|Convective Outlook: Fri 10 May 2019|
|What do these risk levels mean?|
VALID 06:00 UTC Fri 10 May 2019 - 05:59 UTC Sat 11 May 2019
ISSUED 18:50 UTC Thu 09 May 2019br> br>
ISSUED BY: Dan
... FRIDAY DAYTIME ...
Broad westerly flow aloft, though subtle hints of upper ridging. Some patchy / showery rain may affect parts of Scotland and northern England at times through the day, associated with a weakening quasi-stationary occlusion. Nonetheless, cool air aloft combined with surface heating and both orographic forcing and low-level convergence will aid in the development of numerous scattered showers almost anywhere across the British Isles, hence a rather broad LOW threat area.
Instability is somewhat weak (a couple hundred J/kg CAPE) but there is some reasonable shear over England in particular, and so a few isolated lightning strikes will be possible - but most areas will be void of lightning. Small hail will be possible in many of the showers, and perhaps a funnel cloud. Any showers that do form will tend to decay during the evening as diurnal heating subsides.
... FRIDAY EVENING / NIGHT ...
An Atlantic frontal system will approach SW England / Scilly Isles late in the day, influenced by the left exit region of the approaching jet streak as an upper trough migrates across the western English Channel and northern France during the evening / night hours. This increased forcing aloft coupled with several hundred J/kg CAPE, may result in some embedded convection with sporadic lightning possible - particularly over the Channel Islands. A SLGT may be required over parts of the English Channel.