchers have argued that globalization leads to rescaling of the state, as regulatory powers are realigned both upwards to supranational regimes and downwards to regional, local, and urban governance structures. Although this perspective quite usefully treats scale as relational, this ‘glocalization’ argument remains somewhat schematic and does not allow for a full range of possible scalar configurations. Highlighting instead heterogeneity of scalar relations, in this paper I analyze the ways that United States' fishery development in the North Pacific produced both national power and transnational economic activity. After extending political jurisdiction over waters up to 200 nautical miles from shore, the United States implemented fishery development policies that emphasized the ‘Americanization’ of the Alaska pollock fishery at the expense of an international, particularly Japanese, fishery. The outcomes of these policies, however, have been international partnerships, foreign direct investment, and increased international trade, all of which have made the pollock industry simultaneously national and transnational. Efforts to assert and implement control over ocean territory produced both the national state and globalization, which were mutually reinforcing rather than antagonistic. Treating national states and the global economy as complex, contingent scalar configurations facilitates analysis of the causes of variability in state – economy relations.

Delineation of Wellhead Protection Areas: Theory and Practice

1991 ◽  
Vol 24 (11) ◽  
pp. 239-250 ◽  
Author(s):  
Tereza C. B. F. Cleary ◽  
Robert W. Cleary
Keyword(s):  
United States ◽  
Groundwater Protection ◽  
Numerical Models ◽  
The United States ◽  
Pollution Sources ◽  
Theory And Practice ◽  
Safe Operation ◽  
Wellhead Protection ◽  
Protection Area ◽  
Potential Pollution

A preventive approach in groundwater protection programs throughout Europe and the United States, and almost unknown in Brazil, is to define the surface and subsurface areas, the Wellhead Protection Area (WHPA), from which a well or wellfield draws its water during a specified time. Overlaying a map of potential pollution sources on the delineated WHPA (Figure 1), those sources which fall within the WHPA boundaries are identified as definite threats, that need to be closely monitored, to the continued safe operation of the wellfield. Given the importance of effectively delineating the WHPA to protect public water supplies, the current delineation criteria, methods, and zones are presented, as well as analytical and numerical PC model analyses of different hydrogeological scenarios' effects on WHPA's size, shape and direction. Numerical models are shown to more accurately define WHPAs by taking into account the surrounding heterogeneous and anisotropic geology.

scholarly journals Shifts in Precipitation Accumulation Extremes During the Warm Season Over the United States

2018 ◽  
Vol 45 (16) ◽  
pp. 8586-8595 ◽  
Author(s):  
Cristian Martinez‐Villalobos ◽  
J. David Neelin
Keyword(s):  
United States ◽  
Warm Season ◽  
The United States

scholarly journals A Radar-Based Climatology of Mesoscale Convective Systems in the United States

2019 ◽  
Vol 32 (5) ◽  
pp. 1591-1606 ◽  
Author(s):  
Alex M. Haberlie ◽  
Walker S. Ashley
Keyword(s):  
United States ◽  
Agricultural Land ◽  
Gulf Coast ◽  
Warm Season ◽  
The United States ◽  
Corn Belt ◽  
High Plains ◽  
Convective System ◽  
Aquifer Recharge ◽  
Mesoscale Convective

Abstract This research applies an automated mesoscale convective system (MCS) segmentation, classification, and tracking approach to composite radar reflectivity mosaic images that cover the contiguous United States (CONUS) and span a relatively long study period of 22 years (1996–2017). These data afford a novel assessment of the seasonal and interannual variability of MCSs. Additionally, hourly precipitation data from 16 of those years (2002–17) are used to systematically examine rainfall associated with radar-derived MCS events. The attributes and occurrence of MCSs that pass over portions of the CONUS east of the Continental Divide (ECONUS), as well as five author-defined subregions—North Plains, High Plains, Corn Belt, Northeast, and Mid-South—are also examined. The results illustrate two preferred regions for MCS activity in the ECONUS: 1) the Mid-South and Gulf Coast and 2) the Central Plains and Midwest. MCS occurrence and MCS rainfall display a marked seasonal cycle, with most of the regions experiencing these events primarily during the warm season (May–August). Additionally, MCS rainfall was responsible for over 50% of annual and seasonal rainfall for many locations in the ECONUS. Of particular importance, the majority of warm-season rainfall for regions with high agricultural land use (Corn Belt) and important aquifer recharge properties (High Plains) is attributable to MCSs. These results reaffirm that MCSs are a significant aspect of the ECONUS hydroclimate.

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