Convective Outlook: Sun 24 Jul 2016
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Sun 24 Jul 2016 - 05:59 UTC Mon 25 Jul 2016

ISSUED 13:09 UTC Sun 24 Jul 2016


UPDATE 13:09 UTC N & E Scotland upgraded to a low-end SLGT for the potential for embedded lightning activity to develop through the evening / overnight hours as the approaching upper trough causes mid-level lapse rates to steepen. It is quite likely many areas within the SLGT will remain void of lightning, but there is increasing potential at least for lightning over this area later today. The placement of this SLGT is subject to subtle E-W shifts given some uncertainty over the exact track of the developing low this evening

UPDATE 11:56 UTC No changes to the map on this update, although the (already marginal) SLGT is being considered for removal from Northern Ireland. At the same time, parts of NE Scotland may require an upgrade for the evening hours to a SLGT - trends will be monitored

A complex frontal system will spill northeastwards across the British Isles on Sunday, beneath an upper trough. A messy mix of dynamic and convective precipitation is expected with marginal instability, and hence the broad LOW threat level issued - although it is quite likely that many areas will be void of lightning.

The environment may be slightly more conducive for lightning within a narrow window of a few hours on Sunday afternoon over Northern Ireland in the immediate post-frontal airmass. Dewpoints in the mid teens Celsius combined with surface heating should yield 200-400 Jkg-1 MLCAPE, with the potential for a few scattered showers, perhaps a thunderstorm, to develop. 30-40kts DLS should allow some cell organisation to occur, with perhaps some small hail from the strongest cells. Have issued a low-end SLGT to highlight this area better.