Fri Feb 14, 2020 4:21 pm
They are different Met Office charts:
I have just been through my Avbrief feed
Charts supplied by Met Office for Fri /Sat 0600 are called "European Surface Analysis" (and 'forecast' for Saturday) : They don't have thickness lines printed.
However the forecast charts from 12.00 Saturday through till Tuesday are entitled " T + n (where n is hours ahead)MSLP and thickness" charts , which unsurprisingly have thickness on them.
The thickness lines do not seem to chop and change, they only seem to appear in the T+36 (approx) charts onwards. i.e not present Sat 0600 hrs, but present 12.00 hours and rest of charts to end of chart forecast period (Tuesday).
I think the clue in 2D's examples is time interval: I bet a bob all charts after his T+ 36 example also all have thickness lines.
pls don't shoot the messenger I'm only reporting what's on my screen.
Pete S as was
Deputatum stercore excitator