Browsing by Author "Nowotarski, Christopher"

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Collaborative Research: Processes that Regulate Vertical Accelerations in Supercell Updrafts
Atmospheric Sciences; https://hdl.handle.net/20.500.14641/1093; National Science Foundation
The especially intense updrafts in supercell thunderstorms facilitate the production of large hail, tornadoes, extreme rainfall rates, and prolific lightning. As a result of their great impacts on society, considerable research efforts are warranted to better understand and predict the environmental factors that contribute to the vertical accelerations that give way to supercells' impressive updrafts. This collaborative research effort will utilize numerous, innovative high-resolution numerical modeling experiments coupled with observational datasets in order to understand the forcing for supercell updrafts at various heights over a range of realistic near-storm environments. Thus, this work has tangible broader impacts to society through its potential to improve understanding and forecasting of supercell thunderstorms and their related hazards as well as through training of a new generation of scientists. Motivated by a current lack of comprehensive understanding in these areas, this research will investigate the following scientific questions: (1) How do low-level stability, low-level shear, and low-level storm-relative flow conspire to determine a storm's effective inflow layer? (2) How do concurrent changes in low-level stability and shear, as occurs during the evening transition, influence the ratio of air ingested from different layers and the vertical profiles of buoyant and dynamic pressure accelerations in the lower portion of a supercell updraft? (3) How might the connection between storm-relative flow and updraft width influence an updraft's profile of buoyant and dynamic vertical accelerations? These questions will be answered using numerical simulations with a range of realism from highly idealized to real-data simulations of observed storms, wherein quantities such as the effective inflow layer, updraft forcing, and entrainment will be compared and verified via dual-Doppler radar observations when available.
Investigation and Forecast Improvements of Tornadoes in Landfalling Tropical Cyclones
Atmospheric Sciences; TAMU; DOC-National Oceanic and Atmospheric Administration
The two major goals of this project are: (1) Advance our understanding of tropical cyclone tornado (TCTOR) cell attributes and environments, focusing on differences between verified tornado warnings and false alarms. (2) Improve the operational forecasting and warning decision process through integration of observed cell attributes and near-cell environments. The specific objectives to accomplish these goals are as follows: (O1) Build a database of all tornadoes and tornado warnings in TCs in the United States since the NEXRAD dual-polarization upgrade that includes radar-based storm attributes and near-storm environment information from model analyses. (O2) Assess the skill of high-resolution model analyses and forecasts in depicting the low-level, near-cell environment for convective cells in TCs and forecast proxies for low-level rotation. (O3) Compare near-cell environment and storm attribute information between verified warnings and false alarms in the climatology to determine differences that may be leveraged to reduce false alarms. (O4) In partnership with NWS collaborators, assess the performance of current radar, high-resolution NWP, and storm-environment based TCTOR forecasting practices and heuristics. (O5) In partnership with NWS collaborators, improve and streamline TCTOR warning practices using information gained from the climatology, including development and evaluation of probabilistic hazard information (PHI) produced by a statistical model trained on data produced in our climatological database.
Investigation and Forecast Improvements of Tornadoes in Landfalling Tropical Cyclones
Atmospheric Sciences; TAMU; https://hdl.handle.net/20.500.14641/222; DOC-National Oceanic and Atmospheric Administration
Tornadoes in recent landfalling tropical cyclones (TCs) in the United States underscore the threat these phenomena pose to society and the unique forecast challenge they present to operational forecasters. Despite a fairly robust body of research in this area, significant gaps in our knowledge remain regarding the tropical cyclone tornado (TCTOR) climatology, radar-based storm attributes, and near-cell environments of tornadic and nontornadic convective cells in TCs. Moreover, recent improvements in observational networks (e.g., nationwide dual-polarization radar) and high-resolution operational models afford opportunities to study these phenomena in greater detail. Leveraging and expanding existing collaborations between the NWS and Texas A&M, this study seeks to advance our understanding of TCTOR cell attributes and environments, focusing on differences between verified tornado warnings and false alarms. The second major goal of this project is to improve the operational forecasting and warning decision process through integration of observed cell attributes and modeled near-cell environments. Specific objectives under these larger goals include: O1: Build a database of all tornadoes and tornado warnings in TCs in the United States since the NEXRAD dual-polarization upgrade that includes radar-based storm attributes and near-storm environment information from model analyses. O2: Assess the skill of high-resolution model analyses and forecasts in depicting 1) the low-level, near-cell environment for convective cells in TCs and 2) forecast proxies for low-level rotation (e.g., updraft helicity). O3: Compare near-cell environment and storm attribute information between verified warnings and false alarms in the climatology to determine differences that may be leveraged to reduce false alarms. O4: In partnership with NWS collaborators, assess the performance of current radar, high-resolution NWP, and storm-environment based TCTOR forecasting practices and heuristics. O5: In partnership with NWS collaborators, improve and streamline TCTOR warning practices using information gained from this climatology, including development and evaluation of probabilistic hazard information (PHI) produced by a statistical model trained on data produced in our climatological database. This proposed three-year project is relevant to the CSTAR program under the primary objective of engaging university researchers with operational NWS forecasters to improve basic understanding, forecasting, and warning accuracy for high impact weather events. Specifically, the proposed research addresses Program Priority 1b: “Improving application of Numerical Weather Prediction (NWP) information in the forecast and warning process at various time scales.” The proposed research also addresses Program Priority 1cii: through “developing Probabilistic Hazard Information (PHI).
Performance of Meteorological Services to Conduct Soundings in Four Locations Across the Southern USA for the National Severe Storms Lab (NSSL)
Atmospheric Sciences; TAMU; https://hdl.handle.net/20.500.14641/646; DOC-National Oceanic and Atmospheric Administration
This quote is for contracted research conducted at Texas A&M University as part of the Meso18-19 field campaign of the VORTEX-SE experiment managed by NSSL. Specifically, we will provide atmospheric soundings from the Texas A&M University Campus in College Station, TX location (CLIN 0001) under the solicitation. In accordance with the contract solicitation and project objectives, soundings will be launched six-hour intervals during ten special observing periods, each lasting 48 hours between 1 November 2018 and 30 April 2019. We will provide sounding data immediately after each launch and in an archived format on the VORTEX-SE data archive by 1 September 2019.