Bom climate drivers

The Bureau of Meteorology BOM has declared two major climate drivers linked to hot, dry conditions are officially underway in Australia, prompting further warnings that extreme heat could hit this spring and summer.

Victoria is well known for its variable climate. From year to year, four global climate processes vary their behaviour, potentially resulting in wetter or dryer seasons. From a farmer's perspective when they're are behaving they bring moisture from the oceans and allow it to fall over Victoria as rain. Hopefully delivering the right amount at the right time. But they don't always work the way we'd like them to and can sometimes scatter the mob, effectively chasing rainfall away from Victoria.

Bom climate drivers

Cosmos » News. The last positive IOD event occurred in Despite other weather bureaux declaring the climate phenomenon was in effect months ago, the BOM waited for the alignment of at least three of four climate criteria, which include:. The IOD has been trending positive for many weeks. In the last two weeks, we have seen the atmosphere over the tropical Pacific respond to that pattern and lock in a coupling of the ocean atmosphere. In general, southern Australia can expect warmer temperatures than average in spring and summer. The previous record in occurred during a compound event. Cooler oceans near Australia mean reduced evaporation and condensation of seawater in the atmosphere falls as rain over land. Together, warmer temperatures and reduced rainfall can prove challenging for the southern part of the continent, with already hot and dry summer conditions amplified by these events. Although soil moisture and high reservoir levels will potentially buffer against catastrophic fire amid hotter and drier conditions, fire experts say a compound event declaration should prompt bushfire readiness. Cosmos » News September 19, By Matthew Ward Agius. Despite other weather bureaux declaring the climate phenomenon was in effect months ago, the BOM waited for the alignment of at least three of four climate criteria, which include: A clear month sea surface warming trend was observed in key regions of the Pacific Ocean. Weaker-than-average trade winds blowing across the west and central Pacific for 2 in the last 3 months.

Reisinger, A.

But it wasn't until three months later, in September, that the event was officially declared underway. BOM climate researcher Matthew Wheeler, who co-authored a recent report proposing changes to the index , said this year was the "perfect example" of why the system was no longer the best fit. The event, which takes place over the Pacific Ocean, is characterised by a complex interaction between the ocean and the atmosphere which causes the two systems to effectively team up to start rearranging where rain falls. The "coupling" between the two systems is a crucial part of the event, as it leads to the event being locked in for a prolonged period of time. For the ocean component, the bureau compares temperatures in a certain part of the Pacific with the average. Other agencies, such as the US, have a slightly softer criteria and often tend to put more emphasis on the ocean indicators.

So what's next? It's the climate driver generally responsible for cooler, wetter conditions. That has coincided with widespread flooding across Australia in the past couple of years. Flooding continues in South Australia. It now appears that the weather driver which results in wetter conditions is easing rapidly, says BOM meteorologist Pieter Claasen. The latest BOM outlook, released on Wednesday, suggests there is a chance that could change next summer. It's complicated, but the weather drivers depend on water temperatures in the Pacific Ocean. This can lead to a major shift in weather patterns across the Pacific. For Australia this means more cooler water pools off the north coast. El Nino weakens the Walker Circulation over the Pacific, weakening easterly trade winds blowing towards Australia which eventually leads to less rain.

Bom climate drivers

This update confirms the wet conditions are likely to remain for at least a while longer. The update comes as a low pressure system lingers off the southern New South Wales coast, causing yet more rain in the south-east. Showers and storms are expected to continue for the rest of south-east and eastern Australia with potentially severe thunderstorms for coastal areas between Townsville and Wollongong. The BOM is predicting that heavy rainfall will be the primary risk, but warns damaging winds and large hail are possible. Five of the models are predicting the phenomenon to persist until at least the end of the year. Conditions are primed for widespread flooding even beyond what we have already seen over the last few weeks. Saturated catchments mean it is taking relatively little rain to trigger flooding. The update shows all but one climate model indicates that negative IOD conditions are likely to continue through November. The Indian Ocean Dipole typically breaks down as the monsoon moves south at the beginning of summer.

Poppy skins

The Intergovernmental Panel on Climate Change IPCC identified an increased frequency and intensity of heatwaves and extreme fire risk days in recent decades over Australia Reisinger et al. Although soil moisture and high reservoir levels will potentially buffer against catastrophic fire amid hotter and drier conditions, fire experts say a compound event declaration should prompt bushfire readiness. The seasons in which fires typically occur vary across the Australian continent: fires in northern Australia occur during the dry season in winter and spring, while in the southeast and southwest the fire season is in the hot dry summer and autumn. This is Ridgy, or as scientists like to call him, the Sub-tropical Ridge. Sam is an unreliable climate dog often changing his behaviour in a matter of weeks which can affect Victoria's rainfall. Other agencies, such as the US, have a slightly softer criteria and often tend to put more emphasis on the ocean indicators Dr Wheeler said the ocean and atmospheric indices usually tipped over the thresholds "about the same time". Eastie represents the deep low pressure systems that are an important climate feature along the south east coast of Australia. The declaration of the positive IOD comes earlier than expected, with BOM usually needing to see it exceed values for eight weeks before declaring it underway. CoastExchange CoastExchange was CoastAdapt's online forum in which users could interact with their peers to share ideas, approaches, opportunities, and more. The event, which takes place over the Pacific Ocean, is characterised by a complex interaction between the ocean and the atmosphere which causes the two systems to effectively team up to start rearranging where rain falls. Climate models show sustained warming above 0.

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However in recent years Indy has not been chasing moisture down south as often as farmers would like reducing the average rainfall for Victoria. Other adaptation forums. Present-day climate data Present-day climate data sources Understanding climate trends Understanding climate risks CoastAdapt datasets: present-day. The Bureau of Meteorology has several sections on their website to help explain the drivers of Victoria's climate: Australian Climate Influences ENSO wrap up Water and the Land For more information on the Climatedogs series, or to obtain copies of the animations, please contact Graeme Anderson on 03 or the. Figure 1 shows six major climatic zones over Australia. Southern Australia is affected by a large-scale circulation feature known as the sub-tropical ridge. Importance of adaptation Enablers and barriers Role of decision makers Barriers to adaptation Working with consultants. When all of the oceans are warm everywhere, as was the case this year, temperatures in the eastern Pacific must become even warmer to trigger a change in the atmosphere. These extremes can have a significant impact on communities, natural environments and regional economies; for many decisions, an understanding of extremes is more important than an understanding of average climate. Tait, and P.