After a soggy and very warm summer , the temperature trend certainly remained an unseasonably warm one in September. Here in Syracuse, when you average out all the high and low temperatures for September , you arrive at a temperature of 66 degrees. This is about three degrees above average, making September the ninth-warmest on record here. The more unsettled pattern should wind down early in the week as high pressure becomes more established over the Atlantic to the west of the UK.
This will help draw in colder Icelandic air from the north towards the UK that should build throughout the week. Evenings may become cool enough for sharp frosts to develop.
Drier and less windy conditions should also evolve over the week, particularly across Northern Ireland and Wales. There will remain a risk of a passing low pressure system across the North Sea early in the week before the threat should shift further towards the east. However, the Atlantic High will create some interference and impede any stronger systems. This would mean that any systems that do brush the British Isles will tend to be on the weaker side with relatively reduced precipitation.
The primary alternate scenario for this week would be for the Atlantic High to be centred further south and not extend quite as far north. The forecast still would lean a bit on the cool side for the week. However, with more periods of westerly winds as opposed to winds from the north, the risks for anomalous cold would not be as high.
This also would provide an increased chance for wetter and windier conditions to develop across primarily Scotland. Temperatures in York County have been unusually warm for this time of year, according to a meteorologist from the National Weather Service, with positively balmy weather forecast Wednesday and Thursday. Typically at this time in October, temperatures fall in the high 60s with lows in the 40s, Gartner said.
A frontal system coming through Friday should cool things down considerably for the weekend. Higher temperatures this week are in part caused by a high pressure system spreading across the South up through New England — calling for more sunshine and warmer weather.
When it comes to interpreting the results of event attribution studies, it matters what the question is. For example, a study asked whether recent wet summers in northwestern European were a response to retreating Arctic sea ice pdf, p The paper notes that, in a chaotic weather system, the complex dynamics of the atmosphere mean the size and path of a storm or heavy rainfall event has a large element of chance.
This can make it tricky to identify where climate change fits in, potentially underestimating its influence. Higher temperatures mean warmer seas, higher sea levels and more moisture evaporating into the atmosphere. These are changes that scientists can be more confident in, the authors write, and so should be the focus for attribution studies — rather than looking at changes to circulation patterns in the atmosphere.
For example, the paper reexamines an earlier study pdf, p15 that suggested climate change had reduced the chances of the five-day heavy rainfall event that hit north-east Colorado in September Trenberth and colleagues argue that while climate change might not have made the specific weather system that brought the rain more likely, it will have contributed to the sheer volume of moisture in the atmosphere.
While attribution studies of heatwaves are generally more straightforward than storms — as they focus on thermodynamic influences — the type of question they are asking is still important.
The Russian heatwave in is a good example of this. One study looking at the severity of the event did not find a role for climate change. Yet another one , which did find an influence, looked at the likelihood of the event.
This apparent contradiction is tackled by a third study that reconciles the other two. It is also important to stress that the absence of evidence for a link to climate change is not the same as evidence of absence. In other words, it does not necessarily mean there was no human influence, just that a particular analysis did not find one. This is why a single study should never be considered the final word on how climate change influences a given type of extreme weather.
Capetonians queue for water at natural springs around the city during the water crisis, January This mixed bag of results reflects the inherent complexity of droughts. And, again, the specific question matters. Conclusions about the role of climate change in a specific drought could depend on whether a study looks at temperature, precipitation or soil moisture, for example.
While much has been achieved in the field of extreme event attribution in a short space of time, scientists are constantly looking for ways to tailor their work to suit the people who might use it. One major goal since the early days of the field has been to expand extreme event attribution to cover a larger and more diverse geographical area.
Where in the world scientists can carry out attribution studies — and for what kind of events — will always be limited by the quality and availability of observed data and appropriate models. The attribution map highlights, for example, that there are relatively few studies of extreme weather in Africa and South America.
But, at the moment, there is also a heavy leaning towards weather events that are local to the modelling groups, or that have a particular scientific interest. Otto explains:. The UK, California and Boulder [in Colorado] are, therefore, studied much more than other parts of the world, but that does not necessarily make them places particularly impacted by climate change. This means that while the studies carried out so far are indicative of the role climate change is playing in extreme weather around the world, they should not be considered representative of all types of extreme weather everywhere, says Otto.
She tells Carbon Brief:. As well as expanding the science to cover different types of weather and more of the world, scientists are getting faster at turning the handle on extreme event attribution studies — sometimes crunching the numbers just days after an event has occurred. The rapid studies included here are all — bar one — produced by the World Weather Attribution WWA initiative, described earlier.
While the WWA individual rapid assessments are not individually peer-reviewed, they are conducted using methods that have been through the peer-review process. As the BAMS report explains:. By conducting the analysis in the immediate aftermath of a weather event, these rapid studies provide almost-real-time information on the climate change influence, rather than having to wait many months for a formal study.
In some cases, these rapid assessments are later published in peer-reviewed journals. In these cases, the formal study is included in the attribution map, rather than the initial analysis. In some cases, this means earlier rapid assessments are removed from the Carbon Brief map in order to add in the relevant peer-reviewed paper once it is published.
We started at the beginning of the year and so far we have tested our procedures on an analysis of the heatwave in Europe.
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