"Kate Brown" wrote ...

Has Grace something to do with the umcommonly high temperature this
afternoon in SE London? My weather station sensor high was 19C at
16:00 today, and the car sensor out on the street was reading 21C
just now. Humidity about 90, altogether rather horrible.


.... Looking back at the various archive analyses (EXO & DWD), it looks
as if the origin of the air that you (and we here in Dorset) are
experiencing is somewhere in the Madeira area, or even possibly the
Canaries, but I haven't done a proper back-track on that - certainly
from somewhere south of 35 degN.

'Grace' as such isn't actually within that air mass, so it's not that
*particular* air that is impacting us, BUT, as Will mentioned
yesterday, it has got caught up 'in the mix' synoptically and might
have been a factor in keeping the synoptic-scale flow in a SSWly
fashion; as I read it (but others will want to come in I fancy),
'Grace' has 'broadened-out' the main vortex north of the Azores
region, so that we have the aforementioned SSW/long-fetch flow, rather
than a more classical (but still mild/Tropical Maritime) SW or WSW
flow.

It's important (the distinction between SSW & SW or WSW), because as
has been pointed out through the summer/early autumn, SSTs are
above-average (roughly +0.5 to +1.0C 71-00) looking back towards
Madeira, rather than +0.5 or less back to the Azores. Oceanic heat
storage at work!

Martin.


--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023