Intense sea-effect snowfall case on the western coast of Finland

Olsson, Taru; Perttula, Tuuli; Jylhä, Kirsti; Luomaranta, Anna

doi:10.5194/asr-14-231-2017

Cited by 10 publications

(18 citation statements)

References 16 publications

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“…For both periods, the absolute values of CAPE reached during these events (Fig. 7a, b, d, e, g, h) are consistent with the range found by Olsson et al (2017) for the enhancement of snowfall by sea-air interactions. When looking at differences ( CAPE) between the warmer (1999-2018) and colder (1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998) period (Fig.…”

Section: Thermodynamic Changessupporting

confidence: 87%

“…To summarize our findings, there is an interplay of circulation and thermodynamic factors to explain the observed trends in maximum snowfalls in the Balkans: the analysis of CAPE shows that large values of this quantity are associated with heavy snowfalls in the selected countries. CAPE values of 70 J kg −1 are enough to trigger convection during winter time and enhance snowfall precipitation (Olsson et al, 2017). Furthermore, for all countries analyzed, the isobars associated with the cyclonic conditions embedded in Atlantic Ridge patterns indicate winds blowing from sea to land, thus favoring the advection of moisture and the formation of convective precipitation.…”

Section: Discussionmentioning

confidence: 90%

“…6d). The choice of CAPE as an indicator of stability during snowfall is motivated by previous works (e.g., Schultz, 1999;Olsson et al, 2017) where snowfall extremes were coassociated with the occurrence of high CAPE values. The box plots in Fig.…”

Section: Thermodynamic Changesmentioning

confidence: 99%

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An attempt to explain recent changes in European snowfall extremes

Faranda

2020

Weather Clim. Dynam.

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Abstract. The goal of this work is to investigate and explain recent changes in total and maximum yearly snowfall from daily data in light of current global warming or the interdecadal variability of atmospheric circulation. We focus on the period 1979–2018 and compare two different datasets: the ERA5 reanalysis data and the E-OBSv20.0 data, where snowfall is identified from rainfall by applying a threshold to temperature. We compute changes as differences from quantities computed for the periods 1999–2018 and 1979–1998. On the one hand, we show that the decline in average snowfall observed in almost all European regions is coherent with previous findings and can be linked to global warming. On the other hand, we observe contrasting changes in maxima and sometimes disagreement in the sign of changes in the two datasets. Coherent positive trends are found for a few countries in the Balkans. These have been investigated in details by looking at modifications in the atmospheric weather patterns as well as local thermodynamic factors concurring to large snowfall events. We link these changes to the stronger prevalence of Atlantic Ridge or blocking patterns associated with deeper cyclonic structures over the Adriatic and Tyrrhenian seas. These cyclones find warmer surfaces and large availability of humidity and convective available potential energy (CAPE), thus producing large snowfall amounts, enhanced by the Stau effect on the Balkan topography.

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Section: Thermodynamic Changessupporting

confidence: 87%

Section: Discussionmentioning

confidence: 90%

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An attempt to explain recent changes in European snowfall extremes

Faranda

2020

Weather Clim. Dynam.

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“…Despite decreasing monthly snow depth and shortening of the snow season, short-term strong snowfall events may still occur. An example of those was seen on the west coast of Finland in January 2016, when a new national daily snowfall record of 71 cm was measured due to a lake-effect phenomenon (Olsson et al, 2017). Additionally, blizzards may still occur, although their probability of occurrence is projected to decrease in a major part of northern Europe during the ongoing century (Groenemeijer et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

Snow cover trends in Finland over 1961–2014 based on gridded snow depth observations

Luomaranta

Aalto

Jylhä

2019

Intl Journal of Climatology

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Snow conditions in high‐latitude regions are changing in response to climate warming, and these changes are likely to accelerate as the warming proceeds. Here, we analyse daily gridded snow depth, temperature and precipitation data from Finland over the period 1961–2014 to discover the ongoing changes in monthly average snow depths (SN) and several snow‐related indices. Our results indicate that regional differences of changes in snow conditions can be relatively large, even within such a small district as Finland. Moreover, the interannual variation of the various snow indices was found to be larger in southern Finland than in northern Finland. The largest decrease in snow depth occurred in the southern, western and central parts of Finland in late winter and early spring. This decrease was driven by increasing mixed and liquid precipitation and, especially in spring, increasing temperature. In northern Finland, the decreasing trend of snow depth was most evident in spring, but no change occurred during winter months, although the amount of solid precipitation was found to increase in December–February. In the same months, temperature and the amount of mixed and liquid precipitation increased, likely counteracting the effects of the increasing solid precipitation on snow depth. The annual maximum snow depth that typically occurs in March was found to decrease in over 85% of Finland's area, most strongly in western coastal areas. In almost half of Finland's area, this decrease occurred despite increasing solid precipitation. Our findings highlight the complexity of the responses of snow conditions to climatic variability in northern Europe.

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“…Inland convective storms (Achberger and Chen 2006) and intense sea-effect snowfall in coastal regions (Olsson et al 2017) can generate significant EPEs in AF during summer and winter, respectively. Otherwise, regional EPEs are associated predominantly with weather fronts, often with high vertical velocities and moisture content (Hellström and Malmgren 2004;Hellström 2005;Mateeva et al 2015), and extremely strong fronts have become more frequent in Europe (Schemm et al 2017).…”

Section: Introductionmentioning

confidence: 99%

The role of atmospheric circulation patterns in driving recent changes in indices of extreme seasonal precipitation across Arctic Fennoscandia

et al. 2020

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Extreme precipitation events (EPEs) have a major impact across Arctic Fennoscandia (AF). Here we examine the spatial variability of seasonal 50-year trends in three EPEs across AF for 1968–2017, using daily precipitation data from 46 meteorological stations, and analyse how these are related to contemporaneous changes in the principal atmospheric circulation patterns that impact AF climate. Positive trends in seasonal wet-day precipitation (PRCPTOT) are widespread across AF in all seasons except autumn. Spring (autumn) has the most widespread negative (positive) trends in consecutive dry days (CDD). There is less seasonal dependence for trends in consecutive wet days (CWDs), but the majority of the stations show an increase. Clear seasonal differences in the circulation pattern that exerted most influence on these AF EPE trends exist. In spring, PRCPTOT and CDD are most affected by the Scandinavian pattern at more than half the stations while it also has a marked influence on CWD. The East Atlantic/Western Russia pattern generally has the greatest influence on the most station EPE trends in summer and autumn, yet has no effect during either spring or winter. In winter, the dominant circulation pattern across AF varies more between the different EPEs, with the North Atlantic Oscillation, Polar/Eurasia and East Atlantic patterns all exerting a major influence. There are distinct geographical distributions to the dominant pattern affecting particular EPEs in some seasons, especially winter, while in others there is no discernible spatial relationship.

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Intense sea-effect snowfall case on the western coast of Finland

Cited by 10 publications

References 16 publications

An attempt to explain recent changes in European snowfall extremes

An attempt to explain recent changes in European snowfall extremes

Snow cover trends in Finland over 1961–2014 based on gridded snow depth observations

The role of atmospheric circulation patterns in driving recent changes in indices of extreme seasonal precipitation across Arctic Fennoscandia

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