Too dry, too hot, or too wet: Increasing weather persistence in European summer , say researchers

Posted: December 8, 2021 by oldbrew in climate, modelling, research, Temperature, weather
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Omega blocking highs can remain in place for several days or even weeks [image credit: UK Met Office]


No prizes for guessing how this story ends: it’s your fault, or so the researchers want us to believe. Human-caused emissions of trace gases are supposed to have made weather systems more prone to being stationary for longer, reports Phys.org. But where’s the mechanism that points to humans, we may ask. Blocked weather itself is a long-known and well understood phenomenon.
– – –
“In our study, we show that persistent weather conditions have an increasing similarity in summer over the North Atlantic, Europe and Siberia, favoring more pronounced extreme weather events. In Europe alone, about 70% of the land area is already affected by more persistent weather situations,” says Peter Hoffmann from the Potsdam-Institute for Climate Impact Research (PIK), lead author of the study published in Nature’s Scientific Reports.

“This means that people, especially in densely populated Europe, will likely experience more and also stronger and more dangerous weather events.”

Prolonged sunny or rainy conditions lead to extreme events

To prove this, the scientists analyzed the persistence of specific weather conditions. They applied established image comparison methods on atmospheric data, comparing millions of successive weather circulation patterns worldwide over the last 40 years. They especially looked at two individual extreme events, the 2010 heat wave over Russia and the extraordinary dry summer over Europe in 2018.

“We found that weather patterns in general are more persistent now than some decades ago,” says Hoffmann. “Especially in summer, heat waves often last longer now, and also rainfall events tend to linger longer and to be more intense. The longer these weather conditions last, the more intense the extremes can become, both on the warm and dry side as well as on the steady rain side.”

The rise in persistent weather conditions is to a large extent due to dynamical changes in the atmosphere as the westerly winds tend to stop pushing forward weather systems which therefore become more persistent, turning some sunny days into heatwaves of several weeks as well as intensive rainfall into floods.

Full report here.

Comments
  1. […] Too dry, too hot, or too wet: Increasing weather persistence in European summer , say research… […]

  2. ilma630 says:

    Could this be that as natural warming rates differ between the poles and equator, the temperature differential is reduced, so weather systems move more slowly?

  3. oldbrew says:

    No long-term trend in waviness of jet streams in the study cited below. Their focus is on autumn and winter, but they comment that any waviness changes are ‘not statistically significant in either season’ (i.e. spring/summer or autumn/winter).

    In this new study, Dr. Blackport and Professor Screen studied not only climate model simulations but also the observed conditions going back 40 years.

    They found that the previously reported trend toward a wavier circulation during autumn and winter has reversed in recent years, despite continued Arctic amplification.

    This reversal has resulted in no long-term trends in waviness, in agreement with climate model simulations, which also suggest little change in “waviness” in response to strong Arctic warming.

    Jet stream not getting ‘wavier’ despite Arctic warming, say researchers


    – – –
    Pacific Northwest heatwave, end of June 2021 — scroll down to the third GIF (‘JET STREAM’) here: ‘https://twitter.com/ScottDuncanWX/status/1408443318749564935’

    Heat is being transported into areas that don’t normally receive it from such a warm source.

  4. stpaulchuck says:

    more blazing bull hockey changing the story more often than their shorts

    My favorite a couple years ago was, “This is the cooling caused by the global warming.” HUH?

    My other favorite was, “The higher temperatures will create greater oceanic evaporation leading to more and stronger rainstorms…(later in the article) There will be in increase in droughts that will last longer.” HUH??

  5. tom0mason says:

    Ignore this nonsense and read H.H. Lambs discourse on wavy jet-streams causes and effects. It’s saner, more logical, and offers observations as evidence.

  6. Graeme No.3 says:

    @stpaulchuck:
    One that keeps coming up in Australia is the 2008 prediction that the (then current) drought in Australia may never break (Bureau of Meteorology). And from the Climate Commissioner “Sydney dams may never fill”, “Adelaide could run out of water by the end of 2009” and “Perth could be the first city abandoned because of climate change”.
    2010 Floods in northern NSW (and SE Queensland)
    2011 Brisbane Floods January. a wave of brown water inundated the city in the biggest floods to hit Queensland’s capital since 1974
    (The Guardian 2013 Floods in Australia 2010/11 lowered the world sea level).
    2015: the Hunter region, along with Central Coast and Sydney, was lashed by wild weather. It brought heavy rainfall and disrupted power supply to over 200,000 homes. The storms led to some of the most significant flooding that many residents in the region had experienced in 60 years
    2017: Heavy falls were recorded along most coastal districts of New South Wales.
    2020: major flooding in Qld and NSW
    2021 40,000 evacuated from flood zones.The Bureau of Meteorology warned cells like this could become more regular throughout the rest of summer, following the wettest November since records began. He said more rain on the way.

    The overnight drenching prompted Queensland Premier Annastacia Palaszczuk to officially rule out water restrictions this summer.

  7. oldbrew says:

    Published: 19 March 2021
    Past megadroughts in central Europe were longer, more severe and less warm than modern droughts

    Moreover, we show that the recent drought events (e.g., 2003, 2015, and 2018), are within the range of natural variability and they are not unprecedented over the last millennium.
    . . .
    In 2018, the central part of Europe, especially Germany, experienced the warmest April-to-July months since 1880 (Supplementary Fig. 1a) and in some locations all-time maximum temperatures were recorded. This situation was exacerbated by a rainfall deficit from February to November 2018 (Supplementary Fig. 1b), when the average precipitation reached, on average, just 58% of the climatological rainfall amount. The analysis shows that this particular long-lasting warm and dry year was produced and maintained by a long-lived blocking event.
    . . .
    …the two western European megadroughts might have been the result of an interplay between solar extremes, cold North Atlantic surface waters, enhanced blocking activity and explosive volcanism.
    [bold added]

    https://www.nature.com/articles/s43247-021-00130-w
    – – –
    ‘all-time maximum temperatures were recorded’ – meaning what? They don’t have ‘all-time’ data.

  8. oldbrew says:

    Here comes autumn/winter’s version of a blocking high…

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