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Atmospheric blockings are quasi-stationary high-pressure areas with large influences on our weather. We show that using the most common blocking index does not only lead to stationary blocks, but also to east- and westward moving blocks. These respective moving blocks are found to have different characteristics in size and location. Even though they are not stationary, they still impact our surface temperatures. Thus, for impact analyses no restriction in propagation velocity is needed.

The month of March marks the Arctic sea ice maximum when the ice cover extent reaches its peak within the annual cycle. This study chronicles the meteorological conditions that led to the anomalous, tandem March 2023 ice melt event in the Labrador and Bering seas. A sudden stratospheric warming event initiated the development of anticyclonic circulation patterns over these areas which aided northward transport of anomalously warm, moist air and drove their unusual sea ice melt.

The North Atlantic region serves as a source of moisture and energy for Mediterranean storms. Its impact over the Levant region remains an open question due to its smaller weather systems and their longer distance from the ocean. We find an optimal circulation pattern which allows North Atlantic influence to reach farther into the Eastern Mediterranean, thus making storms stronger and rainier. This may be relevant for future Mediterranean climate, which is projected to become much drier.

Mid-latitude atmospheric jet streams sometimes create 'waveguides', thought to increase the chance of quasi-stationary waves — atmospheric circulation patterns that lead to extreme weather events. I describe a new algorithm for identifying atmospheric waveguides, and show maps of waveguide frequency and strength. Waveguide strength is associated with an increased probability of quasi-stationary waves, although not in all regions; the connection is particularly strong over Europe during summer.

Western disturbances (WDs) are storms that predominantly affect north India and Pakistan during the winter months, where they play an important role in regional water security, but can also bring a range of natural hazards. In this review, we summarise recent literature across a range of topics: their structure and lifecycle, precipitation and impacts, interactions with large-scale weather patterns, representation in models, how well they are forecast, and their response to changes in climate.

In this study, we use large-ensemble climate model simulations to analyze extreme winters in the Barents Sea in a changing climate. We find that variability in both atmospheric processes and sea ice conditions determines the formation of such seasons in the present-day climate. The reduction in sea ice variability results in a decreasing importance of surface boundary conditions in a warmer climate, while the robust link shown for surface weather systems persists.

In this article, we analyse the ability of climate models to produce south foehn in the valleys of western Austria using a machine learning technique and assess, how well they capture different aspects of annual foehn occurrence. The performance of these models is largely influenced by the underlying global climate model. After weighting the models based on their performance, we found that foehn occurrence slightly decreases with global warming, but events tend to become more widespread.

Extreme winter cold temperatures in Europe have huge societal impacts. This study focuses on very extreme cold events, such as the record of winter 1963 in France, expected to become rarer due to climate change. We use a light and efficient rare event algorithm to simulate a large number of extreme cold winters over France, to analyse their characteristics. We find that despite fewer occurrences, their intensity remains steady. We analyse prevailing atmospheric circulation during these events.

The predictability of Mediterranean cyclones is investigated through a large data set of 2853 cyclones tracks, ensuring robust statistical results. The velocity of the cyclone appears to be determinant in the predictability of its position. In particular the position of specific slow cyclones located in the Gulf of Genoa is remarkably well predicted. It is also shown that the intensity of deep cyclones occuring in winter is particularly poorly predicted in the Mediterranean region.

The exchange of energy and moisture between the atmosphere and ocean maximises along strong meridional contrasts in sea surface temperature, such as across the Gulf Stream and Kuroshio. We find that these strong meridional contrasts confine and determine the position of evaporation and precipitation, as well as the storm occurrence and intensity. The general intensity of the water cycle and storm activity, however, are determined by the underlying absolute sea surface temperature.

Atmospheric blocking is a recurring phenomenon in midlatitudes, causing winter cold spells and summer heatwaves. Current models underestimate it, hindering understanding of global warming's impact on extremes. In this paper, we investigate whether stochastic parameterizations can improve blocking representation. We find that blocking frequency representation slightly deteriorates, following a change in midlatitude winds. We conclude by suggesting a direction for future model development.

Latent heating due to condensation can influence atmospheric circulation by strengthening or weakening horizontal temperature contrasts. Strong temperature contrasts intensify storms and imply the existence of strong upper tropospheric winds, called jets. It remains unclear whether latent heating preferentially reinforces or abates the existing jet. We show that this disagreement is attributable to how the jet is defined, confirming that latent heating reinforces the jet.

Our study investigates the dynamics of polygonal eyewall structures observed in intensifying hurricanes like Michael (2018) by using a simplified modeling approach. We develop a two-layer model to simulate the interactions between the free atmosphere and boundary layer to demonstrate the importance of different physical mechanisms in the intensification process. This simplified model offers insights into the interactions between dynamics and convection during hurricane intensification.

This study assesses existing methods for identifying the position and tilt of the North Atlantic eddy-driven jet, proposing a new feature-based approach. The new method overcomes limitations of other methods, offering a more robust characterization. Contrary to prior findings, the distribution of daily latitudes shows no distinct multi-modal structure, challenging the notion of preferred jet stream latitudes or regimes. This research enhances our understanding of North Atlantic dynamics.

Recent studies show that convective storms can produce anticyclonically rotating vortices (~10 km) referred to as negative potential vorticity (NPV), which can elongate to larger scales (~1000 km). Our composite analysis shows that elongated NPV frequently occurs along the Western North Atlantic tropopause where they are observed to accelerate jet stream winds and influence its evolution. This may impinge on aviation turbulence and weather forecasting despite its small-scale origin.

To improve decision-making in the water-energy-food nexus, we untangling the complex network of physical processes driving regional precipitation regimes in the present and near-future climates using a data-driven mechanistic approach to reduce the uncertaint of future projections. The main mechanistic link discovered by is that the generalised warming of the oceans promotes a suppression of precipitation in Northeast and Southeast Brazil, likely due to an intensified Hadley circulation.

Mediterranean cyclones are associated with extended rain, wind and wave impacts. Although beneficial for regional water resources, their passage may induce extreme weather, which is specially impactful when multiple hazards combine together. Here we show how the passage of Mediterranean cyclones increases the likelihood of rain-wind and wave-wind compounding, and how compound-cyclone statistics varies by region and season, but also depends on the presence of specific airflows around the cyclone.

A simple model is used to investigate the relation between small scale convective behaviour and large scale variability in the tropics arising from the coupling between moisture and dynamics. The moisture preferentially lies at either moist or dry states, and these clump together to form large scale aggregated regions. With tropical dynamics, these aggregated regions are localised at the equator and propagate. This forms an intermediate model between previous simpler models and numerical GCMs.

This study analyzes the 0 °C isotherm within the free troposphere in Patagonia from 1950 to 2021, using observational and model data. The model aligns well with observations, highlighting significant altitude variations between the western and eastern sides of Andes, a correlation between isotherm fluctuations and AAO index, and an upward trend in the study area (specially in northwest Patagonia).