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Convective/Thunderstorm Discussion: Summer/Autumn/Winter 2014-15
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...British Isles...
Deep cyclone with pressure at the center down to 950 hPa will move from Greenland to Scotland in the evening hours. Advection of cold polar air (-5C at 850 hPa) over warmer water areas will produce lapse rates up to 8C/km and provide thermodynamic instability measured by CAPE up to 200-300 J/kg. Wind flow in low and mid-levels is forecast to reach values of 20-25 m/s and thus such gusts are possible at the ground. NWP models compute that convection in this environment can enhance gusts even up to 30m/s. During the night and in the Monday's morning, rain will change into snow, thundersnow with stron wind in Ireland and Scotland is not ruled out. Although convection will occur, lightning activity will be rather marginal.0 -
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Never seen a level 2 over parts of ireland before :eek:
level 1 for restA level 1 was issued for the British Isles for chances of severe convective wind gusts and tornadoes.
A level 2 was issued for western Ireland and western Scotland mainly for severe convective wind gusts.
A deep low pressure system (<948 hPa in GFS model) moves to the north of Scotland. Its tight pressure gradients over the British Isles combined with the convective activity developing in the cool airmass pose a risk of severe wind gusts.
...Ireland and Scotland...
The threat is particularly concentrated along the west coast as most of the energy for thunderstorms in the unstable airmass is supplied by the lapse rate between ocean and cold mid levels. WInds over 30 m/s at low to mid levels can be transported to ground as severe wind gusts in convective downdrafts. Over land, the friction causes strong low-level wind shear >17 m/s which can support tornadoes, if strong updrafts could be maintained. Convection will initally (09-12Z) be organized linearly along the occlusion curled up around the low and will likely pose a more concentrated threat. A second round with more clustered storms should occur in the evening at the passage of a shortwave trough.0 -
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But, any kind of dusting of snow or even a couple of rumbles of thunder are most welcome. 
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