Slight Risk of Isolated Thunderstorms 15Z-21Z Central & Central East UK 15Z-21Z
Prime Threat Moderate Sized Hail and CG's
Based on the GFS and MMN model there would appear to be some scope for convection (possibly strong) central east regions by late afternoon as some weak influence from upper troughing slides further SE. Upper flow would appear marginally supportive of cluster or even an isolated cell or two if and when a thermal trigger level is breached. The latest GFS run certainly says this will be possible but in reality the GFS can often be bullish regarding these requirements! Hence some suggestion that convective initiation may well be a lot later than what the GFS currently predicts. Current UKMO FAX chart synopsis shows very little in the way of surface troughing though maybe the detail is too fine and between runs ATM!
Winds look fairly straight lined though increase with height is numerically steady ATM. Dry air is noted at 500mb upwards allowing for full potential instability to be utilised if this level can be reached by any building storm cell. The map below shows a fairly broad region of risk though in reality storm are likely to effect a very small portion of the zone. A yellow box highlights a region where solar heating is strong and is overlaid with some workable shear aloft. This is nevertheless not necessarily the most unstable sector for the day, but is realistically more likely to produce storms. In addition to this, based on surface heating and surface vector there would seem to be some small chance for convergence. ATM this is not seen by the GFS or MMN though the combination of cool seas to the east and relatively light winds inland the risk for backing winds is certainly a prospect worth monitoring. Whilst I currently do not see any prevalent risk of tornadoes likely any shift in the surface vector from the SE will certainly bring the risk fully into the equation.
Credit Tony Gilbert