Jetstream co-operating with a cold outlook, first looping S of UK with a weak N-ly return, then (Tue 8th) settling into a strong flow across France before another loop develops a week later to bring it north again. It settles directly across the UK Sun 20th.
GFS - current LP filling and replaced by LP sliding in from NW & crossing Cornwall Tue 8th (also shown on BBC last night) disappearing SE-wards and replaced by a similar one Sat 12th. The next LP Tue 15th stops over, briefly covering all UK and suddenly we're back to mild SW-lies for the last 3 days to Sun 20th. No source of any deep cold air so snow events if any will be marginal/on hills; continental blocking collapses from Wed 16th (Cf shift in jet at about that date above)
GEFS - current wet spell followed by drier until Fri 11th after which some rain about esp in SW. Temps for the present a degree of two below norm and well agreed, return to around norm on same date (i.e. 11th), also more variable between runs but no extreme outliers in S, a few notably warm ones in N.
ECM - doesn't have any truck with sliding LPs after Tue 8th but sticks next LP firmly on Atlantic from Fri 11th, with close approach to NI Sun 13th and something really deep 955mb approaching on Mon 14th
Originally Posted by: DEW