Convective Outlook: Thu 15 Jun 2023 |
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What do these risk levels mean? |
VALID 06:00 UTC Thu 15 Jun 2023 - 05:59 UTC Fri 16 Jun 2023
ISSUED 06:48 UTC Thu 15 Jun 2023
br> br>ISSUED BY: Dan
Broad upper ridging stretches from Scandinavia, across the British Isles and down to Iberia on Thursday, with slightly lower heights aloft across both western Ireland and eastern England. A moist airmass persists across the bulk of Ireland, having been restricted to southwestern areas on Wednesday, and will provide the focus for another day with shower/thunderstorm potential. Areas of low cloud and patchy fog, most extensive across Munster and southern portions of both Connacht and Leinster, should erode through the morning with diurnal heating then likely to yield MLCAPE on the order of 1,000 J/kg given expected maximum temperatures of 23-26C and dewpoints 14-17C. CAM guidance suggests initiation around mid-afternoon, with a gradual increase in the number of scattered heavy showers and thunderstorms developing during the late afternoon and evening hours. A slack surface low is forecast to develop in central/west Ireland, and so like previous days the greatest potential for thunderstorms to grow into a larger cluster will be on its north/northeastern flank where strengthening low-level convergence may develop as easterly winds from the Irish Sea meet a SSEly wind further inland. Therefore, have introduced a MDT to highlight the area where lightning activity may be somewhat more widespread, especially later in the day and into the evening hours. Weak flow aloft will once again result in meagre shear, and given CAPE is a notch down on recent days it is likely hail for the most part should be sub-severe. The main threat, given PWAT 25-30mm and slow storm motion, is the risk of local surface water flooding. Gusts of 30-40mph may accompany the strongest cells.