Convective/Thunderstorm Discussion: Spring/Summer 2016

Day 1 Convective Outlook

VALID 06:00 UTC Mon 06 Jun 2016 - 05:59 UTC Tue 07 Jun 2016

ISSUED 07:39 UTC Mon 06 Jun 2016

ISSUED BY: Chris

A similar synoptic set-up to the last few days will see weak ridging aloft from high pressure north of Scotland, however surface troughing over western Britain along with day-time heating and orographic lift should allow for scattered convection during the PM hours of Monday. As with the last few days, there continues to be uncertainty over the available moisture for isolated to scattered showers and thunderstorms to develop (air generally drier in the mid-levels). However, convection allowing models indicate Monday will be more active than Sunday, with widespread convection/thunder possible over NCen/NW Ireland. However, some pockets of more intense convection are also possible over NW Wales and SW Scotland. CAPE values of 500-800 j/kg are likely in the areas where models simulate showers, therefore they should be able to produce thunder given updraft strength. (Its worth noting that GFS seems to be over-doing surface moisture, thus CAPE, and showers have been much less widespread than it would be indicated the previous few days in that particular model).

Given the slow moving nature of convection the biggest threat will be from highly localised flash flooding under the heaviest showers/thunderstorms. Virtually no wind shear is present, thus storms will be of the pulse variety and in most cases, as previously mentioned, aided by orographic uplift.