committed AUS$62.2 million dollars over a five year period to upgrade the Australian Bureau of Meteorology's weather service provision. The bulk of this funding is committed to acquiring and implementing radar hardware. Funding has also been directed at the development and operational implementation of radar data display software tools, algorithm-based warning decision tools and a graphically based thunderstorm warning production system. A National Thunderstorm Forecast Guidance System (NTFGS), used to display Numerical Weather Prediction (NWP) data, was also deployed for operational use around Australia in the latter part of 2003. This system, in conjunction with the newly developed software used to display radar data (3D- Rapic) with algorithm-based overlays and warning production tools (Thunderstorm Interactive Forecasting System; TIFS), constitute a tool set that

An overview of the Australian Bureau of Meteorology's end-to-end Thunderstorm Forecasting System is presented. This system relies substantially on three components: (a) the National Thunderstorm Forecast Guidance System (NTFGS), a software package that specifically displays those output fields from the 0.125 degrees Australian operational Numerical Weather Prediction (NWP) model (MesoLAPS) that are particularly relevant to diagnosing thunderstorm potential out to 48 hours, (b) a nowcasting visualisation tool called 3D-Rapic, which displays volumetric radar data as well as output from radar-based algorithms, and (c) the Thunderstorm Interactive Forecast System (TIES) for the dissemination of thunderstorm forecasts and severe thunderstorm warnings. TIES can ingest algorithm-diagnosed thunderstorm positions and tracks which are automatically diagnosed from the radar data.An Australian supercell hailstorm case study is then presented to showcase how forecasters can use the system outputs to facilitate decision making at various stages of the severe thunderstorm forecast process. Training and assessment issues associated with implementation of the forecast systems are discussed. In particular, it is concluded that forecasters must have an in-depth understanding of the NTFGS and radar algorithms for them to be used meaningfully. Such algorithms can facilitate the warning and decision-making process when used carefully in conjunction with the base data and other data types.

In July 2003 the Australian Government committed AUS$62.2 million dollars over a five year period to upgrade the Australian Bureau of Meteorology’s weather service provision. The bulk of this funding is committed to acquiring and implementing radar hardware. Funding has also been directed at the development and operational implementation of radar data display software tools, algorithm-based warning decision tools and a graphically based thunderstorm warning production system. A National Thunderstorm Forecast Guidance System (NTFGS), used to display Numerical Weather Prediction (NWP) data, was also deployed for operational use around Australia in the latter part of 2003. This system, in conjunction with the newly developed software used to display radar data (3DRapic) with algorithm-based overlays and warning production tools (Thunderstorm Interactive Forecasting System; TIFS), constitute a tool set that can be used end-to-end in the process of diagnosing potential severe weather environments, assessing storm severity on radar and the issuing of warnings. There are differing time scales for the severe thunderstorm forecasting process, ranging from days ahead where the NTFGS provides support through to the nowcast scale (0 – 3 hours) where 3D-Rapic and TIFS are the underpining tools. In order to utilise these forecast systems in a meaningful way it is important that the service requirements and forecast process be well defined and that forecasters have a clear understanding of these. The required scientific knowledge and system skills distilled from analysing the forecast process are embodied in radar and severe thunderstorm forecast competencies.

The 1996 Central Australian Fronts Experiment (CAFE96) was the third in a series of field experiments designed to better understand the structure and dynamics of late dry-season subtropical cold fronts that affect central Australia. In this paper, the behaviour of three fronts observed during CAFE96 are described in detail and the four other fronts that occurred are examined in the light of previous studies. In total, fourteen fronts were documented during the three field experiments, of which twelve crossed central Australia during the evening or early hours of the morning. Only one of the fourteen crossed central Australia during the late afternoon (Event 4 in CAFE96), and only one in the mid-morning (Event 6 in CAFE96). The latter front arrived at Alice Springs during the mid-morning and, as the daytime turbulent mixing increased, it ceased advancing northeastward and retrogressed. It subsequently retreated through Alice Springs, giving way to strong northwesterly winds and blowing dust. The front reversed direction once again and was observed at a station 70 km southeast of Alice Springs during the mid-afternoon. While it is probably quite common for the position of subtropical cold fronts to oscillate back and forth as the daytime turbulent mixing waxes and wanes, Event 6 is the first example to be documented in detail. Event 3 is more typical of the fronts observed in the two previous experiments, but is discussed briefly here because it is the best example to date exhibiting near-surface warming in a strip following the passage of the cold front. This warming was detected in satellite imagery and confirmed by surface measurements.

Using objective analyses, the synoptic environment and large-scale controlling mechanisms for two frontal events (Events 1 and 2) observed during the Central Australian Fronts Experiment (CAFE) are presented. The analyses are based on the Australian Bureau of Meteorology's Regional Assimilation and Prognosis system (RASP). While Event 1 is the main focus of the paper, we discuss briefly Event 2, mainly highlighting the similarities between the two systems.Although both events are associated with well-developed mid-latitude lows over southern Australia, the strongest gradients in temperature and velocity are analysed in the subtropics. Moreover, the low-level temperature gradients, relative vorticity, divergence and frontogenesis function all weaken during the daytime and rapidly strengthen at night. The nocturnal evolution is emphasised in the paper.In both events the analysed wind fields show that during the afternoon to the rear of the front, the boundary-layer minds are subgeostrophic because of the strong turbulent mixing there. After sunset the turbulent mixing subsides and the boundary layer stress is rapidly reduced. Consequently, the post-frontal ageostrophic winds rotate anticyclonically and a low-level nocturnal jet develops. Localised increases in the ageostrophic deformation and convergence accompany the formation of the nocturnal jet, which in turn rapidly strengthens the northern section of the front. This rapid frontogenesis may be the generation mechanism for the large-amplitude bore-waves observed during CAFE to propagate ahead of Events 1 and 2.