Convective Outlook: Thu 20 Jun 2019
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Thu 20 Jun 2019 - 05:59 UTC Fri 21 Jun 2019

ISSUED 20:00 UTC Wed 19 Jun 2019

ISSUED BY: Dan

An upper trough will swing across the British Isles on Thursday, the associated cool air aloft creating relatively steep mid-level lapse rates and yielding a few hundred J/kg CAPE in repsonse to surface heating. As a result, scattered showers already affecting exposed western areas at the beginning of the forecast period will tend to develop more widely across many areas as the day progresses. An occlusion (or quasi-cold front, marking the boundary between 10-12C and 6-8C dewpoints) will drift southeastwards across England and Wales, providing one focus for scattered heavy showers.


Forecast profiles are generally capped around 600mb, despite a reasonably-sheared environment (though the best shear may be above the equilibrium levels). Deeper convection is more likely across northern Britain, especially eastern Scotland, where the greatest instability is also expected. While the odd isolated lightning strike is possible almost anywhere, it is considered most likely in northern and eastern Scotland - though even here some concerns over restricted cloud height exist (and weak shear). For now, a low-end SLGT has been issued.