A case-study of a monsoon low that formed over the sea and intensified over land as seen in ECMWF analyses: Monsoon Low Intensification over Land in ECMWF Analyses

A case study is presented of a tropical low that formed near Darwin, Australia, during the monsoon and subsequently intensified over land. The study is based on European Centre for Medium Range Weather Forecast (ECMWF) analyses. Interpretations of the formation over the sea are given in terms of vorticity dynamics. The thermodynamic support for the intensification and maintenance of the low over land is investigated also. The analyses indicate that the intensification of the low depends on repeated bursts of deep convection occurring near the centre of the circulation that promote the further concentration of vorticity near the centre. This concentration of vorticity increases the local circulation about the centre, which amounts to increasing the local tangential wind speed and, through approximate gradient wind balance above the boundary layer, to a lowering of the central pressure. It is found that the horizontal transport of moisture into a mesoscale column centred on the low is approximately equal to the moisture lost by precipitation so that total precipitable water levels are not rapidly depleted over land. While the contribution to the overall moisture budget by surface fluxes is comparatively small, these fluxes are necessary to maintain conditionally unstable conditions near the vortex centre so that deep convective bursts can continue to occur there, even when the system is located far inland.GK and RKS acknowledges funding for tropical cyclone research from the German Research Council (Deutsche Forschungsgemeinschaft) under Grant no SM30/23-4 and the Office of Naval Research Global under Grant No. N62909-15-1-N021. MTM acknowledges the support of NSF grant AGS-1313948, NOAA HFIP grant N0017315WR00048, NASA grant NNG11PK021 and the U.S. Naval Postgraduate School.GK and RKS acknowledges funding for tropical cyclone research from the German Research Council (Deutsche Forschungsgemeinschaft) under Grant no SM30/23-4 and the Office of Naval Research Global under Grant No. N62909-15-1-N021. MTM acknowledges the support of NSF grant AGS-1313948, NOAA HFIP grant N0017315WR00048, NASA grant NNG11PK021 and the U.S. Naval Postgraduate School

Forecasting tropical cyclone wind hazards and impacts: Summary from the Tenth International Workshop on Tropical Cyclones (IWTC-10)

In this paper, we summarize findings from the Tenth International Workshop on Tropical Cyclones (IWTC-10) subgroup on forecasting wind hazards and impacts. We found that new approaches to TC wind hazard forecasts continue to be developed and are becoming an increasingly common product offered by operational centres. To add greater context to wind risk information for users, many operational and research centres are also working to develop impact-based forecasts that incorporate hazard, vulnerability, and exposure data. Efforts to develop tropical cyclone wind impact forecasts present resourcing challenges, and when compared to wind hazard forecasting, are generally still in their infancy. Overall, both operational and research centres are extending significant efforts to meet the strong public need for accurate predictions of TC wind hazards and impacts around the world

15 priorities for wind-waves research: an Australian perspective

The Australian marine research, industry, and stakeholder community has recently undertaken an extensive collaborative process to identify the highest national priorities for wind-waves research. This was undertaken under the auspices of the Forum for Operational Oceanography Surface Waves Working Group. The main steps in the process were first, soliciting possible research questions from the community via an online survey; second, reviewing the questions at a face-to-face workshop; and third, online ranking of the research questions by individuals. This process resulted in 15 identified priorities, covering research activities and the development of infrastructure. The top five priorities are 1) enhanced and updated nearshore and coastal bathymetry; 2) improved understanding of extreme sea states; 3) maintain and enhance the in situ buoy network; 4) improved data access and sharing; and 5) ensemble and probabilistic wave modeling and forecasting. In this paper, each of the 15 priorities is discussed in detail, providing insight into why each priority is important, and the current state of the art, both nationally and internationally, where relevant. While this process has been driven by Australian needs, it is likely that the results will be relevant to other marine-focused nations