Convective Outlook: Thu 04 Jun 2020
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Thu 04 Jun 2020 - 05:59 UTC Fri 05 Jun 2020

ISSUED 20:04 UTC Wed 03 Jun 2020

ISSUED BY: Dan

Negatively-tilted upper trough over the North Sea will continue to strengthen through the forecast period, with mid/upper levels continuing to cool. This places the British Isles on the rear side of the trough for Thursday, with a strong northwesterly flow aloft. Early showery rain will clear East Anglia and SE England, although some will persist over western Ireland. There may be quite a bit of cloud around at times, but some sunny spells are likely and any low-level cloud will be subject to convective overturning courtesy of the strong June sunshine. Diurnal heating will yield 100-400 J/kg CAPE, with numerous showers likely to develop, becoming more widespread by the afternoon hours. Convective depth will be rather restricted for most of the day, generally below 600mb (ELTs -10C), but may increase a little towards evening. Showers will be particularly focussed along a pronounced convergence zone which is likely to develop from W / SW Scotland down across N England towards East Anglia. Some complications exist, as showers could grow upscale into an area of showery rain potentially as a small surface low develops. The steering flow will be NNW-SSE initially, but as the winds aloft gradually back through the afternoon then the motion of showers may eventually turn more NW-SE. Speed shear will gradually increase through the day, perhaps reaching 20-30kts through the cloud-bearing layer by evening. Overall any lightning is likely to be at a premium, generally isolated and most areas will remain void of such activity on Thursday. Overnight, the focus for the heaviest showers will shift to western and northwestern Britain.