BAMOS
Sep 2018
Workshop
summary
High Impact Weather Workshop
Kimberley Reid
University of Melbourne
In 2016, around 8000 people died from weather-related
disasters globally. Beth Ebert, from the Bureau of Meteorology,
announced this statistic when she introduced the first AMOS
workshop on High Impact Weather, or HIWeather, at the
University of Melbourne on the 10th of July.
The project aims to use an interdisciplinary approach to
understand high impact weather; increase society’s resilience;
enhance forecasting capacity from time-scales of minutes
to weeks; and produce social, economic and environmental
applications from the research.
The project will focus on five key weather events: flash flooding,
wildfires, winter weather hazards, extreme winds, and urban
heatwaves and air pollution. The talks for the first workshop
discussed the processes and predictability of these events.
Rob Warren (Monash University) revisited his Ph.D. to share a
recipe for Heavy Precipitation Events (HPEs). Flash flooding
from HPEs can develop on time-scales from minutes to hours,
so adequate warnings are a serious challenge. Rob led the
audience on a tour of HPEs from the USA to Cornwall and to
Reunion Island where a Tropical Cyclone interacting with
orography dumped six metres of rain over ten days.
Sarah Harris (Monash University) brought the audience back to
south-east Australia, which is one of the worst regions in the
world for socially disruptive fires. Sarah shared the challenges of
using the MacArthur Forest Fire Danger Index (FFDI) to classify
fire events across different locations. For example, low relative
humidity has a substantial effect on fire danger in central
Victoria, while drought factor is critical in the north. A new
fire danger index is in development and should address these
challenges.
Following a brief afternoon tea break, and the eviction of the
pub-next-door’s cat who had visited the lecture theatre for
head scratches from doting scientists, Hamish Ramsay (CSIRO)
kicked off the second half of the workshop with his talk on
extreme winds. A significant source of extreme winds are
Tropical Cyclones (TC); however TC intensity and wind speeds
are hard to predict and hard to measure. But solutions are
being developed. Quadruply nested grids can be used to model
how complex terrain exacerbates TC intensity, and ‘Doppler on
Wheels’ are being sent into eyewall mesovortices to measure
extreme local winds.
Acacia Pepler (Bureau) discussed winter weather hazards. In
the Northern Hemisphere, winter hazards include freezing rain
and blizzards, but here in Australia, East Coast Lows (ECLs) bring
destruction in the colder months. Defining and identifying ECLs
is still unsettled science. Annual frequencies can range from two
to twenty ECLs depending on who is defining them - and why.
New work in this area is looking at the 3D structure of ECLs to
understand their dynamics further.
Michael Reeder (Monash University) presented the final talk
of the day on Australian heatwaves. Michael’s speech was met
with a furore from the audience as he challenged the existing
paradigm by showing that 80% of the heating during the
heatwave that preceded Black Saturday was due to subsidence
from above and only 20% was due to surface processes or
horizontal advection.
There will be four more HIWeather workshops over the next
four years. Anyone interested in being involved with HIWeather
should contact Beth Ebert ([email protected]).
Visit the WMO website for more information about the project.
Workshop presenters. Left to Right: Rob Warren, Sarah Harris, Hamish Ramsay, Beth Ebert, Acacia Pepler & Michael Reeder.
Image: Kimberley Reid
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