Origin of Strong Winds in an Explosive Mediterranean Extratropical Cyclone

Brancus, Mihaela; Schultz, David M.; Antonescu, Bogdan; Dearden, Chris; Ștefan, Sabina

doi:10.1175/mwr-d-19-0009.1

Cited by 11 publications

(19 citation statements)

References 42 publications

(56 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Severe weather events (e.g., heavy rainfall, intense wind, blizzard) occurring in eastern and southeastern Romania are often associated with extratropical cyclones over western Black Sea, generally of Mediterranean origin [1][2][3][4][5][6] .…”

Section: Introductionmentioning

confidence: 99%

Late-Spring Severe Blizzard Events over Eastern Romania: A Conceptual Model of Development

Caian

Andrei

2019

Atmosphere

View full text Add to dashboard Cite

In this paper, the mechanism and model-representation of a late-spring severe blizzard event on eastern Romania are studied. The mechanism relies on the coupled contribution of the tropospheric ageostrophic circulations associated to jet streaks. These circulations: (1) interact under local and regional forcing (sea surface temperature, topography and latent heat) and (2) feedback on enhancing an upper-level jet’s secondary streak, leading to a persistent, severe event. The enhanced secondary jet streak appears only for developing systems that lead to extreme impact, as shown by 40 years of knowledge of late-spring severe blizzards over the area. It is shown that actual regional high-resolution models are able to represent the occurrence and the mechanism of late-spring severe blizzard events, thus increasing the confidence on their ability to represent current and future climate extreme variability. Understanding the preconditioning of dynamic and thermodynamic processes indicated by this analysis could be useful in supporting the operational forecast analysis.

show abstract

Section: Introductionmentioning

confidence: 99%

Late-Spring Severe Blizzard Events over Eastern Romania: A Conceptual Model of Development

Caian

Andrei

2019

Atmosphere

View full text Add to dashboard Cite

show abstract

“…They conclude that CSI appears crucial for triggering the descent when the SJ is still within the cloud head, while II and SI take over later during the descent with a similar contribution. Similarly Brâncuş et al (2019) find that II was present in the last part of the SJ descent in an explosive Mediterranean cyclone as the SJ entered into the boundary layer, although, in contrast to the previous study, they concluded that mesoscale instability release was not important during the initial SJ descent. Finally, although Smart and Browning (2014) do not explicitly discuss the possible presence of dry instabilities in their case analysis of Storm Ulli (2012), they show the evolution of potential vorticity (PV) along three SJ trajectories in their Fig.…”

Section: Introductionmentioning

confidence: 59%

“…The proportion of cyclones with SJs may also increase in a future warmer climate (Martínez-Alvarado et al, 2018). Although the proportion of cyclones with SJs that lead to strong surface winds is not known, the likely current and future prevalence of cyclones with SJs and diagnosed presence of SJs in case studies of damaging European cyclones such as the Great Storm of 1987 (Browning, 2004) and the St Jude's Day Storm (Browning et al, 2015) motivate further research into their characteristics.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Idealised simulations of cyclones with robust symmetrically unstable sting jets

Volonté

Clark

Gray

2020

Weather Clim. Dynam.

View full text Add to dashboard Cite

Abstract. Idealised simulations of Shapiro–Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it was possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight into SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide range of sensitivity experiments. The control simulation contains a cyclone that fits the Shapiro–Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities along the airstream, including symmetric instability (SI). The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes. Dry instabilities, generated by vorticity tilting via slantwise frontal motions in the cloud head, exist in similar proportions to moist instabilities at the start of the SJ descent and are then released along the SJ. The observed evolution supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study. Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro–Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution. The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified. In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro–Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics.

show abstract

“…Christian in October 2013: Browning et al, 2015;Pantillon et al, 2018). Brâncuş et al (2019) investigate a cyclone, which developed an SJ over the Black Sea in December 2012, showing that SJs can also occur in more continentally influenced areas. To the best of our knowledge, however, no SJ has been documented to occur fully over continental Europe.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of sting‐jet storm Egon over continental Europe: Impact of surface properties and model resolution

Eisenstein

Pantillon

Knippertz

2019

Quart J Royal Meteoro Soc

View full text Add to dashboard Cite

Intense Shapiro–Keyser cyclones are often accompanied by a sting jet (SJ), an air stream that descends from the cloud head into the frontal‐fracture region and can cause extreme surface gusts. Previous case‐studies have concentrated on the North Atlantic and the British Isles. Here we present the first‐ever detailed analysis of an SJ over continental Europe and investigate the influence of topography on its dynamical evolution based on observations and high‐resolution simulations using the ICOsahedral Nonhydrostatic model (ICON). Windstorm Egon intensified over the English Channel and then tracked from northern France to Poland on 12–13 January 2017, causing gusts of almost 150 km·h−1 and important damage. ICON reproduces the storm dynamics, although it delays the explosive deepening, shifts the track southward over Belgium and Germany and underestimates gusts over land. Storm characteristics show weak sensitivity to varying grid spacing between 1.6 and 6.5 km, while switching off the convection parametrization at 3.3 km grid spacing improves correlations with surface observations but deteriorates the mean error. Trajectories reveal typical SJ characteristics such as mid‐level descent, strong acceleration and conditional symmetric and other mesoscale instabilities, while evaporative cooling is stronger than in previous cases from the literature, preventing drying during descent. The SJ identification and the occurrence of mesoscale instabilities depend considerably on model resolution, convective parametrization, output frequency and employed thresholds for trajectory selection. Sensitivity experiments with modified surface characteristics show that the combined effects of warm‐air blocking by the Alps, higher roughness over land and reduced surface fluxes cause Egon to fill more quickly and to move on a faster, more northern track across Germany. While the SJ response is complex, showing some compensating effects, surface gusts strongly increase when roughness is reduced. These results suggest that weather forecasters in continental Europe should be more aware of the potential risks associated with SJs.

show abstract

Origin of Strong Winds in an Explosive Mediterranean Extratropical Cyclone

Cited by 11 publications

References 42 publications

Late-Spring Severe Blizzard Events over Eastern Romania: A Conceptual Model of Development

Late-Spring Severe Blizzard Events over Eastern Romania: A Conceptual Model of Development

Idealised simulations of cyclones with robust symmetrically unstable sting jets

Dynamics of sting‐jet storm Egon over continental Europe: Impact of surface properties and model resolution

Contact Info

Product

Resources

About