This review prepared for the fourth International Workshop on Tropical Cyclone Landfall Processes(IWTCLP-4) summarizes the most recent(2015-2017) theoretical and practical knowledge in the field of tropical cyclone(TC...This review prepared for the fourth International Workshop on Tropical Cyclone Landfall Processes(IWTCLP-4) summarizes the most recent(2015-2017) theoretical and practical knowledge in the field of tropical cyclone(TC) track, intensity, and structure rapid changes at or near landfall. Although the focus of IWTCLPIV was on landfall, this summary necessarily embraces the characteristics of storms during their course over the ocean prior to and leading up to landfall. In the past few years, extremely valuable observational datasets have been collected for TC forecasting guidance and research studies using both aircraft reconnaissance and new geostationary or low-earth orbiting satellites at high temporal and spatial resolution. Track deflections for systems near complex topography such as that of Taiwan and La Réunion have been further investigated, and advanced numerical models with high spatial resolution necessary to predict the interaction of the TC circulation with steep island topography have been developed. An analog technique has been designed to meet the need for longer range landfall intensity forecast guidance that will provide more time for emergency preparedness. Probabilistic track and intensity forecasts have also been developed to better communicate on forecast uncertainty. Operational practices of several TC forecast centers are described herein and some challenges regarding forecasts and warnings for TCs making landfall are identified. This review concludes with insights from both researchers and forecasters regarding future directions to improve predictions of TC track, intensity, and structure at landfall.展开更多
Prediction of the potentially devastating impact of landfalling tropical cyclones(TCs)relies substantially on numerical prediction systems.Due to the limited predictability of TCs and the need to express forecast conf...Prediction of the potentially devastating impact of landfalling tropical cyclones(TCs)relies substantially on numerical prediction systems.Due to the limited predictability of TCs and the need to express forecast confidence and possible scenarios,it is vital to exploit the benefits of dynamic ensemble forecasts in operational TC forecasts and warnings.RSMCs,TCWCs,and other forecast centers value probabilistic guidance for TCs,but the International Workshop on Tropical Cyclones(IWTC-9)found that the“pull-through”of probabilistic information to operational warnings using those forecasts is slow.IWTC-9 recommendations led to the formation of the WMO/WWRP Tropical Cyclone-Probabilistic Forecast Products(TC-PFP)project,which is also endorsed as a WMO Seamless GDPFS Pilot Project.The main goal of TC-PFP is to coordinate across forecast centers to help identify best practice guidance for probabilistic TC forecasts.TC-PFP is being implemented in 3 phases:Phase 1(TC formation and position);Phase 2(TC intensity and structure);and Phase 3(TC related rainfall and storm surge).This article provides a summary of Phase 1 and reviews the current state of the science of probabilistic forecasting of TC formation and position.There is considerable variability in the nature and interpretation of forecast products based on ensemble information,making it challenging to transfer knowledge of best practices across forecast centers.Communication among forecast centers regarding the effectiveness of different approaches would be helpful for conveying best practices.Close collaboration with experts experienced in communicating complex probabilistic TC information and sharing of best practices between centers would help to ensure effective decisions can be made based on TC forecasts.Finally,forecast centers need timely access to ensemble information that has consistent,user-friendly ensemble information.Greater consistency across forecast centers in data accessibility,probabilistic forecast products,and warnings and their communication to users will produce more reliable information and support improved outcomes.展开更多
This review,which was adapted from a Tenth International Workshop on Tropical Cyclones(IWTC-10)report,discusses research findings and operational practices relevant to cyclone types and phase transitions(extratropical...This review,which was adapted from a Tenth International Workshop on Tropical Cyclones(IWTC-10)report,discusses research findings and operational practices relevant to cyclone types and phase transitions(extratropical,subtropical,and tropical).The cyclone phase space(CPS)method is widely used in both historical investigations and real-time evaluation of cyclone type and transition;however,CPS parameter values depend on input data resolution,and universal thresholds do not currently exist to delineate when a cyclone transitions from one type to another.Assessments of phase transitions in a changing climate highlight potential latitude shifts in extratropical transition and increased potential for tropical transition,but realistic projections of future trends likely require high-resolution simulations that can capture the cyclone warm core.Operational meteorological centers apply varied approaches to cyclone classification via CPS parameters and other criteria,some of which depend on the tropical basin,yet these approaches cannot fully address challenges in operational classification and subsequently in communicating risks associated with these phase transitions.We recommend a multivariate historical assessment of tropical and subtropical cyclones across all basins in which they occur,including the South Atlantic Ocean and the Mediterranean Sea,to identify the potential for a more universal cyclone classification approach that meets operational needs.展开更多
文摘This review prepared for the fourth International Workshop on Tropical Cyclone Landfall Processes(IWTCLP-4) summarizes the most recent(2015-2017) theoretical and practical knowledge in the field of tropical cyclone(TC) track, intensity, and structure rapid changes at or near landfall. Although the focus of IWTCLPIV was on landfall, this summary necessarily embraces the characteristics of storms during their course over the ocean prior to and leading up to landfall. In the past few years, extremely valuable observational datasets have been collected for TC forecasting guidance and research studies using both aircraft reconnaissance and new geostationary or low-earth orbiting satellites at high temporal and spatial resolution. Track deflections for systems near complex topography such as that of Taiwan and La Réunion have been further investigated, and advanced numerical models with high spatial resolution necessary to predict the interaction of the TC circulation with steep island topography have been developed. An analog technique has been designed to meet the need for longer range landfall intensity forecast guidance that will provide more time for emergency preparedness. Probabilistic track and intensity forecasts have also been developed to better communicate on forecast uncertainty. Operational practices of several TC forecast centers are described herein and some challenges regarding forecasts and warnings for TCs making landfall are identified. This review concludes with insights from both researchers and forecasters regarding future directions to improve predictions of TC track, intensity, and structure at landfall.
文摘Prediction of the potentially devastating impact of landfalling tropical cyclones(TCs)relies substantially on numerical prediction systems.Due to the limited predictability of TCs and the need to express forecast confidence and possible scenarios,it is vital to exploit the benefits of dynamic ensemble forecasts in operational TC forecasts and warnings.RSMCs,TCWCs,and other forecast centers value probabilistic guidance for TCs,but the International Workshop on Tropical Cyclones(IWTC-9)found that the“pull-through”of probabilistic information to operational warnings using those forecasts is slow.IWTC-9 recommendations led to the formation of the WMO/WWRP Tropical Cyclone-Probabilistic Forecast Products(TC-PFP)project,which is also endorsed as a WMO Seamless GDPFS Pilot Project.The main goal of TC-PFP is to coordinate across forecast centers to help identify best practice guidance for probabilistic TC forecasts.TC-PFP is being implemented in 3 phases:Phase 1(TC formation and position);Phase 2(TC intensity and structure);and Phase 3(TC related rainfall and storm surge).This article provides a summary of Phase 1 and reviews the current state of the science of probabilistic forecasting of TC formation and position.There is considerable variability in the nature and interpretation of forecast products based on ensemble information,making it challenging to transfer knowledge of best practices across forecast centers.Communication among forecast centers regarding the effectiveness of different approaches would be helpful for conveying best practices.Close collaboration with experts experienced in communicating complex probabilistic TC information and sharing of best practices between centers would help to ensure effective decisions can be made based on TC forecasts.Finally,forecast centers need timely access to ensemble information that has consistent,user-friendly ensemble information.Greater consistency across forecast centers in data accessibility,probabilistic forecast products,and warnings and their communication to users will produce more reliable information and support improved outcomes.
文摘This review,which was adapted from a Tenth International Workshop on Tropical Cyclones(IWTC-10)report,discusses research findings and operational practices relevant to cyclone types and phase transitions(extratropical,subtropical,and tropical).The cyclone phase space(CPS)method is widely used in both historical investigations and real-time evaluation of cyclone type and transition;however,CPS parameter values depend on input data resolution,and universal thresholds do not currently exist to delineate when a cyclone transitions from one type to another.Assessments of phase transitions in a changing climate highlight potential latitude shifts in extratropical transition and increased potential for tropical transition,but realistic projections of future trends likely require high-resolution simulations that can capture the cyclone warm core.Operational meteorological centers apply varied approaches to cyclone classification via CPS parameters and other criteria,some of which depend on the tropical basin,yet these approaches cannot fully address challenges in operational classification and subsequently in communicating risks associated with these phase transitions.We recommend a multivariate historical assessment of tropical and subtropical cyclones across all basins in which they occur,including the South Atlantic Ocean and the Mediterranean Sea,to identify the potential for a more universal cyclone classification approach that meets operational needs.
