Convective Outlook: Fri 29 Apr 2016
LOW
SLGT
MDT
HIGH
SVR
What do these risk levels mean?
Convective Outlook

VALID 06:00 UTC Fri 29 Apr 2016 - 05:59 UTC Sat 30 Apr 2016

ISSUED 10:24 UTC Fri 29 Apr 2016

ISSUED BY: Dan

UPDATE 10:24 UTC Low-end (near 30% chance) SLGTs added to highlight areas with greatest potential for lightning activity. Over England, instability is greatest across Midlands/West Country to the Wash, but with much stronger shear to the SE, and hence the extension of the SLGT into SE England where DLS may compensate for lower CAPE

On Friday, a surface low will slowly retreat eastwards from NE England to the North Sea, beneath a broad upper low with various embedded troughs rotating around the main parent low - one such trough will pivot and begin to sharpen and extend towards SW England during the day. The associated cold mid-levels combined with diurnal heating will serve as the main focus for convection.

Expect scattered showers to develop in response to diurnal heating, although a lack of any significant DLS will result in numerous small "pulse type" showers, some perhaps just deep enough to produce sporadic/isolated lightning. Main focus for lightning is in a W-E zone that begins over the north Midlands around noon, and sinks slowly southwards through Wales / Midlands / E Anglia through the afternoon, towards the West Country / Home Counties by evening. Parts of the West Country and the Midlands get close to SLGT category, but confidence is not high enough to upgrade here, especially given lack of any organisation - in fact, multiple consecutive runs of the EURO4, for example, are distinctly lacking in any noteworthy shower development across a good portion of the main interest areas, and hence have chosen to reject this model for now.

Showers that form furthest to the SE may benefit from stronger DLS, and thus automatically increasing their chances of producing lightning. Small hail/graupel is likely in the strongest cells.