Convective Outlook: Thu 27 Jun 2019
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Convective Outlook

VALID 06:00 UTC Thu 27 Jun 2019 - 05:59 UTC Fri 28 Jun 2019

ISSUED 19:57 UTC Wed 26 Jun 2019


Upper ridge continues to dominate across much of western Europe on Thursday, with an upper vortex continuing to spin over the Atlantic well to the west of Biscay. A corridor of significant CAPE will exist between these two systems (1,500 - 2,000 J/kg), stretching from northern France - Channel Islands - Cornwall - SW Ireland, as hot air between 700-900mb is advected northwestwards beneath cold air aloft and atop a (relatively) cool boundary layer. As a result, there will be a sharp low-level temperature inversion, and also very steep mid-level lapse rates.

Subtle impulses running northwestwards in the strong southeasterly flow aloft will aid the development of elevated thunderstorms at various times over the Atlantic and Celtic Sea through this forecast period. Most activity will be offshore to the west and south of Ireland, but may drift over southwestern parts of Munster - primarily during Thursday morning. The strongest cells may produce some hail (along with heavy rain). Some uncertainty exists over how quickly the steering flow will veer more southerly, but elevated thunderstorms could return to SW Ireland during the early hours of Friday (but low confidence at present, with most NWP guidance generally keeping this round of activity offshore).