Warm fronts do not usually grab the weather headlines. Warm air usually glides gently up and over cooler air in front and causes light rainfall. So it is tomorrow with a pencil thin line of warm front precipitation crossing the UK, slowly from west to east during the day.
A complicating factor is that the significantly warmer air advecting behind the front will meet the COOL POOL of air lingering in a trough over Northern Europe and the North Sea. This could intensify the warm front as temperature gradients and lift increase. Another factor of interest is the strong upper winds behind the warm front with only light winds at the surface, Strong wind shear can encourage lift which causes more condensation, thicker cloud and more persistent rain.
The warmest air is kept in the SE where thundery showers are a low risk in the afternoon and evening but possible for a time after the warm front passes and introduces warmer air throughout Friday evening. CAPE values and lifted index values match a low risk of thundery outbreaks at any time afternoon through to early evening. Temps will rise, unusually continuously during the course of the day from 12ºC at 9am to 20ºC still at 9pm: MUGGY! These factors indicate a warm front that may yield more interest than usual. Eyes up, Brollies at the ready!