Convective/Thunderstorm Discussion 2013/14

eastmayo wrote: »

Yes the same here near knock airport.would expect some storms later...hopefully anyway.

Synopsis:

Blocking persists across the North Sea, but troughing will begin to develop and dig further south from the eastern North Atlantic down towards western Iberia. This places the forward side of the upper trough increasingly over SW Britain through this forecast period, particularly later in the day and overnight, promoting some convective weather opportunities.

Discussion:
On the forward side of the approaching upper trough, advection of a high WBPT plume will occur over SW Britain and Ireland. The advance of a shortwave trough from the south will allow destabilisation of this airmass, with the potential for some elevated convection to occur along the plume (ThetaE ridge) axis.

Ongoing elevated thunderstorms may be present during the first part of the morning, moving northwestwards from the Cherbourg Peninsula towards Cornwall/Devon. Naturally NWP output continues to struggle simulating the depth and coverage of elevated convection, but there is some reasonable inter-model agreement for the remnants at least of elevated thunderstorms to affect the far SW through Sunday morning, although probably weakening all the while. These may also continue to drift towards S/SE Ireland by the afternoon, although here models tend to diverge as to how active (electrically) or widespread such elevated convection will be by this stage. For now we cover some parts of Ireland with a SLGT for this potential, but suggest lower confidence here compared to Devon/Cornwall earlier in the day.

As the plume axis continues to nudge slowly northwards through the forecast period, so the attention shifts for areas with the potential for elevated thunderstorms. Some models simulate the development of a few isolated thunderstorms over the West Country and south and west Wales during the late afternoon and evening. Given inter-model differences, there remains some considerable uncertainty as to whether this will occur, and it is likely that this forecast may be updated during Sunday to reflect the latest guidance. During this period of potential (16z-00z) confidence is slightly higher for some convection over western coasts of Wales and the Irish Sea in particular, with less confidence over the West Country.

As the upper trough sharpens and approaches closer through the evening hours, and a shortwave trough tracks northwards, it is likely that scattered elevated thunderstorms will develop over northern France and/or the English Channel, and will be advected inland across southern parts of Britain towards the end of this forecast period and beyond into the early hours of Monday.

In any of these events, PWAT values close to or above 30mm could result with some locally large rainfall totals, along with perhaps some small hail in any stronger cores.

fryup wrote: »

any chance of it making its way inland??