In the extraodinarily warm airmass over Scandinavia, ahead of the cold front advancing from Norway, dewpoints will rise to around 18 deg C by 12 UTC over the area. Despite rather modest lapse rates, MLCAPE values of hundreds to around 1500 J/kg are forecast by models. At the same time, strong flow at low to mid-troposphere will ovespread the unstable airmass, resulting in favourable overlap of CAPE and shear for severe and well-organized convection.
0-6 km vertical wind shear will reach 15 - 25 m/s over a large area, suggesting a potential for supercells. With shear confined mostly to the lower troposphere, linear lift along the front and flow mostly parallel to the initiating boundary, there will be a tendency for storms to cluster quickly to a quasi-linear convective system. Bow-echoes embedded within such system may be capable of severe wind gusts as 850 to 700 hPa flow reaches up to 20 m/s. Excessive rainfall may also occur if numerous storms train over the same area, at least initially, when cold front moves more slowly. In the initial period, before the upscale growth happens, large hail may occur with supercells. Furthermore, given low LCLs, enhanced SRH and LLS reaching 10 - 15 m/s, supercells, or mesovortices embedded within a system, will also bear a risk of tornadoes. Storms will spread NE-wards during the forecast period and may reach Finland by Thursday morning.
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